Dysfunction of Complementarity Determining Region 1 Encoded by T Cell Receptor Beta Variable Gene Is Potentially Associated with African Swine Fever Virus Infection in Pigs

The beta T-cell receptor (<i>TRB</i>) expressed by beta T cells is essential for foreign antigen recognition. The <i>TRB</i> locus contains a <i>TRBV</i> family that encodes three complementarity determining regions (CDRs). CDR1 is associated with antigen recognition and interactions with MHC molecules. In contrast to domestic pigs, African suids lack a 284-bp segment spanning exons 1 and 2 of the <i>TRBV27</i> gene that contains a sequence encoding CDR1. In this study, we used the African swine fever virus (ASFV) as an example to investigate the effect of deleting the <i>TRBV27</i>-encoded CDR1 on the resistance of domestic pigs to exotic pathogens. We first successfully generated <i>TRBV27</i>-edited fibroblasts with disruption of the CDR1 sequence using CRISPR/Cas9 technology and used them as donor cells to generate gene-edited pigs via somatic cell nuclear transfer. The <i>TRBV</i>-edited and wild-type pigs were selected for synchronous ASFV infection. White blood cells were significantly reduced in the genetically modified pigs before ASFV infection. The genetically modified and wild-type pigs were susceptible to ASFV and exhibited typical fevers (>40 °C). However, the <i>TRBV27</i>-edited pigs had a higher viral load than the wild-type pigs. Consistent with this, the gene-edited pigs showed more clinical signs than the wild-type pigs. In addition, both groups of pigs died within 10 days and showed similar severe lesions in organs and tissues. Future studies using lower virulence ASFV isolates are needed to determine the relationship between the <i>TRBV27</i> gene and ASFV infection in pigs over a relatively long period.