Schaefer Rejane, Rech Raquel Rubia, Gava Danielle, Cantão Mauricio Egídio, da Silva Marcia Cristina, Silveira Simone, Zanella Janice Reis Ciacci
Embrapa Swine and Poultry, Genetic and Animal Health Laboratory, Rodovia BR153, Km 110, Concórdia, SC, CEP 89700-000, Brazil,
Arch Virol. 2015 Jan;160(1):29-38. doi: 10.1007/s00705-014-2223-z. Epub 2014 Sep 11.
Passive monitoring for detection of influenza A viruses (IAVs) in pigs has been carried out in Brazil since 2009, detecting mostly the A(H1N1)pdm09 influenza virus. Since then, outbreaks of acute respiratory disease suggestive of influenza A virus infection have been observed frequently in Brazilian pig herds. During a 2010-2011 influenza monitoring, a novel H1N2 influenza virus was detected in nursery pigs showing respiratory signs. The pathologic changes were cranioventral acute necrotizing bronchiolitis to subacute proliferative and purulent bronchointerstitial pneumonia. Lung tissue samples were positive for both influenza A virus and A(H1N1)pdm09 influenza virus based on RT-qPCR of the matrix gene. Two IAVs were isolated in SPF chicken eggs. HI analysis of both swine H1N2 influenza viruses showed reactivity to the H1δ cluster. DNA sequencing was performed for all eight viral gene segments of two virus isolates. According to the phylogenetic analysis, the HA and NA genes clustered with influenza viruses of the human lineage (H1-δ cluster, N2), whereas the six internal gene segments clustered with the A(H1N1)pdm09 group. This is the first report of a reassortant human-like H1N2 influenza virus derived from pandemic H1N1 virus causing an outbreak of respiratory disease in pigs in Brazil. The emergence of a reassortant IAV demands the close monitoring of pigs through the full-genome sequencing of virus isolates in order to enhance genetic information about IAVs circulating in pigs.
自2009年以来，巴西一直在对猪群进行甲型流感病毒（IAV）的被动监测，主要检测到的是A(H1N1)pdm09流感病毒。从那时起，巴西猪群中经常观察到疑似甲型流感病毒感染的急性呼吸道疾病暴发。在2010 - 2011年的流感监测期间，在出现呼吸道症状的保育猪中检测到一种新型H1N2流感病毒。病理变化为颅腹侧急性坏死性细支气管炎至亚急性增生性和脓性支气管间质性肺炎。基于基质基因的逆转录定量聚合酶链反应（RT-qPCR），肺组织样本对甲型流感病毒和A(H1N1)pdm09流感病毒均呈阳性。在无特定病原体（SPF）鸡胚中分离出两种IAV。对两种猪H1N2流感病毒进行血凝抑制（HI）分析，结果显示它们与H1δ簇有反应性。对两种病毒分离株的所有八个病毒基因片段进行了DNA测序。根据系统发育分析，血凝素（HA）和神经氨酸酶（NA）基因与人类谱系的流感病毒（H1-δ簇，N2）聚类，而六个内部基因片段与A(H1N1)pdm09组聚类。这是关于源自大流行H1N1病毒的重组人样H1N2流感病毒在巴西猪群中引起呼吸道疾病暴发的首次报道。重组IAV的出现需要通过对病毒分离株进行全基因组测序来密切监测猪群，以增强关于在猪群中传播的IAV的遗传信息。
