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Title: ANALYZING THE H19- AND T65-EPITOPES IN 38 KD PHOSPHORYLATED PROTEIN OF MAREK'S DISEASE VIRUSES AND COMPARING CHICKEN IMMUNOLOGICAL REACTIONS TO VIRUSES POINT-MUTATED IN THE EPITOPES

Author
item CUI, ZHIZHONG - SHANDONG AGR UNIV CHINA
item ZHANG, ZHI - SHANDONG AGR UNIV CHINA
item QIN, AIJIAN - YANGZHOU UNIVERSITY CHINA
item Lee, Lucy

Submitted to: Science in China
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2003
Publication Date: 12/31/2003
Citation: Cui, Z., Zhang, Z., Qin, A., Lee, L.F. 2003. Analyzing the h19- and t65-epitopes in 38 kd phosphorylated protein of Marek's disease viruses and comparing chicken immunological reactions to viruses point-mutated in the epitopes. Science in China. 33:263-272.

Interpretive Summary: Marek's disease (MD), a virus-induced cancer-like disease of chickens, is a major disease problem in commercial poultry. Vaccination has dramatically reduced the incidence of the disease, but very little is known about the basic mechanisms involved in viral replication and tumor induction. The objective of this research was to study a unique viral DNA (gene), namely, pp38, which is important for viral replication in chickens. In this study, we provide data to demonstrate a critical region in pp38 gene of the vaccine strain CVI988 that is responsible for strong immune responses. This may give insight into one of the reasons that CVI988 vaccine is superior to other attenuated MDV vaccines in protecting chickens against MD. The information obtained from this research is of great interest to scientists and academia as it generated new knowledge on the mechanism of viral replication and vaccine protection.

Technical Abstract: DNA sequencing analysis in 38 kd phosphorylated protein (pp38) ORF of Marek's disease viruses (MDV) indicated that all tested 10 virulent strains with different pathotypes had "A" at the base #320 and glutamine at aa#107 while reacted with monoclonal antibody (Mab) H19 in indirect fluorescence antibody test (IFA). However, vaccine strain CVI988 had "G" at base #320 and arginine at aa#107 instead and was negative in IFA with Mab H19. Some strains were also reactive with Mab T65 in IFA while there was a "G" at base #326 and glycine at aa#109, but the other strains, which had "A" at base #326 and glutamic acid at aa#109, did not react with Mab T65. By comparison of CVI988 to its point mutants CVI/rpp38 (AG) and CVI/rpp38 (AA) with 1 or 2 base(s) changes at bases #320 and/or #326 of pp38 gene for their reactivity with Mab H19 and T65, it was confirmed that the glutamine at aa#107 and glycine at aa#109 were critical to epitopes H19 or T65 respectively. Immuno-reactions to MDV were compared in SPF chickens inoculated with cloned CVI988 and its mutant CVI/rpp38 (AG). It was found that antibody responses to MDV in chickens inoculated with CVIl/pp38 (AG) were delayed and significantly lower than that in chickens inoculated with the native CVI988. By differential comparison of antibody titers to different antigens, a third epitope specific to CVI988 and dependent on arginine at aa#107 was suggested to be responsible for the big difference in antibody responses induced by native CVI988 and its mutant.