Efficacy of a subcutaneously administered, ultraviolet light-killed Pasteurella haemolytica A1-containing vaccine against transthoracic challenge exposure in goats.

OBJECTIVE

To determine the effectiveness of Pasteurella haemolytica biovar A, serovar 1 (Ph A1) killed by UV light and incorporated with an oil adjuvant or carriers.

ANIMALS

40 weaning male Spanish goats.

PROCEDURE

Goats were randomly allotted to 1 of 6 treatment groups: 4 Ph A1 bacterins (agar beads, polyacrylate beads [PA], phosphate-buffered saline solution, Freund's incomplete adjuvant), live Ph A1 with polyacrylate beads (LiPhPA), and polyacrylate beads (UnVac). Each of 4 Ph A1 vaccines was administered SC twice, 21 days apart, to 1 of 4 groups; another group received only PA beads SC, and the last group received live Ph A1 with PA beads by transthoracic injection into the left lung. 14 days after the second vaccination, all goats were challenge exposed with live Ph A1 by transthoracic injection into the right lung, and 4 days later, all goats were euthanatized and necropsied.

RESULTS

Mean volume of consolidated right lung tissue was 1.02 cm3 for the LiPhPA group, 168.1 cm3 for the UnVac group, 2.3 cm3 for the Freund's incomplete adjuvant bacterin group, 5.53 cm3 for the PA bacterin group, 9.01 cm3 for the agar beads bacterin group, and 7.51 cm3 for the phosphate-buffered saline solution bacterin group. Mean volume of consolidated lung tissue was significantly different between the UnVac group and the other 5 groups.

CONCLUSION

The LiPhPA group and 4 bacterin groups developed protective immunity against live Ph A1 challenge exposure.

CLINICAL RELEVANCE

An s.c. administered, UV light-killed Ph A1 bacterin induced protective immunity equal to that induced by virulent live Ph A1 injected into the target organ, the lung.