Identification of virulence mutants of the fungal pathogen Cryptococcus neoformans using signature-tagged mutagenesis.

Journal Article (Journal Article)

Cryptococcus neoformans var. neoformans is an important opportunistic fungal pathogen of patients whose immune system has been compromised due to viral infection, antineoplastic chemotherapy, or tissue transplantation. As many as 13% of all AIDS patients suffer a life-threatening cryptococcal infection at some time during the course of their HIV disease. To begin to understand the molecular basis for virulence in Cryptococcus neoformans var. neoformans serotype A, we have employed signature-tagged mutagenesis (STM) to identify mutants with altered virulence in a mouse model. The critical parameters of signature-tagged mutagenesis in C. neoformans are explored. Data are presented showing that at least 100 different strains can be mixed together in a single animal with each participating in the infection and that there is no apparent interaction between a virulent strain and an avirulent strain in our animal model. Using signature-tagged mutagenesis, we identified 39 mutants with significantly altered growth in a competitive assay. Molecular analyses of these mutants indicated that 19 (49%) contained an insertion in the actin promoter by homologous recombination from a single crossover event, creating a duplication of the actin promoter and the integration of single or multiple copies of the vector. Analysis of the chromosomal insertion sites of those mutants that did not have an integration event in the actin promoter revealed an approximately random distribution among the chromosomes. Individual challenge of the putative mutants in a mouse model revealed five hypovirulent mutants and one hypervirulent mutant.

Full Text

Duke Authors

Cited Authors

  • Nelson, RT; Hua, J; Pryor, B; Lodge, JK

Published Date

  • March 2001

Published In

Volume / Issue

  • 157 / 3

Start / End Page

  • 935 - 947

PubMed ID

  • 11238384

Pubmed Central ID

  • PMC1461580

International Standard Serial Number (ISSN)

  • 0016-6731

Digital Object Identifier (DOI)

  • 10.1093/genetics/157.3.935


  • eng

Conference Location

  • United States