Abstract

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.

Document Type

Article

Publication Date

7-29-2019

Notes/Citation Information

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.

Digital Object Identifier (DOI)

https://doi.org/10.1371/journal.ppat.1007950

Funding Information

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.

Related Content

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).

ppat.1007950.s001.tif (501 kB)
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

ppat.1007950.s002.tif (6421 kB)
S2 Fig. Inflammatory response in the ampullae during long-term EAV persistence. https://doi.org/10.1371/journal.ppat.1007950.s002

ppat.1007950.s003.tif (260 kB)
S3 Fig. Gene ontology analysis (biological process) of DEGs between stallions homozygous and heterozygous for CXCL16S (n = 5) and stallions homozygous for CXCL16R (n = 4). https://doi.org/10.1371/journal.ppat.1007950.s003

ppat.1007950.s004.tif (307 kB)
S4 Fig. Hierarchical clustering of module eigengenes (MEs) for the modules identified. https://doi.org/10.1371/journal.ppat.1007950.s004

ppat.1007950.s005.tif (11202 kB)
S5 Fig. Immunohistochemical staining for EOMES, NFATC2, TBX21 (T-bet), BLIMP-1, pAkt, CTLA-4 and granzyme B on equine palatine tonsil (tissue control). The negative immunostaining control is labeled as isotype control. DAB. 100X. Bar = 80 μm. https://doi.org/10.1371/journal.ppat.1007950.s005

ppat.1007950.s006.xlsx (11 kB)
S1 Table. Top 25 canonical pathways associated with common upregulated genes. Pathway analysis was performed using IPA. https://doi.org/10.1371/journal.ppat.1007950.s006

ppat.1007950.s007.xlsx (11 kB)
S2 Table. Transcription factors (TFs) identified by means of upstream regulator analysis performed on Ingenuity Pathway Analysis (IPA) in long-term carrier stallions. Target molecules in dataset are depicted. https://doi.org/10.1371/journal.ppat.1007950.s007

ppat.1007950.s008.xlsx (35 kB)
S3 Table. Target and correlated genes obtained from the Ingenuity Knowledgebase (IPA), the Immuno-Navigator database and literature search associated with (A) EOMES, (B) NFATC2, (C) TBX21 and (D) PRDM1. https://doi.org/10.1371/journal.ppat.1007950.s008

ppat.1007950.s009.xlsx (13 kB)
S4 Table. Genes positively correlated to CXCL16 and CXCR6 (R2 greater or equal to 0.5) and differentially expressed in long-term carrier stallions. https://doi.org/10.1371/journal.ppat.1007950.s009

ppat.1007950.s010.xlsx (41 kB)
S5 Table. Gene members of modules correlated with the CD3+ T lymphocyte susceptibility phenotype/CXCL16 genotype (blue and lightyellow) following weighted gene co-expression network analysis of 12,303 genes. https://doi.org/10.1371/journal.ppat.1007950.s010

ppat.1007950.s011.xlsx (36 kB)
S6 Table. Network analysis parameters for the "hub" genes in the blue (n = 1135 total genes) and lightyellow (n = 130 total genes) modules (MM≥0.90, p-value<0.05, GS≥0.5). Network analysis was performed using Cytoscape. https://doi.org/10.1371/journal.ppat.1007950.s011

ppat.1007950.s012.xlsx (14 kB)
S7 Table. Gene members in each module (n = 5 modules) following weighted gene co-expression analysis of 494 transcription factor genes in CXCL16S stallions. https://doi.org/10.1371/journal.ppat.1007950.s012

ppat.1007950.s013.xlsx (12 kB)
S8 Table. RNA sequencing mapping statistics. https://doi.org/10.1371/journal.ppat.1007950.s013

ppat.1007950.s014.docx (19 kB)
S9 Table. Primers designed for gene expression analysis by RT-qPCR. https://doi.org/10.1371/journal.ppat.1007950.s014

Share

COinS