INFLUENCE OF RECOMBINANT BOVINE INTERLEUKIN-1-BETA AND INTERLEUKIN-2 IN PIGS VACCINATED AND CHALLENGED WITH STREPTOCOCCUS-SUIS

An experiment was conducted to determine the adjuvanticity of recombin ant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL -2) administered in conjunction with a single Streptococcus suis vacci nation in pigs. Sixty 4-week-old pigs were allotted to eight groups: n onvaccinated controls; vaccinated controls; rBoIL-beta at 0.1, 1, and 10 mu g kg(-1) rBoIL-2 at 2.5, 25, and 250 mu g kg(-1). All pigs (exce pt nonvaccinated controls) were vaccinated on Day 0 with a commercial Streptococcus suis vaccine (serotypes 1 and 2). At vaccination, pigs w ere injected intramuscularly with their respective cytokine treatments . Pigs received additional cytokine injections on 2 consecutive days. On Day 21, all pigs were challenged intravenously with 3.2 X 10(9) col ony forming units of a log phase culture of S. suis (serotype 2). The highest dose of rBoIL-1 beta exceeded the maximum tolerable dose for t he cytokine; however, this dose of rBoIL-1 beta protected pigs from th e S. suis challenge. Pigs administered rBoIL-1 beta at 10 mu g kg(-1) had higher antibody responses to S. suis, less severe clinical signs o f the disease after challenge, better growth performance during the in fection, and less severe gross pathological lesions caused by the bact eria. No pigs in this treatment group died from the bacterial challeng e. These data suggest that rBoIL-1 beta (10 mu g kg(-1)), administered intramuscularly for 3 consecutive days at vaccination, is more effect ive than a single S. suis vaccination alone in protecting pigs against a S. suis challenge.