title: Infectious mutants of HTLV-III with changes in the 3' region and markedly reduced cytopathic effects.
abstract: A variant of human T-lymphotropic virus type III (HTLV-III) is described that replicates but does not kill normal human T cells in vitro. This variant, designated X10-1, was derived from the genome of a cytopathic HTLV-III clone (pHXB2D) by excision of a 200-base pair segment in the 3' region of the virus, spanning the env and 3'-orf genes. Comparable variants with 55 to 109 base pairs deleted exclusively in 3'-orf produced, in contrast, virus that was extremely cytopathic. On the basis of these findings it is concluded that the 3'-orf gene is not required for cytopathogenicity or replication of HTLV-III. In addition, the results suggest that virus replication and cytotoxicity are not intrinsically coupled. Furthermore, since clone X10-1 retains the ability to trans-activate genes linked to the viral long terminal repeats, trans-activation per se is not responsible for T-cell killing by HTLV-III. These results also raise the possibility that the carboxyl terminus of the envelope gene of HTLV-III has a direct role in T-cell killing by this virus.
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000382:microbiology*; D003001:Cloning, Molecular; D017977:Deltaretrovirus / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D009154:Mutation; D009693:Nucleic Acid Hybridization; D012367:RNA, Viral / Q000235:genetics; D013601:T-Lymphocytes / Q000382:microbiology
chemical_list: D012367:RNA, Viral