tetano
Editor, Senior Moderator
J Virol. 2016 Dec 21. pii: JVI.01708-16. doi: 10.1128/JVI.01708-16. [Epub ahead of print]
[h=1]Shifting clade distribution, reassortment, and emergence of new subtypes of highly pathogenic avian influenza A(H5) viruses collected in Vietnamese poultry from 2012 to 2015.[/h] Nguyen DT[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3,[/SUP][SUP]4[/SUP], Jang Y[SUP]5[/SUP], Nguyen TD[SUP]6[/SUP], Jones J[SUP]5[/SUP], Shepard SS[SUP]5[/SUP], Yang H[SUP]5[/SUP], Gerloff N[SUP]5[/SUP], Fabrizio T[SUP]7[/SUP], Nguyen LV[SUP]2[/SUP], Inui K[SUP]8[/SUP], Yang G[SUP]5[/SUP], Creanga A[SUP]5[/SUP], Wang L[SUP]5[/SUP], Mai DT[SUP]6[/SUP], Thor S[SUP]5[/SUP], Stevens J[SUP]5[/SUP], To TL[SUP]6[/SUP], Wentworth DE[SUP]5[/SUP], Nguyen T[SUP]2[/SUP], Pham DV[SUP]2[/SUP], Bryant JE[SUP]3,[/SUP][SUP]4[/SUP], Davis CT[SUP]9[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] Whole genome sequences of representative highly pathogenic avian influenza A(H5) viruses from Vietnam were generated, comprising samples from poultry outbreaks and active market surveillance collected from January 2012 to August 2015. Six hemagglutinin gene clades were characterized. Clade 1.1.2 was predominant in southern Mekong provinces throughout 2012 and 2013, but gradually disappeared and was not detected after April 2014. Clade 2.3.2.1c viruses spread rapidly during 2012 and were detected in the south and center of the country. A number of clade 1.1.2 and 2.3.2.1c inter-clade reassortant viruses were detected with different combinations of internal genes derived from 2.3.2.1a and 2.3.2.1b viruses indicating extensive co-circulation. Although reassortment generated genetic diversity at the genotype level, there was relatively little genetic drift within the individual gene segments suggesting genetic stasis over recent years. Antigenically, clade 1.1.2, 2.3.2.1a, 2.3.2.1b, 2.3.2.1c viruses remained related to earlier viruses and WHO recommended pre-pandemic vaccine strains representing these clades. Clade 7.2 viruses, although only detected in small numbers, were the exception as indicated by introduction of a genetically and antigenically diverse strain in 2013. Clade 2.3.4.4 viruses (H5N1 and H5N6) were likely introduced in April 2014 and appeared to gain dominance across northern and central regions. Antigenic analyses of clade 2.3.4.4 viruses compared to existing clade 2.3.4 candidate vaccine viruses (CVV) indicated the need for an updated vaccine virus. A/Sichuan/26221/2014 (H5N6), was developed and ferret antisera generated against this virus was demonstrated to inhibit some but not all clade 2.3.4.4 viruses suggesting consideration of alternative clade 2.3.4.4 CVVs.
[h=4]IMPORTANCE:[/h] Highly pathogenic avian influenza (HPAI) A(H5) viruses have circulated continuously in Vietnam since 2003 resulting in hundreds of poultry outbreaks and sporadic human infections. Despite significant reduction in the number of human infections in recent years, poultry outbreaks continue to occur and the virus continues to diversify. Vaccination of poultry has been used as a means to control spread and impact of the virus but due to the diversity and changing distribution of antigenically distinct viruses, the utility of vaccines in the face of mismatched circulating strains remains questionable. This study assesses the putative amino acid changes in viruses leading to antigenic variability, underscoring the complexity of vaccine selection for both veterinary and public health purposes. Given the overlapping geographic distribution of multiple, antigenically distinct clades of HPAI A(H5) viruses in Vietnam, the vaccine efficacy of bivalent poultry vaccine formulations should be tested in the future.
Copyright ? 2016, American Society for Microbiology. All Rights Reserved.
