While HIV-1 particles captured by mature DCs, THP-1/CD169 cells or Raji/CD169 cells were transmitted to CD4+ T cells, resulting in robust infection of T cells (Fig. 1C; trans-infection was enhanced more than 10-fold in CD169+ cells compared to CD169low immature DCs or empty vector transduced control cell lines), HeLa/CD169 cells failed to transmit HIV-1 to T cells (Fig. 1C). This evidence concerns the gene SIGLEC1 and infection.