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    Hampered Foraging and Migratory Performance in Swans Infected with Low-Pathogenic Avian Influenza A Virus


    It is increasingly acknowledged that migratory birds, notably waterfowl, play a critical role in the maintenance and spread of influenza A viruses. In order to elucidate the epidemiology of influenza A viruses in their natural hosts, a better understanding of the pathological effects in these hosts is required. Here we report on the feeding and migratory performance of wild migratory Bewick's swans (Cygnus columbianus bewickii Yarrell) naturally infected with low-pathogenic avian influenza (LPAI) A viruses of subtypes H6N2 and H6N8. Using information on geolocation data collected from Global Positioning Systems fitted to neck-collars, we show that infected swans experienced delayed migration, leaving their wintering site more than a month after uninfected animals. This was correlated with infected birds travelling shorter distances and fuelling and feeding at reduced rates. The data suggest that LPAI virus infections in wild migratory birds may have higher clinical and ecological impacts than previously recognised.


    Jan A. van Gils<sup>1</sup><sup>*</sup>, Vincent J. Munster<sup>2</sup>, Reinder Radersma<sup>1</sup>, Daan Liefhebber<sup>1</sup>, Ron A.M. Fouchier<sup>2</sup>, Marcel Klaassen<sup>1</sup>
    1 Department of Plant-Animal Interactions, Centre for Limnology, Netherlands Institute of Ecology (NIOO-KNAW), Nieuwersluis, The Netherlands, 2 Department of Virology, Erasmus MC, Rotterdam, The Netherlands
    It is increasingly acknowledged that migratory birds, notably waterfowl, play a critical role in the maintenance and spread of influenza A viruses. In order to elucidate the epidemiology of influenza A viruses in their natural hosts, a better understanding of the pathological effects in these hosts is required. Here we report on the feeding and migratory performance of wild migratory Bewick's swans (Cygnus columbianus bewickii Yarrell) naturally infected with low-pathogenic avian influenza (LPAI) A viruses of subtypes H6N2 and H6N8. Using information on geolocation data collected from Global Positioning Systems fitted to neck-collars, we show that infected swans experienced delayed migration, leaving their wintering site more than a month after uninfected animals. This was correlated with infected birds travelling shorter distances and fuelling and feeding at reduced rates. The data suggest that LPAI virus infections in wild migratory birds may have higher clinical and ecological impacts than previously recognised.

    Funding: Royal Netherlands Academy of Arts and Sciences
    Competing interests: The authors have declared that no competing interests exist.
    Academic Editor: Tom Pizzari, University of Oxford, United Kingdom
    Citation: van Gils JA, Munster VJ, Radersma R, Liefhebber D, Fouchier RA, et al. (2007) Hampered Foraging and Migratory Performance in Swans Infected with Low-Pathogenic Avian Influenza A Virus. PLoS ONE 2(1): e184. doi:10.1371/journal.pone.0000184
    Received: September 25, 2006; Accepted: December 20, 2006; Published: January 31, 2007
    Copyright: ? 2007 van Gils et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any med`ium, provided the original author and source are credited.
    * To whom correspondence should be addressed. E-mail: j.vangils@nioo.knaw.nl
    ? Current address: School of Biological Sciences, University of Bristol, Woodland Road, Bristol, United Kingdom and Department of Marine Ecology and Evolution, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, The Netherlands

    Introduction

    Influenza A viruses have been isolated from many species including humans, pigs, horses, mink, felids, marine mammals and a wide range of domestic birds, but wild birds belonging to the orders Anseriformes (particularly ducks, geese, and swans) and Charadriiformes (particularly gulls, terns, and waders) are thought to form the virus reservoir in nature [1]. In wild birds and poultry throughout the world, influenza viruses representing 16 hemagglutinin (H) and 9 neuraminidase (N) antigenic subtypes have been detected [1], [2]. In contrast to other virus subtypes, influenza viruses of subtypes H5 and H7 may become highly pathogenic following introduction in poultry and cause outbreaks of highly pathogenic avian influenza (HPAI). Although LPAI viruses may also cause mild symptoms in poultry, it is generally thought that they do not cause disease in wild birds [3]. However, this information is based primarily on experimental infection of captive birds rather than information on natural infections of wild migrating birds. Subclinical or mild diseases observed in the laboratory may have significant ecological fitness consequences in the field.
    Upon infection, migratory birds may reallocate some of their resources to boost their immune system [4], at the expense of other demanding processes such as the accumulation of body stores, which are required to fuel their migratory flights and to overcome periods of adverse weather and foraging conditions. Lower fuelling rates will presumably lead to slower migrations with more frequent stopovers along the route [5]. In the context of our studies on migration and feeding patterns of Bewick's swans (Cygnus columbianus bewickii Yarrell, breeding in NW Russia and wintering in NW Europe), 25 swans were caught in The Netherlands at one of their main wintering sites, and 12 were fitted with a coded GPS-collar (Figure 1). From the same group of birds, cloacal swabs and blood samples were collected to test for the presence of influenza A virus as part of ongoing wild bird influenza A virus surveillance [6]. Three out of 25 swans were infected with influenza A virus at the time of capture, two of which we could track in great detail due to them carrying a GPS-collar. Here we compare their feeding and migratory performance with the performances of their healthy counterparts.
    Figure 1.

    Bewick's swan 923A infected with an H6 influenza A virus. This (adult) individual not only carried an active influenza infection, it also showed the highest antibody response among all 25 sampled birds. Photo by W. Tijsen.
    doi:10.1371/journal.pone.0000184.g001

    Results

    Influenza A virus isolates of subtypes H6N2 and H6N8 were obtained from two out of the three infected birds (the GPS-collared ones). Although no virus isolate could be obtained from the third infected swan, sequence analyses on PCR products obtained from the original sample revealed 100% nucleotide sequence identity of the HA and NA genes with the HA and NA of A/Bewick's swan/Netherlands/2/05 (H6N8). Phylogenetic analyses based on the H6 HA1 nucleotide sequences and all H6 HA1 sequences available from public databases revealed that the H6 HA1 genes clustered in four different groups as described by Spackman et al. [7]. Furthermore, the swan H6 gene segments were closely related to sequences obtained from an influenza A virus found in a free-ranging migrating duck in NW Europe (data not shown). Representative full-length H6 HA sequences from each of the 4 different lineages were used to construct a bootstrapped DNA maximum likelihood tree (Figure 2). BLAST analyses of the 7 other gene segments of the two swan viruses, indicated a 95 to 99 percent nucleotide sequence identity with avian influenza A viruses of Eurasian origin. The phylogenetic and BLAST analyses indicate that the two influenza A viruses obtained from the infected swans are ordinary LPAI viruses circulating in the natural wild bird reservoir.
    Figure 2.

