Genetic Variation in Attachment Glycoprotein Genes of Human Respiratory Syncytial Virus Subgroups A and B in Children in Recent Five Consecutive Years

Human respiratory syncytial virus (HRSV) outranks other viral agents as the cause of respiratory tract diseases in children worldwide. Molecular epidemiological study of the virus provides useful information for the development of globally effective vaccine. We investigated the circulating pattern and genetic variation in the attachment glycoprotein genes of HRSV in Beijing during 5 consecutive seasons from 2007 to 2012. Out of 19,942 tested specimens, 3,160 (15.8%) were HRSV antigen-positive. The incidence of HRSV infection in males was significantly higher than in females. Of the total 723 (23.1%) randomly selected HRSV antigen-positive samples, 462 (63.9%) and 239 (33.1%) samples were identified as subgroup A and B, respectively. Subgroups A and B co-circulated in the 5 consecutive HRSV seasons, which showed a shifting mixed pattern of subgroup dominance. Complete G gene sequences were obtained from 190 HRSV-A and 72 HRSV-B by PCR for phylogenetic analysis. Although 4 new genotypes, NA3 and NA4 for HRSV-A and BA-C and CB1 for HRSV-B, were identified here, they were not predominant; NA1 and BA9 were the prevailing HRSV-A and -B genotypes, respectively. We provide the first report of a 9 consecutive nucleotide insertion in 3 CB1 genotype strains. One Beijing strain of ON1 genotype with a 72 nucleotide insertion was found among samples collected in February 2012. The reversion of codon states in glycosylation sites to previous ones were found from HRSV strains in this study, suggesting an immune-escape strategy of this important virus.人类呼吸道合胞病毒（Human respiratory syncytial virus, HRSV）是全球范围内引发儿童呼吸道疾病的首要病毒性病原体。该病毒的分子流行病学研究可为研发全球通用的有效疫苗提供重要依据。本研究针对2007至2012年连续5个流行季北京地区HRSV的流行模式及附着糖蛋白基因的遗传变异特征展开调查。在19942份检测样本中，3160份（15.8%）HRSV抗原检测呈阳性。男性HRSV感染率显著高于女性。在随机抽取的723份（占HRSV抗原阳性总样本的23.1%）阳性样本中，分别有462份（63.9%）和239份（33.1%）被鉴定为A亚型与B亚型。A、B两亚型在连续5个HRSV流行季中共同循环，呈现出亚型优势地位交替更迭的混合流行模式。研究人员通过PCR技术获取了190株HRSV-A和72株HRSV-B的完整G基因序列，用于系统发育分析。尽管本研究中鉴定出4种新型基因型：对应HRSV-A的NA3基因型（NA3 genotype）、NA4基因型（NA4 genotype），以及对应HRSV-B的BA-C基因型（BA-C genotype）和CB1基因型（CB1 genotype），但这些新型基因型并未成为优势流行株；HRSV-A与HRSV-B的优势基因型分别为NA1基因型（NA1 genotype）与BA9基因型（BA9 genotype）。本研究首次报道了3株CB1基因型毒株存在连续9个核苷酸的插入突变。在2012年2月采集的样本中，发现1株携带72个核苷酸插入突变的ON1基因型（ON1 genotype）北京毒株。本研究中的HRSV毒株出现了糖基化位点的密码子状态向既往状态的回复突变，提示该重要病毒存在免疫逃逸策略。