ITIH4 and nervous system disorder: Because we wanted to mimic the slow progress and long continuance of HIV-1-related neurologic disorders, we chose gp120 V3 loop at 1 μg/mL to treat microglia for investigating HIV-1-associated neurotoxicity as this concentration of HIV-1 gp120 V3 loop is the lowest dose in inducing a significant reduction of microglial viability.