Candida albicanscell wall antigens for serological diagnosis of candidemia

Abstract

Serological tests for diagnosis of disseminated fungal infections in the immunocompromised host are used with varying results. In the present study, the relative ability of antibodies to specifically recognize Candida albicans cell wall components was evaluated in order to find antigenic markers for serological diagnosis of candidemia. Native C. albicans cell wall fragments (CW), periodate- (CWIO4) and proteinase-K- (CWP) treated CW, a mildly extracted phosphopeptidomannan (PPM), and beta(1-3)(1-6)-glucan were used as antigens in ELISA with sera from rabbits immunized with C. albicans (n = 10), patients with culture proven candidemia (n = 8) and healthy individuals (n = 8). The antibody response in rabbits consisted predominantly of anti-PPM antibodies, a finding that was substantiated by inhibition-ELISA. Consistently, periodate treatment (CW104) destroyed a major proportion of the antigenic epitopes. Low rabbit antibody levels were found against glucan, the major Candida cell wall component. These results supported the conclusion that glucan is localized mainly in the inner part of the C. albicans cell wall. In contrast to rabbits' serum IgG antibody response against PPM, which was at least tenfold higher than that raised against CW, patients with candidemia had similar IgG antibody levels against both antigens. These levels were significantly higher than those seen in healthy controls (CW, P = 0.0005 and PPM, P < 0.0001). Although the human anti-glucan and anti-CWIO4 IgG antibody levels were low overall, they were nonetheless significantly increased in the patient group (P = 0.0159 for antiglucan and P = 0.0491 for anti-CWIO4). In addition, a correlation was noticed between levels of these antibodies. No significant differences were found between patients and controls for IgM antibodies when CW, CWIO4, PPM and Glu were used as antigens. In conclusion, IgG antibodies to PPM and native cell wall fragments (CW) were highly discriminatory for recognition of candidemia and these antigens are thus promising candidates for use in serodiagnosis.

Antibodies against a β-glucan-protein complex of Candida albicans and its potential as indicator of protective immunity in candidemic patients

“…albicans and highlighted the importance of the glycosylated moieties of these proteins as target of antibody responses 19 . Overall, non-immunocompromised candidemic patients are evidently able to raise anti- Candida responses during the infection, some of which have also been assumed to be of diagnostic relevance 21, 22, 24, 25 . Here we report that candidemic patients, at the time of candidemia diagnosis, had significantly higher titers of anti-MP65 and anti-β1,6-glucan antibodies than non-candidemic subjects.…”

Prevalence of microbial pathogens in blood cultures: an etiological and histopathological study

“…He also reported that Cryptococcus neofermans was recovered in 10 of invasive fungal infection (blood) besides Saccharomyces cervisiae and Trichosporon mucoides as two emerging pathogens were also isolated. Numerous bacterimia and candidemia studies have documented the increasing importance of invasive microbial infection of blood stream of various groups of patients parallel to those included in the present study (renal failer [24] premature neonates [25,26] in immunocompromised patients [27] ; in bone marrow transplantation [28] and in cancer patients [29].…”