    Phylogenetic tree for H6 influenza A viruses isolated from swans. The DNA maximum likelihood tree was constructed using A/pintail/Alberta/210/2002 (H1N1) as out-group and includes sequences from public databases. Genes clustered into four different groups as described by Spackman et al. [7]. The scale bar represents ~10% of nucleotide changes between close relatives. Small numbers in the tree represent the bootstrap values.
    doi:10.1371/journal.pone.0000184.g002
    Serological analyses revealed that 5 out of 25 swans had detectable antibodies against the nucleoprotein (NP) of influenza A viruses (3 adults, 1 yearling and 1 juvenile out of 20 adults, 2 yearlings and 3 juveniles). The highest antibody response was found in the two swans from which influenza A viruses were isolated (an adult bird and a yearling). The sera of the 5 swans with influenza A virus NP antibodies were further analysed using the hemagglutination inhibition assay (HI). The HI was performed with virus strains representing all currently known influenza A virus subtypes (H1?H16). No specific HI antibody titres were detected in the 5 sera.
    Not knowing the infection status of the swans during processing immediately after capture, two of the three influenza A virus infected swans were fitted with a GPS collar (the ones from which we were able to obtain virus isolates). The 3 infected and 22 uninfected swans did not differ in structural body size (F <sub>1,21</sub> = 0.62, p>0.4; GLM with age [F <sub>2,21</sub> = 0.10, p>0.9] as covariate; body size was calculated as the first principal component [PC1] from a PCA including wing length and total head size, a method often used in avian studies [8], [9], e.g. see [10], [11] for applications in swans), nor in body mass right after catch (F <sub>1,20</sub> = 0.17, p>0.6; GLM with age [F <sub>2,20</sub> = 1.60, p>0.2] and body size [F <sub>1,20</sub> = 23.03, p<0.0005] as covariates). This result was maintained when restricting the analyses to the 12 GPS-collared birds (F <sub>1,8</sub> = 0.81, p>0.3 for body size; F <sub>1,7</sub> = 0.80, p>0.4 for size-corrected body mass).
    While the biometric parameters of the GPS-collared birds did not differ at the time of capture, infected and uninfected birds differed in all ecological parameters collected after release. Date of departure from Wieringermeer, the agricultural area in NW Netherlands where the birds were caught, differed by more than a month, with the infected birds leaving the area later than the uninfected birds (Figure 3A; F <sub>1,7</sub> = 10.53, p<0.05; GLM with age [F <sub>2,7</sub> = 0.29, p>0.7] and body size [F <sub>1,7</sub> = 0.61, p>0.4] as covariates). Compared to the phenology of the population as a whole (Figure 3B), the healthy birds were among the first to leave the study area, while the infected birds were among the last. Furthermore, the next (spring stopover) site visited was nearer by Wieringermeer for infected individuals than for uninfected individuals (Figure 3A; F <sub>1,6</sub> = 11.03, p<0.05; GLM with age [F <sub>2,6</sub> = 0.43, p>0.6] and body size [F <sub>1,6</sub> = 0.58, p>0.4] as covariates; note that we have one degree of freedom less since one bird was never seen after it left the study site). In spite of these differences in distance flown, a possible trigger to move on to the next site is the absolute amount of accumulated body stores [5], [12]. Indeed, rate of fuelling, expressed as the rate of change in the visually scored abdominal-profile index (API) [13]?[15], was lower in infected birds than in uninfected birds (Figure 4A; F <sub>1,2</sub> = 22.96, p<0.05; GLM with age [F <sub>1,2</sub> = 4.95, p>0.1] and body size [F <sub>1,2</sub> = 0.42, p>0.5] as covariates), whereas APIs upon departure did not differ (F <sub>1,2</sub> = 1.90, p>0.3; GLM with age [F <sub>1,2</sub> = 0.15, p>0.7] and body size [F <sub>1,2</sub> = 2.09, p>0.2] as covariates).The observations on fuelling rates are consistent with the lower feeding or bite rates observed in the infected birds compared with the uninfected animals (Figure 4B; F <sub>1,2</sub> = 47.55, p<0.05; GLM with age [F <sub>1,2</sub> = 0.94, p>0.4] and body size [F <sub>1,2</sub> = 23.34, p<0.05] as covariates). Possibly, infected swans cannot achieve high bite rates because they have impaired digestive functions as compared to their healthy counterparts (bite rates in herbivorous waterfowl are generally considered to be digestion- rather than encounter-limited [16]). This is supported by the finding that infected swans took fewer bites per produced faecal dropping than uninfected swans (Figure 4C; F <sub>1,2</sub> = 19.28, p<0.05; GLM with age [F <sub>1,2</sub> = 19.19, p<0.05] and body size [F <sub>1,2</sub> = 29.35, p<0.05] as covariates).
    Figure 3.

    Timing of migration in healthy and infected swans. (A) Infected swans left the study area more than a month after the uninfected birds, indicated by broad vertical grey bars ranging from mean-SE to mean+SE. Moreover, their mean net displacement after departure (closed dots?dashed SE-lines) was shorter than for the uninfected birds (open dots?dashed SE-lines). Sample sizes of displacements estimates: n = 2 for infected birds (whole time span); sample size declined for uninfected birds due to birds that flew out of range: n = 10 (days 0?41), n = 9 (42?47), and n = 8 (48?55). (B) Total number of swans in our study area declined more or less gradually over time (W. Tijsen et al. unpubl. data), suggesting a continuous departure of about 30 birds per day (apart from the short dip around day 12 during a snowy cold spell).
    doi:10.1371/journal.pone.0000184.g003
    Figure 4.

