Clostridium (C.) difficile is a common cause of nosocomial diarrhea in horses. Vancomycin and metronidazole have been used as standard treatments but are only moderately effective, which highlights the need for a novel alternative therapy. In the current study, we prepared antiserum of equine origin against both C. difficile toxins A and B as well as whole-cell bacteria. The toxin-neutralizing activities of the antibodies were evaluated in vitro and the prophylactic effects of in vivo passive immunotherapy were demonstrated using a conventional mouse model. The data demonstrated that immunized horses generated antibodies against both toxins A and B that possessed toxin-neutralizing activity. Additionally, mice treated with the antiserum lost less weight without any sign of illness and regained weight back to a normal range more rapidly compared to the control group when challenged orally with 10(7) C. difficile spores 1 day after serum injection. These results indicate that intravenous delivery of hyperimmune serum can protect animals from C. difficile challenge in a dose-dependent manner. Hence, immunotherapy may be a promising prophylactic strategy for preventing C. difficile infection in horses.
Animals ; Antibodies, Bacterial/blood/*immunology/therapeutic use ; Bacterial Proteins/immunology/therapeutic use ; Bacterial Toxins/immunology/therapeutic use ; Clostridium Infections/microbiology/prevention & control/*veterinary ; Clostridium difficile/*immunology ; Enterotoxins/immunology/therapeutic use ; Female ; Horse Diseases/microbiology/*prevention & control ; Horses ; Immune Sera/*immunology ; Immunization, Passive/*veterinary ; Mice ; Mice, Inbred C57BL ; Spores, Bacterial/immunology

OBJECTIVETo develop a novel dual-modified vaccine, the superantigen-linked intestine-carcinoma cells expressing membrane-bound heat shock protein 70 (HSP70), and further examine its anticancer therapeutic effect.

METHODSThe pre-established intestine carcinoma CT26 line expressing membrane-bound heat shock protein 70 (HSP70) was amplified and incubated with superantigen fusion protein, staphylococcal enterotoxin A (SEA) fused with transmembrane sequence (SEA-TM), thereby the dual-modified vaccine was prepared after inactivation. The anticancer efficacy of the vaccine was examined.

RESULTSThe laser confocal microscopy and flow cytometry showed that there co-existed much HSP70 and SEA on the vaccine membrane surface. Both of the single-modified vaccines, the SEA-linked vaccine and membrane-bound-HSP70-expressing one, displayed marked tumor suppression, a prolonged survival period, augmented lymphocyte proliferation and higher NK and CTL activity in the vaccinated mice when compared with its counterpart. Furthermore, the dually modified vaccine induced lymphocyte proliferation most intensively, generated the highest NK and CTL activity as well as the strongest tumor rejection in the vaccinated mice. The survival period of the mice was further prolonged.

CONCLUSIONA new vaccine, SEA-linked and membrane-bound-HSP70-expressing intestine-carcinoma cells can induce more potent anticancer immunity and produce better therapeutic efficacy.

Animals ; Cancer Vaccines ; therapeutic use ; Cell Line, Tumor ; Cell Membrane ; metabolism ; Enterotoxins ; immunology ; Gene Expression ; Genetic Vectors ; HSP70 Heat-Shock Proteins ; genetics ; immunology ; Mice ; Mice, Inbred BALB C ; Superantigens ; immunology ; Transfection

Two strategies, direct ligation after enzyme digestion and over-lap PCR technology, were adopted to construct a fusion gene which was composed of the antimelanoma single chain antibody gene and the staphylococcal enterotoxin A gene without N-terminal signal sequence. The fusion gene was subcloned into pET28-a vector and transformed into E. coli BL21(DE3). Ni-NTA system was selected to separate and purify the expresstd products. The inhibition ratio of the fusion protein was tested by MTT method. It is shown that the 6His-ScFv-SEA fusion protein can be expressed stably in E. coli BL21 (DE3). The quantity of the fusion protein was shown up to 30% of the total protein of the bacteria and mainly in inclusion body. By activation the effective cells, the fution protein can inhibit the melanoma cell whith expressed corresponding antigen.
Cell Line, Tumor ; Cell Survival ; drug effects ; Cells, Cultured ; Electrophoresis, Polyacrylamide Gel ; Enterotoxins ; genetics ; metabolism ; Escherichia coli ; genetics ; metabolism ; Humans ; Inclusion Bodies ; genetics ; metabolism ; Melanoma ; drug therapy ; immunology ; Recombinant Fusion Proteins ; genetics ; metabolism ; pharmacology ; therapeutic use ; Single-Chain Antibodies ; genetics ; metabolism