Nesbuvir is a selective hepatitis C virus (HCV) nonstructural protein 5B (NS5B) RNA-dependent polymerase inhibitor.Nesbuvir has an IC50 of 9 nM against hepatocellular carcinoma cells containing 1b HCV replicons.

NS5B:5 nM, NS3V170A:13 nM (EC50), NS3V170A:9 nM (EC50), NS5BI424V:13 nM (EC50), NS3K583T:15 nM (EC50)

Nesbuvir (40 or 80 nM) (approximately 10 and 20 times the EC50 in a 3-day replicon inhibition assay, respectively). The EC50 for Nesbuvir in the transient expression assay is 14 nM, whereas it is 5 nM for the stable replicon.[1]
Nesbuvir (0.1 and 1 μM; Huh-7 cells; for 16 days) reduced about 3.6 log10 and 4.2 log10 HCV RNA levels, respectively.[3]

Nesbuvir is demonstrated to yield significant antiviral effects in mice with chimeric human livers and in patients infected with HCV.[2]
Nesbuvir (chimeric mouse model) treatment resulted in a 2.02 +/- 0.55 log reduction in HCV titer, whereas in combination with interferon using a suboptimal dose of 30 mg/kg three times per day showed a 2.44 log reduction and were better than interferon treatment only.[5]

Huh7-BB7 cells are seeded at a density of 20,000 cells per 100 mm dish in DMEM supplemented with 2% FBS, 1 mg/mL G418, and various concentrations of Nesbuvir and/or Boceprevir with DMSO at a final concentration of 0.5% (vol/vol). The medium is removed and is replaced with a fresh medium with the appropriate compound concentrations every 3 or 4 days. After 7 days, the cells are split 1 to 10, placed into fresh 100 mm dishes, and incubated with medium with the appropriate compound concentrations. After 20 days, the medium is removed and the cells are fixed with 7% (wt/vol) formaldehyde and stained with 1% (wt/vol) crystal violet in 50% (vol/vol) ethanol [1].