Efficacy, Safety and Virus Shedding of Inactivated Very Virulent Infectious Bursal Disease Virus in Broiler Chickens

The development of vaccines against very virulent infectious bursal disease virus (vvIBDV) has become pertinent due to the inability of current IBD vaccines to provide full protection.This study aimed to inactivate and evaluate the efficacy and safety of inactivated vvIBDV in broiler chickens.An aliquot of the virus was inactivated by the Binary Ethylene Inime (BEI) method, checked for sterility, and stored at 4 C.Sixty-day-old commercial broiler chickens were grouped into A (non-booster), B (booster), and C (control).Groups A and B were inoculated with 10 7 EID50/0.2mLinactivated vvIBDV subcutaneously at day old.Group B received a booster dose on experimental day 14 while Group C was uninoculated.On day 28, challenged Groups A, B, and C were separated from Groups A, B, and C respectively, and challenged with a pathogenic vvIBDV field strain of 10 5 EID50/1.0mLvia eye drops (0.2mL) and orally (0.8mL).No clinical manifestation was observed in all groups.Chickens in the booster group showed increased body and bursa weight; bursa: and body weight ratio post-challenge.The bursa of Fabricius for all the non-challenged groups appeared normal grossly and histologically.The challenged control group (CCH) showed moderate-severe to severe bursa lesions, indicating a positive vvIBDV infection.Bursal lesion scoring of the challenged booster group was significantly lower (P<0.05)than the other groups.The control-challenged group recorded the highest antibody titer while the booster group had the least, indicating protection.The booster group also had the least viral shedding among all challenged groups.These findings suggested that the inactivated vvIBDV vaccine candidate was safe and efficacious in chickens and could be a good vaccine candidate against vvIBDV in chickens especially when boosted after 14 days.