GENOMIC ORGANIZATION AND EXPRESSION OF THE WC1 HYBRID CORECEPTOR AND PATTERN RECOGNITION RECEPTOR ON PORCINE GAMMA DELTA T CELLS

gd T cells are a crucial component of the immune response to a number of increasingly relevant and largely zoonotic pathogens to which efficacious vaccination is lacking. In ruminants and swine, gd T cells represent a major population of peripheral blood and epithelial tissue-resident lymphocytes. gdT cells respond to both protein and non-protein antigens independently of MHC presentation and possess immunological memory. Upon activation, gamma delta T cells illicit a variety of effector functions and play an indispensable role of orchestrating the downstream immune response. These characteristics make gamma delta T cells a promising candidate for recruitment by vaccination, however, methods for effectively priming these cells remain to be elucidated. The type I transmembrane receptor Workshop Cluster One (WC1) is expressed as a multigenic array on gd T cells in swine and ruminants. In cattle there are 13 unique WC1 genes (WC1-1 to WC1-13) each comprised of 6-11 SRCR domains that selectively bind unprocessed antigen in a manner that resembles a pattern recognition receptor (PRRs). WC1 functions as a hybrid PRR and co-receptor for the gamma delta TCR as it potentiates activation signals from the TCR and dictates antigen specificity of expressing gd T cells. cDNA evidence suggests that porcine WC1 is expressed as a multigenic array consisting of 9 genes (WC1-1 to WC1-9) each encoding 6 SRCR domains with unique pathogen binding potential. The objective of this study is to characterize the multigenic array of porcine WC1, investigate its propensity for pathogen binding, and evaluate its expression on gd T cells. Using the MAKER annotation pipeline, we annotated Sscrofa11.1 for sequence derived from full-length cDNA transcripts representing the 9 porcine WC1 genes. We were able to map 8 of the 9 genes, leaving one (WC1-8) unplaced in the current assembly. We defined three subpopulations of porcine gd T cells based on expression of WC1 and CD2. Finally, we confirmed that porcine WC1 SRCR domains are capable of directly binding whole fixed bacteria including Leptospira spp and Mycobacterium bovis