Extracellular proteins of Clostridium chauvoei are protective in a mouse model.

The anaerobic bacillus Clostridium chauvoei is the causative agent of blackleg, a lethal disease that has an important impact on the sheep and cattle industry worldwide. Immunity to C. chauvoei is considered to be mainly anticellular, and for this reason there is scarce information about the immunogenicity of extracellular proteins. In this work variations in protein profiles, immune response by ELISA and protective capacity of culture supernatants of three C. chauvoei strains, collected at different growth phases, are reported. Sera raised against extracellular antigens also recognised cellular antigens of the same molecular masses. Partially purified cell-free supernatants and those concentrated 10 times by ultrafiltration (C-CFS), obtained at the early stationary phase of growth, induced a strong immunoprotective response, even at low doses, that was more marked for C. chauvoei strain ATCC 10092 (p < or = 0.05). With C-CFS formulations, a clear relationship was observed between IgG titres, protective capacity and concentration of the antigen doses, indicating a specific immune response.

Growth of Helicobacter pylori in medium supplemented with cyanobacterial extract.

Solid and liquid media supplemented only with a cyanobacterial extract (CE) and free of fetal calf serum (FCS), blood, and its derivatives support the growth of Helicobacter pylori. A total of 11 strains of H. pylori isolated from gastric biopsy samples were successfully subcultured in Mueller-Hinton agar supplemented with 0.4% CE. When this medium was used for primary isolation of H. pylori, a low isolation rate (30%) was observed because of the abundant growth of contaminants. The growth kinetics of eight isolates and H. pylori reference strain NCTC 11638 in Mueller-Hinton broth (MHB) supplemented with 0.7% CE were estimated by use of growth parameters, and the results were compared with those obtained with MHB-5% FCS. For four strains the cellular concentrations obtained with CE were statistically higher (P < 0.05) than those obtained with FCS, and in some cases these values were similar to the highest values reported in the literature. Depending on the strain, the specific growth rates obtained with CE were similar to or increased compared with those obtained with FCS. The replacement of FCS by CE in H. pylori cultures would facilitate the retrieval of cultures with high cellular densities as a source of cellular and extracellular proteins free of serum. Also, CE has advantages over conventional supplements, such as easier conservation and compliance with the pressing tendency at present to avoid the use of products derived from animals.