    Feeding parameters as a function of health status. Compared to healthy birds, infected birds (A) fuelled slower, (B) took fewer bites per hour, and (C) took fewer bites per produced dropping. Because of a seasonal increase observed in bite rate (p<0.05 when all observations pooled), bite rate plotted in (B) were standardized to 1 February. In all graphs, bars give least-square means, error bars are SE.
    doi:10.1371/journal.pone.0000184.g004

    Discussion

    Influenza A virus infected Bewick's swans thus showed reduced feeding and migratory performances. Fuelling in avian migrants is thought to be enhanced by the flexible enlargement of digestive organs [17], and indeed fuelling Bewick's swans increase the length of their intestine by 50% throughout winter [18]. In the infected birds the ability to make adjustments to the digestive system may have been impaired (as revealed by the lower bite-to-dropping ratio), leading to reduced bite rates, reduced fuel storage rates and a delayed migration schedule. That the infected birds ended up in a negative feedback loop because they traded off resources allocated towards ?fighting the infection? with resources allocated towards fuelling and developing the digestive machinery can of course only be firmly established by experimental manipulation of infections in otherwise similar wild birds. An obvious alternative explanation is that the infected swans were poor foragers with such reduced energy allocation towards ?infection prevention? that they could not prohibit the control of the infection. However, the previously-infected-but-still-seropositive birds were feeding (F <sub>1,1</sub> = 0.01, p>0.9), fuelling (F <sub>1,1</sub> = 1.87, p>0.4) and migrating (F <sub>1,5</sub> = 1.56, p>0.2) at the same pace as the fully healthy, seronegative birds (all tests are GLMs with body size as covariate), which makes the former point of view more likely since it suggests virus-recovered birds to behave normally again. Moreover, the fact that at capture there was no difference in body condition between infected birds and uninfected birds may be another support for LPAI infection being the cause rather than the consequence. Presumably the two swans with active infections got infected shortly before capture, which resulted in reduced migratory and foraging performance. As migratory (re)fuelling in Bewick's swans takes place from late October onwards [19], the ?poor-forager idea? would predict the infected birds to have had lower body conditions already at the time of capture (mid December), which was not the case. Whatever cause and effect may be in this matter, the epidemiology of at least one LPAI strain appears affected by the fact that birds with an active infection are migrating slower.
    Tentatively accepting an LPAI virus infection to be the cause rather than the consequence, it is tempting to speculate about the knock-on effects of an infection throughout the rest of the annual cycle. Although seropostive birds without an active infection were performing just as well as seronegative birds, a delayed departure by the still infected birds may have cascading effects, even if those birds would eventually overcome their disease during further migration. Namely, a delayed departure from one site may lead to delayed departures from all sites en route (strengthened by the fact that food stocks are largely depleted by the first birds using a stopover site [20]), thereby possibly delaying arrival on their Arctic breeding grounds. If so, reproductive output may be reduced as the best territories may have been occupied [21] by the time infected birds arrive and eventual broods may hatch too late to take full advantage of the food peak [22]. If, on the other hand, they did manage to reach the breeding grounds in time, reproduction may still be affected because of the trade-off between reproductive effort and immunocompetence [23], [24]. Having said this, survival rate does not seem affected, since, at the time of writing, approximately one year after catching the birds, 3 out of the 4 banded seropositive birds (75%) and 5 out of 8 banded seronegative birds (63%) have been seen back at their wintering grounds.
    In domestic birds, the clinical signs and disease observed following infection with LPAI viruses vary with host species, age, the presence of other micro-organisms and environmental factors. In these hosts, LPAI viruses can cause a mild disease consisting primarily of respiratory symptoms, depression and egg production problems in laying birds [25]. Upon experimental infection of ducks, LPAI viruses replicate in the epithelial cells of the intestine of birds and virus may be shed in high concentrations in the faeces, without inducing apparent signs of disease [26], [27]. It is generally believed that LPAI viruses are also non-pathogenic upon natural infection of wild birds, although data are scarce [3]. Influenza A viruses of the H6 subtype are among the most commonly isolated viruses in wild ducks in North America and Europe and have been isolated frequently from other wild birds, including geese, gulls, waders, and auks [7], [28], [29]. Our observations that infection of swans with such ?ordinary? LPAI H6 viruses can result in altered migratory and feeding patterns may indicate that LPAI virus infections in wild birds have a higher clinical, epidemiological, and ecological impact than previously recognised. Based on these observations, the implications of influenza virus infections, including those caused by HPAI H5N1 viruses, for bird health and ecology and virus epidemiology may require re-evaluation.

    Materials and Methods

    Swan catching and processing

    By means of canon netting, we caught 25 Bewick's swans on 18 December 2005 on a sugar beet field in Wieringerwerf, Wieringermeer, The Netherlands (52?48′ N, 05?05′ E). The birds were aged and sexed on the basis of plumage coloration and cloacal examination, respectively. We determined wing length (to nearest mm), total head size (to nearest mm) and body mass (to nearest 0.1 kg). Twelve GPS-collars were fitted to 9 adults (presumably 1 male and 8 females; 4 of which were paired of which 2 were accompanied by young), 2 yearlings (sex unknown; of which one still accompanied its parents) and 1 juvenile male (accompanying its parents).
    GPS-collars

    GPS-collars were manufactured by Microtes Wildlife Engineering (Arnhem, The Netherlands). Each collar was fitted with a miniature GPS-receiver and antenna, a Bluetooth transceiver and antenna, a flash storage device, and a time-scheduled microprocessor controlling data collection and transmission. Total weight of the collar devices was 80 g. The GPS automatically collected geographical positions during 2?4 prescheduled times a day (accuracy<50 m). When within close range of the bird (<300?400 m), GPS-data were downloaded via Bluetooth at prescheduled times. Each collar had an individual code engraved (readable up to 600 m; Figure 1), which enabled us, through the help of many volunteer ring-readers, to trace the birds for data collection. Until our last day in the field (22 February 2006), we were able to collect GPS-data on 8 birds; the whereabouts of the other 4 birds were reconstructed using resightings.
    Visual observations

