Diaz M R, Boekhout T, Theelen B, Fell J W
Rosenstiel School of Marine and Atmospheric Science, University of Miami, Key Biscayne, Florida 33149, USA.
Syst Appl Microbiol. 2000 Dec;23(4):535-45. doi: 10.1016/S0723-2020(00)80028-4.
The pathogen Crytococcus neoformans has been traditionally grouped in two varieties, C. neoforrmans var. neoformans (serotypes A, D and AD) and C. neoformans var. gattii (serotypes B and C). A recent taxonomic evaluation of C. neoformans var. neoformans described C. neoformans var. grubii as a new variety represented by serotype A isolates. Despite immunological, biochemical, ecological and molecular differences the three varieties are classified within one species. We examined the genetic variability of one hundred and five clinical and environmental isolates that included all varieties and serotypes. Sequence analysis of the intergenic spacer (IGS) associated with rDNA revealed significant differences in nucleotide composition between and within the varieties. Parsimony analysis showed five different genotypes representing distinct genetic lineages. Although there was a high degree of relatedness between serotype and genotype this relatedness was not exclusive as serotypes were not restricted to one particular genotypic group. Serotyping and sequence analyses indicate that C. neoformans var. grubii (serotype A) should not be recognized as a separate variety. Based on this study we propose to accept two separate species, C. neoformans (serotypes A, D and AD) and C. bacillisporus (serotypes B and C synonymous with C. neoformans var. gattii).
新型隐球菌病原体传统上分为两个变种，即新型隐球菌变种新型隐球菌（血清型A、D和AD）和新型隐球菌变种格特隐球菌（血清型B和C）。最近对新型隐球菌变种新型隐球菌的分类学评估将新型隐球菌变种格鲁比隐球菌描述为一个由血清型A分离株代表的新变种。尽管这三个变种在免疫学、生物化学、生态学和分子方面存在差异，但它们仍被归为一个物种。我们检测了105株临床和环境分离株的遗传变异性，这些分离株包括所有变种和血清型。对与核糖体DNA相关的基因间隔区（IGS）进行序列分析，结果显示不同变种之间以及变种内部的核苷酸组成存在显著差异。简约分析显示有五种不同的基因型，代表着不同的遗传谱系。尽管血清型和基因型之间存在高度相关性，但这种相关性并非排他性的，因为血清型并不局限于某一个特定的基因型组。血清分型和序列分析表明，新型隐球菌变种格鲁比隐球菌（血清型A）不应被视为一个单独的变种。基于这项研究，我们建议接受两个独立的物种，即新型隐球菌（血清型A、D和AD）和芽孢隐球菌（血清型B和C，与新型隐球菌变种格特隐球菌同义）。
