|Straus, David - TEXAS TECH UNIV, LUBBOCK|
|Sutherland, R - TX VET MED DIAG LAB|
|Ayres, J - TX VET MED DIAG LAB|
Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 1996
Publication Date: N/A
Interpretive Summary: The bacterium Pasteurella haemolytica (Ph) frequently causes pneumonia in market stressed young cattle, sheep, and goats. The cost of this disease complex in cattle alone is estimated at $750,000,000 annually in the U.S.A. The use of efficacious Ph vaccines is one way to help reduce the cost of this disease in ruminant animals. We used ultraviolet light (UV-light) to kill virulent Ph bacteria which were then used as a bacterin. After UV-irradiation the bacterin pool was divided into 4 equal lots, and each lot was combined with 1 of the following: polyacrylate beads (PA), agar beads (AG), oil adjuvant (OIL), and phosphate buffered saline (PBS). Each of these bacterins were subcutaneously (SC) injected into a different group of goats identified as PA, AG, OIL, and PBS. The immunity induced by these 4 bacterins was compared to the immunity induced in positive controls (PC) infected with live Ph and non-immunized negative controls (NC). All goats were later challenge-exposed directly into the lung with live Ph, and 4 days later the volume of the lung lesions were measured. A small lung lesion indicates greater immunity. The mean volume of the lung lesions by treatment groups were as follows: NC, 160 cm**3; PC, 1 cm**3; OIL, 2.3 cm**3; PA, 5.5 cm**3; AG, 7.7 cm**3; and PBS, 7.5 cm**3. The mean volume of the lung lesions of NC goats was significantly greater than those of the PC and 4 bacterin groups. There were no significant differences in mean volume of the lung lesions between the PC and 4 bacterin groups. The use of these bacterins have the potential to lower the economic impact of losses due to pasteurellosis.
Technical Abstract: The effectiveness of a Pasteurella haemolytica A1 (Ph A1) bacterin killed with ultraviolet light and incorporated with various carriers such as agar beads (AG), polyacrylate beads (PA), incomplete adjuvant (OIL), and phosphate buffered saline (PBS) was tested by the subcutaneous (SC) route in goats. The induced immunity was tested against a heterologous Ph A1 transthoracic challenge-exposure. Immunity was quantified by measuring th volume of consolidated lung tissue 4 days after challenge. Nine goats were given 2 transthoracic injections into the left lung 21 days apart with live Ph A1 mixed in polyacrylate beads (positive control group). All goats given polyacrylate beads only or bacterin were injected (SC) in the neck on days 0 and 21. Six goats were given 2 SC injections of polyacrylate beads only (negative control group), 7 goats were given 2 SC injections of bacterin in PA beads (PA bacterin group), 6 goats were given 2 SC injections of bacterin in agar beads (AG bacterin group), and 6 goats were given 2 SC injections of bacterin in phosphate buffer saline (PBS bacterin group). All goats were challenge-exposed on day 36 by transthoracic injection and 4 days later, they were euthanatized and necropsied. Mean volume of consolidated lung tissue was 1.02 cm**3 for the positive control group; 159.5 cm**3 for the negative control group; 2.3 cm**3 for the OIL bacterin group; 5.53 cm**3 for the PA bacterin group; 7.68 cm**3 for the AG bacterin group; and 7.51 cm**3 for the PBS bacterin group. There was a significant (P ó 0.0001) difference in mean volume of consolidated lung tissue between the negative control group and the other groups. There were no significant differences in mean volume of consolidated lung tissue between the positive control group and the 4 bacterin groups.