Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2005
Publication Date: 7/13/2005
Citation: Petry, D., Lunney, J.K., Boyd, P., Kuhar, D.J., Blankenship, E., Johnson, R. 2005. Differential immunity in pigs with high and low responses to PRRSV.Proceedings Symposium on Genetics of Animal Health. p. 10.
Technical Abstract: Duroc/Hampshire crossbred pigs (100) and NE Index line pigs (100) were infected with porcine reproductive and respiratory syndrome virus (PRRSv) and evaluated for resistance/susceptibility. Controls (100/line) were uninfected littermates to each infected pig. Viremia (V), weight change (WT'), and rectal temperature at 0, 4, 7, and 14 days post-infection (dpi) were recorded. Lung, bronchial lymph node (BLN), and blood tissue were collected at necropsy (14dpi). Line differences, and line by treatment interactions across days, indicated genetic variation in responses to PRRSv (Petry et al., 2005). Principal component analyses were used to rank pigs for phenotypic response to PRRSv. Pigs classed as low (L) responders had high WT', low V, and few lung lesions; high (H) responders had low WT', high V, and many lesions. RNA from frozen lung and BLN tissue of the 7 highest and lowest responders per line, and from each of their littermates, were extracted. cDNA expression of 12 specific innate and Th1 immune markers was evaluated in a 2*2*2 factorial treatment design. Significant over-expression in lungs of L pigs relative to controls for certain genes, and of H pigs relative to controls for these same genes, was detected; whereas both over and under-expression of genes in BLN occurred. Serum levels of the immune cytokines affirmed the lung differences. These data are critical for genetic association studies to fine map candidate genes and to determine causative alleles.