Evaluation of commercially available Escherichia coli J5 bacterin as protection against experimental challenge with Pasteurella multocida in rabbits.
OBJECTIVE
To evaluate the ability of commercially available Escherichia coli J5 bacterin to protect rabbits from experimental challenge with Pasteurella multocida.


METHODS
40 P multocida-free New Zealand White rabbits.


METHODS
Rabbits were assigned to 1 of 4 groups of 10 rabbits each. Three of the groups were inoculated SC with J5 bacterin at 8 weeks old. Inoculation was repeated 3 and 6 weeks later. The fourth group was not inoculated and served as controls. Groups 1, 2, and 3 were given 10(9), 10(8), and 10(7) colony forming units (CFU), respectively. Response was monitored by titer assessment, using an E coli J5 antigen capture ELISA. Five weeks after the last inoculation, all rabbits were challenged with P multocida and observed for an additional 5 weeks. Clinical, hematologic, serologic, culture, and necropsy data were collected.


RESULTS
Inoculation of rabbits with 10(9) CFU of E coli J5 bacterin-induced titers that were significantly greater than titers of rabbits vaccinated with 10(8) or 10(7) CFU or those in controls. The incidence of acute bacteremia was lower in rabbits with high titers. At necropsy, prevalence of lesions typical of P multocida was not significantly different among groups. Prevalence of histologic lesions was also not significantly different among groups.


CONCLUSIONS
Although the bacterin induced considerable antibody response and possibly reduced the rate of bacteremia, antibodies were not protective against long-term colonization or infection of the frontal sinuses or tympanic bullae by the challenge strain of P multocida. This bacterin in its currently available form is unlikely to aid in reducing the prevalence of pasteurellosis in rabbits.
Department of Population Health and Reproduction, School of Veterinary Medicine, and Animal Resource Services, University of California, Davis 95616, USA.
R P
RP
Ruble
J S
JS
Cullor
D L
DL
Brooks
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000737:chemistry; D001428:Bacterial Vaccines / Q000627:therapeutic use*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D004926:Escherichia coli / Q000276:immunology; D006400:Hematocrit / Q000662:veterinary; D007114:Immunization / Q000662:veterinary; D008297:Male; D010326:Pasteurella Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D016979:Pasteurella multocida / Q000145:classification / Q000276:immunology* / Q000472:pathogenicity; D011817:Rabbits / Q000276:immunology* / Q000382:microbiology
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001428:Bacterial Vaccines