Global distribution of respiratory syncytial virus A and B infections: a systematic review

Respiratory syncytial virus (RSV) is the main cause of severe respiratory infections in young children. The need for global epidemiologic data regarding RSV has been increasingly recognized. RSV A infections are reported more frequently than RSV B. Nonetheless, the temporal distribution of infections caused by both RSV groups has not been investigated globally. A systematic review was carried out regarding published studies on RSV A and B epidemiology, as well as RSV G gene ectodomain sequence data available at GenBank. A total of 76,668 [45,990 (60%) RSV A and 30,678 (40%) RSV B] positive samples from 83 countries were identified and included in the analysis. Genotype assignment was obtained in 5,340 RSV A and 2,518 RSV B sequences. Two patterns of RSV circulation were observed: continuous seasons with RSV A predominance and alternate predominance of RSV A and B. These patterns were observed in all regions, but the predominant RSV group seldom coincided in all continents during a given year or season. The most frequently identified RSV A genotype was NA1 (including ON1 viruses) (76.30%), and the most frequently identified RSV B genotype was BA (70.65%). Multiple genotypes circulated simultaneously throughout the evolutionary history of RSV, but genotype diversity decreased after the year 2000. The classification of RSV group and genotype is important for the development of vaccines, as well as to understand viral dynamics. This study displays the global and continental RSV circulation patterns from the first report of human RSV infection until the end of 2020.

呼吸道合胞病毒（Respiratory syncytial virus, RSV）是引发婴幼儿重症呼吸道感染的首要病因。全球范围内对呼吸道合胞病毒流行病学数据的需求日益受到重视。据报道，A型呼吸道合胞病毒（RSV A）感染的检出频率高于B型呼吸道合胞病毒（RSV B）。然而，目前全球范围内尚未针对两类呼吸道合胞病毒感染的时间分布特征开展系统性研究。本研究针对已发表的A型、B型呼吸道合胞病毒流行病学相关研究，以及基因银行（GenBank）数据库中收录的呼吸道合胞病毒G基因胞外域序列数据开展了系统综述。最终共纳入来自83个国家的76668份阳性样本，其中A型呼吸道合胞病毒阳性样本45990份（占比60%），B型呼吸道合胞病毒阳性样本30678份（占比40%）。在5340条A型呼吸道合胞病毒序列与2518条B型呼吸道合胞病毒序列中完成了基因型分型。研究观察到两类呼吸道合胞病毒流行模式：一类为A型呼吸道合胞病毒持续占优的流行季，另一类为A型与B型呼吸道合胞病毒交替占优的流行季。两类流行模式在全球各区域均有发现，但在任意一年或一个流行季内，各大洲的优势呼吸道合胞病毒亚型极少完全一致。检出频率最高的A型呼吸道合胞病毒基因型为NA1（包含ON1毒株），占比76.30%；检出频率最高的B型呼吸道合胞病毒基因型为BA，占比70.65%。在呼吸道合胞病毒的整个进化历程中，曾有多种基因型同时流行，但2000年后其基因型多样性有所下降。呼吸道合胞病毒亚型与基因型的分类，对于疫苗研发以及解析病毒传播动力学均具有重要意义。本研究梳理了自人类首次报道呼吸道合胞病毒感染以来，直至2020年末的全球及各大洲呼吸道合胞病毒流行模式。