National Influenza Center and Department of Virology, Erasmus Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
J Virol. 2010 Feb;84(3):1597-606. doi: 10.1128/JVI.01783-09. Epub 2009 Nov 25.
Two viruses isolated during the highly pathogenic avian influenza (HPAI) H7N7 virus outbreak in The Netherlands in 2003, one isolated from a person with conjunctivitis and one from a person who died as the result of infection, were used for an in vitro study of influenza A virus pathogenicity factors. The two HPAI H7N7 viruses differed in 15 amino acid positions in five gene segments. Assays were designed to investigate the role of each of these substitutions in attachment and entry, transcription and genome replication, and virus production and release as determined by hemagglutinin (HA), polymerase proteins, nonstructural protein 1 (NS1), and neuraminidase (NA). These in vitro studies confirmed the roles of the E627K substitution in basic polymerase 2 (PB2) and the A143T substitution in HA in pathogenicity observed in a mouse model previously. However, the in vitro studies identified a contribution of acidic polymerase (PA) and NA to the efficient replication in human cells of the fatal case virus, despite the fact that these are rarely marked as determinants of pathogenicity in in vivo studies. With the exception of PB2 E627K, all substitutions contributing to enhanced replication of the fatal case virus in vitro were present in poultry viruses prior to transmission to the human fatal case, indicating that viruses with enhanced replication efficiency in the mammalian host can be generated in poultry. Thus, detailed in vitro analyses of mutations facilitating replication of avian influenza viruses in mammalian cells are important to assess the zoonotic risk posed by these viruses and, in addition, highlight the value of in vitro studies to complement animal models.
在 2003 年荷兰高致病性禽流感(HPAI)H7N7 病毒爆发期间分离的两种病毒,一种从结膜炎患者中分离,另一种从感染导致死亡的患者中分离,用于研究流感 A 病毒致病性因素的体外研究。两种 HPAI H7N7 病毒在五个基因片段的 15 个氨基酸位置上存在差异。设计了测定法来研究这些取代中的每一个在附着和进入、转录和基因组复制以及病毒产生和释放中的作用,这些作用是由血凝素(HA)、聚合酶蛋白、非结构蛋白 1(NS1)和神经氨酸酶(NA)决定的。这些体外研究证实了在先前的小鼠模型中观察到的基本聚合酶 2(PB2)中的 E627K 取代和 HA 中的 A143T 取代在致病性中的作用。然而,体外研究确定了酸性聚合酶(PA)和 NA 在人细胞中有效复制致命病例病毒的作用,尽管事实上,在体内研究中,这些很少被标记为致病性决定因素。除了 PB2 E627K 之外,所有有助于体外致命病例病毒复制增强的取代都存在于禽类病毒中,然后传播到人类致命病例中,这表明可以在禽类中产生在哺乳动物宿主中复制效率增强的病毒。因此,详细分析促进流感病毒在哺乳动物细胞中复制的突变对于评估这些病毒引起的人畜共患病风险非常重要,此外,还强调了体外研究补充动物模型的价值。