Genotype and mating type analysis ofCryptococcus neoformansandCryptococcus gattiiisolates from China that mainly originated from non-HIV-infected patients

Abstract

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 MATalpha 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 alpha; (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.

Development of a Singleplex PCR Assay for Rapid Identification and Differentiation of Cryptococcus neoformans var.grubii, Cryptococcus neoformans var. neoformans, Cryptococcus gattii, and Hybrids

“…neoformans and C. neoformans var. grubii, respectively, by the PCR analysis, which was in correspondence with other reports using single or a few target genes (3,10,11). This result may be due to genomic instability in AD hybrid strains with loss of heterozygosity for the allele of STR1 gene, which may be resolved by molecular tools designed for use at the whole-genome level, such as amplified fragment length polymorphism (AFLP) and PCR fingerprinting (2,7,19).…”

Cryptococcus gattii Infections

“…It has always been present in the southern temperate zone of Australia. The global distribution of the four major molecular types of C. gattii has been determined by analyses of clinical, animal, and environmental isolates from several studies (33,38,40,(72)(73)(74)(75)(76)(77)(78)(79)(80)(81); W. Meyer and L. Trilles, unpublished data). Acknowledging potential sample biases, in contrast to previous reports, in which the most frequent molecular type was VGI (48,80), VGII is now more common (comprising 47% of all isolates), followed by VGI (34%), VGIII (11%), and VGIV (8%) (Fig.…”

Rapid Differentiation of Cryptic Species within Cryptococcus gattii by a Duplex PCR Assay

“…The four molecular types are also considered cryptic species due to sequence divergence and no nuclear recombination events observed between them (1, 9). The cryptic species differ in their biologies, epidemiologies, virulence characteristics, antifungal susceptibilities, and geographic distributions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Among the four cryptic species, VGII is more concerning because of the outbreak of the C. gattii VGII genotype in the Pacific Northwest and Australia, as well as its higher virulence in experimental models, mating efficiency, and decreased susceptibility to antifungal agents (1,(10)(11)(12)(13)(14)16).…”

“…A wide geographic distribution, other than restriction in tropical and subtropical areas, has been recognized for this species in many studies (1)(2)(3)(4)(5)(6)(7). Based on genetic differences, four molecular types, VGI to VGIV, within C. gattii have been determined (8).…”

“…In addition, VGI accounts for the most cryptococcal cases caused by C. gattii around the world and has the widest geographic distribution (1, 2, 7); VGIII and VGIV are more geographically restricted and usually associated with HIV-infected cases (5,15). Several molecular tools have been developed to distinguish the four cryptic species (1,7,8,(16)(17)(18)(19)(20)(21). However, these techniques include time-consuming and laborious PCR-based methods or molecular methods requiring expensive instruments.…”