|Knowles Jr, Donald|
Submitted to: International Symposium on Animal Genomics for Animal Health
Publication Type: Abstract Only
Publication Acceptance Date: 6/18/2007
Publication Date: N/A
Technical Abstract: A genetic tool hypothesized to predict which OPPV infected sheep will progress to debilitating clinical disease is MHC Class II Ovis aries (Ovar)-DRB1. Previously, fifteen Ovar-DRB1 beta 1 expressed alleles were identified in a ewe-lamb flock of 32 originating from an Idaho flock using RT-PCR, cloning and sequencing (Herrmann et al., 2005, Immunogenetics 57: 855-863). During further studies, eighteen additional Ovar-DRB1 beta 1 expressed alleles were identified in 383 sheep of Columbia, Rambouillet and Polypay breeds originating from the same Idaho flock. In this current study, Ovar-DRB1 allelic frequencies were calculated for the Idaho flock, and specific Ovar-DRB1 expressed alleles were examined for associations with systemic OPP provirus load, a measure of OPPV clinical disease using quantitative PCR. The most frequent Ovar-DRB1 allele was DRB1*1202 (15.7%) followed by DRB1*02032 (11.7%), DRB1*0206 (9.9%), DRB1*0403 (6.5%), DRB1*0353 (5.1%), and DRB1*0404 (5.0%). The presence of DRB1*02032 and DRB1*1101 expressed alleles significantly associated with OPP provirus loads of greater or equal to 212 copies of envelope/ug DNA (Fisher's Exact test, 2-sided p value=0.02 and p value=0.04, respectively). In contrast, the presence of DRB1*07012 expressed allele significantly associated with undetectable OPP provirus loads (Fisher's Exact test, 2-sided p value=0.01). These data indicate that the presence of DRB1*02032 and DRB1*1101 in an OPPV endemic flock may contribute in maintaining OPPV persistence.