The low level of PRRSV RNA that was initially detectable in the DKO line at 12 hpi is likely attributable to the adsorbed PRRSV independent of the existence of CD163, as CD163 is thought to be primarily responsible for the uncoating and viral RNA release processes of PRRSV infection (Chen et al., 2019; Van Gorp et al., 2008). This evidence concerns the gene CD163 and infection.