Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/22/2014
Publication Date: 7/20/2014
Citation: Spatz, S.J., Yu, Q., Zsak, L., Garcia, M. 2014. Newcastle disease virus as a vaccine vector for infectious laryngotracheitis. In: Proceedings of the 10th International Symposium on Marek's Disease and Avian Herpesviruses, July 20-23, 2014, East Lansing, Michigan. p. 66.
Technical Abstract: Effective, safe, and incapable of reverting to virulence are characteristics desirable for infectious laryngotracheitis virus (ILTV) vaccines. Recombinant Newcastle disease virus (NDV) expressing foreign antigens of avian and mammalian pathogens have been demonstrated to elicit protective immunity. Since NDV is an excellent respiratory vaccine vector, we inserted the genes encoding glycoprotein B (gB) and glycoprotein D (gD) of ILTV into the intergenic regions between the P and M genes and generated two NDV/ILTV recombinant viruses using reverse genetics. The recombinant viruses (rLS/ILTV-gB and rLS/ILTV-gD) retained their parental La Sota vaccine growth properties in chicken eggs, with titers of 3.8 X 108 and 1.8 X 109 (EID 50)/ml of allantoic fluid, respectively. Results from standard mean death time studies and intracerebral pathogenicity index tests provided further evidence that the recombinant viruses retained the same low virulence pathotype as the parental La Sota virus. The expression of the ILTV-gB and -gD proteins were detected in the recombinant virus infected DF-1 cells by immunofluorescence assay. Animal studies demonstrated that both rLS/ILTV-gB and rLS/ILTV-gD were safe, without any signs of vaccine induced side effects, and induced a comparable NDV antibody response as strong as their parental NDV vaccine. Two animal experiments were conducted in specific pathogen free (SPF) leghorn chickens and commercial broiler chickens in order to evaluate the protective efficacy conferred by the NDV/ILTV recombinant viruses. Data regarding protection against clinical signs and relative ILTV shedding in tracheal lumen and tears after virulent virus challenge compared with those of CEO and TCO vaccinated boilers will be presented.