Bialek R, Ibricevic A, Fothergill A, Begerow D
Institut für Tropenmedizin, Universitätsklinikum Tübingen, Tübingen, Germany.
J Clin Microbiol. 2000 Sep;38(9):3190-3. doi: 10.1128/JCM.38.9.3190-3193.2000.
The similarities of paracoccidioidomycosis and blastomycosis are highly suggestive of a close relation of the two etiological agents. Whereas the agent of the first disease is exclusively endemic in Latin America, the agent of the latter one is endemic in North America and Africa. In symptomatic travelers visiting both areas of endemicity, differentiation of the diseases might be impossible, even though therapy and prognosis for these two diseases differ significantly. In order to identify differences in the 18S rRNA gene (rDNA) for use as molecular diagnostic tools, we sequenced this gene from five isolates of Paracoccidioides brasiliensis and compared them to known sequences of other fungi. Neighbor-joining, maximum parsimony, and maximum likelihood analyses and, finally, the Kishino-Hasegawa test revealed that P. brasiliensis, Blastomyces dermatitidis, and Emmonsia parva are more closely related than Histoplasma capsulatum and B. dermatitidis, whose teleomorphic forms belong to one genus, Ajellomyces. In accordance with the work of other investigators who have used internal transcribed spacer and large subunit rDNA sequences, our small subunit rDNA data show that the dimorphic fungus P. brasiliensis must be grouped within the order Onygenales and is closely related to members of the family Onygenaceae. There are hints in the molecular phylogenetic analysis that the family Onygenaceae might be further divided into two families. The subgroup that includes P. brasiliensis comprises all zoopathogenic species. The differences in the 18S rDNAs appear to be too small to allow species identification of the members of the family Onygenaceae pathogenic for humans by use of target sequences within this gene.
副球孢子菌病和芽生菌病的相似性强烈提示这两种病原体存在密切关系。第一种疾病的病原体仅在拉丁美洲流行，而后者的病原体在北美和非洲流行。在有症状的旅行者访问这两个流行地区时，即使这两种疾病的治疗方法和预后有显著差异，也可能无法区分这两种疾病。为了确定18S核糖体RNA基因（rDNA）的差异以用作分子诊断工具，我们对来自巴西副球孢子菌的五个分离株的该基因进行了测序，并将它们与其他真菌的已知序列进行了比较。邻接法、最大简约法和最大似然法分析，以及最后的木村-早川检验表明，巴西副球孢子菌、皮炎芽生菌和小埃蒙斯菌比荚膜组织胞浆菌和皮炎芽生菌的关系更密切，后者的有性型属于一个属，即阿耶洛霉属。根据其他研究人员使用内转录间隔区和大亚基rDNA序列的研究结果，我们的小亚基rDNA数据表明，双态真菌巴西副球孢子菌必须归入爪甲团囊菌目，并且与爪甲团囊菌科的成员关系密切。分子系统发育分析中有迹象表明，爪甲团囊菌科可能会进一步分为两个科。包括巴西副球孢子菌的亚组包含所有动物致病性物种。18S rDNA的差异似乎太小，无法通过该基因内的靶序列对人类致病的爪甲团囊菌科成员进行物种鉴定。
