Formalin Inactivated infectious Bursal Disease Virus Vaccine Immunogenicity in Indigenous Chickens in Kenya
Background: Infectious bursal disease vaccination failure and subsequent outbreaks in vaccinated chickens are a challenge in poultry production. This could be due to use of live vaccines which may revert to virulence resulting in disease. Further, live vaccines may become non-viable due to poor handling and yield no immune response. Killed vaccines developed using indigenous strains could offer solutions to the challenge. Immunogenicity of five formalin inactivated virus isolates from field outbreaks in Kenya were determined. The isolates, designated as E3, E9, E19, E34 and, E42, were prepared at 104EID50 and each inoculated into six 4 week old specific antigen negative (SAN) indigenous chicks. 0.3mls was administered intramuscularly at day 0, 14 and 21 and titres levels measured at inoculation (baseline), days 14, 21, 28 and 35.
Results: Immune responses were detected by Agar Gel Precipitation Test (AGPT) and Enzyme Linked Immunosorbent Assay (ELISA). All the isolates elicited detectable immune response by day 14. Antibody titre values by day 21 were above 396 and considered positive. Highest titre value (9140) was recorded on day 28 in response to E19. Titres variations between isolates were not statistically significant (p=0.9639).
Conclusions: All isolates were immunogenic. Isolates E3 and E19 consistently yielded high titres and were recommended as most suitable for development for use in a vaccination regimen.