@article{mbs:/content/journal/micro/10.1099/mic.0.25921-0, author = "Keller, S. M. and Viviani, M. A. and Esposto, M. C. and Cogliati, M. and Wickes, B. L.", title = "Molecular and genetic characterization of a serotype A MATaCryptococcus neoformans isolate", journal= "Microbiology", year = "2003", volume = "149", number = "1", pages = "131-142", doi = "https://doi.org/10.1099/mic.0.25921-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.25921-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = " Cryptococcus neoformans comprises two varieties (neoformans and gattii) and four serotypes (A, B, C and D). Fertile isolates of both mating types have been identified in serotypes B, C and D; however, a fertile serotype A MAT a strain has not been confirmed, although serotype A MATα strains will mate with serotype D MAT a strains. Preliminary analysis of a recent Italian environmental isolate (IUM 96-2828) suggested that this strain was haploid, serotype A and MAT a. In this study, IUM 96-2828 has been characterized in detail. A mating reaction between IUM 96-2828 and H99 (serotype A MATα) produced abundant spores with an equal distribution of MAT a and MATα progeny, all of which were serotype A. Karyotypic analysis of F1 spores revealed evidence of recombination, confirming that IUM 96-2828 was fertile. The MAT a pheromone gene from IUM 96-2828 was sequenced and found to be most closely related to the serotype D MAT a pheromone gene. Phylogenetic comparisons of other genes not linked to mating type also suggested IUM 96-2828 was most closely related to serotype A strains. Biochemical analysis showed that the carbon assimilation profiles of H99 and IUM 96-2828 were identical for 97 % (30/31) of the substrates while isozyme analysis showed 89 % (17/19) identity. Assays of major virulence factors found no difference between H99 and IUM 96-2828. Virulence studies using the mouse model demonstrated that IUM 96-2828 was virulent for mice, although it was less virulent than H99. These data strongly suggest that IUM 96-2828 is a true haploid serotype A MAT a isolate that is fertile.", }