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1.
【目的】研究我国首次临床分离的一株格特隐球菌VGII基因型菌株(XH91)的分子和表型特征。【方法】对受试株XH91进行血清型的分子鉴定;选取核基因组和线粒体基因组中共16个基因片段进行多位点序列分型;对受试株进行单倍体繁育、同性交配及异性交配能力评价;观察受试株的黑色素生成、荚膜厚度及37℃生长等表型特征。【结果】我国首株格特隐球菌VGII基因型菌株XH91为血清B型;该菌株在多位点序列分型上与温哥华岛致病基因型VGIIb一致;XH91能与a交配型发生交配,产生担孢子,而不能与α交配型发生交配且不具备单倍体繁育能力;XH91的黑色素生成、荚膜厚度及37℃生长等表型特征与参考株无明显差异。【结论】我国首株格特隐球菌VGII基因型菌株XH91在基因型、表型特征上均与温哥华岛VGIIb基因亚型一致,该结果将为我国格特隐球菌VGII基因型的分子流行病学和疾病监控提供重要资料。  相似文献   

2.
【目的】建立一种基于格特隐球菌α交配型位点内SXI1α基因和a交配型位点内SXI2a基因的多重PCR分析,用于快速鉴定格特隐球菌的交配型。【方法】设计针对格特隐球菌α交配型位点内SXI1α基因部分片段和格特隐球菌a交配型位点内SXI2a基因部分片段的特异性引物,用于多重PCR鉴定格特隐球菌的交配型;并与交配试验以及已报道的扩增α交配型位点的引物MFα、STE12α,及扩增a交配型位点的引物STE20a、STE3a进行扩增效果的比较。【结果】基于SXI1α基因和SXI2a基因的多重PCR分析,准确鉴定所有受试格特隐球菌(包括VGI、VGII、VGIII和VGIV基因型)的交配型,引物STE12α、STE20a和STE3a在常规PCR鉴定中不能鉴定部分菌株的交配型;66.7%的受试菌株不能发生交配,交配试验无法鉴定其交配型。【结论】建立的多重PCR方法明显优于常规PCR或交配试验鉴定。  相似文献   

3.
目的探讨中国广西地区格特隐球菌菌种复合体的基因型特点、种群结构特征和全球菌株的进化关系。方法收集2014—2018年间分离自临床确诊为隐球菌病患者的隐球菌临床株,利用CGB培养基初步筛选格特隐球菌菌种复合体。采用多位点序列分型方法(MLST)确定基因型。通过MEGA7软件构建系统发育树,利用R语言进行主成分分析。使用微量肉汤稀释法M27-A3方案行体外抗真菌药物敏感性检验。结果120株临床隐球菌中,分离出11株格特隐球菌菌种复合体,6株属于C.deuterogattii(AFLP6/VGII),5株属于C.gattii sensus stricto(AFLP4/VGI)。分离自广西的AFLP6/VGII呈遗传多样性,主要起源进化自南美巴西格特隐球菌菌种复合体。11株分离菌株均对常用抗真菌药物敏感。结论中国广西可能出现高致病性AFLP6/VGII,对格特隐球菌菌种复合体进行有效的全国性监测是必要的。  相似文献   

4.
目的鉴定1株格特隐球菌VGⅢ基因型中的少见基因亚型IGS5b及a交配型菌株。方法采用PCR指纹法、基因内间隔区(IGS)和磷脂酶基因(PLB1)测序分析鉴定基因型。采用PCR特异扩增法和交配试验鉴定交配型。采用GEF1基因序列分析同步鉴定基因型和交配型。结果结合PCR指纹法和序列分析,鉴定受试株RV63979为VGⅢ基因型中的少见基因亚型。针对交配型位点内STE12和STE20基因的特异性引物均扩增阴性。交配试验证实为a交配型。GEF1位点测序准确鉴定其基因型和交配型。结论本文通过多种鉴定手段结合IGS序列分析,鉴定1株VGⅢ基因型中的少见基因亚型IGS5b,证实VGⅢ基因型中至少存在IGS5a和IGS5b2种基因亚型。交配型分析表明该菌为VGⅢ基因型中少见的a交配型。  相似文献   

