Abstract:

Objective In order to provide scientific basis for Brucellosis control and prevention, sero-epidemiological survey, Brucella isolation and genetic characteristic analysis were conducted for the high-risk population in a human Brucellosis epidemic in Weining county of Guizhou province. Methods Tube agglutination test was used to detect the anti-Brucella antibody for the high-risk human population. Rose Bengal Plate Test was applied to detect the antibody in goat blood samples. The blood of antibody positive human population was collected for Brucella isolation. Conventional methods, genus specific BCSP31-PCR and species-specific AMOS-PCR were used to identify the bacteria strain, and the genetic characteristic was analyzed using MLVA and MLST techniques. Results Six people of 43 high-risk populations were confirmed as anti-Brucella antibody positive, 64 out of 302 goat blood samples were anti-Brucella antibody positive, with positive rate of 21.19%. A suspected Brucella strain were isolated from one of the high-risk human populations and was identified as B. melitensis biovar 3. MLVA-16 analysis indicated that the bacteria strain was most closely clustered with B. melitensis biovar 3. Multilocus sequence typing analysis indicated the strain was ST8. Conclusion Genetic characteristic of Brucella strain isolated from the Brucelosis epidemic was consistent with that of M. melitensis biovar 3. Although antibody and Brucella were detected, the high-risk populations did not displayed symptoms, so all of them were asymptomatic infections. The epidemic was seemingly imported due to goats trading, suggested that health and animal disease control and prevention departments and doctors should pay great attention to it.

Key words: Brucella, Multiple-locus variable number tandem repeat analysis, Multilocus sequence typing

摘要：

目的 对贵州省威宁县一起人间布鲁氏菌病（布病）疫情中的高危人群进行血清学调查、菌株分离鉴定及遗传特征分析，为布病疫情的防控提供科学依据。方法 采用试管凝集试验对疫情中的高危人群进行抗体检测，采用虎红平板试验检测该起疫情中羊群血液布鲁氏菌抗体情况，分离抗体阳性患者病原菌进行培养，应用传统方法和布鲁氏菌属特异性PCR（BCSP31-PCR）、种/型特异性PCR（AMOS-PCR）对分离菌株进行鉴定，利用多位点可变数目串联重复序列分析（MLVA-16）和多位点序列分型（MLST）对菌株进行分子流行病学特征分析。结果 43名高危人群中布鲁氏菌抗体阳性6 名，抽取该疫情羊群血液302 份经虎红平板试验检测结果显示，阳性64 份，阳性率为21.19%。1名抗体阳性者分离出布鲁氏菌可疑菌，鉴定为羊种生物3型布鲁氏菌，MLVA-16结果显示与布鲁氏菌羊种生物3型聚类最近，MLST分析显示分离菌株为ST8型。结论 分离自该起疫情的菌株遗传特征和鉴定结果符合羊种生物3型布鲁氏菌，MLST结果为ST8型。尽管抗体阳性并分离出布鲁氏菌，但是无相关症状，均为布鲁氏菌隐性感染者。疑似因贩运羊只引入疫畜而导致布病疫情，应引起医生、卫生及动物检验检疫等相关部门重视。

关键词: 布鲁氏菌, 多位点可变数目串联重复序列分析, 多位点序列分型