MK-2048 is a second generation inhibitor of HIV-1 integrase with IC50 values of 0.075 μM and 0.08 μM for subtype B and subtype C integrase, respectively.Integration of viral cDNA into the host genome is one of the definitive features of retrovirus replication. Integrase inhibitors are active against both B and non-B subtypes in therapy. Subtype C variants are responsible for approximately 50% of infections worldwide, mostly in Sub-Saharan Africa and India. After viral entry and reverse transcription, reverse-transcribed double-stranded blunt-ended DNA is incorporated into the host cell genome through two catalytic activities mediated by integrase. MK-2048 could inhibit the strand transfer process catalyzed by integrase.The inhibition activity of MK-2048 against integrase was evaluated by means of purified recombinant subtype B and C integrase enzymes, which were obtained and amplified from viruses in long-term infected patients. Purified recombinant subtype B and C integrase enzymes were incubated with increasing concentrations of MK-2048 and corresponding templates. MK-2048 possesses inhibition activities for strand transfer against subtype B and C enzymes, whose IC50 values were 0.075 μM and 0.08 μM, respectively. Disintegration was inhibited by high concentrations of MK-2048 to a comparable extent with both subtype B and C enzymes.Inhibition of replication by MK-2048 was also evaluated in cell culture based assays using cord blood mononuclear cells. EC50 for subtype B viruses varies from 0.0003 μM to 0.0148 μM and 0.0007 μM to 0.0033 μM for subtype C viruses.References:1.Bar-Magen T, Sloan R D, Faltenbacher V H, et al. Comparative biochemical analysis of HIV-1 subtype B and C integrase enzymes[J]. Retrovirology, 2009, 6(1): 103.