某地区东方立克次体基因型和遗传特征研究

Genotype and hereditary feature analysis of Rickettsia orientalis in certain area

目的探讨某地区东方立克次体流行株的基因型和遗传特征。方法采用荧光定量PCR技术对该地区东方立克次体感染患者和鼠类标本Sta56蛋白编码基因片段检测,对阳性标本进行基因分型和测序,并与巢式PCR分型结果相比较;对测序结果与GenBank东方立克次体参考序列进行同源性分析。结果东方立克次体感染患者和鼠类标本中可扩增出Gilliam型523bp目的基因片段,与Kawasaki型相似,同源性为96.3%;鼠类标本中还可扩增出318bp目的基因片段,与TA686型相似,同源性为78.5%。东方立克次体感染患者外周血中东方立克次体核苷酸序列与鼠标本的同源性为100.0%。结论粤北山区东方立克次体至少存在Gilliam型和Kawasaki型相似株,鼠类中存在TA686型相似株。粤北山区人、鼠均存在东方立克次体自然感染,已成为恙虫病自然疫源地。

Objective To investigate the genotype and hereditary feature of prevalent strains of Rickettsia orientalis （Ro） in certain area.Methods Gene fragment,encoding Sta50 protein in samples of patients and mice infected by Ro,was detected by real-time fluorescent quantitative polymerase chain reaction assay （qPCR）.Positive samples were analyzed for genotype and sequence,and the results were compared with nest PCR.The homology was analyzed by comparison between sequencing results and nucleotide sequences of Ro registered in GenBank.Results The 523 bp fragments of Gilliam genotype could be amplified in samples of patients and mice,with homology of 96.3% with Kawasaki strain.The 318 bp fragment of Gilliam genotype could be amplified in samples of mice infected by Ro,with homology of 78.5% with TA686 strain.The homology of nucleotide sequences of Ro in samples from patients and mice was 100.0%.Conclusion Gilliam genotype and Kawasaki quasispecies could be detected among Ro in this area,and TA686 quasispecies could be detected in mice.Natural infection of Ro might exist in human and mice in this area,and natural foci of tsutsugamushi disease have formed.