PMID: 28003481 DOI: 10.1128/JVI.01708-16
[PubMed - as supplied by publisher]
[h=1]Shifting clade distribution, reassortment, and emergence of new subtypes of highly pathogenic avian influenza A(H5) viruses collected in Vietnamese poultry from 2012 to 2015.[/h] Nguyen DT[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3,[/SUP][SUP]4[/SUP], Jang Y[SUP]5[/SUP], Nguyen TD[SUP]6[/SUP], Jones J[SUP]5[/SUP], Shepard SS[SUP]5[/SUP], Yang H[SUP]5[/SUP], Gerloff N[SUP]5[/SUP], Fabrizio T[SUP]7[/SUP], Nguyen LV[SUP]2[/SUP], Inui K[SUP]8[/SUP], Yang G[SUP]5[/SUP], Creanga A[SUP]5[/SUP], Wang L[SUP]5[/SUP], Mai DT[SUP]6[/SUP], Thor S[SUP]5[/SUP], Stevens J[SUP]5[/SUP], To TL[SUP]6[/SUP], Wentworth DE[SUP]5[/SUP], Nguyen T[SUP]2[/SUP], Pham DV[SUP]2[/SUP], Bryant JE[SUP]3,[/SUP][SUP]4[/SUP], Davis CT[SUP]9[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] Whole genome sequences of representative highly pathogenic avian influenza A(H5) viruses from Vietnam were generated, comprising samples from poultry outbreaks and active market surveillance collected from January 2012 to August 2015. Six hemagglutinin gene clades were characterized. Clade 1.1.2 was predominant in southern Mekong provinces throughout 2012 and 2013, but gradually disappeared and was not detected after April 2014. Clade 2.3.2.1c viruses spread rapidly during 2012 and were detected in the south and center of the country. A number of clade 1.1.2 and 2.3.2.1c inter-clade reassortant viruses were detected with different combinations of internal genes derived from 2.3.2.1a and 2.3.2.1b viruses indicating extensive co-circulation. Although reassortment generated genetic diversity at the genotype level, there was relatively little genetic drift within the individual gene segments suggesting genetic stasis over recent years. Antigenically, clade 1.1.2, 2.3.2.1a, 2.3.2.1b, 2.3.2.1c viruses remained related to earlier viruses and WHO recommended pre-pandemic vaccine strains representing these clades. Clade 7.2 viruses, although only detected in small numbers, were the exception as indicated by introduction of a genetically and antigenically diverse strain in 2013. Clade 2.3.4.4 viruses (H5N1 and H5N6) were likely introduced in April 2014 and appeared to gain dominance across northern and central regions. Antigenic analyses of clade 2.3.4.4 viruses compared to existing clade 2.3.4 candidate vaccine viruses (CVV) indicated the need for an updated vaccine virus. A/Sichuan/26221/2014 (H5N6), was developed and ferret antisera generated against this virus was demonstrated to inhibit some but not all clade 2.3.4.4 viruses suggesting consideration of alternative clade 2.3.4.4 CVVs.
[h=4]IMPORTANCE:[/h] Highly pathogenic avian influenza (HPAI) A(H5) viruses have circulated continuously in Vietnam since 2003 resulting in hundreds of poultry outbreaks and sporadic human infections. Despite significant reduction in the number of human infections in recent years, poultry outbreaks continue to occur and the virus continues to diversify. Vaccination of poultry has been used as a means to control spread and impact of the virus but due to the diversity and changing distribution of antigenically distinct viruses, the utility of vaccines in the face of mismatched circulating strains remains questionable. This study assesses the putative amino acid changes in viruses leading to antigenic variability, underscoring the complexity of vaccine selection for both veterinary and public health purposes. Given the overlapping geographic distribution of multiple, antigenically distinct clades of HPAI A(H5) viruses in Vietnam, the vaccine efficacy of bivalent poultry vaccine formulations should be tested in the future.
Copyright ? 2016, American Society for Microbiology. All Rights Reserved.
PMID: 28003481 DOI: 10.1128/JVI.01708-16
[PubMed - as supplied by publisher]