Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/25/2003
Publication Date: 1/1/2004
Citation: Lee, L.F., Bacon, L.D., Yoshida, S., Yanagida, N., Zhang, H., Witter, R.L. 2004. The efficacy of recombinant fowlpox vaccine protection against marek's disease: its dependence on chicken line and b haplotype. Avian Diseases. 48:129-137. Interpretive Summary: Marek's disease (MD), a virus induced cancer-like disease of chickens, is considered as a major disease problem in commercial poultry. We have previously shown that two hereditary elements (genes) named gB and gI can induce protective immunity against MD. The objective of this research was to study protection against MD in different genetic lines of chickens using a recombinant fowlpox virus containing these two genes. This important genetic information about MD virus will undoubtedly help scientists in academia and industry understand the function of the interaction between viral genes and the host. This approach eventually will lead to a better control of the disease in poultry.
Technical Abstract: Earlier studies have shown the B-haplotype has a significant influence on the protective efficacy of vaccines against Marek's disease (MD), and that the level of protection varies dependent on the serotype of MD virus used in the vaccine. To determine if the protective glycoprotein gene gB is a basis for this association, we compared recombinant fowlpox virus (rFPV) containing a single gB gene from three serotypes of MDV. The rFPV were used to vaccinate 15.B congenic lines. Non-vaccinated chickens from all three haplotypes had 84-97% MD after challenge. The rFPV containing gB1 provides better protection than rFPV containing gB2 or gB3 in all three B genotypes. Moreover, the gB proteins were critical since the B*21/*21 chickens had better protection than chickens with B*13/*13 or B*5/*5 using rFPV with gB1, gB2 or gB3. A newly described combined rFPV/gB1gEgIUL32 + HVT vaccine was analyzed in chickens of lines15 x 7 (B*2/*15) and N (B*21/*21) challenged with two vv+ strains of MDV. There were line differences in protection by the vaccines and line N had better protection with the rFPV/gB1gEgIUL32 +HVT vaccines (92-100%) following either MDV challenge, but protection was significantly lower in 15 x 7 chickens (35%) when compared with the vaccine CVI988/Rispens (94%) and 301B1 + HVT (65%). Another experiment used four lines of chickens receiving the new rFPV +HVT vaccine or CVI988/Rispens and challenge with 648A MDV. The CVI 988/Rispens generally provided better protection in lines P and 15 x 7, and in one replicate with line TK. The combined rFPV/gB1gEgIUL32 +HVT vaccines protected line N chickens (90%) better than CVI988/Rispens (73%). These data suggest rFPV + HVT vaccines may provide protection against MD that is equivalent or superior to CVI988/Rispens in some chicken strains. It is not clear whether the rFPV/gB1gEgIUL32 + HVT vaccine will offer high levels of protection to commercial strains, but this vaccine used in line N chickens may be a useful model to study interactions between vaccines and chicken genotypes and thereby improve future MD vaccines.