Identification of anti-MPER antibodies in HIV-1 infected individuals. Panel A. The presence of antibodies recognizing the MIN, STAPLE or full-length HIV-1 envelope was tested using the 293T cells stably expressing these proteins. The upper plots show the ratio of mean fluorescence intensity (MFI) of plasma IgG bound to 293–MIN, 293-STAPLE or 293-ENV (full-length) and control 293 cells. Plasma samples from HIV-1 infected individuals were classified according to plasma viral load (VL > 50000, 50000 < VL < 5000 and VL < 5000). Plasma samples from uninfected individuals (HC) were tested as control. Dotted lines show the positivity cutoff calculated as Mean + 2xSD of uninfected plasma samples. Panel B. The longitudinal evolution of MIN, STAPPLE and full-length HIV-1 envelope recognition by plasma samples from HIV-1 infected individuals is shown for the different VL groups defined in Panel A. Time points are separated at least one year. All figures show the ratio of MFI between cells stably expressing MIN (left) STAPLE (middle) or full-length envelope (ENV, right) and 293T control cells. Significant p values are shown.