FIG 4.

Trimer stability and processing of W69 variants. (A) Cell lysates and supernatants from ³⁵S-labeled cells transiently expressing the HIV-1YU2 WT and W69 variants were precipitated with a mixture of sera from HIV-1-infected patients. The precipitated proteins were loaded onto SDS-PAGE polyacrylamide gels and analyzed by autoradiography and densitometry to calculate their association (B) and processing (C) indexes. The processing index is a measure of the conversion of the mutant gp160 Env precursor to mature gp120 relative to that of the wild-type Env trimers, and the association index is a measure of the ability of the mutant gp120 molecule to remain associated with the envelope glycoprotein complex on the expressing cell relative to that of the wild-type envelope glycoproteins. Both indexes were calculated as described in Materials and Methods. Data shown in panel A are representative of 3 experiments. Data shown in panels B and C represent averages ± SD from at least three independent experiments. Statistical significance was tested using an unpaired two-tailed t test. Shown are P values with significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.001).