Citation
- Authors: Bell BN. et al.
- Year: 2023
- Journal: Proc Natl Acad Sci U S A 120 e2215792120
- Applications: in vitro / DNA / FectoPRO
- Cell type: Expi293F
Description: Human embryonic kidney Fibroblast
Known as: Expi 293-F, Expi, HEK-293 Expi
Method
Expi293F cells were cultured in 33% Expi293 Expression/66% FreeStyle Expression medium (Thermo Fisher Scientific) and grown in baffled polycarbonate shaking flasks (Triforest) at 37 °C and 8% CO2. Cells were grown to a density of ~3 × 106/mL and transiently transfected using FectoPro transfection reagent (Polyplus). For transfections, 0.5 μg total DNA (1:1 heavy chain to light chain plasmids) was added per mL final transfection volume to culture medium (1/10 volume of final transfection) followed by FectoPro at a concentration of 1.3 μL per mL final transfection volume and incubated at room temperature for 10 min. Transfection mixtures were added to cells, which were then supplemented with d-glucose (4 g/L final concentration) and 2-propylpentanoic (valproic) acid (3 mM final concentration). Cells were harvested 3 to 5 d after transfection via centrifugation at 18,000 × g for 15 min. Cell culture supernatants were filtered using a 0.22-μm filter prior to purification.
Abstract
HIV-1 strains are categorized into one of three neutralization tiers based on the relative ease by which they are neutralized by plasma from HIV-1-infected donors not on antiretroviral therapy; tier-1 strains are particularly sensitive to neutralization while tier-2 and tier-3 strains are increasingly difficult to neutralize. Most broadly neutralizing antibodies (bnAbs) previously described target the native prefusion conformation of HIV-1 Envelope (Env), but the relevance of the tiered categories for inhibitors targeting another Env conformation, the prehairpin intermediate, is not well understood. Here, we show that two inhibitors targeting distinct highly conserved regions of the prehairpin intermediate have strikingly consistent neutralization potencies (within ~100-fold for a given inhibitor) against strains in all three neutralization tiers of HIV-1; in contrast, best-in-class bnAbs targeting diverse Env epitopes vary by more than 10,000-fold in potency against these strains. Our results indicate that antisera-based HIV-1 neutralization tiers are not relevant for inhibitors targeting the prehairpin intermediate and highlight the potential for therapies and vaccine efforts targeting this conformation.