Fig. 4.

Antiviral activity of ZAPL is regulated by S-farnesylation. Stat1^−/− MEFs were transfected with pCMV-HA (vector), pCMV-HA-ZAPL, pCMV-HA-ZAPL-SaaX, or pCMV-HA-ZAPS (shown in Fig. 2A) and infected with Sindbis virus encoding the enhanced green fluorescent protein (EGFP) from a duplicated subgenomic promoter (TE/5′2J/GFP) with multiplicity of infection (MOI) of 10 for 24 h. Virus replication and ZAP protein levels were examined by flow cytometry using GFP fluorescence and anti-HA staining, respectively. After gating (shown in A), nontransfected and transfected cells expressing ZAP from the same culture were analyzed for the percentage of these cells that were infected (shown in B). *P = 0.00016, **P = 0.00003 by Student t test; error represents SD, n = 3. (C) Percentages in B were normalized such that the difference in infection rates for vector control and HA-ZAPL–transfected cells was set at 100% antiviral activity.