Generation and first characterization of TRDC-Knockout pigs lacking γδ T cells

Abstract

The TRDC-Locus encodes the T cell receptor delta constant region, one component of the {gamma}{delta} T cell receptor which is essential for development of {gamma}{delta} T cells. In contrast to peptide recognition by {beta} T cells, antigens activating {gamma}{delta} T cells are mostly MHC independent and not well characterized. Therefore, the function of {gamma}{delta} T cells and their contribution to protection against infections is still unclear. Higher numbers of circulating {gamma}{delta} T cells compared to mice, render the pig a suitable animal model to study {gamma}{delta} T cells. Knocking-out the porcine TRDC-locus by intracytoplasmic microinjection and somatic cell nuclear transfer resulted in healthy living {gamma}{delta} T cell deficient offspring. Flow cytometric analysis revealed that TRDC-KO pigs lack {gamma}{delta} T cells in peripheral blood mononuclear cells (PBMC) and spleen cells. The composition of the remaining leucocyte subpopulations was not affected by the depletion of {gamma}{delta} T cells. Genome-wide transcriptome analyses in PBMC revealed a pattern of changes reflecting the impairment of known or expected {gamma}{delta} T cell dependent pathways. Histopathology did not reveal developmental abnormalities of secondary lymphoid tissues. However, in a vaccination experiment the KO pigs stayed healthy but had a significantly lower neutralizing antibody titer as the syngenic controls.