5.
张姝  张永杰 《微生物学通报》2015,42(8):1549-1560
【目的】分析3个细胞核蛋白编码基因(csp1、MAT1-1-1和MAT1-2-1)在不同冬虫夏草菌株间的分子进化。【方法】从125个冬虫夏草样品中分别扩增csp1、MAT1-1-1和MAT1-2-1基因序列,比较外显子和内含子间以及2个交配型基因间的序列变异程度,比较基于不同基因或基因区域所构建的系统发育树拓扑结构的差异,分析3个基因承受的选择压力和DNA重组情况。【结果】3个蛋白编码基因外显子区的长度在不同菌株间高度保守,具有4.5%?5.7%的变异位点;内含子区的长度在不同菌株间相同或不同,具有1.8%?22%的变异位点。对于2个交配型基因,MAT1-1-1的碱基变异率低于MAT1-2-1。基于外显子与内含子构建的系统发育树的拓扑结构,以及基于2个交配型基因外显子构建的系统发育树的拓扑结构都存在明显差异。3个蛋白编码基因都经历着净化选择作用。基因内部的不同DNA位点间有重组,但3个基因片段之间没有明显的重组发生。【结论】由于冬虫夏草菌不同基因以及基因的不同区域表现出进化上的差异,所以在开展冬虫夏草菌进化相关的研究时,应该联合使用多个不同的基因片段。  相似文献   

6.
目的 构建格特隐球菌HOG1基因缺陷株和HOG1基因重建株.方法 从格特隐球菌基因组扩增HOG1基因,通过部分基因缺失方法,获得缺陷基因dHOG1.将获得的HOG1基因及其缺陷基因dHOG1分别亚克隆到真核表达载体pGAPzα-A,构建pGAPzα-HOG1及pGAPzcα-dHOG1质粒.将pGAPzα-dHOG1质粒转染隐球菌原始株,通过筛选获得HOG1基因缺陷菌株;同样方法将pGAPzα-HOG1质粒转染格特隐球菌HOGI基因敲除菌株,获得HOGI基因重建株.结果 RTPCR结果示:格特隐球菌HOG1基因缺陷株不转录表达完整的HOG1基因,而HOG1基因重建株可以转录表达完整的HOG1基因片段.结论 成功获得格特隐球菌HOG1缺陷株和HOG1基因重建株,为后续格特隐球菌毒力和致病机制的研究奠定了基础.  相似文献   

7.
目的:了解及比较两组毒力差异明显的新生隐球菌格鲁比变种的多位点序列分型(MLST)的特点并进行交配型鉴定。方法采用多位点序列分型(MLST)的方法,设计7个看家基因(CAP59,GPD1,LAC1,PLB1,SOD1,URA5和IGS1)的引物,扩增并分析来源分别为环境和临床的各10株新生隐球菌格鲁比变种的基因型,并鉴定实验菌株交配型,与多位点微卫星分型(MLMT)结果对比,比较不同基因分型方法在分类中的稳定性和可靠性。结果在微卫星分型中为MLMT-36的10株环境分离株,MLST分型为ST-15,而在微卫星分型中为MLMT-13型的10株临床分离株,MLST分型为ST-32,所有菌株交配型均为MAT-α。结论MLST分型结果与MLMT分型结果高度一致,提示以上两种分子分型技术在真菌分类鉴定研究中可显示对于其分离背景及进化来源的高分辨率及稳定性。  相似文献   

8.
本文旨在调查2003 年1 月― 2007 年12 月分离自上海地区获得性免疫缺陷综合征( AIDS) 患者的新生隐球菌临床株的配型及基因型分布特征, 为隐球菌病的诊疗提供科学依据。首先以M13 为单引物对模板DNA 进行聚合酶链反应( PCR) 扩增, 参照标准株指纹图将临床株鉴定至基因型; 同时对12 株来自AIDS 患者的新生隐球菌临床株的内转录间隔区( ITS) 基因进行PCR 扩增、序列分析, 以CLUSTAL W1. 83 软件多重比对分析ITS序列的差别,MEGA3. 1 软件处理数据, NJ 法绘制系统进化树, Bootstrapping 法对系统进化树结果进行统计学检验, 区分新生隐球菌格鲁比变种、新生变种及格特变种菌株; 最后选用特异性引物PCR 特异性扩增相关基因, 鉴定α和a 配型。结果显示, 分离自上海地区的12 株隐球菌临床株中, 9 株( 75% ) 为VNⅠ基因型/ α配型菌株,3 株( 25%) 为VNⅡ基因型/ α配型菌株, 且ITS基因序列分析可将各临床株鉴定至变种水平。本研究提示, 分离自上海地区AIDS患者的新生隐球菌临床株存在一定的遗传多态性, 以VNⅠ基因型/ α配型菌株为主, 有少量VNⅡ基因型/ α配型菌株。  相似文献   

