Entecavir monohydrate (BMS-200475) is a selective inhibitor of the replication of the hepatitis B virus (HBV). It, a new deoxyguanine nucleoside analog.

HBV (HepG2 cells):3.75 nM(ec50)

In ducks, Entecavir administration results in a 4-log reduction of serum DHBV DNA levels within 80 days and a 2- to 3-log decrease in hepatitis B virus surface antigen within 120 days. Treatment with Entecavir also decreases replication intermediates of DHBV DNA in the liver by a factor of 70, while covalently closed circular DNA levels are only reduced fourfold under stable template conditions. Additionally, Entecavir reduces both the intensity of antigen staining and the percentage of antigen-positive cells in the liver, although there is an increase in antigen staining intensity in bile duct cells.

In liver biopsy samples, Entecavir reduces both covalently closed circular DNA and the negativity of the hepatitis B virus core antigen. Entecavir triphosphate acts as an effective inhibitor of the wild-type HBV polymerase and is 100-300 times more potent than lamivudine triphosphate against 3TC-resistant HBV polymerase. To inhibit the replication of 3TC-resistant HBV, Entecavir requires a concentration that is 20-30 times higher. With an EC50 of 0.1 nM, Entecavir demonstrates significant activity against HIV. It can be utilized in a single-cycle, single-cell line pseudovirus assay, measuring green fluorescent protein in CD4+ lymphocytes using fluorescence-activated cell sorting.

BMS 200475 is prepared in phosphate-buffered saline (PBS) and diluted with appropriate medium containing 2% fetal bovine serum. HepG2 2.2.15 cells are plated at a density of 5×105 cells per well on 12-well Biocoat collagen-coated plates and are maintained in a confluent state for 2 to 3 days before being overlaid with 1 mL of medium spiked with BMS 200475. Quantification of HBV was performed on day 10[1].