Abstract: Protection efficacy of a trivalent HVT recombinant vaccine (HVT-ILT-IBD) against infectious laryngotracheitis (ILT) in broiler chickens
Infectious laryngotracheitis (ILT) is an economic respiratory disease that affects the poultry industry worldwide. Biosecurity and vaccination are needed to control the disease. ILT vaccination with recombinant vaccines is considered a first option in broilers since these vaccines are totally safe and recommended to be applied at the hatchery.
Recombinant vaccines that utilize the herpesvirus of turkey (HVT) vector have become widely available and, more recently, a new trivalent recombinant vaccine that protects against Marek’s disease (MD), Infectious Laryngotracheitis (ILT), and Infectious Bursal disease (IBD) has been developed.
The objective of this study was to evaluate the protection efficacy of a new trivalent recombinant HVT-ILT-IBD vaccine when compared to a bivalent recombinant HVT-ILT vaccine against an ILT challenge in broilers.
Compared to the non-vaccinated/challenged (NVx/Ch) group, both the HVT-ILT-IBD and HVT-ILT vaccines significantly reduced clinical signs, tracheal viral load and histopathological lesions post-challenge.
The probability of chicken survival was significantly higher for the HVT-ILT-IBD (96%) and HVT-ILT (93%) vaccines after challenge compared to the NVx/Ch (68%) group.
The body-weight gain after the challenge for HVT-ILT-IBD and HVT-ILT vaccinated groups was better maintained than the NVx/Ch group of broilers. In particular, the HVT-ILT maintained weight gains similar to the non-vaccinated/non-challenged (NVx/NCh) group.
Overall, this study demonstrated that solid and comparable ILT protection is achieved with trivalent (HVT-ILT-IBD) and bivalent (HVT-ILT) recombinant HVT vaccines against an ILT challenge.
This study was conducted by Daniel Maekawa, Merck Animal Health; Ana Zamora, Roshan Paudel, Caley Ellington, April Skipper, Maurice Raccoursier, Ivan Alvarado, Maricarmen Garcia, University of Georgia.
For more information on the vaccines used in the study, click here.
