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The limulus factor G reacts with (1-->3)-beta-D-glucan, a major structural component of fungal cell walls. The Fungitec G test is a colorimetric assay that measures the concentration of (1-->3)-beta-D-glucan and is used as a serodiagnostic test for deep mycosis. Wako-WB003 is another assay for (1-->3)-beta-D-glucan that determines the change in turbidity of the gelatin reaction of limulus factor G with (1-->3)-beta-D-glucan. In five rabbits inoculated intravenously with 1 x 10(7) CFU of Candida albicans, the concentration of (1-->3)-beta-D-glucan measured by the fungitec G test increased gradually reaching a peak of 660.9 +/- 427.9 pg/ml (mean +/- SD) 4 days after inoculation, but to 42.225 +/- 41.275 ng/ml on day 6 in the Wako-WB003 test. In one rabbit challenged intravenously with 5 x 10(6) CFU of C. albicans, (1-->3)-beta-D-glucan increased to 101.5 pg/ml on day 4 on the fungitec G test, whereas the level remained below the detection limit of the Wako-WB003 test throughout the course of the disease. We also detected high concentrations of (1-->3)-beta-D-glucan in 11 patients with candidemia, 4 with suspected candidemia, 1 with invasive pulmonary aspergillosis, and 12 patients with aspergilloma. The concentration of (1-->3)-beta-D-glucan measured by the Fungitec G test was > 150, > 1006.8; 312.1, and 55.6 +/- 37.4 pg/ml (range, 20.1-138.0 pg/ml), and by the Wako-WB003 test > 153.000, > 17.70, 153.000 and 2.645 +/- 7.248 ng/ml (range, < 25.20 ng/ml) in these patients, respectively. In contrast, the concentration of (1-->3)-beta-D-glucan in 9 patients with pulmonary cryptococcosis and 6 with superficial candida colonization ranged from < 13.2 and < 15.3 pg/ml in the Fungitec G test and < 0.53 and < 0.12 ng/ml in Wako-WB003 test. There was a weak relationship between the concentration of (1-->3)-beta-D-glucan measured by the Fungitec G test and Wako-WB003 test (r = 0.521). Our results indicate that the sensitivity of the Wako-WB003 test is lower than that of the Fungitec G test.

The G test containing factor G, fractioned from the Limulus lysate, was used to detect (1-3)-beta-D-glucan in a rat model of aspergillosis. Aspergillus fumigatus strain MF-13, 1 x 10(4) conidia, were inoculated transtracheally into rats treated with cortisone acetate (100 mg/kg) and fed a low-protein (8%) diet. Increased serum (1-3)-beta-D-glucan was found on the sixth day after inoculation in concentrations of 370 +/- 178 pg/ml (mean +/- SD) in untreated controls, and 154 +/- 43 pg/ml in rats treated with 0.5 mg/kg of amphotericin B. On day 11 (1-3)-beta-D-glucan concentrations were 2,590 +/- 2,940 pg/ml and 448 +/- 442 pg/ml, respectively. The elevation in levels of (1-3)-beta-D-glucan increased in correlation with the elevation of galactomannan antigen titers; (1-3)-beta-D-glucan is thus measurable during experimental aspergillosis in rats.

Two well-known polysaccharides, (1-->3)-beta-D-glucan and mannan, are major structural components of the fungus cell wall. The G test is a direct method to measure (1-->3)-beta-D-glucan using a (1-->3)-beta-D-glucan-sensitive component, factor G, fractionated from the limulus lysate. The concentration of (1-->3)-beta-D-glucan in culture supernatants of Candida albicans increased to 1,390.0 pg/ml at 24 hours. The concentration of mannan also increased parallel with fungal growth. However, after digestion of supernatants with endo-(1-->3)-beta-D-glucanase, the reactivity to factor G disappeared, although titers of antimannan monoclonal antibody-based latex agglutination were unchanged. Our study demonstrated that cell suspensions of both C. albicans and Cryptoccocus neoformans activated the limulus factor G, and that not only the conidia form but also the filamentous form of Aspergillus fumigatus reacted with factor G. Various Candida spp. (C. paraspilosis, C. glabrata, C. tropicalis, C. krusei), Saccharomyces cerevisiae, Rhodotorula rubra, Trichosporon beigelii, and A. fumigatus released soluble (1-->3)-beta-D-glucan into their culture supernatants, but C. neoformans and Cunninghamella bertholletiae showed only a small reaction to the G test during their culture. Our results indicate that the G test is a good method for serodiagnosis of deep mycosis and also as a screening tool for contamination of medical devices, drugs, and experimental materials with (1 --> 3)-beta-D-glucan.

The serodiagnostic value of candida enolase antibody was evaluated in 27 patients with systemic candidiasis. The glycolytic enzyme enolase was prepared from Candida albicans IFM 40009 and used as the antigen for immunoblot assays. IgG class antibody was found in the sera of 17 of 27 patients (62.9%) obtained during the early course of the infection. Serial sampling of sera increased the number of patients with positive Candida enolase antibody, which was detected in 25 of 27 patients (92.5%). None of the patients with localized candidiasis showed a positive IgG titer more than 1:100. The specificity of Candida enolase IgG antibody was 95%. This antibody was observed in various candida species: Candida albicans (6/7, 85.7%); C. parapsilosis (7/9, 77.9%); C. tropicalis (5/5, 100%); C. guilliermondii (4/4, 100%); and C. glabrata (1/3, 33.3%).

An indirect method to measure beta-glucan, a major structural component of yeast cell walls, is available, but has the disadvantage of requiring the combined use of two assays. Recent reports describe the fungal index, which measures the difference between the conventional limulus test, in which factors C and G react with endotoxin and beta-glucan, and a new endotoxin-specific test, in which only factor C reacts with endotoxin. The G test was developed as a direct method to measure beta-glucan, and contains only factor G reacting with beta-glucan alone. In this study, the G test was examined in sera of rabbits with experimental systemic candidiasis, and compared with the fungal index and mannan assay. The G test showed positive in all rabbits with systemic candidiasis faster and with higher titers than with the fungal index. Three rabbits with fulminant systemic candidiasis showed higher levels of reactivity with the G test and the fungal index than two rabbits with mild reactions. Mannan was positive by at least one serum in four of five rabbits by the latex agglutination test, and there was a good correlation between these assays. The G test is a good serodiagnostic method for the detection of candidiasis.