Newcastle disease virus vectored infectious laryngotracheitis vaccines protect commercial broiler chickens in the presence of maternally derived antibodies

Authors: Yu, Qingzhong; Spatz, Stephen; LI, YUFENG - Shandong Poultry Research Institute, China; YANG, JINLONG - Chongqing Academy Of Animal Sciences; ZHAO, WEI - Beijing Centers For Disease And Prevention, Department Of Pest Inspection; ZHANG, ZHENYU - Northeast Agricultural University; WEN, GUOYUAN - Lanzhou University; GARCIA, MARICARMEN - University Of Georgia; Zsak, Laszlo

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2016
Publication Date: 1/2/2017
Publication URL: https://handle.nal.usda.gov/10113/5603951
Citation: Yu, Q., Spatz, S.J., Li, Y., Yang, J., Zhao, W., Zhang, Z., Wen, G., Garcia, M., Zsak, L. 2017. Newcastle disease virus vectored infectious laryngotracheitis vaccines protect commercial broiler chickens in the presence of maternally derived antibodies. Vaccine. 35(5):789-795. doi:10.1016/j.vaccine.2016.12.038.

Interpretive Summary: Infectious laryngotracheitis (ILT), caused by infectious laryngotracheitis virus (ILTV) infection, is one of the most common avian respiratory diseases in the US poultry industry. Vaccination combined with restrict biosecurity has been the recommended strategy for control of the disease. Previously we have demonstrated that Newcastle disease virus (NDV) vectored ILTV vaccine candidates confer complete clinical protection against virulent ILTV and NDV challenges in naive chickens. However, there is a concern that the presence of maternal derived antibodies (MDA) in commercial chickens may interfere with vaccinal protection. In this study, we evaluated the protective efficacies of the NDV vectored ILTV vaccine candidates in commercial broiler chickens with maternal antibodies against NDV and ILTV. The results showed that these vaccine candidates conferred significant clinical protection and reduction of ILTV shedding after challenge. The data also suggest that the presence of maternal antibodies capable of neutralizing ILTV and high titers of NDV MDA did not significantly interfere with the ability of the NDV LaSota strain-vectored ILTV vaccines to confer protective immunity against ILT disease.

Technical Abstract: Newcastle disease virus (NDV) recombinants expressing the infectious laryngotracheitis virus (ILTV) glycoproteins B and D have previously been demonstrated to confer complete clinical protection against virulent ILTV and NDV challenges in naive chickens. We extended this study to assess whether maternally derived antibody (MDA) against NDV and ILTV would interfere with protection in vaccinated broiler chickens. Chickens with a mean NDV MDA hemagglutination inhibition (HI) titer of 6.4 (log2) and detectable ILTV neutralization (VN) antibodies at hatch were vaccinated with rLS/ILTV-gB or rLS/ILTV-gD at 1 or 10 day of age (DOA) or on both days. Groups of birds vaccinated with the commercial ILT vaccines (FPLT and CEO) or sham inoculated were also included in this study. All vaccinated birds were challenged with virulent ILTV strain at 21 DOA. By that time, NDV HI titers declined to 2.6 (log2) in unvaccinated birds, whereas the HI titers in NDV vectored vaccine groups increased to 3.5–6.3 (log2). At standard dosages, both vaccine candidates conferred significant clinical protection; however, the protection elicited by the rLS/ ILTV-gD was superior to that of rLS/ILTV-gB. Recombinant rLS/ILTV-gD reduced ILTV shedding from tracheal and ocular tissues by approximately 3 log10 TCID50. Notably, there was no improvement in protection after booster vaccination at 10 DOA. Overall results indicate that the presence of maternal antibodies to NDV and ILTV did not significantly interfere with the ability of the NDV LaSota strain-vectored ILTV gB and gD vaccine candidates to elicit protective immunity against infectious laryngotracheitis.