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. 2008 Oct 6;3(10):e3339.
doi: 10.1371/journal.pone.0003339.

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam

Mai T Q Le  1 , Heiman F L Wertheim, Hien D Nguyen, Walter Taylor, Phuong V M Hoang, Cuong D Vuong, Hang L K Nguyen, Ha H Nguyen, Thai Q Nguyen, Trung V Nguyen, Trang D Van, Bich T Ngoc, Thinh N Bui, Binh G Nguyen, Liem T Nguyen, San T Luong, Phuc H Phan, Hung V Pham, Tung Nguyen, Annette Fox, Cam V Nguyen, Ha Q Do, Martin Crusat, Jeremy Farrar, Hien T Nguyen, Menno D de Jong, Peter Horby
Affiliations

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam

Mai T Q Le et al. PLoS One. .

Erratum in

  • PLoS ONE. 2008;3(10). doi: 10.1371/annotation/65ab1e39-3b12-4d9d-90e4-905139530448

Abstract

Background: Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.

Methods and findings: Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.

Conclusion: In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Mapping of poultry and human H5N1 cases in northern Vietnam, 2007.
Figure 2
Figure 2. Phylogenetic analysis of hemagglutinin gene sequence of Influenza A H5N1 in humans and poultry in Vietnam 2007 and sequences downloaded from genebank.
The numbers to the right of the figure refer to the World Health Organization H5N1 clade designations.
See this image and copyright information in PMC

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References

    1. Peiris JS, de Jong MD, Guan Y. Avian influenza virus (H5N1): a threat to human health. Clin Microbiol Rev. 2007;20:243–267. - PMC - PubMed
    1. Smith GJ, Naipospos TS, Nguyen TD, de Jong MD, Vijaykrishna D, et al. Evolution and adaptation of H5N1 influenza virus in avian and human hosts in Indonesia and Vietnam. Virology. 2006;350:258–268. - PubMed
    1. Abdel-Ghafar AN, Chotpitayasunondh T, Gao Z, Hayden FG, Nguyen DH, et al. Update on avian influenza A (H5N1) virus infection in humans. N Engl J Med. 2008;358:261–273. - PubMed
    1. Evolution of H5N1 avian influenza viruses in Asia. Emerg Infect Dis. 2005;11:1515–1521. - PMC - PubMed
    1. Nguyen TD, Nguyen TV, Vijaykrishna D, Webster RG, Guan Y, et al. Multiple sublineages of Influenza A virus (H5N1), Vietnam, 2005–2007. Emerg Infect Dis. 2008;14:632–636. - PMC - PubMed

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