Combined infectious bronchitis virus Arkansas and Massachusetts serotype vaccination suppresses replication of Arkansas vaccine virus.

Combined infectious bronchitis virus Arkansas and Massachusetts serotype vaccination suppresses replication of Arkansas vaccine virus. Avian Pathol. 2015 Jul 30;:1-54 Authors: Ndegwa EN, Bartlett SN, Toro H, Joiner KS, van Santen VL Abstract Polyvalent infectious bronchitis virus (IBV) vaccination is common worldwide. The possibility of vaccine interference after simultaneous combined vaccination with Arkansas (Ark) and Massachusetts (Mass)-type vaccines was evaluated in an effort to explain the high prevalence of Ark-type IBV in vaccinated chickens. Chickens ocularly vaccinated with combinations of Ark and Mass showed predominance of Mass vaccine virus before 9 days post-vaccination (DPV) in tears. Even when Mass and Ark vaccines were inoculated into separate eyes, Mass vaccine virus was able to out-compete Ark vaccine virus. Although Mass vaccine virus apparently had a replication advantage over Ark vaccine in ocular tissues, Ark vaccine virus appeared to have an advantage in spreading to and/or replicating in the trachea. When chickens vaccinated with Ark or Mass vaccine were housed together, Mass vaccine virus was able to spread to Ark-vaccinated chickens, but the Ark vaccine was not detected in Mass-vaccinated chickens. Only Mass vaccine was detected in tears of sentinel birds introduced into groups receiving both vaccines. Furthermore, Ark vaccine virus RNA was not detectable until 10 DPV in most tear samples from chickens vacc...
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research