Reverse transcriptase mutation K65N confers a decreased replication capacity to HIV-1 in comparison to K65R due to a decreased RT processivity

In addition to K65R, the other mutation observed at HIV-1 RT codon 65 is K65N. While K65N appears to have a phenotypic effect similar to K65R, it is less frequent during clinical trials. We compared the relative impact of K → N with respect to K → R change on viral replication capacity (RC). Mutant viruses were created and replication kinetics assays were performed in PBM cells. Analysis of RCs revealed a significant loss in replication (p = 0.004) for viruses containing K65N mutation in comparison to those with K65R mutation. RT processivity assays showed a significant decrease in the processivity of K65N RT in comparison to K65R RT. We demonstrated that the significant decrease in RC of K65N viruses is related to the impaired RT processivity of K65N RT in comparison to K65R, and that the selection of the K65R mutation may be favored in clinical use of antiretroviral drugs compared to K65N.

Research highlights►HIV-1 containing K65N mutation is attenuated in comparison to viruses with K65R mutation. ►RT containing K65N mutation has a significant decrease in in vitro RT processivity in comparison to K65R RT. ►Except K → R and K → N changes at RT codon 65, insertion of other amino acids result in a non-functional RT and non-viable virus. ►The deleterious effect on HIV replication by various mutation at RT codon 65 could not be compensated by second site L74V mutation.