9.
为了解中国大陆地区新生隐球菌临床株基因型分布情况, 我们对来自我国中东部地区的18个省、直辖市的120株血清A型和9株血清B型新生隐球菌临床株采用PCR指纹分析、IGS序列测定和MLST(Multilocus sequencing test)方法进行分析。结果显示血清A型菌株的M13指纹图谱中主要条带与VNI型标准株相同, 但次要条带与VNI现有各亚型均不相符, 我们将这种新VNI亚型命名为VNIc型, 但VNIc型并不只分布在中国大陆, MLST分析显示中国大陆地区的VNIc型菌株同来自美国、日本、马拉维和巴西的7株菌株亲缘关系高达75, 提示VNIc型可能是一种世界范围内分布的基因型; 对血清A型菌株采用(GACA)4和URA-5 RFLP指纹分析则呈现与VNI标准株完全一致的主次条带; 9株血清B型菌株基因型为VGI型。本研究初步揭示了我国大陆地区新生隐球菌临床株的基因型分布。  相似文献   

10.
张姝  崔宁波  赵宇翔  张永杰 《微生物学报》2019,59(12):2346-2356
【目的】分析蛹虫草是否存在核内线粒体DNA片段,比较蛹虫草线粒体DNA与细胞核DNA的碱基变异程度及所反映的菌株间的系统发育关系。【方法】通过本地BLAST或LAST对蛹虫草线粒体基因组和核基因组进行序列相似性搜索;从10个已知线粒体基因组的蛹虫草菌株中分别扩增7个细胞核蛋白编码基因片段,并与其在14个线粒体蛋白编码基因上的碱基变异情况进行比较。【结果】蛹虫草核基因组中存在5处较短的核内线粒体DNA片段,总长只有278bp。蛹虫草核DNA的变异频率整体上高于线粒体DNA。核DNA和线粒体DNA所反映的蛹虫草菌株间的系统发育关系存在显著差异。【结论】蛹虫草线粒体DNA与核DNA间不存在长片段的基因交流,二者变异频率不同,所反映的蛹虫草菌株间的系统发育关系也有差异。本研究增加了对蛹虫草线粒体与细胞核DNA进化关系的认识。  相似文献   

11.
The inheritance of mitochondrial genes and genomes are uniparental in most sexual eukaryotes. This pattern of inheritance makes mitochondrial genomes in natural populations effectively clonal. Here, we examined the mitochondrial population genetics of the emerging human pathogenic fungus Cryptococcus gattii . The DNA sequences for five mitochondrial DNA fragments were obtained from each of 50 isolates belonging to two evolutionary divergent lineages, VGI and VGII. Our analyses revealed a greater sequence diversity within VGI than that within VGII, consistent with observations of the nuclear genes. The combined analyses of all five gene fragments indicated significant divergence between VGI and VGII. However, the five individual genealogies showed different relationships among the isolates, consistent with recent hybridization and mitochondrial gene transfer between the two lineages. Population genetic analyses of the multilocus data identified evidence for predominantly clonal mitochondrial population structures within both lineages. Interestingly, there were clear signatures of recombination among mitochondrial genes within the VGII lineage. Our analyses suggest historical mitochondrial genome divergence within C. gattii , but there is evidence for recent hybridization and recombination in the mitochondrial genome of this important human yeast pathogen.  相似文献   

