杭州地区严重急性呼吸道感染住院患儿人博卡病毒感染的流行病学特征及其遗传进化研究

Epidemiological characteristics and genetic evolution of human bocavirus infection in hospitalized children with severe acute respiratory infection in Hangzhou

目的 对杭州地区严重急性呼吸道感染（SARI）住院患儿人博卡病毒（HBoV）感染的流行病学特征及其遗传进化进行研究.方法 连续收集2011年1月至2014年12月浙江大学医学院附属儿童医院SARI住院患儿病例样本共1388份,采用荧光定量PCR进行HBoV1～4及其他常见呼吸道病原体检测,采用普通PCR对HBoV1阳性样本进行VP1全基因扩增和测序,所得序列采用Clustal X和MEGA 6.0软件进行分析.采用χ2检验和Fisher确切概率法进行数据统计分析.结果1388份SARI住院患儿样本中,共检出HBoV阳性85份,阳性检出率为6.12％,其中83份（97.65％）阳性样本为HBoV1,2份（2.35％）阳性样本为HBoV2.男性和女性患儿HBoV阳性检出率分别为6.54％和5.35％（χ2=0.780,P〉0.05）.各年龄段HBoV阳性检出率比较,差异具有统计学意义（χ2=47.446,P〈0.01）.〉6个月～1岁年龄段HBoV阳性检出率最高,为12.84％,〉3岁年龄段检出率最低,仅1.64％,≤6个月和〉1～3岁年龄段HBoV阳性检出率相当,为3.04％和3.33％.按季节划分,HBoV检出率最高的是夏季（14.97％）,其次是秋季（7.14％）,春季（3.19％）和冬季（1.97％）检出率较低（χ2=58.807,P〈0.01）.HBoV在2011至2014年各年的检出率分别为7.39％、7.31％、5.58％和4.72％（χ2=3.447,P〉0.05）.合并其他呼吸道病原体感染率为62.35％,主要病原体为人鼻病毒（33.96％）、副流感病毒（28.30％）和呼吸道合胞病毒（20.75％）等.HBoV感染阳性患儿中气促和喘鸣的比例均高于阴性患儿（χ2=15.161和13.914,P值均〈0.01）.VP1基因序列分析发现,44株与瑞典株ST2属于同一分支,另2株毒株HZ12-S32和HZ12-S199单独成一分支.结论 HBoV是杭州地区SARI住院患儿中的重要病原体,与其他呼吸道病原体有较高的合并感染. 大部分毒株与瑞典株ST2属同一分支,HZ12-S32和HZ12-S199两株毒株进化关系较远,单独成一新的分支.

Objective To study the epidemiological characteristics and genetic evolution of human bocavirus （ HBoV ） infection in hospitalized children with severe acute respiratory infection （ SARI ） in Hangzhou.Methods A total of 1388 clinical specimens were collected from children with SARI admitted in Affiliated Children＇ s Hospital, Zhejiang University School of Medicine from January 2011 to December 2014.HBoV1-4 and other respiratory pathogens were identified by fluorescent real -time polymerase chain reaction （fRT-PCR）.The VP1 gene in HBoV1 positive samples was amplified and sequenced for genetic analysis with Clustal X and MEGA 6.0.Chi-square test and Fisher exact probability were used to analyze the data.Results Eighty five HBoV positive samples were detected from 1388 samples （6.12％）, among which 83 （97.65％） were HBoV1 positive and 2 （2.35％） were HBoV2 positive.The positive rates of HBoV in males and females were 6.54％and 5.35％（χ2 =0.780, P〉0.05）.The posititve detection rate of HBoV in all age groups was statistically significant （χ2 =47.446,P 〈0.01）.The detection rate in children aged 6 months-1 year was highest （12.84％）, in children aged 〉3 years was lowest （1.64％）, in children aged ≤6 months and aged 1-3 years was 3.04％ and 3.33％, respectively.The detection rate of HBoV in summer was the highest （14.97％）, followed by that in autumn （7.14％）, spring （3.19％） and winter （1.97％） （χ2 =58.807, P〈0.01）.The detection rates of HBoV in 2011 to 2014 were 7.39％, 7.31％, 5.58％ and 4.72％ （χ2 =3.447, P 〉0.05 ）.The co-infection rate with other respiratory pathogens was 62.35％.The main pathogens were human rhinovirus （33.96％）, parainfluenza virus （28.30％） and respiratory syncytial virus （20.75％）.The incidence of anhelation and wheezing in HBoV positive group was higher than that in HBoV negative group （χ2 =15.161 and 13.914, P 〈0.01）. Sequence analysis of VP 1 gene showed that 44 isolates belonged to the same branch （ clade 1 ） as Swedish strain ST2, and 2 isolates HZ12-S32 and HZ12-S199 belonged to a separated branch.Conclusion HBoV is an important causative agent of hospitalized children with SARI in Hangzhou area and has high co -infection with other respiratory pathogens.Most of the strains belong to the same clade as the Swedish strain ST 2, and two strains of HZ12-S32 and HZ12-S199 are identified in a separated clade.