We previously demonstrated that decreased HO-1 protein expression in the prefrontal cortex of PLWH associates with HIV-NCI and encephalitis, and that this HO-1 reduction is associated with the level of HIV expression, type I interferon (IFN)-stimulated gene expression, and macrophage activation (Ambegaokar and Kolson 2014; Gill et al. 2014). This evidence concerns the gene IFNA1 and encephalitis.