# Validation of Polymorphisms Associated with the Immune Response After Vaccination Against Porcine Reproductive and Respiratory Syndrome Virus in Yorkshire Gilts

## TL;DR

This study identifies three genetic markers linked to improved immune response in pigs vaccinated against a costly viral disease, which could help improve vaccination outcomes in swine farming.

## Contribution

The study validates three SNPs in RNF144B, XKR9, and BMAL1 as molecular markers for immune response to PRRSV vaccination in Yorkshire gilts.

## Key findings

- Three SNPs (rs707264998, rs708860811, rs81358818) were significantly associated with the antibody response (S/P ratio) to PRRSV vaccination.
- The identified SNPs showed an additive effect and were validated in two independent gilt populations.
- These SNPs are proposed as candidate markers for genetic selection programs to enhance immune response in pigs.

## Abstract

Over the past 30 years, global swine producers have been battling with the porcine reproductive and respiratory syndrome (PRRS), an economically important disease caused by a virus that can infect pigs of any age. Biosecurity and vaccination are the primary strategies to control the PRRS virus (PRRSV), but the immune response against the virus and vaccines have been highly variable among animals, suggesting that a genetic component is involved in regulating such a response. Recently, genomic technology has been proposed as a tool to explore the genetic architecture related to the response to vaccination against the PRRSV. In the current study, we sequentially utilized genomic and marker-assisted technologies. This strategy allowed us to identify and further validate three polymorphisms in the genes RNF144B, XKR9, and BMAL1 as potential molecular markers linked to the antibody response, measured as the S/P ratio, in gilts vaccinated against the PRRSV. We propose these polymorphisms as genetic markers that should be included in selection programs on pig farms aimed at enhancing the host immune response to vaccination against the PRRSV.

Porcine respiratory and reproductive syndrome is a viral disease that impacts the health and profitability of swine farms, largely due to significant variation in the vaccination response. The objective was to identify and validate molecular markers associated with the antibody response in gilts following vaccination against the PRRSV. The study included one hundred (n = 100) 6-month-old Yorkshire gilts that were negative for the PRRSV. Gilts were randomly assigned to one of two treatments, PRRS-vaccinated (n = 75) and control (n = 25) groups. Blood samples collected on day 21 were analyzed to evaluate the antibody response, as indicated by the sample-to-positive (S/P) ratio, to the PRRSV following vaccination. DNA was extracted and genotyped using a low-density chip containing 10,000 single nucleotide polymorphisms (SNPs). A genome-wide association study (GWAS) was conducted to identify candidate SNPs associated with the S/P ratio, which were validated in two independent gilt populations (n = 226). The SNPs rs707264998, rs708860811, and rs81358818 in the genes RNF144B, XKR9, and BMAL1, respectively, were significantly associated (p < 0.01) with the S/P ratio and demonstrated an additive effect. In conclusion, three SNPs are proposed as candidate markers for an enhanced immune response to vaccination against the PRRSV and may be beneficial in genetic selection programs.