Circulation and genetic variation of A/H5N1 avian influenza virus on poultry in some Mekong delta provinces

Abstract

Avian influenza is an acute infectious disease caused by Orthomyxoviridae virus. Research on circulation and genetic variation of A/H5N1 avian influenza virus in 4 provinces of Mekong delta (An Giang, Kien Giang, Dong Thap provinces and Can Tho city) was conducted from the throat swab samples collecting from the healthy chickens and ducks at the live bird selling markets and slaughterhouses in the above mentioned provinces. The swab samples were tested by using Realtime RT-PCR technique to identify A/H5N1 avian influenza virus and to define the HA gene sequence so as to determine genetic variation and clade of virus. The studied result showed that the average prevalence of A/H5N1 avian influenza virus in poultry in the 4 Mekong delta provinces was 4.8%, of which the infection rate in duck was 5.5% and in chicken was 4.2%. Besides, result of investigation on genetic variation showed that nucleotide similarity rate between circulating virus strains in the 4 provinces was 98.2-99.3%, and the difference in comparison with other virus strains isolated in Viet Nam and the world was 3.7-10.3%. The amino acid sequence motif at connection position between HA1 and HA2 virulent segments was RRRK-R, and high similarity with the sequences of the studied virus strains and reference strain: A/chicken/Korea/IC546/2011(H5N1) and A/Hubei/1/2010(H5N1). The A/H5N1 avian influenza virus strains circulating in the provinces of Kien Giang and An Giang belonged to virus clade 2.3.2.1c.