Equine arteritis virus (EAV) has the unique ability to establish long-term persistent infection in the reproductive tract of stallions and be sexually transmitted. Previous studies showed that long-term persistent infection is associated with a specific allele of the CXCL16 gene (CXCL16S) and that persistence is maintained despite the presence of local inflammatory and humoral and mucosal antibody responses. Here, we performed transcriptomic analysis of the ampullae, the primary site of EAV persistence in long-term EAV carrier stallions, to understand the molecular signatures of viral persistence. We demonstrated that the local CD8+ T lymphocyte response is predominantly orchestrated by the transcription factors eomesodermin (EOMES) and nuclear factor of activated T-cells cytoplasmic 2 (NFATC2), which is likely modulated by the upregulation of inhibitory receptors. Most importantly, EAV persistence is associated with an enhanced expression of CXCL16 and CXCR6 by infiltrating lymphocytes, providing evidence of the implication of this chemokine axis in the pathogenesis of persistent EAV infection in the stallion reproductive tract. Furthermore, we have established a link between the CXCL16 genotype and the gene expression profile in the ampullae of the stallion reproductive tract. Specifically, CXCL16 acts as a “hub” gene likely driving a specific transcriptional network. The findings herein are novel and strongly suggest that RNA viruses such as EAV could exploit the CXCL16/CXCR6 axis in order to modulate local inflammatory and immune responses in the male reproductive tract by inducing a dysfunctional CD8+ T lymphocyte response and unique lymphocyte homing in the reproductive tract.

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Published in PLOS Pathogens, v. 15, no. 7, 1007950, p. 1-42.

© 2019 Carossino et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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This study was supported by the Agriculture and Food Research Initiative competitive grant number 2013-68004-20360 from the USDA National Institute of Food and Agriculture. This work was also supported by the USDA National Institute of Food and Agriculture hatch project number KY014055 (College of Agriculture, Food and Environment, University of Kentucky), and partially supported by Louisiana State University, School of Veterinary Medicine start-up fund (PG 002165) to Dr. Udeni B. R. Balasuriya.

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The RNA sequencing data from this study were deposited in the Gene Expression Omnibus (GEO, NCBI, NIH) database under study GSE114982 (accession numbers GSM3161940- GSM3161951).

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S1 Fig. Gene ontology analysis of DEGs between long-term carrier (n = 3) and short-term carrier stallions (n = 6). (A) Biological process. (B) Molecular function. https://doi.org/10.1371/journal.ppat.1007950.s001

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