Cross-Protection Conferred by Combined Vaccine Containing Infectious Bronchitis Virus Attenuated Massachusetts and Recombinant LaSota Virus Expressing Arkansas Spike.

We previously demonstrated that a prime-boost regime with an infectious bronchitis virus (IBV) Massachusetts (Mass)-type vaccine and recombinant LaSota virus (rLS) coexpressing IBV Arkansas (Ark)-type trimeric spike ectodomain (Se) and granulocyte macrophage colony stimulating factor (GMCSF) enhances heterologous protection against virulent Ark challenge. This study evaluates protection against Ark-type challenge conferred by administering the rLS/ArkSe.GMCSF and the attenuated Mass viruses mixed in the same vial as a combined vaccine.

Protection Against Infectious Bronchitis Virus Vaccine Recombinants and Chicken-Selected Vaccine Subpopulations.

Outbreaks of infectious bronchitis (IB) continue to occur from novel variants of IB virus (IBV) emerging from selection of vaccine subpopulations and/or naturally occurring recombination events. S1 sequencing of Arkansas (Ark) -type viruses obtained from clinical cases in Alabama broilers and backyard chickens shows both Ark Delmarva Poultry Industry (ArkDPI) vaccine subpopulations as well as Ark vaccine viruses showing recombination with other IB vaccine viruses. IB Ark-type isolates AL5, most similar to an ArkDPI vaccine subpopulation selected in chickens, AL4, showing a cluster of three nonsynonymous changes from ArkDPI subpopulations selected in chickens, and AL9, showing recombination with Massachusetts (Mass) -type IBV, were examined for pathogenicity and ability to break through immunity elicited by vaccination with a commercial ArkDPI vaccine.

Distribution of Infectious Bronchitis Virus Resistance in a Naïve Chicken Population.

Resistance to infectious bronchitis (IB) is a polygenic trait, but little is known about how resistance distributes in the host population. In this study, a relatively large number (n = 369) of specific-pathogen-free white leghorn chickens () were challenged with an Arkansas -type virulent IB virus (IBV), and resistance was evaluated 5 days after challenge by viral load (IBV RNA) in the trachea and cecal tonsils, as well as by tracheal histomorphometry (mucosal thickness and lymphocyte infiltration). Contrary to expectations, results showed a non-Gaussian distribution of resistance of the whole population against challenge.