Phylogenetic analysis of NS gene of avian infuenza viruses (H9N2) isolated from chicken in Iran during 2007 2011

Abstract

To determine sequence characteristics and phylogenetic relationships of the nonstructural (NS) gene, the NS genes of 9 avianinfuenza (AI) viruses were sequenced and compared with other Iranian AI H9N2 viruses available in GenBank. Te similarity amongthe earliest Iranian H9N2 isolate (A/chicken/Iran/ZMT-101/1998) and recent (2007 2011) studied isolates was low (94%). Some of thestudied viruses revealed substitutions in RNA-binding and efector domains as well as antigenic regions of the NS protein. Recentlystudied isolates have a high similarity (97.4% 98.7%) with some Pakistani isolates (like A/chicken/Sawabi/NARC-2434/2006) in the NSgene. In the phylogenetic analysis, recently studied isolates composed a cluster separate from other Iranian isolates and were placed inthe neighborhood of some Pakistani isolates. Hence, new Iranian H9N2 isolates may originate from Pakistani isolates. Te NS proteinof the Iranian H9N2 isolates difered from that of the Iranian highly pathogenic H5N1 viruses. Te potential risk of the emergence of apandemic virus because of the reassortment of the internal genes between H9N2 viruses and highly pathogenic AI viruses on one handand the genetic and amino acid changes of AI viruses afecting their pathogenicity and immunogenicity on the other hand confrm theimportance of continued surveillance of AI viruses.