安徽三界地区啮齿动物感染恙虫病东方体调查

Investigation on rodents infection of Orientia tsutsugamushi in Sanjie,an area of An Hui province,China

目的调查安徽三界地区啮齿动物自然感染恙虫病东方体分离株,并确定其基因型别。方法流行季节在野外用鼠笼捕鼠并鉴定鼠种、携螨率;巢式PCR对鼠脏器进行恙虫病东方体56 kD基因片段检测;将鼠脏器接种小白鼠进行病原体分离,PCR扩增分离株Ot 56 kD基因片段,并将目的片段进行测序,基因序列同源性及进化分析。结果捕获啮齿动物数及其携螨率,黑线姬鼠60%(15/25);褐家鼠45.5%(5/11);东方田鼠和鼩鼱各2只,均阴性。40只野鼠脏器有3只恙虫病东方体PCR扩增阳性,阳性率为7.5%;从黑线姬鼠标本中分离到1株恙虫病东方体Sanjie,56 kD基因片段测定该株与台湾TT0711a和NT0511b分离株同源性最高(98%),系统发生树分析也显示与Kawasaki型共处于同一分支。结论安徽三界地区存在鼠类恙虫病东方体自然感染,黑线姬鼠为其主要宿主,当地恙虫病东方体属Kawasaki基因型。

The purpose of this study was to investigate the rodents infection of Orientia tsutsugamushi and determine the genetype of the Ot strain in Sanjie, anhui province. In epidemic season, the rodents were capturied and the mites were collected in the field, then the dominant kind of rodents were determined after classifying and calculating them. The DNA of 40 rodent spleens were detected by PCR; The mice were peritoneal injected by the homogenized spleen of rodents to isolate orientia tsut- sugamushi in this region. The partial gene of Ot 56 kD outmembrane protein was amplified from the spleen of infectious mice and sequneced. Phylogenetic tree was constructed on the 56 kD gene of 17 strains. The results showed that the captured ro- dents and the rates of carrying mite were Apodemus agrarius 25, 60 ~ （ 15/25） ; Rattus norvegicus 11,45.5 ~ （5 / 11 ）, Microtus fortis 2 and S. inutus Linnaeus with negative carrying mite rate respectively; The DNA of 3 spleen of rodents were positive by PCR using Ot specific primers. One Ot strain named Sanjie was isolated from Apodemus agrarius. The gene sequence of Sanjie 56kD protein showed 98~ homology with TT0711a and NT0511b strans isolated from Taiwan. Phylogenetic analysis showed that Sanjie was in the same branch with TT0711a and NT0511b, and the three were also in the same branch with kawasaki strain. This study indicated that Ot infection was presented in rodents from Sanjie and Apodemus agrarius was the main host. The genotype of Sanjie was determined as Kawasaki type.