2020-2022年湖南省鼠类钩端螺旋体病监测与菌株分型

Epidemiological surveillance and typing of Leptospira strains in rodents in Hunan Province during 2020—2022

目的初步了解湖南省钩端螺旋体病主要宿主动物鼠类的流行病学概况及分离菌株血清学和MLST基因型特征。方法2020-2022年在湖南省湘潭、涟源、双峰及浏阳4个钩体病监测点,开展鼠种构成调查、钩体分离培养、菌株鉴定工作。采用暗视野显微凝集试验(Microscopic agglutination test,MAT)对分离菌株开展血清群鉴定。利用MLST(Multilocus sequence typing)方法开展基因分型分析,分别对7个位点(glmU、pntA、sucA、tpiA、pfkB、mreA和caiB)进行普通PCR扩增、测序、序列分析。结果4个湖南钩体病监测点共捕啮齿类和食虫目动物461只,平均鼠密度为2.52%,共分离菌株56株,来源于黑线姬鼠、黄胸鼠和鼩鼱3个种类,钩体分离率是12.15%。湖南省4个监测点以黑线姬鼠为优势鼠种,占88.72%。经MAT鉴定显示:56株湖南钩体分离株隶属于黄疸出血群和澳洲群两个血清群,黄疸出血群为当地主要流行血清群,占94.64%。MLST分型结果显示:56株湖南省分离株ST型别包括ST1、ST128和ST1053个基因型,其中ST1(57.14%)和ST128(37.50%)为湖南主要流行ST型。利用BioNumerics软件进行UPGMA聚类分析显示:56株菌株被分为3个不同Clades,分别对应3个不同ST型,ST型分布在不同动物种类和地域上呈现明显差异。结论黄疸出血群、ST1和ST128为湖南省主要流行型别,初步了解湖南省钩端螺旋体病鼠类动物流行病学概况及流行菌株分子分型特征,对湖南省钩体病的防控和疫苗制备提供科学依据。

To investigate the epidemiology and conduct etiological characterization of pathogenic Leptospira,we trapped 461 rodents and soricidae belonging to seven species in four regions with leptospirosis cases in Hunan province during 2020-2022.The density of rodents was 2.52%,and the most prevalent rodent species in these four regions was Apodemus agrarius.A total of 56 pathogenic Leptospira isolates from Apodemus agrarius,Rattus flavipectus and Sorex araneus Linnaeus were successfully isolated;the isolation rate in rodents was 12.15%.Microscopic agglutination tests(MATs)with 15 Chinese standard serogroup-specific rabbit antisera were conducted for serogroup identification.Multilocus sequence typing(MLST)based on seven loci(glmU,pntA,sucA,tpiA,pfkB,mreA and caiB)was performed for genotyping.Two serogroups were identified among the 56 Leptospira isolates.Icterohaemorrhagiae was the dominate serogroup,accounting for 94.64%.Three sequence types(STs),ST1,ST128 and ST105,were identified through MLST analysis.ST1(57.14%)and ST128(37.50%)were the dominant STs in Hunan.Phylogenetic analysis using UPGMA in BioNumerics software version 5.1 identified three clades(clades 1-3)corresponding to three different STs among the 56 pathogenic Leptospira isolates.The leptospiral diversity of STs differed across animal species and regions in Hunan.Icterohaemorrhagiae was the main serogroup;and ST1 and ST128 were the main STs in Hunan.The epidemiology of rodents and the detailed serological and molecular characteristics of strains circulating in this province may aid in developing strategies or guidelines for vaccine preparation and the control of leptospirosis in Hunan.