Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, NY, USA.
mBio. 2012 Jul 31;3(4):e00166-12. doi: 10.1128/mBio.00166-12. Print 2012.
From September to December 2011, 162 New England harbor seals died in an outbreak of pneumonia. Sequence analysis of postmortem samples revealed the presence of an avian H3N8 influenza A virus, similar to a virus circulating in North American waterfowl since at least 2002 but with mutations that indicate recent adaption to mammalian hosts. These include a D701N mutation in the viral PB2 protein, previously reported in highly pathogenic H5N1 avian influenza viruses infecting people. Lectin staining and agglutination assays indicated the presence of the avian-preferred SAα-2,3 and mammalian SAα-2,6 receptors in seal respiratory tract, and the ability of the virus to agglutinate erythrocytes bearing either the SAα-2,3 or the SAα-2,6 receptor. The emergence of this A/harbor seal/Massachusetts/1/2011 virus may herald the appearance of an H3N8 influenza clade with potential for persistence and cross-species transmission.
The emergence of new strains of influenza virus is always of great public concern, especially when the infection of a new mammalian host has the potential to result in a widespread outbreak of disease. Here we report the emergence of an avian influenza virus (H3N8) in New England harbor seals which caused an outbreak of pneumonia and contributed to a U.S. federally recognized unusual mortality event (UME). This outbreak is particularly significant, not only because of the disease it caused in seals but also because the virus has naturally acquired mutations that are known to increase transmissibility and virulence in mammals. Monitoring the spillover and adaptation of avian viruses in mammalian species is critically important if we are to understand the factors that lead to both epizootic and zoonotic emergence.
2011 年 9 月至 12 月，162 只新英格兰港海豹因肺炎爆发而死亡。对尸检样本的序列分析显示，存在一种禽流感 H3N8 甲型流感病毒，类似于自 2002 年以来一直在北美的水禽中流行的病毒，但具有表明最近适应哺乳动物宿主的突变。这些突变包括病毒 PB2 蛋白中的 D701N 突变，此前在感染人类的高致病性 H5N1 禽流感病毒中已有报道。凝集素染色和凝集试验表明，海豹呼吸道中存在禽源偏好的 SAα-2,3 和哺乳动物 SAα-2,6 受体，并且该病毒能够凝集携带 SAα-2,3 或 SAα-2,6 受体的红细胞。这种 A/harbor seal/Massachusetts/1/2011 病毒的出现可能预示着具有潜在持久性和跨物种传播能力的 H3N8 流感谱系的出现。
新的流感病毒株的出现总是引起公众的极大关注，尤其是当感染新的哺乳动物宿主有可能导致广泛的疾病爆发时。在这里，我们报告了一种禽流感病毒（H3N8）在新英格兰港海豹中的出现，该病毒导致了肺炎爆发，并导致了美国联邦政府认可的不寻常死亡事件（UME）。此次爆发尤其重要，不仅因为它在海豹中引起的疾病，还因为该病毒自然获得了已知可增加哺乳动物传播性和毒力的突变。如果我们要了解导致动物传染病和人畜共患病出现的因素，那么监测禽病毒在哺乳动物物种中的溢出和适应就至关重要。