    Throughout winter, we were able to regularly observe six of the GPS-collared swans, the two virus-infected birds included. We performed so-called focal scans [30], which meant that we carefully observed one of the collared swans for a one-hour period, or less when disturbed. Through a 20?60?spotting scope (Kowa Company Ltd., Chuo-Ku Tokyo, Japan) and a 60?optolite (Meade Instruments Corporation, Irvine, USA), we counted the number of bites taken (when feeding on grass) and, when possible, the number of droppings produced (mean?SE number of scans per bird = 9?2, of which during 5?2 scans the bird was near enough to enable dropping scans). At constant bite and dropping mass, the bite/dropping ratio is a measure of a bird's digestive performance (high at a high ratio). At the end of each scan we estimated the bird's abdominal profile index (API). This is a measure frequently used in waterfowl ecology to estimate a bird's abdominal fat storage [13], [15] (on a scale of 1?6, in steps of ? unit). The change in API over time can be used to estimate a bird's rate of body store accumulation [14]; here we used the first and last API-estimate for this purpose (mean?SE of time interval between first and last score per bird = 31?6 days). All observations were performed by DL and RR, who were unaware of the identity of the infected birds, and therefore all measurements can be considered as blind with respect to infection-status. The design of the measurements was such that each observer observed all six birds, with no difference between observers in the number of observations per bird (F <sub>1,10</sub> = 1.61, p>0.2; GLM). Moreover, observations were equally spread in time for infected (range = 22 Dec?21 Feb; mean?SE = 27 Jan?3.4 days) and uninfected birds (29 Dec?22 Feb; 24 Jan?2.5 days).
    Statistics

    Generalized Linear Models were used for statistical comparison of infected and uninfected birds, with age and body size as covariates (using the GLM package in SYSTAT 10 [31]). The number of birds varied between comparisons; 25 swans were caught for analysis of biometric data at the start of the study (3 infected, 22 uninfected), 12 of these were GPS collar-banded (2 infected, 10 uninfected), and 6 of these were regularly observed to perform focal scans (2 infected, 4 uninfected).
    Specimens

    Cloacal swabs were collected using sterile cotton swabs, stored in transport media (Hanks balanced salt solution containing 0.5% Lactalbumin, 10% glycerol, 200 U/ml penicillin, 200 ?g/ml streptomycin, 100 U/ml polymyxin B sulfate, 250 ?g/ml gentamycin [ICN, The Netherlands]), and shipped to the laboratory where they were stored at −70?C. Blood samples were obtained by using manual restraint from the ulnar vein, centrifugation for 10 minutes at 14,000 rpm and separation of serum.
    RNA isolation and virus detection

    RNA isolation and RT-PCR was performed as described previously [32]. In short, RNA was isolated using a MagnaPure LC system with the MagnaPure LC Total nucleic acid isolation kit (Roche Diagnostics, Almere, The Netherlands) and influenza A virus was detected using a real-time RT-PCR assay. Amplification and detection was performed on an ABI7700 with the TaqMan EZ RT-PCR Core Reagents kit (Applied Biosystems, Nieuwerkerk a/d IJssel, The Netherlands). The samples were prepared and processed in parallel with several negative and positive control samples in each run.
    Virus isolation and characterization

    For influenza A virus RT-PCR positive samples, 200 ?l of the original material was inoculated into the allantoic cavity of 11-day-old embryonated hens' eggs. The allantoic fluid was harvested two days after inoculation and influenza A virus was detected using hemagglutination assays with turkey erythrocytes. When no influenza A virus was detected upon the initial virus isolation attempt, the allantoic fluid was passaged once more in embryonated chicken eggs. Virus isolates were characterized using the hemagglutination inhibition (HI) assay with turkey erythrocytes and subtype-specific hyperimmune rabbit antisera raised against all HA subtypes [2].
    Sequence analysis and phylogeny

    All eight gene segments of the influenza A virus isolates were characterized by RT-PCR and sequencing, essentially as described by others [33]. PCR products were purified from agarose gels using the Qiaquick Gel Extraction kit (Qiagen, Leusden, The Netherlands) and sequenced using the Big Dye terminator sequencing kit version 3.0 (Amersham Pharmacia Biotech, Roosendaal, The Netherlands) and an ABI PRISM 3100 genetic analyzer (Applied BioSystems, Nieuwerkerk a/d IJssel, The Netherlands), according to the instructions of the manufacturer. All primer sequences are available upon request. Trees were generated using full-length HA nucleotide sequences, including sequences from public databases. Sequences were aligned using the Clustal W program running within the BioEdit software package, version 5.0.9 [34]. Alignments were bootstrapped 100 times using the Seqboot package of Phylip version 3.6 and trees were constructed with the Dnaml package, using 3 jumbles. The consensus tree was calculated using the Consense package of Phylip 3.6 and this tree was used as usertree in Dnaml to recalculate the branchlengths from the nucleotide sequences. Trees were visualized with the Treeview 1.6.6 program distributed with Bioedit version 5.0.9. All nucleotide sequences presented in this manuscript are available from GenBank under accession numbers DQ822187 - DQ822202.
    Serology

    Swan sera were analysed using a commercially available influenza A virus antibody ELISA kit (European Veterinary Laboratory, Woerden, The Netherlands) as previously described [35]. For the detection of specific anti-NP antibodies, we used horseradish peroxidase-conjugated goat anti-wild bird immunoglobulin (Ig) G (Bethyl Laboratories, Inc., TX, USA) instead of the supplied anti-bird conjugate. Positive sera were analysed using the HI assay against all currently known HA subtypes, as previously described [2].

