CLINICAL VALIDATION OF A WHOLE-CELL VACCINE FOR HAEMOLYTIC UREMIC SYNDROMEDIVYA SASITHARAN AND M. MASILAMANI SELVAM
Background: A major public health goal is to prevent Enterohemorrhagic Escherichia coli (EHEC)- induced diseases in humans and the same can be met by the development of vaccine against the EHEC strains, such as Escherichia coli O157:H7. Aim and Objective: To determine the efficacy of whole-cell vaccine prepared out of Escherichia coli O157:H7, for having its pathogenicity lost, using laboratory animals such as rats. Samples such as ground beef, chicken intestine, raw milk and pasteurized milk was collected and analysed for the isolation and identification of Escherichia coli strain by standard microbiological techniques. Apart from general characterization, antibiotic sensitivity tests were performed to determine antimicrobial resistance profiles. Conventional PCR amplification confirmed the presence of five selected virulence genes, namely Intimin (eae), Shigatoxin1 (stx)1, Shigatoxin (stx2), Hemolysin (hlyA) and Flagellar antigen (fliCh7) genes. One isolate was found to possess maximum number of tested virulence genes and hence chosen for vaccine preparation. A whole cell formalin killed vaccine was produced out of selected isolate strain of Escherichia coli O157:H7 as per Jan Holmgren et al., (2003) protocol. Prepared vaccine was subjected to its efficacy test using rat models after obtaining proper ethical clearance. After challenging with ATCC and isolates, screening methods emphasised on studying the histopathology effects on test rats as well as on control rats (mortality as well as morbidity in liver and kidney) were done. Normal histology was seen in liver and kidney specimens of vaccinated and challenged rat groups as well as control uninoculated unvaccinated rat groups. However, toxic evidences were observed in liver as well as kidneys of rat groups which were unvaccinated and challenged with pathogenic strains. Vaccine is believed to have lost its pathogenicity as validated by animal studies as expected. However, this is just a preliminary confirmation before proceeding to clinical trials with human volunteers.
Enter your contact information below to receive full paper.