Replacement and Positive Evolution of Subtype A and B Respiratory Syncytial Virus G-Protein Genotypes From 1997-2012 in South Africa
Replacement and Positive Evolution of Subtype A and B Respiratory Syncytial Virus G-Protein Genotypes From 1997-2012 in South Africa
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DOI：
10.1093/infdis/jit477
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发表时间：
2013-12-15
影响因子：
6.4
通讯作者：
Venter, Marietjie
中科院分区：
文献类型：
--
作者：
Pretorius, Marthi A.;van Niekerk, Stephanie;Venter, Marietjie
背景。呼吸道合胞病毒（RSV）基因型以前在南非于1997-2002年描述，只有GA2和GA5持续到2006年，BA取代了所有以前的RSV- b基因型。这就提出了RSV-A是否比RSV-B更稳定以及正选择是否驱动基因型进化的问题。在2009-2012年期间随机选择RSV阳性标本，进行亚型分型、测序，并与1997-2001年和2006-2009年期间获得的标本中回收的RSV进行比较。对g蛋白进行贝叶斯系统发育分析。系统发育分析表明，RSV-A基因型GA2溶解形成SAA2（南非特有）、NA1和NA2（日本发现）和ON1（加拿大发现，插入72bp）， GA5在1999-2012年间漂移形成3个亚基因型（GA5 I-III）。RSV-B基因型均具有BA基因型典型的60 bp插入，但聚集在BA8-10亚基因型中。两种亚型的g蛋白均存在正选择，但RSV-A的进化速度比RSV-B慢，其最近的共同祖先分别为1945年和1951年。在南非菌株中发现7个新的阳性选择位点，其中2个为RSV-A位点，5个为rsv - b位点。阳性选择驱动RSV-A和-B基因型进化，在南非15年的研究期间导致所有基因型的替换。
Background. Of the respiratory syncytial virus (RSV) genotypes previously described in South Africa during 1997-2002, only GA2 and GA5 persisted until 2006, with BA having replaced all previous RSV-B genotypes. This poses the question whether RSV-A is more stable than RSV-B and whether positive selection drives evolution of genotypes.Methods. RSV-positive specimens were randomly selected during 2009-2012, subtyped, sequenced, and compared to RSV recovered from specimens obtained during 1997-2001 and 2006-2009. Bayesian phylogenetic analysis was performed on the G-protein.Results. Phylogenetic analysis indicated that RSV-A genotype GA2 dissolved to form SAA2 (unique to South Africa), NA1 and NA2 (identified in Japan), and ON1 (identified in Canada and having a 72-bp insertion) and that GA5 drifted from 1999-2012 to form 3 subgenotypes (GA5 I-III). RSV-B genotypes all had the 60-bp insertion typical of BA genotypes but clustered into subgenotypes BA8-10. Positive selection was identified in the G-protein of both subtypes, but RSV-A's rate of evolution was slower than that of RSV-B, with the most recent common ancestors dating from 1945 and 1951, respectively. Seven new positively selected sites were identified in South African strains, 2 for RSV-A and 5 for RSV-B.Conclusion. Positive selection drove both RSV-A and -B genotypes to evolve, resulting in replacement of all genotypes over the 15-year study period in South Africa.