Evidence for a major QTL associated with host response to Porcine Reproductive and Respiratory Syndrome Virus challenge1

Abstract

Porcine reproductive and respiratory syndrome (PRRS) causes decreased reproductive performance in breeding animals and increased respiratory problems in growing animals, which result in significant economic losses in the swine industry. Vaccination has generally not been effective in the prevention of PRRS, partially because of the rapid mutation rate and evolution of the virus. The objective of the current study was to discover the genetic basis of host resistance or susceptibility to the PRRS virus through a genome-wide association study using data from the PRRS Host Genetics Consortium PRRS-CAP project. Three groups of approximately 190 commercial crossbred pigs from 1 breeding company were infected with PRRS virus between 18 and 28 d of age. Blood samples and BW were collected up to 42 d post infection (DPI). Pigs were genotyped with the Illumina Porcine 60k Beadchip. Whole-genome analysis focused on viremia at each day blood was collected and BW gains from 0 to 21 DPI (WG21) or 42 DPI (WG42). Viral load (VL) was quantified as area under the curve from 0 to 21 DPI. Heritabilities for WG42 and VL were moderate at 0.30 and litter accounted for an additional 14% of phenotypic variation. Genomic regions associated with VL were found on chromosomes 4 and X and on 1, 4, 7, and 17 for WG42. The 1-Mb region identified on chromosome 4 influenced both WG and VL, exhibited strong linkage disequilibrium, and explained 15.7% of the genetic variance for VL and 11.2% for WG42. Despite a genetic correlation of −0.46 between VL and WG42, genomic EBV for this region were favorably and nearly perfectly correlated. The favorable allele for the most significant SNP in this region had a frequency of 0.16 and estimated allele substitution effects were significant (P < 0.01) for each group when the SNP was fitted as a fixed covariate in a model that included random polygenic effects with overall estimates of −4.1 units for VL (phenotypic SD = 6.9) and 2.0 kg (phenotypic SD = 3 kg) for WG42. Candidate genes in this region on SSC4 include the interferon induced guanylate-binding protein gene family. In conclusion, host response to experimental PRRS virus challenge has a strong genetic component, and a QTL on chromosome 4 explains a substantial proportion of the genetic variance in the studied population. These results could have a major impact in the swine industry by enabling marker-assisted selection to reduce the impact of PRRS but need to be validated in additional populations. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Key words: genetic parameters, genomic regions, porcine, reproductive and respiratory syndrome, swine ABSTRACT: Porcine reproductive and respiratory syndrome (PRRS) causes decreased reproductive performance in breeding animals and increased respiratory problems in growing animals, which result in significant economic losses in the swine industry. Vaccination has generally not...

Genomic selection in pigs: state of the art and perspectives

“…Genomic selection would make it possible to predict breeding values also for healthy pigs, distantly related to those with the phenotypes that could be collected in specific environments or only at occasionally disease outbreak (Bishop 2014). For example, PRRS seems largely controlled by many genomic regions with generally relatively small effects, but chromosome 4 might harbour an important QTL for PRRS resistance (Boddicker et al 2012). Based on these findings, various strategies were proposed to predict GEBV by using both the QTL region on chromosome 4 or whole genome data (Boddicker et al 2013(Boddicker et al , 2014, eventually integrated by a specific emphasis given on other chromosome regions following the progresses in QTL mapping for other important traits related to biological features of PRRS resistance (Lough et al 2014;Orrett et al 2014).…”

A Single Amino Acid Deletion in the Matrix Protein of Porcine Reproductive and Respiratory Syndrome Virus Confers Resistance to a Polyclonal Swine Antibody with Broadly Neutralizing Activity

“…All experiments involving animals and viruses were approved by the Kansas State University institutional animal care and biosafety committee. As part of a study on host genetics associated with PRRS (25)(26)(27)(28), 200 pigs, 7 weeks of age, were experimentally infected with a type 2 PRRSV isolate, KS62 (GenBank accession number KM035798), and porcine circovirus 2b (PCV2b) (GenBank accession number JQ692110) (42). Four weeks prior, half of the pigs were vaccinated with a commercial MLV vaccine (Ingelvac PRRS MLV; Boehringer Ingelheim) according to the label instructions (GenBank accession number AF159149).…”

Genomics to benefit livestock production: improving animal health

“…The challenge experiments with porcine reproductive and respiratory syndrome virus (PRRSV) conducted at Kansas State University show this very clearly. The amount of virus produced by the animals and their growth varies greatly (Boddicker et al, 2012). Indeed, in some cases, the animals continue to grow as fast as uninfected controls.…”

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