Generation of Pigs Resistant to Highly Pathogenic-Porcine Reproductive and Respiratory Syndrome Virus through Gene Editing of <i>CD163</i>

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious disease and the most economically important disease of the swine industry worldwide. Highly pathogenic-PRRS virus (HP-PRRSV) is a variant of PRRSV, which caused high morbidity and mortality. Scavenger receptor CD163, which contains nine scavenger receptor cysteine-rich (SRCR) domains, is a key entry mediator for PRRSV. A previous study demonstrated that SRCR domain 5 (SRCR5), encoded by exon 7, was essential for PRRSV infection <i>in vitro</i>. Here, we substituted exon 7 of porcine <i>CD163</i> with the corresponding exon of <i>human CD163-like 1</i> (<i>hCD163L1</i>) using a CRISPR/Cas9 system combined with a donor vector. In <i>CD163^Mut/Mut</i> pigs, modifying <i>CD163</i> gene had no adverse effects on hemoglobin-haptoglobin (Hb-Hp) complex clearance or erythroblast growth. <i>In vitro</i> infection experiments showed that the <i>CD163</i> mutant strongly inhibited HP-PRRSV replication by inhibiting virus uncoating and genome release. Compared to wild-type (WT) pigs <i>in vivo</i>, HP-PRRSV-infected <i>CD163^Mut/Mut</i> pigs showed a substantially decreased viral load in blood and relief from PRRSV-induced fever. While all WT pigs were dead, there of four <i>CD163^Mut/Mut</i> pigs survived and recovered at the termination of the experiment. Our data demonstrated that modifying <i>CD163</i> remarkably inhibited PRRSV replication and protected pigs from HP-PRRSV infection, thus establishing a good foundation for breeding PRRSV-resistant pigs via gene editing technology.