Sexual reproduction and virulence of zygomycete fungi

描述(申请人提供)：卷状毛霉和米根霉是致命性真菌感染的最常见病原体，毛霉病是免疫功能低下患者的一种新出现的疾病，在血液系统恶性肿瘤患者和移植受者中都是第二常见的真菌感染。然而，与其他真菌病原体相比，人们对这些物种的毒力知之甚少。本研究重点研究了两个合菌种复合体的性发育遗传学和致病力。在为圆环毛霉提出的研究中，我们将研究编码三糖磷酸转运蛋白同源物、HMG结构域蛋白和RNA解旋酶的三个基因在三个相关毛霉亚种的共性基因座中的作用。这些基因在性发育过程中的表达模式将被研究。将产生每个基因和同基因菌株的中断突变，以测试它们在性发育中的作用。我们最近的研究发现，性基因座可能与圆环芽胞杆菌的孢子大小和毒力有关，在这种情况下，(-)菌株比()菌株产生更大的毒性孢子。我们将在三个宿主模型中研究共性基因如何参与孢子大小和致病力的决定：培养的巨噬细胞、蜡蛾和小鼠。同时，在对稻瘟病菌的研究中，我们将建立一个分类系统，对稻瘟病菌复合体中的两个亚种--稻瘟病菌和德尔玛稻瘟病菌进行分类。根据MLST和乳酸脱氢酶基因序列，将以高分辨率区分这两个亚种。我们的初步研究表明，稻瘟病菌是有性的和腐生的，而德尔玛稻瘟病菌在实验室条件下是不育的，可能更具致病力。我们还将进一步测试这两个亚种的性行为以及蜡蛾和老鼠的毒性，以探索性和毒性之间的联系。了解这些病原体的生活史和详细的系统发育将极大地提高我们的知识，开发新的药物靶点和诊断分型方法，并可能为控制人类致病合菌提供手段。 公共卫生相关性：毛霉病是一种机会性真菌感染，最近被认为是新出现的感染性疾病的原因，死亡率很高。然而，与其他真菌病原体相比，合子菌有性繁殖与致病的关系知之甚少。该项目将为开发新的药物靶点、确定引起感染的物种的分型方法以及可用于控制接合菌感染的信息提供洞察力。

DESCRIPTION (provided by applicant): Mucor circinelloides and Rhizopus oryzae are the most prevalent causal agents of the deadly fungal infection, mucormycosis, which is an emerging disease in immunocompromised patients and the second most common fungal infection in both hematopoietic malignancy patients and transplant recipients. However, considerably less is known about the virulence of these species compared to other fungal pathogens. This study focuses on the genetics of sexual development and pathogenicity of two zygomycete species complexes. In the studies proposed for M. circinelloides, we will investigate the roles of three genes that encode a triose phosphate transporter homolog, HMG domain protein, and RNA helicase in the syntenic sex locus of three related Mucor sub-species. The expression patterns of these genes during sexual development will be investigated. Disruption mutants of each gene and isogenic strains will be generated to test their roles in sexual development. Our recent studies found evidence that the sex locus may be involved in spore size and virulence of M. circinelloides, in which (-) isolates produce more virulent larger spores when compared to (+) isolates. We will investigate how genes in the syntenic sex locus are involved in spore size determination and virulence in three host models: cultured macrophages, the wax moth Galleria mellonella, and the mouse. In parallel, in the studies proposed for R. oryzae, we will establish a typing system to classify R. oryzae and R. delemar that are two sub-species in the R. oryzae complex. The two sub-species will be discriminated at high resolution based on MLST and lactate dehydrogenase gene sequences. Our preliminary studies indicate that R. oryzae is sexual and saprobic, whereas R. delemar is infertile under laboratory conditions and may be more virulent. We will also further test sexuality of the two sub-species as well as virulence in the wax moth and the mouse to investigate links between sexuality and virulence. Understanding the life cycles and detailed phylogeny of these pathogens will greatly enhance our knowledge to develop new drug targets and diagnostic typing approaches, and may provide the means to control human pathogenic zygomycetes. PUBLIC HEALTH RELEVANCE: Mucormycosis is an opportunistic fungal infection recently recognized as emerging cause of infectious disease with a high mortality rate. However, little is known about the relationship of sexual reproduction to pathogenesis in the zygomycetes compared to other fungal pathogens. This project will provide insight to develop novel drug targets, typing methodology to assign species causing infection, and information that can be applied to control zygomycete infections.