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Equine veterinary journal2026; doi: 10.1002/evj.70191

CXCL16-associated genetic susceptibility to equine viral arteritis in export-bound horses from Spain.

Abstract: Equine viral arteritis (EVA) remains a relevant health and economic concern due to the ability of some infected stallions to establish long-term persistent infection with equine arteritis virus (EAV). Allelic variation in the CXCL16 gene has been identified as a determinant of susceptibility or resistance to the carrier state, positioning genotyping as a useful tool for risk-based reproductive and health management. Objective: To characterise the distribution of CXCL16 genotypes in export-bound horses from Spain and to assess the utility of CXCL16 genotyping for EVA prevention and control. Methods: Cross-sectional observational study. Methods: A total of 1004 horses of multiple breeds and geographic origins were included. CXCL16 genotypes were determined in all animals, and EAV serological status was assessed in a subset of 358 samples using ELISA. Genotypic frequencies were calculated, and associations with breed and sex were analysed. Results: The resistant genotype (CXCL16) predominated in the study population (57.3%), although marked breed-related variability was observed. Lower frequencies of the resistant genotype were detected in Iberian breeds, including Spanish Purebred (53.3%) and Lusitano (38.3%), with higher frequencies observed in Thoroughbreds (77.6%) and European sport horse breeds. Breed composition was the main factor associated with differences in CXCL16-associated susceptibility profiles, while the effect of sex was limited. Among the 358 horses tested by ELISA, 3.9% (n = 14) were seropositive for EAV. Conclusions: The study population was restricted to export-bound horses; some breeds were underrepresented, and the cross-sectional design did not allow direct assessment of long-term viral persistence. Conclusions: This is the first large-scale characterisation of CXCL16 genotype distribution in export-bound horses in Spain and demonstrates marked breed-related differences in genetic susceptibility to EAV persistence. CXCL16 genotyping represents a valuable complementary tool to serological surveillance for supporting risk-based EVA management and informed decision-making in breeding and export programmes.
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Publication Date: 2026-05-14 PubMed ID: 42135260DOI: 10.1002/evj.70191Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This research article investigates how genetic variations in the CXCL16 gene influence the susceptibility of export-bound horses from Spain to equine viral arteritis (EVA), a viral disease affecting horses.
  • The study evaluates the distribution of CXCL16 genotypes across different horse breeds and discusses the potential of CXCL16 genotyping to improve EVA prevention and control strategies in horse breeding and export programs.

Background and Importance

  • Equine viral arteritis (EVA) is a disease caused by the equine arteritis virus (EAV), which can have significant health and economic impacts within the horse industry.
  • One major concern is that some stallions infected with EAV can become long-term persistent carriers, contributing to the spread of the virus.
  • Previous research has identified that allelic variation in the CXCL16 gene is a key factor determining whether a horse is susceptible or resistant to becoming a carrier of EAV.
  • Thus, identifying the CXCL16 genotype can help in managing risk by informing strategies that prevent the establishment of persistent EAV infection.

Study Objectives

  • Characterize the distribution of CXCL16 genotypes in a large population of export-bound horses from Spain.
  • Assess the potential utility of CXCL16 genotyping as a tool to inform EVA prevention and control measures.

Methods

  • Design: Cross-sectional observational study involving 1004 horses of various breeds and geographic origins bound for export.
  • Genotyping: All horses were genotyped for CXCL16 allelic variants related to EVA susceptibility or resistance.
  • Serology: A subset of 358 horses was tested for the presence of antibodies against EAV using ELISA to determine previous exposure or infection status.
  • Data Analysis: The study calculated the frequency of CXCL16 genotypes overall and by breed, as well as investigated associations between genotype frequency and factors such as breed and sex.

Key Results

  • The resistant CXCL16 genotype was the most frequent in the overall studied population (57.3%), indicating a majority with genetic resistance to EAV persistence.
  • However, considerable variability in genotype distribution was observed between breeds:
    • Iberian breeds such as the Spanish Purebred (53.3%) and Lusitano (38.3%) had lower frequencies of the resistant genotype.
    • In contrast, Thoroughbreds (77.6%) and European sport horse breeds showed higher frequencies of the resistant genotype.
  • Breed composition was strongly associated with differences in CXCL16 susceptibility profiles.
  • The effect of sex on genotype distribution was minimal.
  • Among the subset tested serologically, 3.9% (14 horses) were seropositive for EAV, showing a low level of prior viral exposure or infection.

Conclusions and Implications

  • This study is the first large-scale examination of CXCL16 genotype distribution in export-bound horses in Spain, highlighting notable breed-related genetic differences in susceptibility to EAV persistence.
  • The breed-related variability suggests that certain breeds may be at higher risk of becoming carriers and hence may require tailored risk management strategies.
  • Because the study was cross-sectional and export-bound, it could not directly assess long-term viral persistence or fully represent other horse populations and breeds.
  • CXCL16 genotyping emerges as a valuable complementary tool to serological testing, providing genetic information that supports more informed decision-making in breeding, reproductive management, and export programs.
  • Incorporating CXCL16 genotyping could:
    • Enhance risk-based EVA surveillance programs.
    • Help identify horses less likely to become carriers before breeding or export.
    • Reduce transmission risks and economic losses associated with EVA.

Cite This Article

APA
Gago P, Cruz-Lopez F, Dorrego A, Rivera B, de Juan L, Lorente-Leal V. (2026). CXCL16-associated genetic susceptibility to equine viral arteritis in export-bound horses from Spain. Equine Vet J. https://doi.org/10.1002/evj.70191

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Gago, Paloma
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
  • Animal Health Department, Faculty of Veterinary Medicine, Universidad Complutense Madrid, Madrid, Spain.
Cruz-Lopez, Fatima
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
Dorrego, Abel
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
Rivera, Belen
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
de Juan, Lucia
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
  • Animal Health Department, Faculty of Veterinary Medicine, Universidad Complutense Madrid, Madrid, Spain.
Lorente-Leal, Víctor
  • VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain.
  • Genetics, Physiology and Microbiology Department, Faculty of Biological Sciences, Universidad Complutense Madrid, Madrid, Spain.

Grant Funding

  • CT82/20-CT83/20 / Universidad Complutense de Madrid - Banco Santander
  • Grants for Predoctoral Researchers Training Contracts

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