Fig. 5

The biosynthesis of HIV-1 proteins is attenuated in the presence of β-coronavirus E proteins. HEK293 cells were transfected with either the empty pcDNA3.1( +) or vectors expressing SARS-CoV-2, SARS-CoV, MERS-CoV, or HCoV-OC43 E proteins and pNL4-3. At 30 h post-transfection, cells were starved of methionine/cysteine for 2 h and radiolabeled with ³⁵S-methionine/cysteine for 16 h. The culture medium was collected, and cell lysates were prepared as described in the Materials and Methods section. HIV-1 proteins were immunoprecipitated using anti-HIV-1 antibodies while the E proteins were immunoprecipitated with antibodies directed against the HA-tag. The immunoprecipitates were collected on protein-A-Sepharose, washed, and boiled in sample-reducing buffer. The proteins were separated by SDS-PAGE and visualized using standard radiographic techniques. A-B Immunoprecipitation of HIV-1 and E proteins from cell lysates and culture medium from HEK293 cells co-transfected with either pcDNA3.1( +) alone, pcDNA3.1( +)/pNL4-3, or pcDNA3.1( +) expressing SARS-CoV-2 E-HA protein/pNL4-3. C-D Immunoprecipitation of HIV-1 and E proteins from cell lysates and culture medium from HEK293 cells co-transfected with pcDNA3.1( +) alone, or pcDNA3.1( +)/pNL4-3, or pcDNA3.1( +) expressing the SARS-CoV E-HA/pNL4-3. E–F Immunoprecipitation of HIV-1 and E proteins from cell lysates and culture medium from HEK293 cells co-transfected pcDNA3.1( +) alone, pcDNA3.1( +)/pNL4-3, or pcDNA3.1( +) expressing the MERS-CoV E-HA/pNL4-3. G-H Immunoprecipitation of HIV-1 and E proteins from cell lysates and culture medium from HEK2933 cells co-transfected pcDNA3.1( +) alone, pcDNA3.1( +)/pNL4-3, or pcDNA3.1( +) expressing the HCoV-OC43 E-HA/pNL4-3