January 9-13, 2010
Town & Country Convention Center
San Diego, CA
Michelle R. Mousel1 , Stephen N. White2 , Lynn M. Herrmann-Hoesing2
A deletion in the promoter region of CCR5 associates with a 50% reduction in proviral concentration (log10 env copies/microgram DNA) of ovine progressive pneumonia virus (OPPV) in sheep blood. Because OPP provirus blood concentrations correlate with the degree of histological lesions in affected tissues, use of the CCR5 promoter variant in marker-assisted selection might reduce pathology. We determined whether the three CCR5 promoter genotypes and four ewe lifetime production traits were associated. DNA and lifetime records from 370 Rambouillet, Polypay, and Columbia ewes were used. Production traits, per ewe, included: total adjusted 120-d weaning weight of all lambs born (120d kg), total lifetime number of lambs born (TB), total count of lambs raised to weaning (TR), and age of ewe, in years, at last lambing. A TaqMan assay was used to genotype the CCR5 promoter insertion/deletion. For association analysis, mixed procedure of SAS 9.1 was used. The model included breed, CCR5 promoter insertion/deletion genotype, year ewe was born, and age at last lambing as fixed effects, sire as a random effect, and OPP provirus concentration as a covariate. Breed and age at last lambing were significantly associated with TB (P<0.01), TR (P<0.01), and 120d kg (P<0.01). None of the three CCR5 promoter insertion/deletion genotypes had significant positive or negative associations with any of the ewe lifetime production traits (all P>0.59). Thus, using the CCR5 promoter deletion in marker-assisted selection to reduce concentrations of OPPV should not result in deleterious correlated responses with the economically important production traits we evaluated.