Genome-wide analysis of TNF-alpha response in pigs challenged with porcine circovirus 2b

Authors

• C. A. Kreikemeier, University of Nebraska-Lincoln
• T. B., University of Nebraska-Lincoln
• K. L. Lucot, University of Nebraska-Lincoln
• Thomas E. Burkey, University of Nebraska-LincolnFollow
• Daniel C. Ciobanu, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

4-2015

Citation

Published in Animal Genetics 46:2 (April 2015), pp 205–208. doi: 10.1111/age.12262

Comments

Copyright © 2015 Stichting International Foundation for Animal Genetics. Used by permission.

Abstract

Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory cytokine with a role in activating adaptive immunity to viral infections. By inhibiting the capacity of plasmacytoid dendritic cells to produce interferon-α and TNF-α, porcine circovirus 2 (PCV₂) limits the maturation of myeloid dendritic cells and impairs their ability to recognize viral and bacterial antigens. Previously, we reported QTL for viremia and immune response in PCV₂- infected pigs. In this study, we analyzed phenotypic and genetic relationships between TNFα protein levels, a potential indicator of predisposition to PCV₂ co-infection, and PCV₂ susceptibility. Following experimental challenge with PCV₂b, TNF-α reached the peak at 21 days post-infection (dpi), at which time a difference was observed between pigs that expressed extreme variation in viremia and growth (P < 0.10). A genome-wide association study (n = 297) revealed that genotypes of 56 433 SNPs explained 73.9% of the variation in TNF-α at 21 dpi. Major SNPs were identified on SSC8, SSC10 and SSC14. Haplotypes based on SNPs from a SSC8 (9 Mb) 1-Mb window were associated with variation in TNF-α (P < 0.02), IgG (P = 0.05) and IgM (P < 0.13) levels at 21 dpi. Potential overlap of regulatory mechanisms was supported by the correlations between genomic prediction values of TNF-α and PCV2 antibodies (21 dpi, r > 0.22), viremia (14–21 dpi, P > 0.29) and viral load (r = 0.31, P < 0.0001). Characterization of the QTL regions uncovered genes that could influence variation in TNF-α levels as well as T- and B-cell development, which can affect disease susceptibility.