    Acknowledgments

    We thank Trinus Haitjema, Miranda Klaij and Kees Oosterbeek for catching the birds and Family Verheijen for kindly hosting us on their farm and allowing us to catch ?their? swans. Wim Tijsen and his large network of volunteer ring-readers located the GPS-collared birds and counted the numbers. GPS-collars were manufactured by Theo Gerrits and Kees van't Hoff (Microtes Wildlife Engineering), who continued to support us during occasional technical hiccups in the field. Thijs de Boer, Olivier Duriez and Peter de Vries gave helping hands during field observations. We thank Chantal Baas for excellent technical assistance. The animal experiments here reported were in compliance with Dutch law and were carried out under DEC-protocol CL 04.02. Zoltan Barta, Theunis Piersma, Eileen Rees, Jonas Waldenstr?m, and an anonymous referee provided constructive comments on draft manuscripts. This is publication 3983 of the Netherlands Institute of Ecology (NIOO-KNAW) and 469 of the Centre for Wetland Ecology.

    Author ContributionsConceived and designed the experiments: Jv. Performed the experiments: Jv RR DL. Analyzed the data: Jv VM. Contributed reagents/materials/analysis tools: Jv VM. Wrote the paper: RF Jv MK.
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    27. Webster RG, Yakhno M, Hinshaw VS, Bean WJ, Murti KG. (1978) Intestinal Influenza - Replication and Characterization of Influenza-Viruses in Ducks. Virology 84: 268?278. Find this article online
    28. Fouchier RAM, Olsen B, Bestebroer TM, Herfst S, van der Kemp L, et al. (2003) Influenza A virus surveillance in wild birds in Northern Europe in 1999 and 2000. Avian Dis 47: 857?860. Find this article online
    29. Krauss S, Walker D, Pryor SP, Niles L, Li CH, et al. (2004) Influenza A viruses of migrating wild aquatic birds in North America. Vector-Borne Zoon. Dis. 4: 177?189. Find this article online
    30. Martin P, Bateson P (1993) Measuring behaviour: An introductory guide.. Cambridge: Cambridge University Press.
    31. Systat Software. (2000) SYSTAT Version 10.. Point Richmond, CA: Systat Software.
    32. Munster VJ, Wallensten A, Baas C, Rimmelzwaan GF, Schutten M, et al. (2005) Mallards and highly pathogenic avian influenza ancestral viruses, northern Europe. Emerg Infect Dis 11: 1545?1551. Find this article online
    33. Hoffmann E, Stech J, Guan Y, Webster RG, Perez DR. (2001) Universal primer set for the full-length amplification of all influenza A viruses. Arch Virol 146: 2275?2289. Find this article online
    34. Hall TA. (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl Acids Symp Ser 41: 95?98. Find this article online
    35. Wallensten A, Munster VJ, Osterhaus ADME, Waldenstr?m J, Bonnedahl J, et al. (2006) Mounting evidence for the presence of influenza A virus in the avifauna of the Antarctic region. Antarct Sci 18: 353?356. Find this article online

  • #2
    Re: migratory performance in swans with LPAI




    Low-pathogenic forms of bird flu do cause illness among birds

    Wild birds were thought not to suffer from mild forms of avian influenza. But new data suggest that so-called ?low-pathogenic? avian influenza viruses do affect the lives of birds. The Bewick?s swan (Cygnus columbianus bewickii) is a migratory bird that breeds in NW-Russia and overwinters in NW-Europe, especially in The Netherlands. In this species, a team of ecologists and virologists showed that infected individuals initiate their migration by the end of January or early February, while uninfected individuals already do so by the end of December. Also, their next ?fuelling station? is only 35 km away instead of the usual 250 km. Sick birds fuel at a lower rate: they take fewer bites per day and their digestion seems to be impaired. Presumably, this is due to their need to channel more energy towards their immune system.

    (PressZoom) - NIEUWERSLUIS / ROTTERDAM / WIERINGERWERF -- Migratory swans carrying a mild form of avian influenza depart from The Netherlands more than a month after their healthy counterparts do. They also feed slower and fly shorter distances. These insights will be published on January 31, 2007 in PLoS ONE, the International, peer-reviewed, open-access, online publication from the Public Library of Science ( PLoS ) by scientists from the Netherlands Institute of Ecology ( NIOO-KNAW ) and the Department of Virology of the Erasmus MC. This contrasts previous ideas that mild forms of bird flu do not cause illness among wild birds. Moreover, these patterns can affect the rate of spread of avian influenza.

    Wild birds were thought not to suffer from mild forms of avian influenza. But new data suggest that so-called ?low-pathogenic? avian influenza viruses do affect the lives of birds. The Bewick?s swan ( Cygnus columbianus bewickii ) is a migratory bird that breeds in NW-Russia and overwinters in NW-Europe, especially in The Netherlands. In this species, a team of ecologists and virologists showed that infected individuals initiate their migration by the end of January or early February, while uninfected individuals already do so by the end of December. Also, their next ?fuelling station? is only 35 km away instead of the usual 250 km. Sick birds fuel at a lower rate: they take fewer bites per day and their digestion seems to be impaired. Presumably, this is due to their need to channel more energy towards their immune system.

    Being ill is no fun for us, but for a migratory bird being ill could potentially mess up its whole calendar for the rest of the year. According to scientist Jan van Gils from NIOO, "Infected swans clearly suffer from their ?mild? disease. The late departure from the wintering grounds could lead to late arrival in the breeding grounds, and thus to a lost breeding season. All in all, these low-pathogenic viruses have a much greater impact than previously thought. Because of their slower migration, ill birds get in touch with many more healthy birds passing by them on migration. In this way the virus can spread itself more rapidly than previously thought."

    Acquiring more knowledge about mild but illness-causing avian influenza viruses is very important. Van Gils adds, "These mild virus-types always formed the origin of massive pandemics such as the Spanish Flu. Only such viruses that are non-lethal to birds can be spread easily by ( wild or captive ) birds, simply because the birds stay alive." Only after mixing with human flu can such a low-pathogenic avian flu cause the nightmare of a deadly pandemic among humans. "High-pathogenic avian flu that causes death among birds seems to originate from intensive poultry farms."

