It might be further speculated, by analogy with HIV-1 that binds to DC-SIGN on dendritic cells and remains available for more than 4 days for trans infection of CD4(+) cells [7], or against neutralization by certain antibodies, when compared to free HIV-1 [8], that infectious HIV-1 bound to the erythrocyte surface in vivo might also be present in a type of protected state. This evidence concerns the gene CD4 and infection.