Objective  The purpose of this study was to generate CD163 gene knockout (CD163-KO) Large White pigs by CRISPR/Cas9 gene editing and somatic cell nuclear transfer technologies, investigate the resistance to blue ear disease and the biosafety effect including physiology, productive and reproductive performances of the gene knockout pigs, and assess the main production performances of CD163-KO Large White pigs.

Method  In this study, the 11 CD163-KO pigs and five age- and body weight-matched wild type Large White pigs were challenged with NADC30-like strain of porcine reproductive and respiratory syndrome virus (PRRSV). The rectal temperature, PRRSV antibody and virus variation were monitored continuously for 14 days. The lung tissues were examined by immunofluorescence of PRRSV antigen. Expression of CD163 protein on the surface of pulmonary alveolar macrophages in wild type and CD163-KO Large White pigs were examined through immunofluorescence staining. We compared the differentiation potential of monocytes into macrophages between CD163-KO and wild type pigs, and observed their uptake capacities to hemoglobin-haptoglobin complex. In addition, we analyzed the growth and reproductive production of the boars between CD163-KO pigs and wild type control to assess their biosafety and breeding value.

Result  CD163-KO pigs were completely resistant to NADC30-like strain without impairing the biological function associated with the modified gene, as well as productive and reproductive performances.

Conclusion  This study is an evidence and supplement of CD163-KO pigs resistance to blue ear disease, and demonstrates that CD163 gene knockout has no potentially negative effects on production performance, which provides evidences for the biosecurity of CD163-KO pigs.