FIG. 2.

Effect of Nef on a single round of virus transmission in the absence of MA. GHOST-CXCR4 cells were infected with 293T cell-derived recombinant viruses that differed in gag and nef as indicated. To ensure that only a single round of infection occurred, C-terminally truncated HIV-1 Env was provided in trans during virus production. The target cells were incubated overnight with 50,000 RT units of the parental Nef⁺ and Nef⁻ virus stocks and with 250,000 RT units of the MA mutants to compensate for the approximately fivefold reduction in infectivity caused by the Δ8-126 and ΔMA/R3 deletions. (A) Cell-associated Gag proteins detected by immunoprecipitation with patient serum after metabolic labeling of the infected cultures with [³⁵S]cysteine. (B) Virions released during the labeling period were pelleted through sucrose and directly analyzed by SDS-PAGE. Pr55, full-length Gag precursor; Pr', shortened Gag precursors produced by the Δ8-126 and ΔMA/R3 mutants. NC, nucleocapsid.