COMPARISON OF SPLEEN-CELL PROLIFERATION IN RESPONSE TO BRUCELLA-ABORTUS-2308 LIPOPOLYSACCHARIDE OR PROTEINS IN MICE VACCINATED WITH STRAIN-19 OR RB51

Mice vaccinated with Brucella abortus 19 (S19) or RB51 (SRB51) had spl een cells which proliferated in response to proteins of 32, 27, 18, an d <18 kDa but not in response to proteins of 106, 80, and 49 kDa from B. abortus 2308 (S2308) following vaccination and challenge infection with S2308. Spleen cells from mice vaccinated with S19 but not with SR B51 had increased proliferation in response to S2308 lipopolysaccharid e (LPS) following challenge infection with S2308. We Previously report ed that mice vaccinated with S19 or SRB51, which were analyzed in the current study, have increased resistance to infection with S2308 and t hat only mice vaccinated with S19 produce antibody to S2308 LPS (M. St evens, S. Olsen, G. Pugh, Jr., anti D. Brees, Infect. Immun. 63:264-27 0, 1995). The results from our current and previous studies support th e contention that vaccination of mice with S19 or SRB51 induces protec tion from infection with S2308 by cell-mediated immune responses to th e same immunodominant (32, 27, 18, and <18 kDa) protein antigens of S2 308. In addition, the absence of S2308 LPS-responsive spleen cells and antibody to S2308 LPS in mice vaccinated with SRB51 suggests that imm une responses to LPS have no role in SRB51-induced protective immunity .