Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/16/2014
Publication Date: 10/16/2014
Citation: Dunn, J.R., Cheng, H.H., Fadly, A.M., Heidari, M., Hunt, H.D., Zhang, H. 2014. Avian Disease & Oncology Lab (ADOL) Research Update. Proceedings of the One Hundred and Eighteenth Annual Meeting of the United States Animal Health Association. p. 411-413.
Technical Abstract: Employing Genomics, Epigenetics, and Immunogenetics to Control Diseases Induced by Avian Tumor Viruses - Gene expression is a major factor accounting for phenotypic variation. Taking advantage of allele-specific expression (ASE) screens, we found the use of genetic markers was superior to traditional pedigree selection. We also conducted studies on the role of host genetics affecting MD vaccine efficacy. Strikingly different protection by HVT was observed between lines of chickens sharing a common MHC type but with known difference in resistance to MD, which indicate genes outside of the MHC domain also significantly affect vaccine protective efficacy. Genetic and Biological Determinants of Avian Tumor Virus Pathogenicity, Transmission, and Evolution - A study comparing MDV clones produced around the world found viruses derived from BAC clones encompassed all three virulent pathotypes (vMDV, vvMDV and vv+MDV). We conducted studies on the influence of altering the di-codon bias of select MDV genes on pathogenicity of the virus. Our altered virus was less virulent with a pronounced decrease in tumors and increased survivability compared to the control. In a study to determine the role of endogenous ALV-E, we found the incidence of spontaneous LL-like tumors in chickens that harbor endogenous ALV was higher than in chickens that lack ALV-E following vaccination with serotype 2 MDV at hatch. We conducted studies to evaluate the protective efficacy of a high passage level of a recombinant MD virus vaccine candidate named rMd5 REV-LTR BAC. Passage 70 of rMd5 REV-LTR BAC virus provided protection comparable to that provided by the most effective currently available commercial vaccine, namely Rispens following challenge with a vv+MDV, suggesting that this virus is a good candidate vaccine that can be used in flocks where a vv+MDV challenge is expected. Finally, we also conducted studies to investigate the effect of MDV infection on cecal tonsils (CT) structural changes and gene expression profiling in MD-susceptible and resistant chicken lines. We found loss of germinal follicular centers within the CT during lytic infection, however, atrophy was transient and there were no visible differences between the CT of the infected and control birds of either line by 21 days post infection.