Newcastle disease virus (NDV) recombinants expressing infectious laryngotracheitis virus (ILTV) glycoproteins gB and gD protect chickens against ILTV and NDV challenges

Authors: ZHAO, WEI - Northwest Agricultural & Forestry University; Spatz, Stephen; ZHANG, ZHENYU - Northeast Agricultural University; WEN, GUOYUAN - Hubei Academy Of Agricultural Sciences; GARCIA, MARICAMEN - University Of Georgia; Zsak, Laszlo; Yu, Qingzhong

Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2014
Publication Date: 5/14/2014
Publication URL: http://handle.nal.usda.gov/10113/59865
Citation: Zhao, W., Spatz, S.J., Zhang, Z., Wen, G., Garcia, M., Zsak, L., Yu, Q. 2014. Newcastle disease virus (NDV) recombinants expressing infectious laryngotracheitis virus (ILTV) glycoproteins gB and gD protect chickens against ILTV and NDV challenges. Journal of Virology. 88:8397-8406. doi: 10.1128/JVI.01321-14.

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. The disease is mainly controlled through biosecurity and vaccination with live-attenuated strains of the virus and herpesvirus (HVT) and fowlpox virus (FPV) vectored vaccines. However, the current live attenuated ILTV vaccines, (chicken embryo origin [CEO] and tissue culture origin [TCO]), although effective, can regain virulence, whereas the vectored vaccines provide only partial protection. Therefore, there is a need to develop safer and more efficacious vaccines for protection of chickens against the disease. In the present study, we generated Newcastle disease virus (NDV) LaSota vaccine-based recombinant viruses expressing the antigenic proteins gB and gD of ILTV. These recombinant vaccines were stable and safe to all age of chicks. Leghorn chickens and broiler chickens vaccinated with these vaccines were protected against virulent ILTV and NDV challenge, showing little or no clinical signs and no decrease in body weight gains. The results suggested that the NDV/ILTV recombinant viruses are safe, stable and effective bivalent vaccines that can be mass-administered via aerosol or drinking water to large chicken populations, which will impact the US poultry industry and make their products (meat and eggs) even more inexpensive to the consumer.

Technical Abstract: Infectious laryngotracheitis (ILT) is a highly contagious acute respiratory disease of chickens caused by infectious laryngotracheitis virus (ILTV). The disease is mainly controlled through biosecurity and vaccination with live-attenuated strains of the virus and vectored vaccines based on turkey herpesvirus (HVT) and fowlpox virus (FPV). The current live attenuated vaccines (chicken embryo origin [CEO] and tissue culture origin [TCO]), although effective, they can regain virulence, whereas HVT- and FPV-vectored ILTV vaccines are less efficacious than live-attenuated vaccines. Therefore, there is a pressing need to develop safer and more efficacious ILTV vaccines. In the present study, we generated Newcastle disease virus (NDV) recombinants, based on the LaSota vaccine strain, expressing the glycoproteins B (gB) and D (gD) of ILTV using reverse genetics technology. These recombinant viruses, rLS/ILTV-gB and rLS/ILTV-gD, were slightly attenuated in vivo, yet retained similar growth dynamics, stability, and virus titers in vitro when compared to the parental LaSota virus. Expression of the ILTV gB and gD proteins in the recombinant virus-infected cells was detected by immunofluorescence assay. Vaccination of specific pathogen free (SPF) chickens with these recombinant viruses conferred significant protection against virulent ILTV and velogenic NDV challenges. Immunization of commercial broilers with rLS/ILTV-gB provided a similar level of protection against clinical disease as well as that provided by the live attenuated commercial vaccines (TCO and CEO), with no decrease in body weight gains. The results of the study suggested that the rLS/ILTV-gB and -gD viruses are safe, stable and effective bivalent vaccines that can be administered en mass via aerosol or drinking water to large chicken populations.