| Purpose Candida albicans is one of the major pathogens agents of candidiasis,invases the hosts through dimorphic transion,attachment and colonization on surface of endothelial cells and mucous membrane.Incidence of invasive candidiasis has increased over the past several decades. Early and accurate diagnosis of these infections is important for several reasons, including timely institution of antifungal therapy and to decrease the unnecessary use of toxic antifungal agents. In addition, the availability of accurate and timely diagnoses could reduce the use of empirical antifungal therapy, thereby reducing antifungal selection pressure and the emergence of antifungal resistance. Since early diagnosis is important, there has been considerable interest in developing nonculture approaches to diagnose fungal infections. These approaches include detection of specific host immune responses to fungal antigens, detection of specific macromolecular antigens using immunologic reagents,detection of specific fungal DNA sequences and the detection and quantitation of specific fungal metabolic products. Serologic techniques include detection of specific anti-C. albicans antibodies and antigens.The detection of circulation C. albicans antigens in serum is promising currently, but despite the development of several methods for such detection, none has gained widespread acceptance. To control infections caused by C. albicans, the host must generate a wide range of defensive responses directed to neutralize the virulence factors displayed by the fungus. Although the role of antibody immunity in protection against candidiasis has been controversial, recent evidence demonstrates that antibodies with defined specificities show different degrees of protection against systemic and mucosal candidiasis. The exact mechanisms by which these antibodies protect against Candida infection are unknown but are likely to include the inhibition of adhesion or germ tube formation, opsonization, neutralization of virulence-related enzymes, and direct candidacidal activity. In our study,Monoclonal antibody Mab03.2C1C2 specific against C. albicans germ tube has been prepared,which was used to detect circulating germ tube antigen in rabbit sera by ELISA. At the same time study the inhibition function to the germ tube formation and adhesion of C. albicans with Mab03.2C1C2. Methods and Results The human buccal epithelial cells were isolated and the umbilical veins endothelial cells were cultured. By incubation different concentration of Mab03.2C1C2 with (1)C. albicans spors, (2)mixed suspenion of C. albicans spors and human buccal epithelial cells, (3) mixed suspenion of C. albicans spors and endothelial cells of fetal umbilical vein,the results were observed. In the ptotective Mab screening experiment ,it was found that Mab03.2C1C2 could decrease the filamentation of C. albicans and the number of C.albicans adhering to the surface of epithelial and endothelial cells. In our model,20 rabbits were infected intravenously with C. albicans. Sera were collected before and after challenged. Portions of the rabbits's organs were homogenized and plated onto SDA to cultivate the causative fungu. Portions of the organs were stained with HE and PAS for histopathologic demonstration.The HRP and Mab03.2C1C2 were coupled by improved periodate method. Germ tube specific antigen of 70 serum samples from rabbits with invasive candidiasis was detected by ELISA. The result showed positive after infected 24h,the sensitivity and specificity of the ELISA were 61.4% and 90%,respectively. The positive rate of blood culture was 4.29%. The clinical samples :normal human beings,patients who suffered from oral mucosa candidiasis ,were negative.The specificity of the ELISA were 100%. Conclusions Mab03.2C1C2 can inhibit the formation of C. albicans germ tube, further more it can inhibt the adhesion of C.albicans to the epithelial and endothelial cells and decrease the invasion of C.albicans. According to the ELISA results above, the detection of circulation C. albicans antigens in serum is highly specific.It is helpful to find early invasive candidiasis that blood is drown and examined repeatedly. |
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