Isolation and Genetic Characterization of Influenza A (Subtype H5N1) Virus from Crows in India

摘要

We isolated two influenza A (subtype H5N1) viruses from crows in India, in 2011 and 2012. Nucleotide sequence of all eight genome segments of both the viruses (A/crow/India/11TI07/2011 and A/crow/India/01TR01/2012) was determined and used for analysis. The two isolates shared >99% nucleotide sequence identity in all the eight genes. Phylogenetic analysis revealed that both the viruses belonged to haemagglutinin (HA) clade 2.3.2.1 of H5N1 viruses. Within clade 2.3.2.1, the crow viruses grouped with contemporary H5N1 viruses isolated from poultry in India; poultry, crows and environmental sampleas in Bangladesh; and poultry and wild birds in Bhutan. The viruses have the characteristic feature of high pathogenicity to chickens, and possessed avian-like (α 2, 3-linked sialic acid) receptor-specificity in the HA. Analysis of amino acid sequences in the neuraminidase (NA) and M2 indicated that the crow viruses are susceptible to currently available influenza drugs.