2018-2019年河北省流感流行特征及乙型流感病毒Victoria系血凝素基因特征分析

Epidemiological characteristics of influenza and characteristics of hemagglutinin gene of B-Victoria strains in Hebei Province from 2018 to 2019

目的了解2018-2019年河北省流感流行特征,分析乙型流感病毒Victoria(BV)系毒株血凝素(HA)基因特征和变异情况。方法于2018年4月至2019年3月,在河北省28所国家级哨点医院采集发热3 d内的流感样病例(ILI)咽拭子标本,同时通过"中国流感监测信息系统"收集2018-2019年河北省ILI的监测数据。对ILI的咽拭子标本进行核酸检测、病毒分离,并选取不同地区的14株BV毒株进行HA基因测序,利用DNASTAR 7.0和Mega-X软件分析HA基因序列特征并构建进化树。结果 2018-2019年,河北省28所国家级流感监测哨点医院共监测门、急诊病例总数为4 689 103例,ILI例数为 99 266例(2.12%);共检测ILI样本18 730份,流感病毒核酸阳性2 752份(14.69%),检出高峰在2019年第3周(44.92%),流行前期以甲型H1N1为主,流行后期以BV为主。HA基因序列分析显示14株BV病毒均属于162-164位氨基酸缺失株,氨基酸同源性为97.16%~100%,与疫苗株B/Colorado/06/2017相比氨基酸同源性为97.16%~98.95%,涉及11个氨基酸位点突变。结论 2018-2019年河北省流感冬、春季流行,BV流行毒株有多个抗原位点发生了变异,可能是引起暴发疫情的原因。

Objective To understand the epidemiological characteristics of influenza in Hebei Province from 2018 to 2019,and to analyze the characteristics and variation of hemagglutinin(HA)gene of influenza B-Victoria(BV)strains.Methods Throat swab specimens of influenza-like cases within 3 days of fever were collected from 28 sentinel hospitals in Hebei province,meanwhile,The surveillance data was collected by the Chinese National Influenza Surveillance Network from April 2018 to March 2019,Throat swab specimens were collected from patients with influenza-like symptoms in sentinel hospitals,and tested by RT-PCR and virus isolation.14 influenza B-Victoria strains from different regions were selected to sequence HA gene,Phylogenetic tree and the molecular characteristics were analyzed by DNASTAR 7.0 and Mega-X software.Results From 2018 to 2019,A total of 99266 cases of influenza-like illness(ILI)were detected from 4689103 cases by 28 influenza sentinel hospitals in Hebei Province,the visit percentage of ILI was 2.12%.During the period,18730 samples were detected,and 2752(14.69%)samples were positive tested by RT-PCR,the peak was in the third week of 2019(44.92%),In the early stage of epidemic season,Influenza A(H1N1)pdm09 virus was the main type,while BV virus was the main type in the late stage.HA gene sequence analysis showed that the 14 BV viruses belonged to 162-164 amino acid deletion strains,the amino acid homology between HA sequences was 97.16%-100.00%,and 97.16%-98.95%compared with the vaccine strain B/Colorado/06/2017 recommended by WHO.Compared with the vaccine strains,14 strains involved 11 amino acid site mutations.Conclusion Influenza was prevalent in winter and spring in Hebei province from 2018 to 2019,Multiple mutations in antigenic sites of BV viruses might be related to the outbreaks.