Early function of HIV-1 Gag proteins is cell-dependent.

Various gag gene mutants of human immunodeficiency virus type 1 (HIV-1) were monitored for their replication potentials and defective replication sites in various CD4-positive T-cell lines. Some matrix, capsid, and nucleocapsid mutants displayed a replication defect in a cell-dependent manner. The single-round replication assays demonstrated that these mutants were defective at an early infection phase also in a cell-dependent way. These results indicated that interaction of a cell factor(s) and Gag proteins is involved in an early process of HIV-1 replication.