Host genetics of response to porcine reproductive and respiratory syndrome in nursery pigs

Abstract

A B S T R A C TPRRS is the most costly disease in the US pig industry. While vaccination, biosecurity and eradication effort have had some success, the variability and infectiousness of PRRS virus strains have hampered the effectiveness of these measures. We propose the use of genetic selection of pigs as an additional and complementary effort. Several studies have shown that host response to PRRS infection has a sizeable genetic component and recent advances in genomics provide opportunities to capitalize on these genetic differences and improve our understanding of host response to PRRS. While work is also ongoing to understand the genetic basis of host response to reproductive PRRS, the focus of this review is on research conducted on host response to PRRS in the nursery and grow-finish phase as part of the PRRS Host Genetics Consortium. Using experimental infection of large numbers of commercial nursery pigs, combined with deep phenotyping and genomics, this research has identified a major gene that is associated with host response to PRRS. Further functional genomics work identified the GBP5 gene as harboring the putative causative mutation. GBP5 is associated with innate immune response. Subsequent work has validated the effect of this genomic region on host response to a second PRRSV strain and to PRRS vaccination and co-infection of nursery pigs with PRRSV and PCV2b. A genetic marker near GBP5 is available to the industry for use in selection. Genetic differences in host response beyond GBP5 appear to be highly polygenic, i.e. controlled by many genes across the genome, each with a small effect. Such effects can by capitalized on in a selection program using genomic prediction on large numbers of genetic markers across the genome. Additional work has also identified the genetic basis of antibody response to PRRS, which could lead to the use of vaccine response as an indicator trait to select for host response to PRRS. Other genomic analyses, including gene expression analyses, have identified genes and modules of genes that are associated with differences in host response to PRRS and can be used to further understand and utilize differences in host response. Together, these results demonstrate that genetic selection can be an additional and complementary tool to combat PRRS in the swine industry.

Genetic susceptibility to infectious diseases: Current status and future perspectives from genome-wide approaches

“…As is the case for cattle, infections represent major economic problems for the swine industry, with one viral pathogen, porcine reproductive and respiratory syndrome virus (PRRSV) accounting for substantial burden (Dekkers et al, 2017). Several GWASs for PRRSV susceptibility converged to identify a major locus on chromosome 4 (reviewed in (Dekkers et al, 2017)).…”

“…Several GWASs for PRRSV susceptibility converged to identify a major locus on chromosome 4 (reviewed in (Dekkers et al, 2017)). Fine mapping of the QTL region and a further functional genomics work identified a variant in the GBP5 gene as likely causal (Dekkers et al, 2017). GPB5 encodes an interferoninducible guanosine triphosphatase which plays central roles in cellintrinsic immunity.…”

“…In humans, GBP5 acts as a restriction factor for HIV (Krapp et al, 2016). For the purpose of swine breeding, this result is relevant as a variation at GBP5 can be used for marker-assisted selection (Dekkers et al, 2017).…”

The Veterinary Immunological Toolbox: Past, Present, and Future

“…Animal genetics can provide insights into responses to infection and vaccination which can be translated into livestock breeding programmes (53,54). Breeding programmes require several generations to observe population effects and conclusive proof for the effect of a specific genotype on immune status requires functional evidence, hence reliance on the toolbox.…”

Invited review: Piglet survival: benefits of the immunocompetence

“…Promising genetic resistance against the porcine reproductive and respiratory syndrome (PRRS) was reviewed by Reiner (2016) and Dekkers et al (2017). However, Dekkers et al (2017) stress that due to the variability of PRRS a resistance is not feasible, but a reduced susceptibility is. Furthermore, the need for a closer inspection of the complete function of potential candidate genes (e.g.…”