FIG. 8.
Contribution of LVS-specific CD4+ T cells to protective immunity against SCHU S4 challenge. Groups of BALB/c mice (n = 8) were either vaccinated orally with 103 CFU of LVS or mock immunized with PBS. Mice were rested for 3 weeks and received i.p. injections of either an anti-CD4 neutralizing antibody, a control rat Ig, or PBS at day −2, day −1, the day of i.n. challenge with 80 CFU of SCHU S4 (day 0), and every subsequent third day. Mice were monitored daily for morbidity and mortality. Differences in survival between vaccinated mice receiving rat Ig and those receiving anti-CD4 antibody treatment were significant at a P value of 0.0185 (statistical power, 0.996 with an alpha of 0.50). Results are representative of two separate experiments.