[Molecular biological and clinical characteristics of respiratory syncytial virus in children with bronchiolitis].

Objective: To investigate the clinical characteristics of respiratory syncytial virus(RSV)bronchiolitis and molecular biological characteristics of RSV in children in Beijing. Method: In a systematic retrospective study, 2 296 nasopharyngeal aspirates (NPA) were collected from children diagnosed with bronchiolitis from July 2006 to June 2016 for respiratory virus screening using direct immunofluorescence assay (DFA). For specimens positive for RSV, subgroup A or B was confirmed by real time RT-PCR and genotype of RSV was determined by amplifying the full G glycoprotein gene and sequencing. Clinical data were evaluated by the modified Tal score to compare the severity between RSV subtypes, as well as genotypes. Statistical analyses were performed using t test, Mann-Whitney U test and χ(2) test. Result: In 2 296 bronchiolitis cases, 961(41.9%) were RSV positive, including 719(74.8%) RSV A and 236 (24.6%) RSV B. The dominant RSV subtype changed from year to year: A-A-B-B-A-A-B-AB-A-AB and more bronchiolitis cases were identified in RSV A dominant years. Six genotypes of RSV A (NA1, NA2, NA3, NA4, GA5 and ON1) and 5 genotypes of RSV B (BA3, BA7, BA9, BA10 and CB1) were prevalent in Beijing. The dominant genotypes of RSV A were NA1 (55.9%) with high rates (50.0%-100%) before 2014 and ON1 (39.1%), mainly detected after 2014, while BA9 (90.6%) was the absolute dominant RSV B genotype. No significant difference in the severity of bronchiolitis was shown between cases of RSV A and B. Children positive for NA1 were more likely to stay longer in hospital (Median time: 8 days) compared to the group positive for ON1(Median time: 6 days ) (U=1.035, P=0.005) and had higher proportion of moderate to severe degree symptoms (Moderate: 41.0%, Severe: 10.0%) compared with ON1 group (Moderate: 22.9%, Severe: 4.3%) (U=9.785, P=0.008). In the group positive for ON1, more children had fever (ON1: 38.6%, NA1: 15.0%) (χ(2)=11.064, P=0.001) and more were younger than 3 months(ON1: 54.3%, NA1: 33.0%) (χ(2)=77.408, P<0.001). Conclusion: The dominant RSV subgroup changed from year to year with a shifting pattern. The correlation between RSV genotypes and the severity of disease was documented in the study.目的： 探讨呼吸道合胞病毒(RSV)毛细支气管炎患儿的临床特征和病毒的分子生物学特征。 方法： 系统性回顾性研究，收集2006年7月至2016年6月首都儿科研究所毛细支气管炎患儿的鼻咽部分泌物标本(NPA)进行多种呼吸道病毒抗原检测；RSV阳性标本实时PCR法区分亚型；扩增RSV G蛋白全基因确定基因型别；改良Tal评分法评价疾病严重程度。采用t检验、Mann－Whitney U检验及χ(2)检验。 结果： 2 296例分泌物标本中，961例(41.9%)为RSV阳性，其中719例(74.8%)为RSV A亚型，236例(24.6%)为B亚型；10年间亚型转换模式为A－A－B－B－A－A－B－AB－A－AB，且在A亚型流行季发病例数较多。RSV G蛋白全基因序列分析结果提示6种A亚型基因型(NA1、NA2、NA3、NA4、GA5、ON1)和5种B亚型基因型(BA3、BA7、BA9、BA10、CB1)在北京地区被检出，A亚型中以NA1基因型(55.9%)和ON1基因型(39.1%)为主导基因型，2014年以前以NA1为主(50.0%～100%)，之后以ON1为主(68.0%～90.9%)；B亚型以BA9(90.6%)为绝对优势基因型。对比NA1感染与ON1感染患儿，NA1感染者中位住院时间8 d、ON1患儿中位住院时间6 d(U＝1.035，P＝0.005)，且其中重度者(中度：41.0% ，重度：10.0%)比ON1患儿(中度：22.9%，重度：4.3%)多(U＝9.785，P＝0.008)；而ON1患儿出现发热症状的比例(38.6%)较NA1感染者(15.0%)高(χ(2)＝11.064，P＝0.001)，其低月龄者(0～3月龄)所占比例(54.3%)高于NA1感染者(33.0%)(χ(2)＝77.408，P<0.001)。 结论： 北京地区毛细支气管炎患儿中RSV A、B亚型轮换或共同主导不同的流行季，多个基因型共同存在，基因型别与疾病的临床特征和严重程度存在一定相关性。.