Efficacy of autogenous killed vaccine of Avibacterium paragallinarum

The efficacy of killed vaccine of Avibacterium paragallinarum with mineral oil adjuvant and aluminum hydroxide gel adjuvant was tested for antibody titers and protection. The autogenous vaccines at a concentration of 10(10) colony-forming units (CFU)/ml were administered to 5-wk-old male layers by subcutaneous injection in the neck twice at a 3-wk interval. Each chicken was challenged with 10(8) CFU/ml in 400 microl of an homologous isolate of A. paragallinarum serotype A, IR1, at 4 wk after the second vaccination via the nasal route. Sera were collected and the antibodies were tested by the hemagglutination inhibition test. The results revealed that the autogenous mineral oil adjuvant vaccine provided the antibody titer significantly faster than the other groups (P < 0.05). The average antibody titers of the group vaccinated with autogenous mineral oil adjuvant vaccine were higher than those of the group vaccinated with autogenous aluminum hydroxide gel adjuvant vaccine. The protective ability of vaccines was assessed by infraorbital sinus swab after 5 days postchallenge. The autogenous vaccines prepared with mineral oil adjuvant and aluminum hydroxide gel adjuvant protected all the chickens after challenge. No bacteria were isolated from the infraorbital sinuses of chickens in either autogenous vaccine group with either high or low antibody titers. The commercial vaccines prepared from mineral oil or aluminum hydroxide gel adjuvant revealed some protection. This is in contrast to the unvaccinated control group, in which facial edema and serous nasal discharge was found, and bacteria could be isolated from all chickens in the group.