Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) plays an essential role in the life cycle of the virus. Therefore. RT has been a primary target in the development of antiviral agents against HIV-1. Given the prevalence of resistant viruses, evaluation of the resistance profile of potential drug candidates is a key step in drug development. A simplified RI purification protocol would facilitate this process, as it provides an efficient method by which to purify RT variants for compound evaluation. Traditional purification protocols require the use of several columns to purify untagged RT. The entire procedure usually requires at least one week to complete. Herein, we report two novel methods that enable us to purify highly active RI in either one or two steps. First, a one-step purification protocol was developed by employing an affinity column that was prepared by conjugating an RNase H specific inhibitor (RNHI) with NHS-activated resin. Cell lysate containing RI was loaded onto the column followed by washing in the presence of 2 mM Mn2+. The RI retained in the column was eluted after soaking overnight in 10 mM EDTA to retrieve the Mn2+. In the other method, a vector was constructed that encodes RT fused to cleavable intein and AviTag (a biotin tag) sequences at the C-terminus. Cell lysate containing biotinylated RI was passed through a DE-52 column and then loaded onto an avidin column. Untagged RI was released from the column by reductive cleavage of the intein by DTT. These two methods significantly shorten the time required to purify untagged WT and mutant RTs. (C) 2010 Elsevier Inc. All rights reserved.