Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
mSphere. 2024 Jun 25;9(6):e0000924. doi: 10.1128/msphere.00009-24. Epub 2024 May 21.
Histoplasmosis is an endemic mycosis that often presents as a respiratory infection in immunocompromised patients. Hundreds of thousands of new infections are reported annually around the world. The etiological agent of the disease, is a dimorphic fungus commonly found in the soil where it grows as mycelia. Humans can become infected by through inhalation of its spores (conidia) or mycelial particles. The fungi transition into the yeast phase in the lungs at 37°C. Once in the lungs, yeast cells reside and proliferate inside alveolar macrophages. Genomic work has revealed that is composed of at least five cryptic phylogenetic species that differ genetically. Three of those lineages have received new names. Here, we evaluated multiple phenotypic characteristics (colony morphology, secreted proteolytic activity, yeast size, and growth rate) of strains from five of the phylogenetic species of to identify phenotypic traits that differentiate between these species: , , , , and an African lineage. We report diagnostic traits for three species. The other two species can be identified by a combination of traits. Our results suggest that (i) there are significant phenotypic differences among the cryptic species of and (ii) those differences can be used to positively distinguish those species in a clinical setting and for further study of the evolution of this fungal pathogen.IMPORTANCEIdentifying species boundaries is a critical component of evolutionary biology. Genome sequencing and the use of molecular markers have advanced our understanding of the evolutionary history of fungal pathogens, including , and have allowed for the identification of new species. This is especially important in organisms where morphological characteristics have not been detected. In this study, we revised the taxonomic status of the four named species of the genus (), , , and and propose the use of species-specific phenotypic traits to aid their identification when genome sequencing is not available. These results have implications not only for evolutionary study of but also for clinicians, as the species could determine the outcome of disease and treatment needed.
组织胞浆菌病是一种地方性真菌病，常发生于免疫功能低下的患者的呼吸道感染。全球每年报告数十万例新感染病例。该疾病的病原体是一种双相真菌，通常存在于土壤中，以菌丝形式生长。人类可以通过吸入其孢子（分生孢子）或菌丝颗粒而感染。真菌在 37°C 的肺部转变为酵母相。一旦进入肺部，酵母细胞就会在肺泡巨噬细胞内寄居和增殖。基因组研究表明，至少有五个遗传上不同的隐生种组成了。其中三个谱系获得了新的名称。在这里，我们评估了来自五个组织胞浆菌属隐生种的菌株的多种表型特征（菌落形态、分泌的蛋白水解活性、酵母大小和生长速度），以确定可区分这些种的表型特征：，，，，和一个非洲谱系。我们报告了三个种的诊断特征。其他两个种可以通过特征组合来识别。我们的结果表明：（i）隐生种之间存在显著的表型差异，（ii）这些差异可用于在临床环境中区分这些种，并进一步研究该真菌病原体的进化。
确定物种界限是进化生物学的一个关键组成部分。基因组测序和分子标记的使用促进了我们对真菌病原体（包括）进化历史的理解，并允许识别新的物种。在形态特征尚未被发现的生物体中，这一点尤为重要。在这项研究中，我们修订了该属（）的四个命名种（）、、、和的分类地位，并提出使用种特异性表型特征来辅助在无法进行基因组测序时识别它们。这些结果不仅对组织胞浆菌的进化研究具有重要意义，而且对临床医生也具有重要意义，因为种可能决定疾病的结果和所需的治疗。
