中国部分地区实验猕猴巴尔通体感染状况及其遗传特征

【目的】五日热巴尔通体(Bartonella quintana)由体虱在人群中传播,可引起多种人类疾病包括战壕热。为进一步搜集猕猴是五日热巴尔通体自然宿主的证据,本研究调查了国内4个地区实验用猕猴五日热巴尔通体的感染状况,对菌株遗传特征进行了分析。【方法】采集猕猴全血和血清样品各550份,用于菌株分离、核酸和血清IgG抗体检测。应用6个管家基因扩增及测序方法进行菌株鉴定、系统发育及核苷酸多态性分析;应用随机扩增多态性DNA标记(Random amplified polymorphic DNA,RAPD)技术分析不同宿主来源菌株RAPD指纹图谱差异;应用间接免疫荧光法(Indirect immunofluorescence assay,IFA)检测血清中抗五日热巴尔通体IgG抗体水平。【结果】从550只猕猴中分离到8株五日热巴尔通体菌株,带菌率为1.5%;直接PCR检测550份全血核酸的总感染率为8.2%。普通猕猴血清阳性率为19.0%,感染水平明显高于食蟹猕猴(5.6%)。五日热巴尔通体与汉赛巴尔通体RAPD指纹图谱的带型完全不同,猴源和人源五日热巴尔通体菌株Fuller带型基本一致。不同宿主来源菌株核苷酸多态性分析显示,猴源菌株之间差异小,其与人源菌株差异较大。【结论】中国猕猴五日热巴尔通体感染水平较高,普通猕猴自然感染率及抗体水平明显高于食蟹猕猴,猴源与人源菌株的基因型有明显差异。

Prevalence and genetic characteristics of Bartonella quintana in macaque populations of China

Objective] Bartonella quintana, transmitted by the body louse (Pediculus humanis), is the etiologic agent of a variety of disease manifestations in humans including trench fever. To further confirm if macaques can be the natural reservoir of B. quintana, we studied the infections of B. quintana in the experimental macaque populations from the four regions in China and characterized the islolates of B. quintana originated from the macaques.Methods] The samples of blood and serum collected from 550 macaques were used to isolate strains, detect the specific nucleic acid fragment and test IgG antibody. The molecular taxonomic characterization and nucleotide polymorphisms of the strains were analyzed based on the sequences of the six housekeeping genes using PCR, sequecing and phylogenetic analysis. The fingerprint pattern of random amplified polymorphic DNA (RAPD) were also used to discriminated the stains from the different hosts by the three random primers. The IgG antibody anti-B. quintana were detected using indirect iocmmunofluorescence assay (IFA).Results] Totally, 8 strains of B. quintana were isolated from 5 females and 3 males from 250 rhesus macaques in Sichuan province, with 3.2% infection rate. Our molecular test, detecting 550 blood samples using qPCR with a total of 8.2% infection rate of B. quintana, showed that the prevalence of macaques from Sichuan was significantly higher than that of the macaques from the other areas. The seropositivity rate was 19.0% in the rhesus macaques which was higher than that of the cynomolgus macaques (5.6%) and there was no difference between males and females and among the different areas. The RAPD-figerprints of the strains from the rhesus macaques in Sichuan province have an identical 8-bands pattern and was discriminated from the pattern of B. henselae. While the fingerprint of the human str. Fuller of B. quintana showed a 6-bands pattern. According to the nucleotide polymorphism analysis, the strains of B. quintana from different hosts show obvious genetic diversity. There was a higher diversity between the monkey strains and the human strains and a smaller difference among the monkey strains.Conclusion] There are high prevalence of B. quintana in the macaques population in China. The natural infection rate and antibody level in the rhesus macaques were significantly higher than that of the cynomolgus macaques. The genotype of the strains originated from the macaques is different from that of the strains from human. We demonstrated that the macaques are the natural reservoir of B. quintana.