Fidelity of HIV-1 Reverse Transcriptase

TLDR

HIV‑1 exhibits extensive genetic variation and rapid evolution, and its misincorporation specificity may guide the design of antiviral nucleosides. Purified HIV‑1 reverse transcriptase fidelity was assessed in vitro during DNA polymerization using three distinct assays. HIV‑1 reverse transcriptase introduces base‑substitution errors at frequencies of 1/2000–1/4000, with a mismatch specificity of A:C ≫ A:G > A:A, leading to roughly five to ten errors per genome per replication cycle and contributing to the virus’s hypermutability.

Abstract

The human immunodeficiency virus type 1 (HIV-1) shows extensive genetic variation and undergoes rapid evolution. The fidelity of purified HIV-1 reverse transcriptase was measured during DNA polymerization in vitro by means of three different assays. Reverse transcriptase from HIV-1 introduced base-substitution errors in DNA from the bacteriophage φX174 amber 3 at estimated frequencies of 1/2000 to 1/4000. Analyses of misincorporation rates opposite a single template adenine residue showed that HIV-1 reverse transcriptase catalyzed nucleotide mismatches with a specificity of A:C >> A:G > A:A. The high error rate of HIV-1 reverse transcriptase in vitro translates to approximately five to ten errors per HIV-1 genome per round of replication in vivo. This high error rate suggests that misincorporation by HIV-1 reverse transcriptase is, at least in part, responsible for the hypermutability of the AIDS virus. The specificity of misincorporation may provide a basis for the systematic construction of antiviral nucleosides.