Clinical and pathological responses of broilers to ocular vaccination using plant gum delivery and challenge with infectious bursal disease virus

Few studies have investigated phytogenic gums as vaccine delivery agents in veterinary diseases. This study therefore evaluates the changes in clinical, haematological and histopathologcal responses of broilers vaccinated with infectious bursal disease virus (IBDV) vaccine, administered with the Cedrela odorata and Khaya senegalensis as phytogenic mucoadhesive following experimental infection with virulent IBDV. Two hundred (200)-day-old birds were divided into four groups: as combined gums-IBDV vaccine (A), IBDV vaccine alone (B), gums alone (C) and no gum not vaccinated (D), respectively. The IBDV vaccination was administered ocularly at 14 and 28 days and later challenged with the virulent IBDV at 21 days. All the birds were observed clinically post-infection, blood samples were collected for complete blood count while lymphoid tissues were examined from sacrificed chicks. The haematologic, clinical and lesion score data were descriptively analysed. There were no significant differences in haematological indices except for basophil (p < 0.05). Group A chicks had better immunity with less clinical signs and no lesions in the organs post-infection compared with other groups. Groups B and C had similar clinical signs and histopathological and haematological changes, while in group D, high morbidity with severe clinical signs and lesions were observed. In conclusions, mucoadhesives from phytogenic origin showed potential as delivery vehicle for IBDV vaccines with protection against clinicopathological derangements associated with virulent Gunboro virus. © 2020, Springer-Verlag London Ltd., part of Springer Nature.