    In the Dutch study 25 swans were investigated. The birds were caught in polder Wieringermeer ( NW-Netherlands ) last winter and were measured, weighed and screened for the prevalence of avian influenza viruses. Twelve birds were equipped with a GPS attached to their neck collar ( 80 g in total ). This enabled the researchers to follow the birds? movements in great detail. When within 300 m of the bird, all "travel data" were downloadable by wireless modern technology. Birds were found back by volunteer bird watchers reading and reporting the code on each bird?s neck collar. Among the twelve neck-collared birds, two were infected with bird flu: type H6N2 and H6N8. These mild virus types are common among free-living waterfowl. From antibodies found back in blood samples it could be concluded that a few more individuals had been infected before but were fully recovered and behaved as the other healthy birds. Both birds that were infected last winter have returned this winter and seem fully recovered too.

    ###
    Disclaimer

    The above press release refers to an upcoming article in PLoS ONE. The release has been provided by the article authors and/or their institutions. Any opinions expressed in this release are the personal views of the contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the releases and articles and your use of such information.

    Citation: van Gils JA, Munster VJ, Radersma R, Liefhebber D, Fouchier RAM et al ( 2007 ) Hampered Foraging and Migratory Performance in Swans Infected with Low-Pathogenic Avian Influenza A Virus. PLoS ONE 2( 1 ): e184. doi:10.1371/journal.pone.0000184

    PLEASE ADD THE LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT: http://dx.doi.org/10.1371/journal.pone.0000184

    PRESS ONLY PREVIEW OF THE ARTICLE: http://www.plos.org/press/pone-02-01-vanGils.pdf

    Comment


    • #3
      Re: migratory performance in swans with LPAI

      Swans are thought to be particularly susceptible to AI (among waterbirds) and have even been suggested as a "sentinel species". It is noteworth that during the outbreaks of early 2006 in Europe there was an overproportion of swans found to be infected.

      The rate of 3/25 swans infected is consistent with data usually found in European wildlife monitoring programs.

      If we start from the assumption that a much greater share of swans has recovered from LPAI infection and developed Abs and C cell immune response with possible cross immnuity to HPAI strains we have a hypothesis why the outbreaks did not lead to a large scale epidemic in spring 2006 but was rapidly extincted.

      Comment


      • #4
        99% identity of LPAI H6N2 NP with H5N1

        It has been hypothesized, that previous LPAI infection can provide t-cell mediated protection to HPAI H5N1 strians through shared, conserved epitopes - particularly in NP, Pb2 and M1 proteins.

        A brief Analysis of the H6N2 strain used in the present study shows a 99 &#37; NP identity (494/497) with current H5N1 HPAI strains.
        (490/494 to A/duck/Yokohama/aq10/2003(H5N1))

        Sequence 1: gi|111035060|gb|ABH03490.1|NP [Influenza A virus (A/Bewick's swan/Netherlands/1/2005(H6N2))]
        Length = 497 (1 .. 497)

        Sequence 2: gi|54126502|gb|AAV30830.1|nucleoprotein [Influenza A virus (A/swine/Fujian/1/2003(H5N1))]
        Length = 504 (1 .. 504)

        Score = 984 bits (2544), Expect = 0.0
        Identities = 493/497 (99%), Positives = 494/497 (99%), Gaps = 0/497 (0%)

        Query 1 INIMASQGTKRSYEQMETGGERQNATEIRASVGRMVGGIGRFYIQMCTEL KLSDYEGRLI 60
        Sbjct 4 .................................................. .......... 63

        Query 61 QNSITIERMVLSAFDERRNKYLEEHPSAGKDPKKTGGPIYRRRDGKWMRE LILYDKEEIR 120
        Sbjct 64 .................................................. .......... 123

        Query 121 RIWRQANNGEDATAGLTHLMIWHSNLNDATYQRTRALVRTGMDPRMCSLM QGSTLPRRSG 180
        Sbjct 124 ............................S............................... 183

        Query 181 AAGAAVKGVGTMVMELIRMIKRGINDRNFWRGENGRRTRIAYERMCNILK GKFQTAAQRA 240
        Sbjct 184 .................................................. .......... 243

        Query 241 MMDQVRESRNPGNAEIEDLIFLARSALILRGSVAHKSCLPACVYGLAVAS GYDFEREGYS 300
        Sbjct 244 .................................................. .......... 303

        Query 301 LVGIDPFRLLQNSQVFSLIRPNENPAHKSQLVWMACHSAAFEDLRVSSFI RGTRVVPRGQ 360
        Sbjct 304 .................................................. .......... 363

        Query 361 LSTRGVQIASNENMETMDSSTLELRSRYWAIRTRSGGNTNQQRASAGQIS VQPTFSVQRN 420
        Sbjct 364 .................................................. .......... 423

        Query 421 LPFERATIMAAFTGNNEGRTSDMRTEIIRMMESARPEDVSFQGRGVFELS DEKPTNPIVP 480
        Sbjct 424 ...............T.....................................A...... 483

        Query 481 SFDMSNEGSYIFGDNAE 497
        Sbjct 484 ..........F...... 500
        ************************************************** ***
        The closest PB2 sequence ist A/chicken/Hubei/wh/1997(H5N1) (753/759)
        Score = 1485 bits (3845), Expect = 0.0
        Identities = 753/759 (99%), Positives = 759/759 (100%), Gaps = 0/759 (0%)

        Query 1 MERIKELRDLMSQSRTREILTKTTVDHMAIIKKYTSGRQEKNPALRMKWM MAMKYPITAD 60
        Sbjct 1 .....................Q...................................... 60

        Query 61 KRIMEMIPERNEQGQTLWSKTNDAGSDRVMVSPLAVTWWNRNGPTTSTIH YPKVYKTYFE 120
        Sbjct 61 ................................................V........... 120

        Query 121 KVERLKHGTFGPVHFRNQVKIRRRVDINPGHADLSAKEAQDVIMEVVFPN EVGARILTSE 180
        Sbjct 121 .................................................. .......... 180

        Query 181 SQLTITKEKKEELQDCKISPLMVAYMLERELVRKTRFLPVAGGTSSVYIE VLHLTQGTCW 240
        Sbjct 181 ..................A......................................... 240

        Query 241 EQMYTPGGEVRNDDVDQSLIIAARNIVRRATVSADPLASLLEMCHSTQIG GIRMVDILRQ 300
        Sbjct 241 .................................................. .V........ 300

