IDENTIFICATION AND PURIFICATION OF SPECIFIC PENICILLIUM-MARNEFFEI ANTIGENS AND THEIR RECOGNITION BY HUMAN IMMUNE SERA

Disseminated infection with the dimorphic pathogenic fungus Penicilliu m marneffei is increasingly seen among patients with AIDS in southeast Asian countries. Previous studies have demonstrated the presence of h umoral immune responses to this fungus in patient sera; we have confir med this work using sera from P. marneffei-infected patients (n = 21) to develop Western blots of P. marneffei cytoplasmic yeast antigen (CY A). P. marneffei CYA was then partially purified by liquid isoelectric focusing, and fractions were subjected to sodium dodecyl sulfate-poly acrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Immuno enzyme development of the Western blots with pooled sera from patients with P. marneffei infection and with pooled sera from patients with a spergillosis (n = 20), candidiasis (n = 10), cryptococcosis (n = 9), a nd histoplasmosis (n = 11) revealed three antigens with relative molec ular masses of 61, 54, and 50 kDa. These antigens were specifically re cognized by the pooled sera from the P. marneffei-infected patients. T he 61- and 54-kDa antigens were subsequently purified to homogeneity b y preparative gel electrophoresis, and the 50-kDa antigen was partiall y purified by the same technique. N-terminal amino acid sequencing rev ealed that the 61-kDa antigen had a strong homology (87% identity) wit h the antioxidant enzyme catalase. The three antigens were then subjec ted to SDS-PAGE and Western blotting and to immunoenzyme development w ith individual patient sera; sera from 86% of P. marneffei-infected pa tients recognized the 61-kDa antigen, sera from 71% recognized the 54- kDa antigen, and sera from 48% recognized the 50-kDa antigen. These sp ecifically recognized antigens are the first to be purified from P. ma rneffei and can be used either singly or in combination to detect anti body responses in a large percentage of individuals infected with P. m arneffei.