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American Society for Microbiology, Antimicrobial Agents and Chemotherapy, 8(59), p. 4870-4881, 2015

DOI: 10.1128/aac.00137-15

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Incomplete APOBEC3G/F Neutralization by HIV-1 Vif Mutants Facilitates the Genetic Evolution from CCR5 to CXCR4 Usage

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

ABSTRACT Incomplete APOBEC3G/F neutralization by a defective HIV-1Vif protein can promote genetic diversification by inducing G-to-A mutations in the HIV-1 genome. The HIV-1 Env V3 loop, critical for coreceptor usage, contains several putative APOBEC3G/F target sites. Here, we determined if APOBEC3G/F, in the presence of Vif-defective HIV-1 virus, can induce G-to-A mutations at V3 positions critical to modulation of CXCR4 usage. Peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM) from 2 HIV-1-negative donors were infected with CCR5-using 81.A-Vif WT virus (i.e., with wild-type [WT] Vif protein), 81.A-Vif E45G , or 81.A-Vif K22E (known to incompletely/partially neutralize APOBEC3G/F). The rate of G-toA mutations was zero or extremely low in 81.A-Vif WT - and 81.A-Vif E45G -infected PBMC from both donors. Conversely, G-to-A enrichment was detected in 81.A-Vif K22E -infected PBMC (prevalence ranging from 2.18% at 7 days postinfection [dpi] to 3.07% at 21 dpi in donor 1 and from 10.49% at 7 dpi to 8.69% at 21 dpi in donor 2). A similar scenario was found in MDM. G-to-A mutations occurred at 8 V3 positions, resulting in nonsynonymous amino acid substitutions. Of them, G24E and E25K strongly correlated with phenotypically/genotypically defined CXCR4-using viruses ( P = 0.04 and 5.5e−7, respectively) and increased the CXCR4 N-terminal binding affinity for V3 (WT, −40.1 kcal/mol; G24E, −510 kcal/mol; E25K, −522 kcal/mol). The analysis of paired V3 and Vif DNA sequences from 84 HIV-1-infected patients showed that the presence of a Vif-defective virus correlated with CXCR4 usage in proviral DNA ( P = 0.04). In conclusion, incomplete APOBEC3G/F neutralization by a single Vif amino acid substitution seeds a CXCR4-using proviral reservoir. This can have implications for the success of CCR5 antagonist-based therapy, as well as for the risk of disease progression.