To evaluate the importance of the four mutations (3A-R54W, 2C-M187V, 2B-F17L, and 2B-Q20H mutations) in infection, we first analyzed plaque phenotypes of PV(Mahoney) mutants with the mutations in wild type (WT) and PI4KB-knockout RD cells—RD(WT) and RD(ΔPI4KB) cells, respectively (Fig. 1A). The gene discussed is PI4KB; the disease is infection.