Objectives

This project is designed to study the effect of temperature upon the production of new outer membrane proteins on the both the fatal and mild Salmonella typhi bacterial cells. Since the temperature parameter is being investigated, it would follow that these new proteins synthesized after temperature shifts would most likely be heat shock proteins. This study might help to explain how S. typhi cells survive in the host’s body even after the release of S. typhi Vi antigens has triggered the release of interleukin-1 and prostaglandins initiating fever. This project also aims to determine the heat shock proteins which cause autoimmune responses in the infected human host by cross-reacting with human heat shock proteins, and if these proteins are all produced in the cells in low concentration under normal circumstances, or if they are only induced by heat stress. If these proteins can be identified, then they might pose as a prospect for further study in the field of rapid diagnosis of S. typhi, especially since present diagnostic methods are not fast, sensitive or reliable enough (Edelman and Levine, 1986), and also in the field of vaccine development. This is of high importance, since typhoid fever has still high prevalency in developing countries. So far, it has been determined that outer membrane protein preparations from S. typhimurium protect mice against salmonellosis (Udhayakumar and Muthukkarupan, 1987), and that patients with typhoid fever generate antibodies that recognize S. typhi outer membrane proteins (Caldéron et al, 1986); therefore the knowledge of these outer membrane proteins would be of great benefit to those who are working on ways to quickly diagnose and therefore prevent the outbreak of typhoid fever. A comparison of fatal and mild S. typhi strains might also yield results regarding the homogeneity or heterogeneity of these outer membrane or heat shock proteins, and would help determine if, when constructing diagnosis kits and vaccines, it would be necessary to have different sets for pathogenetically different strains, or if one set would suffice for this species of bacteria.