Nature of Candida albicans-derived carbohydrate antigen recognized by a monoclonal antibody in patient sera and distribution over Candida species

Abstract

The minimal epitope of an anti-Candida albicans mannan monoclonal antibody (MAb) EB-CA1, used to detect mannanemia in patient sera, was determined. MAb EB-CA1 exhibited reactivity with oligomannosides released from the mannan acid stable domain, converted into neoglycolipids (NGLs) and coated onto ELISA plates. Reactivity occurred with mannopentaose and higher oligomers, whereas mannotriose and mannotetraose were unreactive. MAb EB-CA1 binding to mannan acid stable mannopentaose NGL displayed a dose dependent and saturable specific reactivity curve whereas there was a complete absence of binding, even at high concentrations, with NGLs constructed from the L-1,2-linked mannopentaose derived from the mannan acid labile fraction. MAb EB-CA1 binding to acid stable mannopentaose NGL was inhibited by the homologous oligomannoside but not by mannotriose and mannotetraose. NMR analysis showed that mannotriose and mannotetraose contained exclusively K-1,2-linked D-mannopyranose units and that mannopentaose was a mixture of a mannopentaose K-1,2-linked and an isomer in which the fifth mannose was K-1,6-linked to the reducing unit of manno-K-1,2 tetraose. Western blot analysis has shown that MAb EB-CA1 epitope was expressed on a wide range of C. albicans manno-glycoconjugate as well as on manno-glycoconjugates of other pathogenic species of the genus Candida, viz. C. tropicalis, C. glabrata, C. parapsilosis and C. krusei. z

Combined detection of mannanaemia and anti-mannan antibodies as a strategy for the diagnosis of systemic infection caused by pathogenic Candida species

“…This property is important when considering the sensitivity of the test (i.e., the more epitope that is present, the more chance it has of being detected) and also for development of a two-site immunoenzymetric assay (previously sandwich ELISA) which requires the repetitive expression of epitopes on molecules. The MAb EBCA1 epitope was also found in large amounts on mannoproteins of C. glabrata, C. tropicalis and C. guilliermondii, but was present to a lesser extent on mannoproteins of C. krusei, C. kefyr and C. parapsilosis [39,57].…”

“…These tests are now marketed as Platelia Candida Ag and Platelia Candida Ab, respectively. MAb EBCA1 recognises sequences of AE-linked oligomannoses, comprised of more than four residues, present in a large number of mannoproteins extracted from C. glabrata and C. tropicalis, and to a lesser extent C. parapsilosis and C. krusei [39]. Thus, it seemed likely that Platelia Candida Ag would also detect antigens of non-albicans Candida spp.…”

ECIL recommendations for the use of biological markers for the diagnosis of invasive fungal diseases in leukemic patients and hematopoietic SCT recipients

“…40 ELISAs quantifying Mn Ag and A-Mn Abs are marketed as Platelia Candida Antigen and Platelia Candida Antibody (Bio-Rad Laboratories, Marnes-la-Coquette, France). 40,41 These markers are not included in the revised EORTC/MSG criteria for diagnosis of IFD. 1 A systematic review of studies using ELISA (Platelia Candida Antigen and Antibody) to measure Mn and A-Mn in serum was performed.…”

Specific Recognition of Candida albicans by Macrophages Requires Galectin-3 to Discriminate Saccharomyces cerevisiae and Needs Association with TLR2 for Signaling

“…After washing, 200 l of yeast suspension was added to the wells and incubated for 2 h at 20°C. Unbound yeasts were discarded by washing with PBS containing 0.5% BSA and bound yeasts were revealed using the mAb EBCA1 directed against C. albicans mannan (26) and anti-mouse IgM FITCconjugated Ab. Plates were read in a Fluorocount reader (Packard).…”