|Straus, David - TX TECH HEALTH SCI CTR|
|Cooley, J - TX TECH HEALTH SCI CTR|
Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 14, 1996
Publication Date: N/A
Interpretive Summary: It is not well understood how Pasteurella multocida A:3 (Pm A:3) produces disease in the ruminant animal. A number of virulence factors have been described, however, it is possible that other undiscovered virulence factors may contribute to the ruminant stress related pneumonia. Neuraminidase produced by other species of bacteria has been implicated as a potential virulence factor. We have determined that the neuraminidase enzyme is produced in the animal during a Pm A:3 lung infection. The Pm A:3 anti-neuraminidase antibodies which are capable of decreasing the enzymes activity in the test tube, and we suspect, in the animal during infection. Neuraminidase appears to be another virulence factor. This information is important to the scientist to understand the pathogenesis of this disease, and to the feed calf industry, as it may help in determining the Pm A:3 immune status of any ruminant and it may be important in developing efficacious Pm A:3 vaccines.
Technical Abstract: Six goats were injected transthoracicly with live Pasteurella multocida A:3 to examine if an extracellular enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (N=6) each received 1 ml of 7.5 x 10**4 P. multocida mixed with polyacrylate beads transthoracicly in the left lung on day 0 and 1 ml of live P. multocida (2.2 x 10**8 cfu) mixed with polyacrylate beads transthoracicly in the left lung on day 22. Six goats 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 obtained from all animals on days 0, 7, 14, 22, 29, and 36. Preimmune sera 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 titer 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 day 14 in the infected animals. These data show that the enzyme neuraminidase is produced in vivo during an active P. multocida A:3 lobar infection.