Immunodiffusion and complement fixation assays with sera from mucormycotic-infected mice

Effect of immunosuppression on the clinicopathological changes in experimental zygomycosis in rabbits

A study was undertaken to investigate the effect of immunosuppression by cyclophosphamide or methylprednisolone on the clinicopathological alterations in respiratory absidiosis in rabbits. Infected rabbits showed respiratory distress that was more severe in immunosuppressed groups. Leukocytosis due to neutrophilia was observed in the non-immunosuppressed group in the initial stages, whereas leukopenia was observed in both the immunosuppressed groups initially, owing to polymorphopenia in the cyclophosphamide-treated group and to lymphopenia in the methylprednisolone-treated group, followed by leukocytosis in both groups. Total serum proteins increased significantly in the non-immunosuppressed group but were significantly decreased in the immunosuppressed groups. Serum creatinine increased significantly in all the infected groups from 20 days post inoculation (DPI) onwards. Blood urea nitrogen increased significantly in the initial stages only in the methylprednisolone-treated group. AST and ALT also showed significant increases in the infected animals. Total serum immunoglobulins and circulating immune complexes increased gradually in all three infected groups, except for an initial significant drop in the immunosuppressed rabbits. Re-isolation of fungus was only achieved from the lungs of infected rabbits up to 15 DPI in the non-immunosuppressed group and 30 DPI in the immunosuppressed groups. Pathological lesions in all the infected groups were found mainly in the lungs and consisted of pyogranulomas. The lesions were most severe in the cyclophosphamide-treated group and least severe in the non-immunosuppressed group.

Sequential clinical, haematological, biochemical, immunopathological and histopathological alterations in buffalo calves (Bubalus bubalis) intravenously infected with Absidia corymbifera

Absidiosis was produced experimentally in 18 buffalo calves by intravenous inoculation of spores of Absidia corymbifera. Infected animals exhibited dullness, depression, partial anorexia and an initial pyrexia and coughing during the first week and two animals died on each of 9, 13 and 16 days post infection (DPI). The haemoglobin concentration and total erythrocyte count showed no appreciable change from their basal values at any stage of the experiment. However, the erythrocyte sedimentation rate and total leukocyte count increased significantly in the infected animals. The differential leukocyte count revealed a relative neutrophilia from 5 to 20 DPI. There was a significant increase in the serum total proteins, blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, serum alkaline phosphatase, total immunoglobulins and circulating immune complexes in the infected animals as compared to the controls. In the sera of the infected animals, specific Absidia corymbifera IgM and IgG antibodies were detected from 3 DPI to 6 DPI respectively by Dot-EIA. Type I and type III skin hypersensitivity were detected from 10 DPI and type IV hypersensitivity from 15 DPI onwards. The gross and microscopic pathological lesions were seen mainly in the lungs, in all except one of the affected animals. This animal died 9 DPI and mycotic granulomas were also seen in its heart and kidneys. The microscopic lesions in the lung took the form of well-developed granulomas.

Immunohistochemical identification of aetiological agents of systemic bovine zygomycosis

The reactivity of a panel of rabbit hyperimmune antisera raised against somatic antigens of three zygomycetes, Absidia corymbifera, Rhizopus oryzae and Rhizomucor (Mucor) pusillus was assessed by crossed immunoelectrophoresis (XIE) and indirect immunofluorescence (IIF) staining of experimentally infected murine tissues. Despite a widespread cross-reactivity of the neat antisera, heterologous absorption rendered antisera monospecific as assessed by XIE. Heterologous absorption also rendered the antisera against R. oryzae and R. (Mucor) pusillus specific by IIF, whereas heterologous absorption of Abs. corymbifera antiserum did not abolish reactivity with R. oryzae. The reactivity of the heterologously absorbed antisera and a murine monoclonal IgG1 antibody against Abs. corymbifera enabled zygomycetes within bovine lesions to be identified. Of 113 zygomycotic lesions of 95 cattle examined, 82 (72.5 per cent) showed a pattern of reactivity compatible with Abs. corymbifera, 21 (18.6 per cent) with R. oryzae, and 5 (4.4 per cent) with R. (Mucor) pusillus. Fungi in four lesions reacted with the monoclonal antibody only, and fungal elements in one lesion showed no reactivity at all. Each of the bovine lesions contained only a single fungal species, but one animal was infected by Abs. corymbifera in the rumen and by R. oryzae in the other stomach compartments. Apart from being the main cause of systemic bovine zygomycosis in Denmark, Abs. corymbifera also seems to be the most pathogenic due to its frequent haematogenous and lymphatic spread (87.8 per cent) as compared with R. oryzae (1.4 per cent) and R. (Mucor) pusillus (5.4 per cent).

Electrophoretic and immunoblot analyses of Rhizopus arrhizus antigens

Four antigen preparations from Rhizopus arrhizus were made and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and column chromatography. Electrophoretic analyses of these antigens indicated that there are 18 to 28 component bands with a molecular mass range of approximately 10,500 to 83,000 daltons. Seven of these bands appear to be components common to three antigen preparations. Several of the bands identified by SDS-PAGE were composed of glycoproteins or carbohydrates as determined by their affinity for concanavalin A. Western blots, using sera from five patients with mucormycosis, consistently identified five different determinants in the R. arrhizus antigens separated by SDS-PAGE. This suggests that several of the Rhizopus antigens are present during mucormycosis. Four of the antigenic determinants recognized by patient sera reacted with the concanavalin A-peroxidase stain, indicating that they are composed of glycoproteins or carbohydrate. Enzyme-linked immunosorbent assays of sera from five patients with mucormycosis and with rabbit antisera resulted in antibody titers ranging from 1:64 to 1:32,000 for the R. arrhizus antigens.