Lee Eun-Kyoung, Kang Hyun-Mi, Kim Kwang-Il, Choi Jun-Gu, To Thanh Long, Nguyen Tho Dang, Song Byung-Min, Jeong Jipseol, Choi Kang-Seuk, Kim Ji-Ye, Lee Hee-Soo, Lee Youn-Jeong, Kim Jae-Hong
Animal and Plant Quarantine Agency, 175 Anyangro, Manan, Anyang, Gyeonggi, 430-757, Republic of Korea.
National Center for Veterinary Diagnosis, Department of Animal Health, 11/78 Giai Phong St. Dong Da disk Hanoi, Vietnam.
Poult Sci. 2015 Apr;94(4):650-61. doi: 10.3382/ps/pev036. Epub 2015 Mar 5.
In spite of highly pathogenic avian influenza H5N1 vaccination campaigns for domestic poultry, H5N1 viruses continue to circulate in Vietnam. To estimate the prevalence of avian influenza virus in Vietnam, surveillance was conducted between November 2011 and February 2013. Genetic analysis of 312 highly pathogenic avian influenza H5 viruses isolated from poultry in Vietnam was conducted and possible genetic relationships with strains from neighboring countries were investigated. As previously reported, phylogenetic analysis of the avian influenza virus revealed two H5N1 HPAI clades that were circulating in Vietnam. Clade 1.1, related to Cambodian strains, was predominant in the southern provinces, while clade 2.3.2.1 viruses were predominant in the northern and central provinces. Sequence analysis revealed evidence of active genetic evolution. In the gene constellation of clade 2.3.2.1, genotypes A, B, and B(II) existed during the 2011/2012 winter season. In June 2012, new genotype C emerged by reassortment between genotype A and genotype B(II), and this genotype was predominant in 2013 in the northern and central provinces. Interestingly, enzootic Vietnamese clade 2.3.2.1C H5 virus subsequently reassorted with N2, which originated from wild birds, to generate H5N2 highly pathogenic avian influenza, which was isolated from duck in the northeast region. This investigation indicated that H5N1 outbreaks persist in Vietnam and cause genetic reassortment with circulating viruses. It is necessary to strengthen active influenza surveillance to eradicate highly pathogenic avian influenza viruses and sever the link between highly pathogenic avian influenza and other circulating influenza viruses.
尽管针对家禽开展了高致病性禽流感H5N1疫苗接种运动，但H5N1病毒仍在越南传播。为了估计越南禽流感病毒的流行情况，于2011年11月至2013年2月期间开展了监测。对从越南家禽中分离出的312株高致病性禽流感H5病毒进行了基因分析，并调查了与邻国毒株可能存在的基因关系。如先前报道，禽流感病毒的系统发育分析显示有两个H5N1高致病性禽流感分支在越南传播。与柬埔寨毒株相关的1.1分支在南部省份占主导地位，而2.3.2.1分支病毒在北部和中部省份占主导地位。序列分析揭示了活跃的基因进化证据。在2.3.2.1分支的基因组合中，A、B和B（II）基因型在2011/2012年冬季存在。2012年6月，新的C基因型通过A基因型和B（II）基因型之间的重配出现，并且该基因型在2013年在北部和中部省份占主导地位。有趣的是，越南地方流行的2.3.2.1C分支H5病毒随后与源自野生鸟类的N2进行了重配，产生了从东北地区鸭子中分离出的H5N2高致病性禽流感。这项调查表明H5N1疫情在越南持续存在，并导致与传播中的病毒发生基因重配。有必要加强主动流感监测，以根除高致病性禽流感病毒，并切断高致病性禽流感与其他传播中的流感病毒之间的联系。
