Fig. 9

HERV-K CA-NTD and MHR are not required for reduction of HIV-1 infectivity. HeLa cells were cotransfected with pNL4-3 and indicated plasmids. a Virus in the supernatant from cotransfected HeLa cells were collected and fractionated in rate-zonal gradient analysis. The amount of HIV-1 Gag were measured by ELISA. b Virus stocks were prepared from each fraction after rate-zonal gradient analysis. The viruses were purified and normalized by p24 ELISA. TZM-bl cells, which harbor an HIV-1 LTR-driven luciferase-reporter gene, were infected with the purified viruses. At 2 days post-infection, luciferase activities were measured by luminometor. Data from three independent experiments are shown as means ± standard deviations. P values were determined using a Student’s t test. *P < 0.01; **P < 0.001; ***P < 0.0001; n.s. not significant