        Query 301 NPTEEQAVDICKAAMGLRISSSFSFGGFTFKRTSGSSVKREEEVLTGNLQ TLKIRVHEGY 360
        Sbjct 301 .................................................. .......... 360

        Query 361 EEFTMVGRRATAILRKATRRLIQLIVSGKDEQSIAEAIIVAMVFSQEDCM IKAVRGDLNF 420
        Sbjct 361 ............................R............................... 420

        Query 421 VNRANQRLNPMHQLLRHFQKDAKVLFQNWGIEPIDNVMGMIGILPDMTPS TEMSLRGVRV 480
        Sbjct 421 .................................................. .......... 480

        Query 481 SKMGVDEYSSTERVVVSIDRFLRVRDQRGNVLLSPEEVSETQGTEKLTIT YSSSMMWEIN 540
        Sbjct 481 .................................................. .......... 540

        Query 541 GPESVLVNTYQWIIRSWETVKIQWSQDPTMLYNKMEFEPFQSLVPKAARG QYSGFVRTLF 600
        Sbjct 541 ...............N............................................ 600

        Query 601 QQMRDVLGTFDTVQIIKLLPFAAAPPEQSRMQFSSLTVNVRGSGMRILVR GNSPVFNYNK 660
        Sbjct 601 .................................................. .......... 660

        Query 661 ATKRLTVLGKDAGALTEDPDEGTAGVESAVLRGFLILGKEDKRYGPALSI NELSNLAKGE 720
        Sbjct 661 .................................................. .......... 720

        Query 721 KANVLIGQGDVVLVMKRKRDSSILTDSQTATKRIRMAIN 759
        Sbjct 721 ....................................... 759
        *************************************************
        PB1 reveals a 753/758 identity to A/duck/Hokkaido/Vac-1/04(H5N1)
        and 751/758 A/chicken/Hubei/wj/1997(H5N1)

        PA 709/716 to A/duck/Guangxi/35/2001(H5N1)

        M1 249/250 to A/chicken/Hubei/wl/1997(H5N1) and A/chicken/Henan/210/2004(H5N1)

        NS1 225/225 to A/Tree sparrow/Henan/3/2004(H5N1)
        ************************************************** **
        NP Epitope Analysis:
        Comparison of known (human) NP- T-cell epitopes (based on PR8) with swan NL and the H5N1 isolates from R&#252;gen shows 100 % identity.
        Conservation of NP epitopes between A/Bewick's swan/Netherlands/1/2005(H6N2)
        and R&#252;gen isolates of H5N1 viruses (A/swan/Germany/R65/2006 (H5N1)
        <TABLE style="WIDTH: 378pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=504 border=0 x:str><COLGROUP><COL style="WIDTH: 54pt" span=7 width=72><TBODY><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" width=72 height=15>Epitope</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72>HLA restrict.</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72>PR8</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72 x:str="swan NL ">swan NL </TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72>Conservation</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; WIDTH: 54pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" width=72>Reference</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent; mso-ignore: colspan" colSpan=2>sw/NL=sw/Germ</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 383–391</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">B*2705</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">SRYWAIRTR</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">SRYWAIRTR</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" x:str="id ">id </TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 418–426</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">B*3501</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">LPFDRTTIM</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">LPFERATIM</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 44–52</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">A*01</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">CTELKLSDY</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">CTELKLSDY</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 265–273</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">A*03</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">ILRGSVAHK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">ILRGSVAHK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 188–198</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">A*1101</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">TMVMELVRMIK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">TMVMELIRMIK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 338-347</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">HLA B 37</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">FEDLRVSSFI</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">FEDLRVSSFI</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>2</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 380–388</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">B*08</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">ELRSRYWAI</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">ELRSRYWAI</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR><TR style="HEIGHT: 11.25pt" height=15><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; HEIGHT: 11.25pt; BACKGROUND-COLOR: transparent" height=15>NP 174–184</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">B*2705</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"></TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">RRSGAAGAAVK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">RRSGAAGAAVK</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent">id</TD><TD style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" align=right x:num>1</TD></TR></TBODY></TABLE>


        Conclusion:

        These findings support the hypothesis that T-cell mediated crossimmunity plays a role in the wild bird H5N1- epidemics of 2006 providing a partial protection against HPAI H5N1 strains, - a time gain which keeps the birds alive until fully protective Ab mediated immunity is built up.

        (1) Paul G. Thomas,* Rachael Keating: Cell-mediated Protection in Influenza Infection Paul G. Thomas,* Rachael Keating CDC Vol. 12, No. 1 January 2006 http://www.cdc.gov/ncidod/EID/vol12no01/05-1237.htm
        (2) J. T. M. Voeten, T. M. Bestebroer, N. J. Nieuwkoop, R. A. M. Fouchier, A. D. M. E. Osterhaus, and G. F. Rimmelzwaan: Antigenic Drift in the Influenza A Virus (H3N2) Nucleoprotein and Escape from Recognition by Cytotoxic T Lymphocytes
        Journal of Virology, August 2000, p. 6800-6807, Vol. 74, No. 15 0022-538X/00/$04.00+0
        <TABLE style="WIDTH: 378pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=504 border=0 x:str><COLGROUP><COL style="WIDTH: 54pt" span=7 width=72></COLGROUP><TBODY></TBODY></TABLE>
        Last edited by Ganseerpel; February 1, 2007, 09:37 AM.

        Comment


        • #5
          Re: 99% identity of LPAI H6N2 NP with H5N1

          Originally posted by G?nseerpel View Post
          It has been hypothesized, that previous LPAI infection can provide t-cell mediated protection to HPAI H5N1 strians through shared, conserved epitopes - particularly in NP, Pb2 and M1 proteins.
          My hazy understanding of the immune response led me to believe that internal proteins like Pb2 and NP were of little use in generating an acquired immune response unless and until fragments were externally expressed on the MHC protein. Is this correct? also as the M1 protein is immersed in the lipid layer acquired from the cell wall of the previous host and buried below a forest of HA & NA surface proteins it too has difficulty making direct contact with host immune cells and so illiciting antibody production. I would be most grateful if someone with a better understanding of this system could write a basic explanation to help those of us struggling with this complex set of interactions.

