Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 7, 1996
Publication Date: N/A
Technical Abstract: Chickens have recently been shown to possess class I and class II Mhc-like genes, collectively termed the Rfp-Y haplotype, that assort independent of the B-complex. Cornell line N and P chickens, selected for resistance or susceptibility, respectively, to Marek's disease (MD), possess different Rfp-Y haplotypes; i.e. N has Y**5, Y**7 and Y**8, whereas P has Y**5, Y**8 and Y**9. In addition, the ADOL inbred lines 63 and 72, resistant or susceptible to MD respectively, each contain an additional unique Rfp-Y haplotype (tentatively termed Y**11 and Y**12). The effect of Rfp-Y haplotype on MD was studied in chickens from two crosses: 1) a backcross using P males (B**19B**19/Y**9Y**9) X NXP F1 hens (B**19B**21/Y**5Y**9), and 2) an F2 mating of 72X63 F1 parents (B**2B**2/Y**11Y**12). The chicks were assessed for B-genotype by blood-typing, and for Rfp-Y genotype by RFLP analysis using Bam HI enzyme and a Rfp-Y LBIII probe, or Taq I enzyme and a B-FIV probe. Chicks were challenged with 2000 pfu of JM virus at 1-2 weeks of age and termination was at 10 weeks. The B haplotype had major influences on MD tumors and MD viremia in the P X (NXP) chicks, whereas Rfp-Y genes were non-significant. In contrast, the Rfp-Y haplotype influenced both MD viremia and tumor development in the 72X63 F2 chickens. We conclude that genes within the Rfp-Y haplotype influence MD resistance; however, the size of effect is less than that conferred by the Mhc B haplotype.