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Sarkar S, Bailey E, Go YY, Cook RF, Kalbfleisch T, Eberth J, Chelvarajan RL, Shuck KM, Artiushin S, Timoney PJ, Balasuriya UBR. Allelic Variation in CXCL16 Determines CD3+ T Lymphocyte Susceptibility to Equine Arteritis Virus Infection and Establishment of Long-Term Carrier State in the Stallion. PLoS Genet 2016; 12:e1006467. [PMID: 27930647 PMCID: PMC5145142 DOI: 10.1371/journal.pgen.1006467] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/05/2016] [Indexed: 12/25/2022] Open
Abstract
Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory, systemic, and reproductive disease of horses and other equid species. Following natural infection, 10-70% of the infected stallions can become persistently infected and continue to shed EAV in their semen for periods ranging from several months to life. Recently, we reported that some stallions possess a subpopulation(s) of CD3+ T lymphocytes that are susceptible to in vitro EAV infection and that this phenotypic trait is associated with long-term carrier status following exposure to the virus. In contrast, stallions not possessing the CD3+ T lymphocyte susceptible phenotype are at less risk of becoming long-term virus carriers. A genome wide association study (GWAS) using the Illumina Equine SNP50 chip revealed that the ability of EAV to infect CD3+ T lymphocytes and establish long-term carrier status in stallions correlated with a region within equine chromosome 11. Here we identified the gene and mutations responsible for these phenotypes. Specifically, the work implicated three allelic variants of the equine orthologue of CXCL16 (EqCXCL16) that differ by four non-synonymous nucleotide substitutions (XM_00154756; c.715 A → T, c.801 G → C, c.804 T → A/G, c.810 G → A) within exon 1. This resulted in four amino acid changes with EqCXCL16S (XP_001504806.1) having Phe, His, Ile and Lys as compared to EqCXL16R having Tyr, Asp, Phe, and Glu at 40, 49, 50, and 52, respectively. Two alleles (EqCXCL16Sa, EqCXCL16Sb) encoded identical protein products that correlated strongly with long-term EAV persistence in stallions (P<0.000001) and are required for in vitro CD3+ T lymphocyte susceptibility to EAV infection. The third (EqCXCL16R) was associated with in vitro CD3+ T lymphocyte resistance to EAV infection and a significantly lower probability for establishment of the long-term carrier state (viral persistence) in the male reproductive tract. EqCXCL16Sa and EqCXCL16Sb exert a dominant mode of inheritance. Most importantly, the protein isoform EqCXCL16S but not EqCXCL16R can function as an EAV cellular receptor. Although both molecules have equal chemoattractant potential, EqCXCL16S has significantly higher scavenger receptor and adhesion properties compared to EqCXCL16R.
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Affiliation(s)
- Sanjay Sarkar
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Ernest Bailey
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail: (UBRB); (EB)
| | - Yun Young Go
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - R. Frank Cook
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Ted Kalbfleisch
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Louisville, Louisville, Kentucky, United States of America
| | - John Eberth
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - R. Lakshman Chelvarajan
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Kathleen M. Shuck
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Sergey Artiushin
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Peter J. Timoney
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
| | - Udeni B. R. Balasuriya
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail: (UBRB); (EB)
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Modification of SR-PSOX functions by multi-point mutations of basic amino acid residues. Biochimie 2012; 95:224-30. [PMID: 23009930 DOI: 10.1016/j.biochi.2012.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 09/14/2012] [Indexed: 11/23/2022]
Abstract
SR-PSOX can function as a scavenger receptor, a chemokine and an adhesion molecule, and it could be an interesting player in the formation of atherosclerotic lesions. Our previous studies demonstrated that basic amino acid residues in the chemokine domain of SR-PSOX are critical for its functions. In this study the combinations of the key basic amino acids in the chemokine domain of SR-PSOX have been identified. Five combinations of basic amino acid residues that may form conformational motif for SR-PSOX functions were selected for multi-point mutants. The double mutants of K61AR62A, R76AK79A, R82AH85A, and treble mutants of R76AR78AK79A, R78AR82AH85A were successfully constructed by replacing the combinations of two or three basic amino acid residues with alanine. After successful expression of these mutants on the cells, the functional studies showed that the cells expressing R76AK79A and R82AH85A mutants significantly increased the activity of oxLDL uptake compared with that of wild-type SR-PSOX. Meanwhile, the cells expressing R76AK79A mutant also dramatically enhanced the phagocytotic activity of SR-PSOX. However, the cells expressing the construct of combination of R78A mutation in R76AK79A or R82AH85A could abolish these effects. More interestingly, the adhesive activities were remarkably down regulated in the cells expressing the multi-point mutants respectively. This study revealed that some conformational motifs of basic amino acid residues, especially R76 with K79 in SR-PSOX, may form a common functional motif for its critical functions. R78 in SR-PSOX has the potential action to stabilize the function of oxLDL uptake and bacterial phagocytosis. The results obtained may provide new insight for the development of drug target of atherosclerosis.
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