CD81 is downregulated in acutely infected lymphocytes. Jurkat T lymphocytes were infected with NL4-3, then fixed and stained for Gag and CD81. (A) A representative image of CD81 labeling in infected Jurkat cells. A single Z-section is shown. Scale bar represents 10 μm. (B) Quantification of immuno-fluorescence labeling of CD81 in infected (Gag+) and uninfected (Gag-) cells. Data shown represent the mean +/- SEM. * denotes a statistically significant difference from uninfected cells (p < 0.05). See Methods for more details. (C) Jurkat cells were infected with NL4-3. 4 days post-infection, when the percentage of infected cells was above 50%, cells were lysed, and CD81 and GAPDH protein levels were analyzed by Western blot. (D) Recruitment of CD81 to the VS in acutely infected Jurkat cells. Target Jurkat cells were labeled with CMAC Cell-tracker (blue) and co-cultured with NL4-3-infected producer Jurkat cells for 2 hours on PLL-coated coverslips. The cells were then fixed and stained for the indicated antigens as described in Methods. A single Z-section is shown. Maximum and minimum intensity of each wavelength were adjusted in order to highlight the areas with the most intense signal. Scale bars represent 10 μm.