Mechanism of protection provided by active immunization with porins in mice challenged with Salmonella typhi.

Oxygen free radical (OFR) generation capacity of peritoneal macrophages was studied by chemiluminescent technique. Chemiluminescent (CL) response of macrophages from control, infected and immunized-infected mice was observed using non specific (Latex) and specific (S. typhi, cells and porins) stimulants at different time intervals. CL response was found to be significantly higher in immunized-infected group throughout the study period using all the three stimulants as compared to that in the infected as well as uninfected control mice. The mode of action of porin vaccine in increasing capacity of generating OFR is probably through increased expression of porin (protein) as well as carbohydrate receptors on the macrophage surface which leads to the stimulation of the whole caseade of respiratory burst or through the increase in the respiratory burst enzyme activities linked with each receptor or both.

Humoral and cell mediated immune responses to porins of Salmonella typhi.

Humoral and cell mediated immune responses were studied in control, infected and immunized-infected mice at different time intervals. The levels of antiporin antibodies were found to be higher throughout the study period in immunized-infected group in which 87.5% protection was observed by mouse potency test. A significant increase in stimulation index of lymphocyte blast transformation as well as delayed type hypersensitivity response was observed in the same group as compared to infected and control group when porins were used as antigens. Using nonspecific mitogens like PHA and Con A the lymphocyte proliferation was maximum in control group whereas a significant depression was observed in infected mice. It is indicated from this study that porins are excellent antigens interacting efficiently with both arms of the host immune systems which could play a role in providing protection against the disease.