Influenza A(H6N2) Virus in Indian Ducks

As always, nature will surprise us over and over again. As Michael Coston said here: Nature's laboratory is open 24/7 and it never stops tinkering with the evolutionary process.

Influenza A(H6Nx) is well established in terrestrial poultry, has jumped species barriers and caused human infection, thus indicating the pandemic potential of the virus. Indian scientists have discovered two different novel reassorted Influenza A(H6N2) viruses isolated from apparently healthy domestic ducks in Kerala and Assam, India during 2014 and 2015, respectively[1].
Hemagglutination (HA) 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). The sequence analysis of the viruses indicated avian receptor specificity, avian origin and low pathogenicity to poultry.

However, the isolate from Kerala had a V27I mutation marker for amantadine resistance in M2. The isolate from Assam had an additional N-linked glycosylation on HA2 (position 557) compared to the Kerala isolate. Analysis of the HA gene revealed that both the viruses belonged to distinct lineages. 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 different Influenza A(H6N2) viruses into India. Migratory wild birds using the Central Asian flyway might be the source of these Influenza A(H6N2) viruses in ducks in India.

[1] Kumar et al: Emergence of novel reassortant H6N2 avian influenza viruses in ducks in India in Infection, Genetics and Evolution - 2018

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