Retrovirus and filovirus "immunosuppressive motif" and the evolution of virus pathogenicity in HIV-1, HIV-2, and Ebola viruses.

The "immunosuppressive motif" was found to be present in the glycoproteins of retroviruses and filoviruses. This sequence is also conserved in the pathogenic lentiviruses, HIV-1 and SIV, and is absent from HIV-2 gp41 and from an apathogenic simian retrovirus. The present analysis deals with the possible involvement of the "immunosuppresessive motif" in the pathogenicity of retroviruses and filoviruses, and the reasons for the conservation of this motif. The ancestral gene from which the "immunosuppressive motif" originated is not known.