Reduced pathogenicity of a Candida albicans MAP kinase phosphatase (CPP1) mutant in the marine mastitis model

Candida albicans strains with a deletion of the mitogen-activated protein k inase tyrosine phosphatase gene (CPP1) are derepressed in the yeast-to-hyph al transition on solid surfaces in vitro at ambient temperatures and this g ene is therefore required for repression of the yeast-to-hyphal switch. The pathology caused by a CPP1 null mutant strain was compared with that of th e null mutant into which the wild-type CPP1 gene was introduced by homologo us recombination and with the wild-type parent strain in a murine mycotic m astitis model. The mammary glands of lactating mice (at day 5 postpartum) w ere infected for 2, 4 and 6 days with 1x10(5), 1x10(6) and 1x10(7) cell-for ming units before euthanasia. Infected and non-infected control glands were evaluated histopathologically. The null mutant strains showed less severe pathology than the two control strains. The Cpp1p tyrosine phosphatase may thus be considered a virulence determinant during localized infection in C. albicans.