Investigation of the location and secretion features of Candida albicans enolase with monoclonal antibodies

The glycolytic enzyme enolase plays important role in the pathogenesis of Candida albicans infection and has been also considered as a promising molecular marker for the diagnosis of invasive candidiasis. This study aimed to investigate the location and secretion features of Candida albicans enolase (CaEno) with a couple of specific monoclonal antibodies (mAbs). Two mAbs named 9H8 and 10H8 against CaEno were generated by fusing SP2/0 myeloma cell with the spleen lymphocytes from CaEno immunized mice. The specificity of the mAbs was then validated by Western blot and liquid chromatography-mass spectrometry (LC–MS/MS). A diverse set of experiments were conducted based on the pair of mAbs which involved immunohistochemical staining analysis, whole cell enzyme-linked immunosorbent assay (ELISA), double antibody sandwich ELISA, and confocal microscopy to analyze the possible location and secretion features of CaEno. CaEno is abundantly expressed in the cytoplasm of C. albicans blastospores and is distributed in a ring-shaped pattern along the cell wall. CaEno appeared in the hyphal C. albicans as just a “mushroom” form. CaEno was found to be weakly expressed on the surface of blastospores but constantly expressed at various stages of growth. CaEno concentrations in C. albicans blastospores culture supernatant are considerably higher than in C. albicans hyphae culture supernatant. The dynamic changes of supernatant CaEno concentration in blastospores and hyphal C. albicans exhibit distinct features, although both appear to be associated with the C. albicans growth state. When cultivated under normal circumstances, however, no apparent CaEno degradation was seen in the cell-free supernatant. Our results implied that CaEno was constantly expressed on the cell surface and its secretion features varied according to the growth stage of C. albicans. However, further experimental and theoretical studies are needed in future to identify the specific mechanisms by which this phenomenon can arise.