English: Intravital microscopy showing differential movement of adoptively transferred naïve CD4 + T cells from adult and old mice in explanted LN. Naïve CD4+ T cells from adult and old mice were sorted, differentially labeled with fluorescent dyes (adult = green; old = blue) and adoptively transferred into adult mice that had been infected subcutaneously with WNV-KUN 48 hours earlier. Six hours later, the DLN was explanted and evaluated by intravital microscopy. Measurements of velocity and distance movement by individual naïve CD4+ T cells (see Fig 4and S4 Fig) were obtained from these videos. One representative experiment of several independent trials is shown. The time of analysis and scale bar are indicated.