12.
Cryptococcus gattii is a primary pathogenic basidiomycetous yeast comprising four genotypic groups. Here we present data on two mitochondrial loci (MtLrRNA and ATP6 ). Two of the genotypic groups, namely amplified fragment length polymorphism (AFLP)5/VGIII and AFLP6/VGII, formed monophyletic lineages. The AFLP4/VGI genotypic group, however, possessed five different mitochondrial genotypes that did not form a monophyletic lineage. The majority of these isolates contained mitochondrial genomes that are partially identical to those found in isolates belonging to AFLP6/VGII, which is causing the ongoing and expanding Vancouver Island outbreak. Two out of four AFLP7/VGIV isolates contained an AFLP4/VGI allele of MtLrRNA. These observations are best explained by assuming a process of mitochondrial recombination. If this is true, mitochondrial recombination seems possible between cells belonging to different genotypic groups of C. gattii , especially between AFLP6/VGII or AFLP7/VGIV and AFLP4/VGI. We also have to assume that mitochondria, most likely, were transferred from cells belonging to AFLP6/VGII to AFLP4/VGI. As such a process of mitochondrial recombination is only possible after cell–cell conjugation, this may also allow the further exchange of genetic material, for example nuclear or plasmid in nature, between different genotypes of C. gattii . This may be relevant as it may provide a possible mechanism contributing to the modulation of virulence attributes of isolates, such as has been observed in the ongoing Vancouver Island outbreak of C. gattii .  相似文献   

13.
Feng X  Yao Z  Ren D  Liao W  Wu J 《FEMS yeast research》2008,8(6):930-938
Cryptococcosis has been reported to be mostly associated with non-HIV-related patients in China. However, little is known about the molecular characteristics of clinical isolates from the Cryptococcus neoformans species complex in this country. In this study, 115 clinical isolates were included. Molecular type VNI was the most representative ( n =103), followed by VGI ( n =8), VNIII ( n =2), VNIV ( n =1), and VGII ( n =1). With the exception of a serotype D mating type a isolate, all possessed the MAT α locus. Multilocus sequence typing (MLST) revealed that most Cryptococcus gattii isolates from China shared identical MLST profiles with the most common MLST genotype reported in the VGI group, and the only one VGII isolate resembled the Vancouver Island outbreak minor genotype. The C. gattii strains involved in this study were successfully grouped according to their molecular type and mating types by PCR-restriction fragment length polymorphism (RFLP) analysis of the GEF1 gene. Our results suggest that (1) in China, cryptococcosis is mostly caused by C. neoformans var. grubii (molecular type VNI), and mating type α; (2) The most common causative agents of C. gattii infection in China are closely related to a widely distributed MLST genotype; and (3) The PCR-RFLP analysis of the GEF1 gene has the potential to identify the molecular and mating types of C. gattii simultaneously.  相似文献   

14.
Cryptococcus gattii has recently emerged as a pathogen of humans and animals in the temperate climate of Vancouver Island, British Columbia (B.C.). The majority (approximately 95%) of the isolates from the island belong to the VGII molecular type, and the remainder belong to the VGI molecular type. The goals of this study were to compare patterns of molecular variation among C. gattii isolates from B.C. with those from different areas of the world and to investigate the population structure using a comparative gene genealogy approach. Our results indicate that the C. gattii population in B.C. comprises at least two divergent lineages, corresponding to previously identified VGI and VGII molecular types. The genealogical analysis of strains suggested a predominantly clonal population structure among B.C. isolates, while there was evidence for sexual recombination between different molecular types on a global scale. We found no geographic pattern of strain relationships, and nucleotide sequence comparisons revealed that genotypes among isolates from B.C. were also present among isolates from other areas of the world, indicating extensive strain dispersal. The nucleotide sequence diversity among isolates from B.C. was similar to that among isolates from other areas of the world.  相似文献   

