Department of Virology, Istituto Zooprofilattico Sperimentale della Lombardia ed Emilia Romagna, Via Bianchi, 9, 25124 Brescia, Italy.
Vet Res. 2013 Dec 1;44(1):112. doi: 10.1186/1297-9716-44-112.
European H1N2 swine influenza viruses (EU H1N2SIVs) arose from multiple reassortment events among human H1N1, human H3N2, and avian influenza viruses. We investigated the evolutionary dynamics of 53 Italian H1N2 strains by comparing them with EU H1N2 SIVs. Hemagglutinin (HA) phylogeny revealed Italian strains fell into four groups: Group A and B (41 strains) had a human H1 similar to EU H1N2SIVs, which probably originated in 1986. However Group B (38 strains) formed a subgroup that had a two-amino acid deletion at positions 146/147 in HA. Group C (11 strains) contained an avian H1 that probably originated in 1996, and Group D (1 strain) had an H1 characteristic of the 2009 pandemic strain. Neuraminidase (NA) phylogeny suggested a series of genomic reassortments had occurred. Group A had an N2 that originated from human H3N2 in the late 1970s. Group B had different human N2 that most likely arose from a reassortment with the more recent human H3N2 virus, which probably occurred in 2000. Group C had an avian-like H1 combined with an N2 gene from one of EU H1N2SIVs, EU H3N2SIVs or Human H3N2. Group D was part of the EU H3N2SIVs clade. Although selection pressure for HA and NA was low, several positively selected sites were identified in both proteins, some of which were antigenic, suggesting selection influenced the evolution of SIV. The data highlight different evolutionary trends between European viruses and currently circulating Italian B strains and show the establishment of reassortant strains involving human viruses in Italian pigs.
欧洲 H1N2 猪流感病毒（EU H1N2SIV）是由人流感 H1N1、人流感 H3N2 和禽流感病毒之间的多次重配事件产生的。我们通过比较意大利的 53 株 H1N2 株与 EU H1N2SIV，研究了这些病毒的进化动态。血凝素（HA）系统发育树显示，意大利株分为 4 组：A 组和 B 组（41 株）具有与 EU H1N2SIV 相似的人类 H1，可能起源于 1986 年。然而，B 组（38 株）形成了一个亚组，HA 中的 146/147 位有两个氨基酸缺失。C 组（11 株）含有可能起源于 1996 年的禽源 H1，D 组（1 株）含有与 2009 年大流行株特征相似的 H1。神经氨酸酶（NA）系统发育提示发生了一系列基因组重配。A 组具有一种起源于 20 世纪 70 年代后期的人类 H3N2 的 N2。B 组具有不同的人类 N2，最有可能是与最近的人类 H3N2 病毒发生重配的结果，可能发生在 2000 年。C 组具有一种禽源样的 H1 与来自 EU H1N2SIV、EU H3N2SIV 或人类 H3N2 的 N2 基因结合。D 组是 EU H3N2SIV 进化枝的一部分。尽管 HA 和 NA 的选择压力较低，但在这两种蛋白中都鉴定出了几个正选择位点，其中一些是抗原性的，表明选择影响了 SIV 的进化。这些数据突出了欧洲病毒与目前流行的意大利 B 株之间的不同进化趋势，并显示了涉及人类病毒的重配株在意大利猪中的建立。
