The HIV-1 interaction with astrocytes is likely to be mediated by the viral envelope glycoprotein gp120 because preincubation of GFP-Vpr tagged virions with soluble CD4 prevented HIV-1 binding in our study (Fig. 1) and it was shown to block astrocyte infection by HIV-1 in a previous report [61]. Here, ERVW-1 is linked to infection.