Assessment of Mycoplasma gallisepticum vaccine efficacy in a co-infection challenge model with QX-like infectious bronchitis virus.

Assessment of Mycoplasma gallisepticum vaccine efficacy in a co-infection challenge model with QX-like infectious bronchitis virus. Avian Pathol. 2018 Feb 16;:1-28 Authors: Bwala DG, Ponman S, Duncan N, Wandrag DBR, Abolnik C Abstract Mycoplasma gallisepticum (MG) is the primary cause of chronic respiratory disease in poultry. We investigated the protective efficacy of the live attenuated ts-11 and 6/85 MG vaccines against a local MG strain, and in order to enhance symptoms and mimic a typical field situation, we co-infected birds with a virulent strain of QX-like infectious bronchitis virus (IBV). Both vaccines showed similar ability to protect infected chickens from clinical signs, although ts-11 performed slightly better. Despite the lower protection against clinical disease, 6/85-vaccinated birds had significantly (P≤0.05) lower tracheal lesion scores and mucosal thickness at day 28 post vaccination (7 days post challenge [dpc] with MG, 2 dpc IBV) and day 31 post vaccination (10 dpc MG challenge, 5 dpc IBV) compared to ts-11 vaccinated birds, but these difference was not significant at day 33 (12 dpc MG, 7dpc IBV). Pathogen infection and replication was assessed by qPCR, and the 6/85 vaccine produced a more significant (P≤0.05) reduction in MG replication in the lungs, kidneys and livers but enhanced late replication in bursae and caecal tonsils. In contrast, the ts-11 vaccine had a more pronounced reductive effect on replica...
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research