Clinical validation of vaccines against hemolytic uremic syndrome

To compare the efficacy of a whole-cell vaccine and a toxoid vaccine prepared for Escherichia coli O157:H7 strain using rats as animal models. Methods: Isolation and identification of study strain from samples such as ground beef, chicken intestine, raw milk and pasteurized milk was followed by confirmation of five selected virulence genes by conventional PCR amplification. Whole cell vaccine and a toxoid vaccine, prepared as protein produced out of stx1 gene variant from an isolate strain of study were subjected to its efficacy test using rat models after obtaining proper ethical clearance. After challenging with ATCC and isolates, screening performed by histology in liver and kidney on test rats as well as on control rats. Results: Normal histology was seen in liver and kidney specimens of vaccinated and challenged rat groups as well as control un-inoculated unvaccinated rat groups with very few exceptional lesions. However, severe toxic evidences were observed in rat groups which were unvaccinated and challenged with pathogenic strains. Conclusions: Vaccine is believed to have lost its pathogenicity to a greater extent as validated by animal studies. When comparison was made between whole cell vaccine and toxoid, whole cell vaccine had greater extent of efficiency than toxoid.