Many studies have demonstrated that CD163 is an indispensable receptor for PRRSV infection, since the introduction of CD163 into non-permissive cell lines can confer susceptibility to infection (Calvert et al., 2007; Delrue et al., 2010; Wang et al., 2013; Li et al., 2017) and absolute resistance to PRRSV infection is observed in CD163 knock-out pigs (Whitworth et al., 2016; Burkard et al., 2017, 2018; Yang et al., 2018). This evidence concerns the gene CD163 and infection.