Peng Michael M, Meshnick Steve R, Cunliffe Nigel A, Thindwa Benson D M, Hart C Anthony, Broadhead Robin L, Xiao Lihua
Centers for Disease Control and Prevention, Atlanta, GA, USA.
J Eukaryot Microbiol. 2003;50 Suppl:557-9. doi: 10.1111/j.1550-7408.2003.tb00628.x.
Few studies have examined the molecular epidemiology of cryptosporidiosis in developing countries. In this study, DNA of 69 microscopy-positive human fecal samples collected from Malawi were examined by multilocus genetic analyses. From 43, 27 and 28 of the samples, the SSU rRNA, 70 kDa heat shock protein (HSP70) and 60 kDa glycoprotein (GP60) genes, respectively, were successfully PCR-amplified. Restriction analysis of the SSU PCR products showed that 41 of the 43 PCR-positive samples had C. hominis and 2 had C. parvum. Sequence analysis of the HSP70 and GP60 gene confirmed the species identification by SSU rRNA PCR-RFLP analysis, but also revealed high intraspecific variations. Altogether, six HSP70 subtypes and six GP60 subtypes (belonging to four subtype alleles) of C. hominis were found. Linkage disequilibrum analysis of the two genetic loci showed possible intraspecific recombination. Thus, cryptosporidiosis in the study area was largely caused by anthroponotic transmission. The high intraspecific variation and existence of genetic recombination were probably results of high transmission of cryptosporidiosis in this area.
很少有研究调查发展中国家隐孢子虫病的分子流行病学。在本研究中，对从马拉维收集的69份显微镜检查呈阳性的人类粪便样本的DNA进行了多位点基因分析。分别从43份、27份和28份样本中成功PCR扩增出小亚基核糖体RNA（SSU rRNA）、70 kDa热休克蛋白（HSP70）和60 kDa糖蛋白（GP60）基因。对SSU PCR产物的限制性分析表明，43份PCR阳性样本中有41份为微小隐孢子虫，2份为鼠隐孢子虫。HSP70和GP60基因的序列分析证实了通过SSU rRNA PCR-RFLP分析进行的物种鉴定，但也揭示了种内的高度变异。总共发现了微小隐孢子虫的六种HSP70亚型和六种GP60亚型（属于四个亚型等位基因）。对两个基因位点的连锁不平衡分析显示可能存在种内重组。因此，研究区域的隐孢子虫病主要由人传人传播引起。种内的高度变异和基因重组的存在可能是该地区隐孢子虫病高传播率的结果。
