Vincent Gemma, Stenos John, Latham Jennie, Fenwick Stanley, Graves Stephen
Australian Rickettsial Reference Laboratory, University Hospital Geelong, Bellerine Street, Geelong, VIC 3220, Australia; School of Veterinary and Life Science, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia.
Microbiology Services Division, Public Health England, Manor Farm Road, Porton Down, Wiltshire SP4 0JG, United Kingdom.
Int J Med Microbiol. 2016 Sep;306(6):463-70. doi: 10.1016/j.ijmm.2016.05.014. Epub 2016 May 25.
Coxiella burnetii, the causative agent of Q fever, was first discovered in Australia in 1937. However, little is known about the strains of C. burnetii present in this country. In this study, six published genotyping methods were applied to 42 isolates from Australian patients with acute (n=39) and chronic (n=3) Q fever. All the isolates contained the plasmid QpRS and lacked the acute disease antigen A (adaA) gene. Two methods of genotyping based on single nucleotide polymorphisms (SNPs) also failed to discriminate between the isolates. However, results from the method based on SNPs within the multi-spacer sequence typing (MST) loci determined a novel MST genotype, with the Australian isolates forming a unique phylogenetic clade. Multi-locus variable number of tandem repeats (VNTR) analysis (MLVA) determined 14 genotypes, all of which were novel compared with those previously identified in strains from other countries. Many of these were single locus variants, differing from each other at just one of the 15 loci tested. Our results show that the Australian isolates exhibit significant diversity from previously characterised strains, but are genetically closely related to each other, supporting a model of evolution by clonal expansion in a geographically isolated location.
伯氏考克斯体是Q热的病原体，于1937年在澳大利亚首次发现。然而，对于该国存在的伯氏考克斯体菌株知之甚少。在本研究中，将六种已发表的基因分型方法应用于来自澳大利亚急性Q热患者（n = 39）和慢性Q热患者（n = 3）的42株分离株。所有分离株均含有质粒QpRS，且缺乏急性疾病抗原A（adaA）基因。两种基于单核苷酸多态性（SNP）的基因分型方法也无法区分这些分离株。然而，基于多间隔序列分型（MST）位点内SNP的方法的结果确定了一种新的MST基因型，澳大利亚分离株形成了一个独特的系统发育分支。多位点可变数目串联重复序列（VNTR）分析（MLVA）确定了14种基因型，与之前在其他国家菌株中鉴定出的基因型相比，所有这些基因型都是新的。其中许多是单一位点变体，仅在测试的15个位点中的一个位点上彼此不同。我们的结果表明，澳大利亚分离株与先前表征的菌株表现出显著的多样性，但它们在遗传上彼此密切相关支持了在地理隔离区域通过克隆扩增进行进化的模型。
