A multimodal evaluation of immunogenicity and field performance of infectious bursal disease vaccines in Ethiopian broilers

Abstract

Infectious bursal disease (IBD) continues to undermine poultry health and productivity in Ethiopia. Despite the availability of commercial vaccines, there are raising concerns about vaccine performance, particularly in broiler production systems. This study employed a multi-modal evaluation to compare the immunogenicity and field performance of commercially available IBD vaccines in Ethiopia. The research integrated a controlled in vivo trial assessing vaccine-induced antibody responses and a field-level serological survey of broiler flocks under typical management conditions. Additionally, a structured questionnaire was administered to poultry producers to gather data on vaccination practices, biosecurity measures, and general flock management. A total of 100 one-day-old broiler chicks were assigned into four groups. Group 1 received the CEVAC® TRANSMUNE IBD vaccine at day one; Group 2 received the CEVAC® GUMBO L IBD vaccine at day 14; and Group 3 received the IBD VIRUS LC-75 vaccine at day 14 and booster dose at day 21; Group 4 served as an unvaccinated control. Blood samples were collected at multiple time points up to day 42 post-vaccination, and antibody titers were measured using ELISA. Additionally, blood samples were also collected at the same time points from commercial broiler chickens vaccinated with CEVAC® TRANSMUNE IBD vaccine. In parallel, a field survey involving 93 poultry sector participants was implemented to assess vaccine usage and management practices. In the controlled experimental setting, groups vaccinated with the CEVAC® TRANSMUNE IBD vaccine showed higher antibody titers at day 7 post-vaccination (p<0.05), while the ones vaccinated with CEVAC® GUMBO L IBD and IBD VIRUS LC-75 vaccines demonstrated robust responses from day 14 post-vaccination onward. Similarly, chickens vaccinated with the CEVAC® TRANSMUNE IBD vaccine at the field level showed relatively higher antibody titers at day 7 post vaccination, but lower when compared with the one under controlled experimental conditions. Despite those differences, each vaccine elicited a measurable humoral immune response, though the timing of seroconversion and peak antibody levels varied depending on the specific vaccine platform used. Survey results indicated that improved vaccines and optimized vaccination schedules were crucial for effective disease control. Additionally, 63% of respondents emphasized the importance of awareness and training to enhance IBD management. Hence, our findings highlighted the need for improved vaccines, optimized vaccination schedules, veterinarians, and farmer training to improve Gumboro disease management in Ethiopia.