ABSTRACT
H9N2 avian influenza viruses are endemic in domestic poultry in Asia and are grouped into three major sublineages represented by their prototype strains A/Duck/Hong Kong/Y280/97 (Y280-like), A/Quail/Hong Kong/G1/97 (G1-like) and A/Chicken/Korea/38349-p96323/96 (Korean-like). To understand the genetic relationship of Indian viruses, we determined the partial nucleotide sequence of five H9N2 avian influenza viruses isolated from chicken in India during 2003-2004 and compared them with H9N2 sequences available in GenBank. Deduced amino acid sequence analysis revealed that four isolates shared an R-S-S-R/G motif at the cleavage site of HA, representing low pathogenicity in chickens, while one virus harbors an R-S-N-R/G motif at the same position. All the viruses maintained the human-like motif 226Lysine (H3 numbering) at the HA receptor binding site. Phylogenetic analysis showed that 50% of the genes (HA, NA, NP and M) were similar to G1-like viruses, whereas the remaining genes of the Indian isolates formed a separate, not yet defined, sublineage in the Eurasian lineage. Our finding provides evidence of a novel reassortant H9N2 genotype of G1-like viruses circulating in India.
Subject(s)
Chickens/virology , Hemagglutinin Glycoproteins, Influenza Virus/chemistry , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Influenza A Virus, H9N2 Subtype/classification , Influenza in Birds/virology , Amino Acid Sequence , Animals , Binding Sites/genetics , Humans , India , Influenza A Virus, H9N2 Subtype/genetics , Influenza A Virus, H9N2 Subtype/isolation & purification , Influenza A Virus, H9N2 Subtype/pathogenicity , Influenza in Birds/genetics , Influenza in Birds/immunology , Phylogeny , Poultry Diseases/epidemiology , RNA, Viral/genetics , Sequence Analysis, DNAABSTRACT
Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 virus were reported for the first time in India during February 2006. Herein, we have sequenced and analyzed the PB2 genes of five influenza virus isolates obtained from three affected states (Gujarat, Madhya Pradesh and Maharashtra) in India during the outbreaks. In the phylogenetic analysis, the Indian isolates were grouped in the mixed-migratory bird sub-lineage of the Eurasian lineage. From the phylogenetic tree, it is evident that viruses were probably introduced to India from China via Europe because they share a direct ancestral relationship with the Indian isolates. The virus might have spread through migratory waterfowls that survived the HPAI H5N1 infection. These viruses were able to replicate in cultured cells of avian and mammalian hosts and posses lysine at position 627 of the PB2 protein, indicating that they might be able to cross the host barrier to infect mammals.
