Dolutegravir (GSK1349572) (IC50=2.7 nM), a two-metal-binding HIV integrase inhibitor, exhibits medium activity against raltegravir-resistant signature mutants Y143R, Q148K, N155H, and G140S/Q148H.

HIV integrase:2.7 nM

In vitro strand transfer assay: The inhibitory potencies of S/GSK1349572 and other INIs are measured in a strand transfer assay using recombinant HIV integrase. A complex of integrase and biotinylated preprocessed donor DNA-streptavidin-coated Acintillation proximity assay (SPA) beads is formed by incubating 2 μM purified recombinant integrase with 0.66 μM biotinylated donor DNA-4 mg/mL streptavidin-coated SPA beads in 25 mM sodium morpholinepropanesulfonic acid (MOPS) (pH 7.2), 23 mM NaCl, and 10 mM MgCl2 for 5 minutes at 37 °C. These beads are spun down and preincubated with diluted INIs for 60 minutes at 37 °C. Then a 3H-labeled target DNA substrate is added to give a final concentration of 7 nM substrate, and the strand transfer reaction mixture is incubated at 37 °C for 25 to 45 minutes, which allows for a linear increase in the strand transfer of donor DNA to radiolabeled target DNA. The signal is read using a Wallac MicroBeta scintillation plate reader.

MT-4 cells growing exponentially at a density of 500000 or 600000 /mL are infected with HIV-1 strain IIIB at a viral multiplicity of infection of 0.001 or a 50% tissue culture infective dose of 4 to 10. The cells are then aliquoted to 96-well plates in the presence of varying concentrations of S/GSK1349572. After incubation for 4 or 5 days, antiviral activity is determined by a cell viability assay that either measured bioluminescence with a CellTiter-Glo luminescent reagent or measured absorbance at 560 and 690 nm using the yellow tetrazolium MTT reagent [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide]. (Only for Reference)