Determination of the shelf life of inactivated fowl cholera vaccine developed from local isolates of Pasteurella multocida
No Thumbnail Available
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Abeba University
Abstract
Fowl cholera (FC) is caused by Pasteurella multocida (P. multocida) and is a highly contagious disease that causes very high economic losses to the poultry industry around the world through high mortality, weight loss, low production of hatching eggs, reduction of fertility and carcass condemnation. Vaccination is one of the most widely used preventative strategies in the world to minimize illness prevalence and incidence of diseases including FC. Although NVI started to produce the killed FC vaccine in 2019, the shelf-life of the vaccine at 2-8 0C storage conditions was not determined; this was the objective of the current study. The shelf life was determined based on an indirect approach i.e. through evaluation of immune response to the vaccine stored at different time points as a direct approach to determining antigen content was not practicable. Hence, a total of 175 layer chickens (8 weeks old Bovans Brown) hatched and grown at Research and Development Laboratory, National Veterinary Institute (NVI) were used to determine the shelf life of the formalin-inactivated alum adjuvant FC vaccines. The vaccine's shelf life was determined using primary and secondary (booster) dose immunization of chicken with formalin-inactivated alum adjuvanted FC vaccine stored at 2- 8 0C for two weeks, three, six, nine, twelve, eighteen and twenty-four months. Blood was collected from each chicken before primary immunization (at day zero), and on days 21 and 35 after primary vaccination to determine serum antibody levels by Indirect Enzyme-Linked Immunosorbent Assay (I-ELISA). All chickens used for this study indicated a low cut-off OD value of 0.2 and that they were free from serum antibody response against Avian P.
multocida before immunization (at day 0). The level of chicken serum antibody (IgG) titre was significantly increased after 3 weeks of the first immunization. After two weeks of the second vaccination, the titre substantially increased in all chickens. Antibody titre was increased within the group from primary vaccination to secondary (booster) vaccination. However, antibody titre was decreased among the groups with advancing storage time of the vaccine. As a result, formalin-inactivated alum adjuvant FC vaccine-induced antibody response while being kept at the standard recommended condition of storage for up to twenty-four months.
Description
Keywords
Fowl cholera,, Pasteurella multocida, Vaccine, Adjuvant, Formalin, shelf life