To determine whether a mutation in Lpro also disrupts its ability to remove Ub moieties from cellular substrates, we assayed Lpro W105A DUB activity by transfecting porcine LFPKαVβ6 cells with a plasmid encoding hemagglutinin (HA)-tagged Ub, followed by infection with A12-WT, A12-LLV, or A12-Lpro W105A viruses (Fig. 4C). This evidence concerns the gene ZUP1 and infection.