Heterozygosis and pathogenicity of Cryptococcus neoformans AD-hybrid isolates

Nineteen Cryptococcus neoformans AD-hybrid isolates were investigated to assess whether hybrid genomic background could affect virulence in a mouse model. The level of heterozygosity of each strain was analyzed using primers specific for allele A and D of 15 polymorphic genes. Virulence was tested in a mouse model of systemic infection by measuring time of survival. In addition, the putative virulence attributes, melanin, phospholipase, and capsule production, as well as growth at 39°C and UV sensitivity were investigated. Eight strains showed to be heterozygous in up to 70% of loci, other eight strains were heterozygous in less than 60% of loci, while the remaining three strains were homozygous at all tested loci. Mice infected with hybrids with a high percentage of heterozygosis showed significantly (P?