从棘突蛋白基因重组探讨严重急性呼吸综合征冠状病毒的来源

Analysis on the recombination in spike gene,which can facilitate the exploration of severe acute respiratory syndrome coronavirus' origin

目的探讨SARS冠状病毒(SARS-CoV)的起源。方法运用生物信息学的方法,比较不同SARS样冠状病毒之间的异同,着重分析蝙蝠所携带的SARS样冠状病毒(SL-CoV)跨越种属屏障传播的可能性。结果除编码棘突蛋白(S蛋白)基因外,SARS-CoV与蝙蝠SL-CoV间编码结构蛋白的基因与编码复制酶的基因相似程度均很高;而S基因的差异主要集巾在S1片段,且该片段的GC含量与SARS-CoV基因组的GC含量明显不同。进一步分析表明,由S1片段构建的冠状病毒进化树与由S2片段构建的进化树存在拓扑结构上的不平行性。结论人类SARS病毒可能来源于蝙蝠SL-CoV,但在S基因内发生了基因重组事件,从而导致其获得跨越种属屏障传播的能力。

Objective To explore the origin of severe acute respiratory syndrome（SARS） coro- navirus（SARS-CoV） by analyzing the recombination in spike gene. Methods Utilized various bioin- formatic methods to compare the similarities and differences among several SARS-CoV with emphasis on analyzing the possibility that bat SARS like coronavirus might overcome the species barrier. Results Bat SARS-like coronavirus was very similar to SARS-CoV in most open reading frame （ORF）, except spike gene（S gene）. Further investigation revealed this difference mainly resulted from the variation in the S1 gene segment, which also had anomalous GC content in all SARS-CoV genomes. Moreover, phylogenetic tree reconstructed by S1 gene segment was topologically incongruent with that reconstructed by S2 gene segment. Conclusions The analyses indicate that the bat SARS-like coronavirus may be the origin of SARS-CoV when certain recombination occurs in S gene, which can help the former virus to overcome species barrier.