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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Endemic Poultry Viral Diseases Research » Research » Research Project #432116

Research Project: Intervention Strategies to Prevent and Control Enteric Diseases of Poultry

Location: Endemic Poultry Viral Diseases Research

2018 Annual Report


Objectives
1. Characterize the intestinal virome associated with poultry enteric diseases, including assessing the intestinal microbiome of poultry for the presence of novel enteric pathogens, and developing molecular tools to study the epidemiology, ecology, and evolution of enteric pathogens. 2. Investigate the role of the poultry gut microbiome in promoting overall health and performance gains, including defining the interactions between the gut microbiome and the host immune system that contribute to enteric diseases and performance problems and developing the microbiome as a poultry health phenotype. 3. Develop vaccine platforms that will lead to highly efficacious vaccines that have been rationally designed to control enteric diseases of poultry, including developing vaccines targeting specific enteric pathogens early during the poultry production cycle.


Approach
Viral infections of the avian gastrointestinal tract negatively impact poultry production; however, determining the complex etiologies of the viral enteric diseases in poultry has been difficult. Research in our Unit over the past five+ years has focused in part on the characterization of the poultry gut virus community and initial characterizations of novel viruses. The research proposed in Objective 1 will continue and expand upon this line of investigation. As a logical extension of our viral metagenomic work, we have further performed comparative metagenomic analyses of healthy and enteric disease-affected poultry flocks, leading to descriptions of potential disease-associated viruses such as the enteric picornaviruses. Objective 2 again continues and expands upon these investigations, proposing extensive flock comparisons using powerful next-generation sequencing techniques, pathogenesis work with viruses, and defining the immune response of poultry suffering from enteric maladies. Finally, the discovery of disease-associated genes and infectious agents in Objective 2 will directly inform the design of targeted interventions in Objective 3, which will use our established, efficacious recombinant vectored vaccine platforms to produce vaccines targeting enteric viruses early during the poultry production cycle.


Progress Report
Turkey enteric coronavirus (TCoV) causes clinical enteric disease in turkeys, resulting in significant economic losses to the turkey industry in the United States and abroad. To date, there is no commercial vaccine available to prevent the disease because TCoV does not readily grow in cell culture, which hampers conventional vaccine development. To overcome this barrier to vaccine development, ARS scientist at Athens, Georgia, are developing a novel approach using an enteric Newcastle disease virus (NDV) PHY-LMV42 vaccine as a vector. TCoV spike glycoprotein (S) subunit 1 (S1) and subunit 2 (S2), and nucleocapsid (N) protein genes have been cloned into the enteric NDV vaccine vector. Several NDV/TCoV recombinant viruses have been rescued. Biological assessments of these recombinant viruses showed that they retained a similar growth ability in cell cultures, and were slightly attenuated in chicken embryonated eggs and day-old chickens, when compared with the PHY-LMV42 vaccine vector. The expression of TCoV S or N protein was detected from the virus infected-cells by immune fluorescence assay (IFA). Currently, these recombinant viruses are being evaluated in turkeys for safety and immune responses as vaccine.


Accomplishments
1. Newcastle disease virus (NDV) has been used as a vector in the development of vaccines and gene therapy. A majority of these NDV vectors express only a single foreign gene through either an independent transcription unit (ITU) or an internal ribosomal entry site (IRES). In the present study, ARS researchers at Athens, Georgia, combined the ITU and IRES methods to generate a novel NDV LaSota strain-based recombinant virus vectoring the red fluorescence protein (RFP) and the green fluorescence protein (GFP) genes. Biological assessments of the recombinant virus, rLS/IRES-RFP/GFP, showed that it was slightly attenuated in vivo, yet maintained similar growth dynamics and viral yields in vitro when compared to the parental LaSota virus. Expression of both the RFP and GFP was detected from the virus-infected DF-1 cells by fluorescence microscopy. These data suggest that the rLS/IRES-RFP/GFP virus may be used as a multivalent vector for the development of vaccines and gene therapy agents.


Review Publications
Ji, Y., Liu, T., Du, Y., Cui, X., Yu, Q., Wang, Z., Li, Y., Zhu, Q. 2018. A novel genotype VII Newcastle disease virus vaccine candidate generated by mutation in the L and F genes confers improved protection in chickens. Veterinary Microbiology. 216:99-106. https://doi.org/10.1016/j.vetmic.2018.01.021.
Eldemery, F., Li, Y., Yu, Q., Van Santen, V., Toro, H. 2017. infectious bronchitis virus S2 of 4/91 expressed from recombinant virus does not protect against ark-type challenge. Acarology International Congress Proceedings. 61(3):397-401. https://doi.org/10.1637/11632-032017-ResNoteR.
Hu, H., Roth, J., Zsak, L., Yu, Q. 2017. Engineered newcastle disease virus expressing the F and G protein of AMPV-C confers protection against challenges in turkeys. Scientific Reports. 7:4025. http://doi:10.1038/s41598-017-04267-7.
Yu, Q. 2017. Metapneumovirus infections. In: Saif, Y.M., Toro H., editors. Diagnosis of Major Poultry Diseases. Zaragozo, Spain: Grupo Asis Biomedia, S.L. p.38-40.
Noh, J., Lee, D., Lim, T., Lee, J., Day, J.M., Song, C. 2018. Isolation and genomic characterization of a novel avian orthoreovirus in Korea, 2014. Archives of Virology. 163:1307-1316. https://doi.org/10.1007/s00705-017-3667-8.
Ji, Y., Liu, T., Liu, B., Yu, Q., Cui, X., Guo, F., Chang, H., Zhu, Q. 2017. Two single mutations in the fusion protein of Newcastle disease virus confer hemagglutinin-neuraminidase independent fusion promotion and attenuate the pathogenicity in chickens. Virology. 509:146-151. https://doi.org/10.1016/j.virol.2017.06.021.
Dimitrov, K.M., Afonso, C.L., Yu, Q., Miller, P.J. 2017. Newcastle disease vaccines- a solved problem or a continuous challenge? Veterinary Microbiology. 206:126-136. https://doi.org/10.1016/j.vetmic.2016.12.019.