IN-VIVO PRODUCTION OF NEURAMINIDASE BY PASTEURELLA-MULTOCIDA A-3 IN GOATS AFTER TRANSTHORACIC CHALLENGE

Six goats were injected transthoracically with live Pasteurella multoc ida A:3 to examine if an extracellular enzyme, neuraminidase, was prod uced in vivo during infection with this organism. The principal group of goats (n = 6) each received 1 mi of live 7.5 X 10(4) cfu of P. mult ocida mixed with polyacrylate beads transthoracically in the left lung on day 0 and 1 ml of live P. multocida (2.2 X 10(8) cfu) mixed with p olyacrylate beads transthoracically in the left lung on day 22. Six go ats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 22. Serum was ob tained from all animals on days 0, 7, 14, 22, 29, and 36. Preimmune se ra from all animals showed no detectable antibody to P. multocida A:3 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals demonstrated a significant antibody tite r against the P. multocida A:3 neuraminidase. On day 36, serum samples from the six infected animals possessed complete enzyme-neutralizing activity. Anti-neuraminidase antibody could be detected as early as da y 14 in the infected animals. These data show that neuraminidase is pr oduced in vivo during an active P. multocida A:3 lobar infection.