Clostridium difficile and Clostridium perfringens type A are infectious agents of enteric diseases. The main virulence factors of these microorganisms include toxins A and B of C. difficile (ToxA and ToxB) and enterotoxin of C. perfringens (Cpe). In this study genetic constructions have been created for the expression of ToxA, ToxB and Cpe fragments either as individual components or as a hybrid multidomain (ToxA-ToxB-Cpe) protein. Rabbit monospecific sera raised against individual peptides reacted with the chimeric product indicating that the corresponding antigenic determinants were correctly expressed on the hybrid molecule. Furthermore, mice immunized with the fusion protein produced antibodies specific to each of the three separate components. These data suggest that the constructed three-domain molecule could be used in future studies for development of a vaccine against enteric clostridial diseases.
A mutant strain characterized by hyperproduction of a number of cell wall and supernatant proteins was isolated after N‐methyl‐N′‐nitro‐N‐nitrosoguanidine treatment of Listeria monocytogenes strain NCTC10527. Several of these proteins were identified as virulence factors. When a wild‐type strain was grown in the presence of activated charcoal it was shown to exhibit the same protein pattern as the isolated mutant.
A method for identification of Listeria in food samples was developed. It consisted of cultivating of suspected specimen on standard agar medium, direct absorption of grown colonies onto nitrocellulose membrane and processing of the latter with rabbit serum raised against purified cell wall protein Lm79/39 of L. monocytogenes. Analysis using anti-rabbit peroxidase conjugate and 4-chloro-1-naphthol and H2O2 solutions allowed direct detection of Listeria colonies which remained readily available for subsequent isolation.
A mutant strain characterized by hyperproduction of a number of cell wall and supernatant proteins was isolated after N'methyl-N'-nitro-N-nitrosoguanidine treatment of Listeria monocytogenes strain NCTC10527. Several of these proteins were identified as virulence factors. When a wild-type strain was grown in the presence of activated charcoal it was shown to exhibit the same protein pattern as the isolated mutant.
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