Interestingly, some AIDS patients exhibited the presence of HIV-1 DNA in their infected brains, while the others had no detectable viral DNA after autopsies.34 HIV-1 Nef modulates progression of AIDS in patients with HAD compared with those without and subtype D is most likely associated with HAD.35 Although the neurotoxicity of HIV-1 gp120 and Tat has been widely studied and better understood,36 the neurotoxicity of HIV-1 Nef is still not clear despite some recent reports. Here, S100B is linked to AIDS.