Induction of systemic and mucosal immune response in mice immunised with porins of Salmonella typhi

Abstract

Porins, purified from Salmonella @phi strain 0901 provided 90% protection to BALB/c mice against a lethal dose (300 X LD50) of S. typhi Ty2 when given intraperitoneally. To measure the porin-induced cellular immune responses, macrophages and lymphocytes were isolated from spleen and lamina propria (LP) of porin immunised-challenge mice and of infected and control mice; T-cell phenotypes, lymphocyte proliferation and cytokine production were studied. The secretory IgA (sIgA) antibody level in the intestinal fluid was also measured to study mucosal immune response. After immunisation, the splenic lymphocytes exhibited a significant increase in total T-cell count and CD4+/CD8+ ratio, while the LP lymphocytes (LPL) exhibited an increase in CD4+/CD8+ ratio only. They also exhibited a significant increase in porin-specific proliferative response and cytokine levels (IL-1, IL-2, IFN-y and IL-4). After immunisation, slgA antibody was also found to be increased. These results suggest that porins given intraperitoneally induce cellular and humoral immune responses both at systemic and mucosal levels.

Cellular immune response induced by Salmonella enterica serotype Typhi iron-regulated outer-membrane proteins at peripheral and mucosal levels

“…3b); this may be due to a change in the antigen expression on the surface of the antigen-presenting cells along with the major histocompatibility complex (MHC) molecules by that time. It was interesting to observe that a significantly lower amount of IROMPs (1 ìg) was required for the transformation of lymphocytes in this study, in contrast to the porins (20 ìg) used previously (Singh et al, 1999). This points towards the sensitivity of OMPs regulated by iron availability.…”

“…5 ìg of the protein was observed to enhance the DTH response significantly. This is in contrast to a 50 ìg dose of the same antigen as discussed recently (Chanana et al, 2005) or of porins extracted under normal conditions (Singh et al, 1999). Since organisms under environmental stresses have been reported to express more virulence determinants, lower concentrations of bacteria/ bacterial products might be required.…”

“…T-cell reactivity to the pure IROMPs preparation was determined by in vitro stimulation. The lymphocytes isolated from spleens and PPs of mice from each group (on days 0, 3, 7 and 15) were cultured at a concentration of 1 3 10 6 cells ml À1 in RPMI 1640 containing 10 % heat-inactivated FCS in the presence of Con A (2 ìg) and IROMPs (1 ìg) at 37 8C in a humidified atmosphere with 5 % CO 2 for 66 h. After 66 h, 3 H-thymidine (1 ìCi) was added to each well under sterile conditions (Singh et al, 1999). The cultures were kept under similar conditions for a further 6 h and thereafter the cells were harvested and the radioactivity was measured by suspending the harvested cells in Bray's scintillation fluid and counting on a â-counter (Rackbeta, 1214).…”

Protective Efficacy and Immunogenicity of Vi‐Porin Conjugate against Salmonella typhi

“…Earlier studies have shown that porins of S. typhi induce both cellular and humoral immune response (6,25,33). We, in another study, also observed that porins induce Tcell responses both at systemic and mucosal levels (24). In the present study, the Vi and porin were first purified from S. typhi Ty2 and S. typhi 0901 strains, respectively.…”

“…also induces sIgA in the intestine (24). Therefore, porin might be playing an important role in the conjugateinduced sIgA.…”