Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam.
Transbound Emerg Dis. 2011 Dec;58(6):537-43. doi: 10.1111/j.1865-1682.2011.01229.x. Epub 2011 May 18.
We report 15 new avian influenza virus A/H5N1 haemagglutinin (HA) sequences sampled from visibly sick domestic poultry in southern Vietnam, between 1 January 2010 and 6 March 2010. These HA sequences form a new sub-clade of the clade 1 H5N1 viruses that have been circulating in Vietnam since 2003/2004. The viruses are characterized by a change from isoleucine to valine at position 514 (I514V) and are 1.8% divergent at the nucleotide level from HA sequences sampled in Vietnam in 2007. Five new amino acid changes were observed at previously identified antigenic sites, and three were located within structural elements of the receptor-binding domain. One new mutation removed a potential N-linked glycosylation site, and a methionine insertion was observed in one virus at the polybasic cleavage site. Five of these viruses were sampled from farms where poultry were vaccinated against H5N1, but there was no association between observed amino acid changes and flock vaccination status. Despite the current lack of evidence for antigenic drift or immune escape in Vietnamese H5N1 viruses, continued surveillance remains a high priority.
我们报告了 15 个新的禽流感病毒 A/H5N1 血凝素（HA）序列，这些序列是在 2010 年 1 月 1 日至 2010 年 3 月 6 日期间从越南南部可见病禽中采集的。这些 HA 序列形成了自 2003/2004 年以来在越南流行的 1 型 H5N1 病毒的一个新亚群。这些病毒的特征是第 514 位由异亮氨酸变为缬氨酸（I514V），与 2007 年在越南采样的 HA 序列在核苷酸水平上有 1.8%的差异。在先前确定的抗原位点观察到了 5 个新的氨基酸变化，其中 3 个位于受体结合域的结构元件内。一个新的突变消除了一个潜在的 N-连接糖基化位点，并且在一个病毒中观察到多碱性切割位点处有一个甲硫氨酸插入。其中 5 个病毒是从接种了 H5N1 疫苗的农场中采集的，但观察到的氨基酸变化与禽类接种状态之间没有关联。尽管目前没有证据表明越南 H5N1 病毒发生抗原漂移或免疫逃逸，但持续监测仍然是当务之急。
