MOLECULAR SURVEILLANCE OF AVIAN INFLUENZA VIRUS IN SEMI-SCAVENGING DUCKS IN SYLHET DIVISION OF BANGLADESH

Abstract

Ducks are the natural reservoir of influenza A virus and the central host for highly pathogenic avian influenza (H5N1), while domestic ducks rearing in semi-scavenging system could serve as re-assortment vessels for re-emerging new subtypes of influenza viruses. The present active surveillance study hereby reports the molecular detection of different subtypes of avian influenza viruses (AIVs) in semi-scavenging ducks. A total of 700 cloacal swabs were collected from semiscavenging ducks from six selected haor basin areas of Sylhet division of Bangladesh during the

period from January 2015 to December 2015. AIVs were identified from collected swab samples

by

detecting M gene using real-time RT-PCR (RT-qPCR). Sub-typing of AIV positive samples were performed using RT-qPCR specific for H5, H7 and H9 genes. Out of 700 samples 12 (1.71%) were found positive for AIVs. Sub-typing of AIV positive samples (n=12) revealed that 7 (58.33%) samples were positive for H9 sub-type and 5 samples were negative for the selected genes (H5, H7, H9). Our results were validated by detecting the same genes after propagation of virus in embryonating chicken eggs from positive samples. Based on our findings, we conclude that semi-scavenging ducks reared in hoar areas acts as a carrier of low pathogenic AIVs. Although H9 subtype of AIV is low pathogenic and has lower risk for human, it is alarming that this virus may change its pathogenicity in ducks by re-assortment and may become highly pathogenic. Our large data set from six migratory bird sanctuaries might provide a strong background for furthermore studies of AIV prevalence, evolution and ecology.