NBN and infection: To identify potential resistance mutations that might emerge in the presence of this drug, MT-2 cells were infected with HIV-1 IIIb at a high multiplicity of infection (MOI = 0.1) and then passaged for 35 days in culture in the presence of GS-9770 or ATV (control PI) at fixed drug concentrations equal to twofold, threefold, or fourfold their mean respective 95% effective concentration (EC95) values of 21.6 and 19.5 nM, respectively.