Mechanism of viperin action in MDMs. (A) HIV-1 alters viperin distribution in infected MDMs. Five days pi, mock- and HIV-1–treated MDMs were fixed in 3% paraformaldehyde, permeabilized with 0.05% Triton-X, and labeled for viperin (red), p24 (green), CD81 (blue), and nucleus (white). Images shown are representative of n = 10 cells and were acquired as described in Figure 1C. (B) HIV-1 infection of MDMs disperses lipid rafts. Five days pi, mock- and HIV-1–treated MDMs were immunostained with the lipid raft marker CTB–Alexa Fluor-488 (lipid raft, green), fixed in 3% paraformaldehyde, permeabilized with 0.05% Triton-X, and then labeled with anti-p24 antibody (red). Top and middle panels: HIV-1-treated culture. Top panels: Infected cell. Middle panels: In addition to the infected cell (red), a noninfected cell (no red staining; as only a small proportion of cells are infected). Therefore, in the right middle panel, which shows merged images, it is clear that the infected cell (p24 antigen-positive) has lost its lipid raft staining. Bottom panel: Noninfected cell in a mock-treated culture. Images shown are representative of n = 10 cells and were acquired as described in Figure 1C. (C) Farnesol stimulates HIV-1 production by HIV-1–infected MDMs to a greater degree than geranylgeraniol. MDMs were infected with HIV-1 (MOI = 0.5) for 3 days and were then either treated with farnesol or geranylgeraniol (10μM) or mock treated. At the indicated times point after infection, HIV-1 DNA was quantified by quantitative PCR. Levels of HIV-1 DNA are presented as percentage of up-regulation after farnesol or geranylgeraniol treatment, compared with mock-treated HIV-1–infected cultures (set at 100%). The mean data from 3 experiments are shown with SE bars. *P < .05 (paired t test). **P > .3 (paired t test).