ERVW-1 and measles: The envelope/polymerase interactions of replicative homeostasis suggested herein are obvious therapeutic targets, and a site of interferon action: Heterologous envelope proteins from different viruses or genotypes of the same virus, or their structural homologues, are likely to inhibit viral replication, as suppression of HIV replication during measles [50] and Dengue [85] co-infection suggests.