Author
Purdy, Charles | |
STRAUS, DAVID - TEXAS TECH UNIV., LUBBOCK | |
AYRES, J - TEXAS A&M UNIV., AMARILLO |
Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/16/1997 Publication Date: N/A Citation: N/A Interpretive Summary: The bacterium Pasteurella multocida (Pm) is frequently associated with pneumonia in market stressed young cattle, sheep, and goats. Its importance as a primary causative agent in stress related acute pneumomia of calves is still speculative, however it is a primary agent in pneumonia of fowl, rabbits, sheep, and goats. As better Pasteurella haemolytica (considered an important cause of pneumonia in calves) vaccines become available, the importance of Pm as a causative agent in calf stress-related pneumonia will probably occur. The cost of this pneumonia complex in calves alone is estimated at $750,000,000 annually in the U.S.A. The use of efficacious Pm vaccines is one way to help possibly reduce the cost of this disease in calves and should definitely reduce the cost of this disease in other ruminants and other animal species. We used ultraviolet light to kill Pm bacteria which were then used as a bacterin injected subcutaneously into 6 principal goats. The immunity induced by this bacterin was compared to the immunity induced in 6 positive controls (PC) infected with live Pm and 6 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 indicated greater immunity. The mean volume of the lung lesions by treatment groups were as follows: NC, 15.2 cm**3; PC group 1.8 cm**3; and vaccinates 3.9 cm**3. The NC group had significantly greater lung lesions than the vaccinates and the PC group. The use of this bacterin has the potential to lower the economic impact of losses due to pasteurellosis. Technical Abstract: Objective-To determine the effectiveness of Pasteurella multocida biovar A, serovar 3 (Pm A:3) killed with UV-light and incorporated with a polyacrylate bead carrier as a vaccine. Design-Prospective, randomized controlled study with 3 treatment groups: positive control (PC); negative control group (NC); principal Pm A:3 bacterin group (PA). Animals-Eighteen weanling male Spanish goats. Procedure-Six PC goats each received live Pm A:3 and polyacrylate beads, twice, 22 days apart by transthoracic injection into the left lung. Six NC goats each received only PA beads, twice, 22 days apart by transthoracic injection. Six principal goats each received Pm A:3 vaccine SC twice, 22 days apart. Fourteen days after the second vaccination all goats were challenge exposed to live Pm A:3 by transthoracic injection into othe right lung, and 4 days later they were euthanatized and necropsied. Results-Mean volume of consolidated lung tissue at the challenge site was 1.75 cm**3 for the PC group; 15.18 cm**3 for the NC group; and 3.9 cm**3 for the PA vaccine group. The NC group had a significantly (P <\= 0.002) larger mean volume of consolidated lung tissue than the PC and PA groups after challenge exposure. Conclusions-The PA bacterin and the PC groups developed protective immunity against a live Pm A:3 challenge exposure. Clinical Relevance-A SC administered, UV light killed, Pm A:3 bacterin induced protective immunity similar to that induced by virulent live Pm A:3 injected into the target organ, the lung. |