NATURE OF CANDIDA-ALBICANS-DERIVED CARBOHYDRATE ANTIGEN RECOGNIZED BYA MONOCLONAL-ANTIBODY IN PATIENT SERA AND DISTRIBUTION OVER CANDIDA SPECIES

The minimal epitope of an anti-Candida albicans mannan monoclonal anti body (MAb) EB-CA1, used to detect mannanemia in patient sera, was dete rmined. MAb EB-CA1 exhibited reactivity with oligomannosides released from the mannan acid stable domain, converted into neoglycolipids (NGL s) and coated onto ELISA plates. Reactivity occurred with mannopentaos e and higher oligomers, whereas mannotriose and mannotetraose were unr eactive. MAb EB-CA1 binding to mannan acid stable mannopentaose NGL di splayed a dose dependent and saturable specific reactivity curve where as there was a complete absence of binding, even at high concentration s, with NGLs constructed from the beta-1,2-linked mannopentaose derive d from the mannan acid labile fraction. MAb EB-CA1 binding to acid sta ble mannopentaose NGL was inhibited by the homologous oligomannoside b ut not by mannotriose and mannotetraose. NMR analysis showed that mann otriose and mannotetraose contained exclusively alpha-1,2-linked D-man nopyranose units and that mannopentaose was a mixture of a mannopentao se alpha-1,2-linked and an isomer in which the fifth mannose was alpha -1,6-linked to the reducing unit of manno-alpha-1,2 tetraose. Western blot analysis has shown that MAb EB-CA1 epitope was expressed on a wid e range of C. albicans manno-glycoconjugate as well as on manno-glycoc onjugates of other pathogenic species of the genus Candida, viz. C. tr opicalis, C. glabrata, C. parapsilosis and C. krusei. (C) 1998 Federat ion of European Microbiological Societies. Published by Elsevier Scien ce B.V. All rights reserved.