J Virol. Genetic and Pathobiologic Characterization of Pandemic H1N1 2009 Influenza Viruses from a Naturally Infected Swine Herd.

[Giuseppe]

J Virol. 2009 Dec 16. [Epub ahead of print]

Genetic and Pathobiologic Characterization of Pandemic H1N1 2009 Influenza Viruses from a Naturally Infected Swine Herd.

Weingartl HM, Berhane Y, Hisanaga T, Neufeld J, Kehler H, Emburry-Hyatt C, Hooper-McGreevy K, Kasloff S, Dalman B, Bystrom J, Alexandersen S, Li Y, Pasick J. - Canadian Food Inspection Agency (CFIA), National Centre for Foreign Animal Disease (NCFAD), 1015 Arlington Street, Winnipeg, Manitoba, Canada; Food Safety Division, Alberta Agriculture and Rural Development, Edmonton, Alberta; University of Manitoba, Department of Medical Microbiology, Winnipeg, Manitoba, Canada; National Microbiology Laboratory (NML), Public Health Agency of Canada (PHAC), Winnipeg, Canada.

Since its initial identification in Mexico and the United States, concerns have been raised that the novel H1N1 influenza virus might cause a pandemic of comparable severity to the one of 1918. In late April 2009, viruses phylogenetically related to pandemic H1N1 influenza virus were isolated from an outbreak on a Canadian pig farm. This outbreak also had epidemiological links to a suspected human case. Experimental infections carried out on pigs using one of the swine isolates from this outbreak and the human isolate A/Mexico/InDRE4487/2009 showed differences in virus recovery from the lower respiratory tract. Virus was consistently isolated from the lungs of pigs infected with A/Mexico/InDRE4487/2009 while only one pig infected with A/swine/Alberta/OTH-33-8/2008 yielded live virus from lung, despite comparable amounts of viral RNA and antigen in both groups of pigs. Clinical disease resembled other influenza virus infections in swine, albeit with somewhat prolonged virus antigen detection and delayed viral RNA clearance from the lungs. There was also a noteworthy amount of genotypic variability among the viruses isolated from the pigs on this farm. This, along with the somewhat irregular pathobiological characteristics observed in experimentally infected animals, suggests that although the virus may be of swine origin, significant viral evolution may still be ongoing.

PMID: 20015998 [PubMed - as supplied by publisher]
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[gsgs]

Re: J Virol. Genetic and Pathobiologic Characterization of Pandemic H1N1 2009 Influenza Viruses from a Naturally Infected Swine Herd.

http://jvi.asm.org/cgi/content/full/84/5/2245


> Whether the observed genetic heterogeneity reflects the true variability of virus circulating
> in this swine herd or is an artifact resulting from virus propagation and/or viral-RNA
> manipulation is of concern

why can't they let another lab redo the sequencing ?

 

[gsgs]

Re: J Virol. Genetic and Pathobiologic Characterization of Pandemic H1N1 2009 Influenza Viruses from a Naturally Infected Swine Herd.

did they also find mutations in the experimentally infected pigs ?
I can't find it.
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OK, now I found:
A/Mexico/InDRE4487/2009 (H1N1) was isolated from a bronchoalveolar lavage fluid (BALF) sample that was submitted to the Public Health Agency of Canada's National Microbiology Laboratory using Madin-Darby canine kidney (MDCK) cells. This was followed by propagation in ECE prior to animal inoculation.

hmm, submitted from Mexico or Alberta, BALF in human or pig
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> Virus was recovered from the turbinates of piglets inoculated with A/Mexico/InDRE4487/2009
> at 3, 5, and 7 days p.i.,


> In summary, the genetic variability found among the isolates from pigs following this
> single introduction event, along with a phenotype that is not entirely consistent with
> other influenza infections in swine,

nor in humans nor in other ** - swine sequences

> suggests that the pandemic H1N1 2009 virus may also be a relatively new virus for pigs.

no. "Being new" didn't result in increased mutation rates this way in the past.
Compare with the mutation rates in triple reassortant swine flu since 1998,
which was more new to swine than ****** in 2009.

> Repeated introductions of this virus from humans to pigs may have a significant impact
> on virus evolution and subsequent epidemiology.

it's still the same virus, the same genetics. The envelope is stolen from the host-cell,
though. Can this be different for human or swine ?

> Because of this, human-to-pig transmission of pandemic H1N1 2009 should be minimized.

sure. For this and other reasons.

> If infected pig herds are identified, changes in the viral genotype and phenotype
> should be closely monitored.

and suspected sequencing errors examined by sending a sample to another lab
(CDC ?)