Phylogenetic analysis of the N8 neuraminidase gene of influenza A viruses.
Phylogenetic analysis of the N8 neuraminidase gene of influenza A viruses.
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DOI：
10.1006/viro.1993.1196
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发表时间：
1993-04
期刊：
影响因子：
3.7
通讯作者：
T. Saito;Y. Kawaoka;R. Webster
中科院分区：
文献类型：
--
作者：
T. Saito;Y. Kawaoka;R. Webster
对来自18株代表不同地理位置的马和禽宿主的甲型流感病毒的N8神经氨酸酶（NA）基因进行系统发育分析，发现了3个主要谱系：（i）目前流行的马2型病毒;（ii）欧亚地区分离的禽病毒，包括A/Equine/Jilin/1/89，这是最近在中国马中发现的禽样N8分离株;及（iii）在北美洲分离的禽病毒。突变率的比较表明，鸟类N8基因的进化速度比马的相应基因要慢。也就是说，在这两种禽类谱系中，72%的核苷酸变化在系统发育树的末端分支中是沉默的，而在马2型病毒中，59%的核苷酸变化是沉默的。这表明哺乳动物免疫系统对NA基因施加了更大的选择压力，导致了渐进进化。或者，鸟类N8基因突变率较慢可能反映了从更长的连续进化中获得的选择优势。N8马2病毒谱系的系统发育树形状、进化速率和计算的起源日期与马2病毒血凝素（HA）基因的发现相当（Bean等人，J. Virol. 66，1129-1138，1992）。这表明马2型病毒的两种病毒膜糖蛋白一起进化，并受到相似水平的选择压力。发现几个氨基酸残基在三种宿主特异性谱系中不同，但它们可能不参与NA的宿主限制，因为它们是EQ/Jilin/1/89和禽源病毒所共有的。目前的研究结果补充了N2和N9亚型的详细结构信息，并应证明在理解未来的X射线衍射研究N8晶体的价值。
Phylogenetic analysis of the N8 neuraminidase (NA) genes from 18 influenza A viruses, representing equine and avian hosts in different geographic locations, revealed three major lineages: (i) currently circulating equine 2 viruses; (ii) avian viruses isolated in the Eurasian region, including A/Equine/Jilin/1/89, a recent avian-like N8 isolate found in horses in China; and (iii) avian viruses isolated in North America. Comparison of mutation rates indicated that avian N8 genes have evolved more slowly than their equine counterparts. That is, in both avian lineages, 72% of the nucleotide changes were silent in the terminal branches of the phylogenetic tree, whereas in equine 2 viruses, 59% of the nucleotide changes were silent. This suggests greater selective pressure on the NA gene from the mammalian immune system, leading to progressive evolution. Alternatively, the slower mutation rate for avian N8 genes could reflect a selective advantage gained from a longer, continuous span of evolution. The shape of the phylogenetic tree, the evolutionary rate, and the calculated date of origin for the N8 equine 2 virus lineage were comparable to findings for the equine 2 virus hemagglutinin (HA) gene (Bean et al., J. Virol. 66, 1129-1138, 1992). This suggests that both viral membrane glycoproteins of equine 2 viruses have evolved together and have been subjected to similar levels of selective pressure. Several amino acid residues were found to differ among the three host-specific lineages, but they may not be involved in host restriction of the NA, as they are shared by EQ/Jilin/1/89 and viruses of avian origin. The present findings complement detailed structural information on the N2 and N9 subtypes and should prove valuable in understanding future X-ray diffraction studies of N8 crystals.