Biomedical subjects
Publications and source records attributed to M J Corbel.
A subcutaneous granuloma developed in a C3H mouse ca. 5 months after sequential intravenous and intracerebral inoculation of Absidia corymbifera spores. A. corymbifera was demonstrated microscopically and culturally in the lesion. Infection is believed to have been secondary to fungal infection of the kidney. The histopathological features of the lesion are described.
The properties of a smooth phage resistant variant of Brucella abortus were studied in an attempt to determine the mechanism of phage resistance. This strain was fully capable of adsorbing phage but penetration, and hence replication, did not occur. No evidence of lysogeny or a phage carrier state could be obtained and gross chemical differences between the resistant strain and its phage susceptible parent were not detected. The phage resistant variant showed increased resistance to lysis from without, either by phage or by lysozyme, in the presence of chelating agents. It was concluded that resistance was the result of a modification in cell wall structure conferring resistance to lysozyme-like enzymes, thus preventing penetration of phage.
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The morphological, cultural, biochemical, serological and pathogenic properties of two bacterial strains of the group designated ;Br. suis biotype 5' were examined. Both strains were found to be atypical of the genus Brucella in many of these characteristics. No serological relationship to known brucella strains could be detected. On the basis of the evidence obtained the two strains examined were classified as Moraxella duplex and the status of ;Br. suis biotype 5' questioned.
The nature of the antibody response of cattle to the antigen of Yersinia enterocolitica IX cross-reacting with Brucella spp. was examined. Density-gradient ultracentrifugation, ion-exchange chromatography, antibody adsorption and elution and disulphide bond reduction tests showed that both 19 S IgM and 7 S IgG(1) and IgG(2) antibodies were produced in response to the cross-reacting antigen. The highest titres of cross-reacting antibodies were detected by the agglutination and Coombs antiglobulin tests. Production of complement-fixing and precipitating antibodies cross-reacting with Br. abortus was transient and high titres were not attained.In contrast, although infection with Br. abortus also evoked cross-reacting antibodies of the IgM and IgG classes, much higher titres were produced in the complement fixation and precipitation tests and these persisted for long periods. At all stages of the serological response to both organisms, the two infections could be differentiated by the quantitative Rose Bengal plate test.
The direct fluorescent antibody test was assessed for detection of Brucella abortus in bovine abortion material. Br. abortus organisms could be readily detected as characteristic intra-cellular clumps, in smears stained with fluorescent antibody. Counterstaining with Evans Blue was necessary to suppress tissue auto-fluorescence. The method was specific and enabled brucella infection to be differentiated, inter alia, from Q-fever infection.
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The antibodies active in the Rose Bengal plate test (RBPT) for bovine brucellosis have been studied. The results of fractionation experiments showed that RBPT activity was associated with fractions containing immunoglobulin of the IgG(1) class; other immunoglobulin classes were inactive in this respect although active in other tests. These results were confirmed by inhibition tests with specific antisera and by elution of the antibody from agglutinated RBPT antigen.The major proportion of the serum complement-fixing activity was also present in the IgG(1) fraction and it is suggested that the RBPT and CF reactions are probably mediated by the same antibodies.