          JJ

          Comment


          • #6
            Re: migratory performance in swans with LPAI

            my understanding is, that T-cell immunity checks inside the cells
            where the inner genes are free.MHC=?

            major histocompatibility complex (MHC).


            are the swans now somehow immune or can we expect the same scenario
            in a few weeks on Ruegen as last year ?
            Last edited by gsgs; February 1, 2007, 12:02 PM.
            I'm interested in expert panflu damage estimates
            my current links: http://bit.ly/hFI7H ILI-charts: http://bit.ly/CcRgT

            Comment


            • #7
              Re: migratory performance in swans with LPAI

              T-cell mediated immunity is generally believed to be only mildly protective, but T cells can promote recovery from otherwise lethal secondary viral infections and -targeting internal proteins common to heterologous viral strains- can induce protective cellular immune responses against heterologous viral strains.

              Immunecompetent CD8+ T-cells do not directly react with the virions or parts of it, but with specificly processed ligands presented within the MCH I complexes on the the surface of infected cells, in which they elicit apoptosis.

              Comment


              • #8
                Re: migratory performance in swans with LPAI

                are the swans now somehow immune or can we expect the same scenario in a few weeks on Ruegen as last year ?
                IMO there is a more or less widespread cross immunity in wild birds that prevents larger outbreaks.


                my understanding is, that T-cell immunity checks inside the cells
                where the inner genes are free.MHC=?
                The AG's are processed within the cell cut into peptides and built into the MHC I which is transported to the cell surface afterward. Activated T cells bind to the MHC I and trigger cell death. schematic details here

                Comment


                • #9
                  Re: migratory performance in swans with LPAI

                  Thanks G&#228;nseerpel.

                  So the T-cell immune response is derived by contact with viral protein fragments attached to the exterior part of the MHC I in infected cells and that is how viral epitopes from internal viral proteins become visible to the immune system. This 'posting' of viral protein fragments also causes an attack on the infected cell killing it and halting any further replication by that cell.

                  Comment


                  • #10
                    Re: migratory performance in swans with LPAI

                    Yes, it's a basic principle of cell homeostasis. The cells are constantly presenting a great number of different "antigens" (not only foreign, but also own AG`s) on their surface to have them checked by the "system". If something is "odd" the cell is eliminated. Some Cancer cells seem to escape because they don't work up the apoptosis signal. The NS1 protein also can block apoptosis.

                    Comment


                    • #11
                      Re: migratory performance in swans with LPAI

                      Can we speculate that a human pre-pandemic vaccine might have the same effects as the prior LPAI infections did on swans?

                      .
                      "The next major advancement in the health of American people will be determined by what the individual is willing to do for himself"-- John Knowles, Former President of the Rockefeller Foundation

                      Comment


                      • #12
                        Re: migratory performance in swans with LPAI

                        I don't think so, as long as it is a (killed) split vaccine. 1st Split vaccines contain only a part of the virus and 2nd even killed full virus vaccines elicit only a very insufficient cellular response, because no infection takes place. With flumist which is a life vaccine it seems to be different. Though the data are not 100 &#37; consistent, flumist seems to have a cross reactive potential.


                        the same effects as the prior LPAI infections did on swans?
                        Up to now this only a hypothesis. It will be some work to support it. The main problem is, that nobody knows, if in birds we have the same epitopes. The epitopes I mentionned above are human. But as the the H6/H5 NP is more than 99 % matching - epitope identy (of probably unknown epitopes ) is very probable.

                        One of the few studies in this issue is Websters H9 H5 comparison in HK poultry markets:
                        JOURNAL OF VIROLOGY,
                        0022-538X/01/$04.0010 DOI: 10.1128/JVI.75.6.2516–2525.2001
                        Mar. 2001, p. 2516–2525 Vol. 75, No. 6
                        Cross-Reactive, Cell-Mediated Immunity and Protection of Chickens
                        from Lethal H5N1 Influenza Virus Infection in
                        Hong Kong Poultry Markets
                        SANG HEUI SEO AND ROBERT G. WEBSTER*

                        and

                        JOURNAL OF VIROLOGY, May 2002, p. 4886–4890 Vol. 76, No. 10
                        0022-538X/02/$04.000 DOI: 10.1128/JVI.76.10.4886–4890.2002
                        Protective Cross-Reactive Cellular Immunity to Lethal
                        A/Goose/Guangdong/1/96-Like H5N1 Influenza Virus
                        Is Correlated with the Proportion of Pulmonary
                        CD8 T Cells Expressing Gamma Interferon
                        Sang Heui Seo,1 Malik Peiris,2 and Robert G. Webster1*

                        If you check the sequences the identity is striking.
                        Last edited by Ganseerpel; February 2, 2007, 04:28 PM.

                        Comment


                        • #13
                          Re: migratory performance in swans with LPAI

                          Those sound like the articles I read over a year ago, that got me to wondering about the cross-reactive immunity path. Isn't part of the value of the H9 prior infection in HK, due to the timing - within 30 days prior to H5N1 challenge? I thought the timing allowed a normally "quiet" part of our immune system to have been activated by the H9 and still be active when the H5 showed up- allowing it to fight the H5 effectively.

                          I believe those articles also said...."it needs more study."

                          .
                          "The next major advancement in the health of American people will be determined by what the individual is willing to do for himself"-- John Knowles, Former President of the Rockefeller Foundation

                          Comment


                          • #14
                            Re: migratory performance in swans with LPAI

                            >The cells are constantly presenting a great number of different
                            >"antigens" (not only foreign, but also own AG`s) on their surface to have
                            >them checked by the "system". If something is "odd" the cell is eliminated

                            I see.
                            we should put it in the wiki
                            we should attach a wiki to FT, info get's scattered
                            I'm interested in expert panflu damage estimates
                            my current links: http://bit.ly/hFI7H ILI-charts: http://bit.ly/CcRgT

                            Comment

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