Infect Genet Evol. 2018 Mar 9. pii: S1567-1348(18)30092-3. doi: 10.1016/j.meegid.2018.03.005. [Epub ahead of print]
Emergence of novel reassortant H6N2 avian influenza viruses in ducks in India.

Kumar M1, Nagarajan S1, Murugkar HV1, Saikia B2, Singh B1, Mishra A1, Tripathi SK1, Agarwal S1, Shukla S1, Kulkarni DD1, Singh VP1, Tosh C3.
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H6 subtype avian influenza viruses (AIV), established in terrestrial poultry, have jumped species barriers and caused human infection indicating pandemic potential of the virus. Here, we report isolation, and antigenic and genetic characterization of two H6N2 viruses isolated from apparently healthy domestic ducks in Kerala and Assam, India during 2014 and 2015, respectively. Hemagglutination inhibition assay revealed antigenic divergence between the two isolates. This result was corroborated by amino acid differences at 55 positions (15.98%) between their hemagglutinin (HA) 1.The sequence analysis of the viruses indicated avian receptor specificity, avian origin, low pathogenicity to poultry and sensitivity to oseltamivir. However, Kerala14 had V27I mutation marker for amantadine resistance in M2. The Assam15 virus had an additional N-linked glycosylation on HA2 (position 557) compared to Kerala14 virus. Analysis of the HA gene revealed that both the viruses belonged to distinct lineages (Eurasian and Asia I). Analysis of neuraminidase (NA) and internal gene segments revealed distinct gene constellation indicating that both the viruses are novel reassortants and are genetically distinct. The results suggest independent introductions of the two H6N2 viruses into India and migratory wild birds in the Central Asian flyway might be the source of H6N2 viruses in ducks in India. Therefore, continued AIV surveillance in poultry and wild birds is essential for detection of emergence of novel strains, which may have pandemic potential and control of their spread.


Ducks; H6N2 subtype; India; Low pathogenic avian influenza virus; Phylogenetic analysis; Reassortment

PMID: 29530659 DOI: 10.1016/j.meegid.2018.03.005