Journal of Bacteriology & Parasitology

Abstract

On-Station and Field Evaluation of Inactivated Fowl Cholera Vaccine Produced from Local Pasteurella multocida Isolates, Ethiopia

Zewde Tariku Wolde*, Gezahegn Mamo, Esayas Gelaye, Takele Abayneh and Jaleta Shuka

Vaccination is one of the common preventive measures of fowl cholera. On-station and field study was carried out from November 2017 to April 2018 to evaluate the safety, immunogenicity and protective efficacy of inactivated fowl cholera vaccine developed from local Pasteurella multocida isolate at national veterinary institute, Ethiopia. A total of 60 chickens (8 weeks old; bovan brown breed) randomly divided into 3 groups, each 20 chick, were used for onstation study. The first and second groups were vaccinated twice (three weeks apart) with 1 ml and 0.5 ml of inactivated fowl cholera vaccine containing 2.5 × 10⁸ cfu/ml, respectively both through the IM route. The third group was kept as unvaccinated control. Sera were collected from all groups at day 0, 14, 21, 28 and 35 and kept at -20°C until analysis using Indirect Haemagglutination Test (IHT). All groups were challenged using virulent isolate of Pasteurella multocida containing 1.67 × 10⁸ cfu/ml 15 days after the booster vaccination. Moreover, field or on-farm evaluation was conducted on 200 layers kept in a separate compartment from a selected commercial poultry farm. The chickens were divided into two groups of each 100 chicken and vaccinated twice (three weeks apart) with 0.5 mL and 1 mL through IM route. Sera were collected at day 0, 21 and 35 and examined by indirect haemagglutination test. In the experimental evaluation, mean antibody titers of group I were found to be 1.6 ± 1.2, 211.3 ± 2.1, 244.5 ± 1.2, 319.8 ± 1.2 and 502 ± 1.2 on day 0, 14, 21, 28 and 35 respectively. In group II, mean antibody titers were 1.3 ± 1.2, 203.7 ± 3.0, 234.2 ± 1.2, 367.2 ± 1.2.5 and 452.9 ± 1.2 on day 0, 14, 21, 28 and 35 respectively. In group III, the mean antibody titer was similar on the respective days which were not different from the value on day 0, 1.4 ± 1.2. In case of protective efficacy, both 1 ml and 0.5 mL dose vaccinated chicken had survival rate of 87.5%. On field evaluation, the mean antibody titers were 4.2 ± 1.1, 310.4 ± 1.0 and 532.6 ± 1.0 on day 0, 21 and 35 respectively. Both on-station and farm (field) evaluation showed that formalin killed fowl cholera vaccine induced good immune response with significant increase in mean antibody titer after booster vaccination, which corresponded to significant (87.5%) protection as observed in the challenge experiment. No difference was found in the protective efficacy and immunogenicity between 1 ml and 0.5 ml dose rates of the vaccine suggesting that the use of 0.5 ml dose rate in two injections 3 weeks apart would be economical that could provide optimal protection under field condition.

Published Date: 2023-08-16; Received Date: 2022-10-19