15.
Disease caused by the pathogenic yeast Cryptococcus gattii begins with the inhalation of an infectious propagule. As C. gattii is heavily encapsulated, this propagule is most likely to be a basidiospore. However, most C. gattii strains are infertile in laboratory crosses, and population studies indicate that recombination and dispersal are very restricted. In addition, strains of the alpha mating type predominate, which would not be expected in a mating population. C. gattii comprises four genetically distinct molecular genotypes, designated VGI to VGIV. C. gattii molecular type VGI has a strong association with Eucalyptus camaldulensis and can be found in high numbers in E. camaldulensis hollows. Previous work on isolates obtained from E. camaldulensis suggested that environmental populations of C. gattii are highly fragmented, have limited ability to disperse, and are confined to individual tree hollows. In the current study, we examined large numbers of isolates from three separate hollows for evidence of recombination. In two hollows, the alpha and a mating types were present in approximately equal numbers. The third hollow had alpha cells only and was from a region where a isolates have never been found. Statistical analysis of multilocus genotypes revealed recombining subpopulations in the three Eucalyptus hollows. Recombination was equally present in the alpha-a and alpha-only populations. This is consistent with recent studies that have found evidence suggestive of alpha-alpha mating in C. gattii and Cryptococcus neoformans and raises the possibility this may be a widespread phenomenon, allowing these fungi to recombine despite a paucity of a mating partners.  相似文献   

16.
Cryptococcus neoformans and Cryptococcus gattii are pathogenic yeasts causing meningoencephalitis in immunocompromised and immunocompetent hosts. The fungus is typically haploid, and sexual reproduction occurs normally between individuals with opposite mating types, α and a. C. neoformans var. grubii (serotype A) is comprised of molecular types VNI, VNII, and VNB, and C. neoformans var. neoformans (serotype D) contains the molecular type VNIV. Additionally, diploid or aneuploid AD hybrids (VNIII) have been reported. C. gattii contains the molecular types VGI, VGII, VGIII, and VGIV, which encompass both serotypes B and C. To identify possible hybrid strains, URA5-RFLP analysis was performed on 350 globally obtained clinical, environmental, and veterinary isolates. Four clinical isolates from cerebrospinal fluid showed combination patterns of C. neoformans var. grubii and C. gattii: Brazil (n = 2), Colombia (n = 1), and India (n = 1). These strains were monokaryotic and diploid or aneuploid. M13 PCR fingerprinting showed that they contained fragments of both proposed parental groups. Luminex IGS genotyping identified these isolates as hybrids with two different molecular type combinations: three VNI/VGII and one VNI/VGI. Blue color development on CGB agar was delayed in three isolates and absent in one. C. gattii-specific PCR confirmed the presence of C. gattii in the hybrids. CAP59 allele-specific PCR revealed that all the hybrids contained both serotype A and B alleles. Determination of mating-type allelic patterns by PCR revealed that the isolates were αA aB. This is the first study discovering novel natural hybrids between C. neoformans molecular type VNI and C. gattii molecular type VGII.  相似文献   

17.
The Cryptococcus species complex contains two sibling taxa, Cryptococcus neoformans and Cryptococcus gattii. Both species are basidiomycetous yeasts and major pathogens of humans and other mammals. Genotyping methods have identified major haploid molecular types of C. neoformans (VNI, VNII, VNB and VNIV) and of C. gattii (VGI, VGII, VGIII and VGIV). To investigate the phylogenetic relationships among these haploid genotypes, we selected 73 strains from 2000 globally collected isolates investigated in our previous typing studies, representing each of these genotypes and carried out multigene sequence analyses using four genetically unlinked nuclear loci, ACT1, IDE, PLB1 and URA5. The separate or combined sequence analyses of all four loci revealed seven clades with significant support for each molecular type. However, three strains of each species revealed some incongruence between the original molecular type and the sequence-based type obtained here. The topology of the individual gene trees was identical for each clade of C. neoformans but incongruent for the clades of C. gattii indicating recent recombination events within C. gattii. There was strong evidence of recombination in the global VGII population. Both parsimony and likelihood analyses supported three major clades of C. neoformans (VNI/VNB, VNII and VNIV) and four major clades of C. gattii (VGI, VGII, VGIII and VGIV). The sequence variation between VGI, VGIII and VGIV was similar to that between VNI/VNB and VNII. MATa was for the first time identified for VGIV. The VNIV and VGII clades are basal to the C. neoformans or the C. gattii clade, respectively. Divergence times among the seven haploid monophyletic lineages in the Cryptococcus species complex were estimated by applying the hypothesis of the molecular clock. The genetic variation found among all of these haploid monophyletic lineages indicates that they warrant varietal status.  相似文献   

