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

Abstract
Candida albicans strains with a deletion of the mitogen‐activated protein kinase tyrosine phosphatase gene (CPP1) are derepressed in the yeast‐to‐hyphal transition on solid surfaces in vitro at ambient temperatures and this gene 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 the null mutant into which the wild‐type CPP1 gene was introduced by homologous recombination and with the wild‐type parent strain in a murine mycotic mastitis model. The mammary glands of lactating mice (at day 5 postpartum) were infected for 2, 4 and 6 days with 1 times 105, 1 times 106 and 1 times 107 cell‐forming 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.