Spread of equine arteritis virus among Hucul horses with different EqCXCL16 genotypes and analysis of viral quasispecies from semen of selected stallions

Wojciech Socha,Barbara Jaklinska,Magdalena Dunowska,Pawel Sztromwasser,Jerzy Rola

doi:10.1038/s41598-020-59870-y

Wojciech Socha, Barbara Jaklinska + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-59870-y

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Abstract

Equine arteritis virus (EAV) is maintained in the horse populations through persistently infected stallions. The aims of the study were to monitor the spread of EAV among Polish Hucul horses, to analyse the variability of circulating EAVs both between- and within-horses, and to identify allelic variants of the serving stallions EqCXCL16 gene that had been previously shown to strongly correlate with long-term EAV persistence in stallions. Serum samples (n = 221) from 62 horses including 46 mares and 16 stallions were collected on routine basis between December 2010 and May 2013 and tested for EAV antibodies. In addition, semen from 11 stallions was tested for EAV RNA. A full genomic sequence of EAV from selected breeding stallions was determined using next generation sequencing. The proportion of seropositive mares among the tested population increased from 7% to 92% during the study period, while the proportion of seropositive stallions remained similar (64 to 71%). The EAV genomes from different stallions were 94.7% to 99.6% identical to each other. A number (41 to 310) of single nucleotide variants were identified within EAV sequences from infected stallions. Four stallions possessed EqCXCL16S genotype correlated with development of long-term carrier status, three of which were persistent shedders and the shedder status of the remaining one was undetermined. None of the remaining 12 stallions with EqCXCL16R genotype was identified as a persistent shedder.

Highlights

Equine viral arteritis (EVA) is one of the economically important diseases of horses and other equids[1]
All 14 seronegative mares that were introduced to the stud in 2012 seroconverted to Equine arteritis virus (EAV) by May 2013 with titres ranging from 32 to 128
Six full consensus sequences of EAV from four different stallions were obtained, with the sequencing depth that allowed for identification of genetic variants appearing with as low as 10% frequency for four of them

Summary

Introduction

Equine viral arteritis (EVA) is one of the economically important diseases of horses and other equids[1]. Important for the epizootiology of EAV is venereal route of transmission through semen of a persistently infected stallion to susceptible mares. It has been recently shown that EqCXCL16 gene is correlated with the establishment of a long-term (>1 year) carrier status by EAV infected stallions. Those with at least one copy of the dominant allele (EqCXCL16Sa or EqCXCL16Sb) associated with in-vitro susceptibility of CD3 + T lymphocytes to EAV infection are more likely to become long-term shedders than those with two copies of the recessive allele (EqCXCL16R) linked to the resistant phenotype[11]. The aims of the current study were: (1) to monitor the spread of EAV within a population of Hucul horses at one of the Polish national studs in the absence of targeted infection control measures; (2) to determine the variability of circulating EAVs, both within- and between EAV-infected Hucul horses; and (3) to determine the allelic variants of the serving stallions’ EqCXCL16 gene

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