SHIV_89.6P replication in macrophages in the presence of sense or AS IL-4 plasmid. Plasmids expressing AS (▪) or sense IL-4 (▦) were transfected into infected macrophages with the use of the cationic lipid, in vitro jetPEI-Man. □ indicates no IL-4. SHIV infection was then monitored by RT activity at different time intervals. *P < .01; ** P ≤ .001 compared with control-infected cultures.