18.
Cryptococcus gattii infections in southern California have been reported in patients with HIV/AIDS. In this study, we examined the molecular epidemiology, population structure, and virulence attributes of isolates collected from HIV/AIDS patients in Los Angeles County, California. We show that these isolates consist almost exclusively of VGIII molecular type, in contrast to the VGII molecular type isolates causing the North American Pacific Northwest outbreak. The global VGIII population structure can be divided into two molecular groups, VGIIIa and VGIIIb. Isolates from the Californian patients are virulent in murine and macrophage models of infection, with VGIIIa significantly more virulent than VGIIIb. Several VGIII isolates are highly fertile and produce abundant sexual spores that may serve as infectious propagules. The a and α VGIII MAT locus alleles are largely syntenic with limited rearrangements compared to the known VGI (a/α) and VGII (α) MAT loci, but each has unique characteristics including a distinct deletion flanking the 5' VGIII MATa alleles and the α allele is more heterogeneous than the a allele. Our studies indicate that C. gattii VGIII is endemic in southern California, with other isolates originating from the neighboring regions of Mexico, and in rarer cases from Oregon and Washington state. Given that >1,000,000 cases of cryptococcal infection and >620,000 attributable mortalities occur annually in the context of the global AIDS pandemic, our findings suggest a significant burden of C. gattii may be unrecognized, with potential prognostic and therapeutic implications. These results signify the need to classify pathogenic Cryptococcus cases and highlight possible host differences among the C. gattii molecular types influencing infection of immunocompetent (VGI/VGII) vs. immunocompromised (VGIII/VGIV) hosts.  相似文献   

19.
Cryptic species are common in Diplodia, a genus that includes some well-known and economically important plant pathogens. Thus, species delimitation has been based on the phylogenetic species recognition approach using multigene genealogies. We assessed the potential of mating type (MAT) genes sequences as phylogenetic markers for species delimitation in the genus Diplodia. A PCR-based mating type diagnostic assay was developed that allowed amplification and sequencing of the MAT1-1-1 and MAT1-2-1 genes, and determination of the mating strategies used by different species. All species tested were shown to be heterothallic. Phylogenetic analyses were performed on both MAT genes and also, for comparative purposes, on concatenated sequences of the ribosomal internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1-α) and beta-tubulin (tub2). Individual phylogenies based on MAT genes clearly differentiated all species analysed and agree with the results obtained with the commonly used multilocus phylogenetic analysis approach. However, MAT genes genealogies were superior to multigene genealogies in resolving closely related cryptic species. The phylogenetic informativeness of each locus was evaluated revealing that MAT genes were the most informative loci followed by tef1-α. Hence, MAT genes can be successfully used to establish species boundaries in the genus Diplodia.  相似文献   

20.
The molecular types of 443 Brazilian isolates of Cryptococcus neoformans and Cryptococcus gattii were analyzed to determine their geographic distribution within Brazil and their underlying host conditions. The following data, imported from previous epidemiological studies as well as two culture collections, were analyzed for: place of isolation, source (clinical or environmental), host risk factors, species, serotype, mating type, and molecular type. Molecular typing by PCR-fingerprinting using primers for the minisatellite-specific core sequence of the wild-type phage M13 or microsatellites [(GACA)4, (GTG)5], restriction fragment length polymorphism of URA5 gene analysis, and/or amplified fragment length polymorphism (AFLP) identified eight major genotypes: VNI/AFLP1, VNII/AFLP1A, VNIII/AFLP2, and VNIV/AFLP3 for C. neoformans, and VGI/AFLP4, VGII/AFLP6, VGIII/AFLP5, and VGIV/AFLP7 for C. gattii. The most common molecular type found in Brazil was VNI (64%), followed by VGII (21%), VNII (5%), VGIII (4%), VGI and VNIV (3% each), and VNIII (< 1%). Primary cryptococcosis caused by the molecular type VGII (serotype B, MAT) prevails in immunocompetent hosts in the North and Northeast regions, disclosing an endemic regional pattern for this specific molecular type in the Northern Brazil.  相似文献   

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