Role of Glycoproteins Isolated from Epicoccum purpurascens in Host-Pathogen Interaction.

OBJECTIVE Attachment to host matrix is an important provisory step for the institution of any fungal infection. The present study investigates the role of glycoproteins of Epicoccum purpurascens in host-fungal adherence. METHODS Epicoccum spore-mycelial extract was fractionated on a concanavalin A-Sepharose column. Three glycoproteins of 12, 17 and 33 kDa (Epi p 1) were electroeluted and checked for hemagglutination and hemagglutination inhibition. The monosaccharide content of the highly potent protein Epi p 1 was determined by high-performance anion exchange chromatography and pulsed amperometric detection. The interaction of Epi p 1 with mannose-binding lectin (MBL) leading to the activation of the complement system was studied by immunoblot, ELISA and ELISA inhibition techniques. Immunoblot and immunoblot inhibition were carried out with culture filtrate to determine the nature of Epi p 1. RESULTS 33 (Epi p 1)-, 17- and 12-kDa proteins were 58, 46 and 38 times more potent than crude extract in hemagglutination activity (HA). The HA of Epi p 1 was inhibited by N-acetyl glucosamine, glucose and laminin. Epi p 1 had a high mannose content, showed MBL binding in ion-dependent manner and caused complement activation. The protein was detected in culture filtrate and thus seems to play a significant role in fungal invasion. CONCLUSION Epi p 1, an allergenic glycoprotein of E. purpurascens, is involved in host-fungal interactions through MBL.