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SAMHD1 specifically affects the antiviral potency of thymidine analog HIV reverse transcriptase inhibitors.

Antimicrobial agents and chemotherapy (2014-06-11)
Ester Ballana, Roger Badia, Gerard Terradas, Javier Torres-Torronteras, Alba Ruiz, Eduardo Pauls, Eva Riveira-Muñoz, Bonaventura Clotet, Ramon Martí, José A Esté
ABSTRACT

Sterile alpha motif and histidine-aspartic domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase recently recognized as an antiviral factor that acts by depleting dNTP availability for viral reverse transcriptase (RT). SAMHD1 restriction is counteracted by the human immunodeficiency virus type 2 (HIV-2) accessory protein Vpx, which targets SAMHD1 for proteosomal degradation, resulting in an increased availability of dNTPs and consequently enhanced viral replication. Nucleoside reverse transcriptase inhibitors (NRTI), one of the most common agents used in antiretroviral therapy, compete with intracellular dNTPs as the substrate for viral RT. Consequently, SAMHD1 activity may be influencing NRTI efficacy in inhibiting viral replication. Here, a panel of different RT inhibitors was analyzed for their different antiviral efficacy depending on SAMHD1. Antiviral potency was measured for all the inhibitors in transformed cell lines and primary monocyte-derived macrophages and CD4(+) T cells infected with HIV-1 with or without Vpx. No changes in sensitivity to non-NRTI or the integrase inhibitor raltegravir were observed, but for NRTI, sensitivity significantly changed only in the case of the thymidine analogs (AZT and d4T). The addition of exogenous thymidine mimicked the change in viral sensitivity observed after Vpx-mediated SAMHD1 degradation, pointing toward a differential effect of SAMHD1 activity on thymidine. Accordingly, sensitivity to AZT was also reduced in CD4(+) T cells infected with HIV-2 compared to infection with the HIV-2ΔVpx strain. In conclusion, reduction of SAMHD1 levels significantly decreases HIV sensitivity to thymidine but not other nucleotide RT analog inhibitors in both macrophages and lymphocytes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Thymidine, powder, BioReagent, suitable for cell culture
Sigma-Aldrich
Thymidine, ≥99%
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3′-Azido-3′-deoxythymidine, ≥98% (HPLC)
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Thymidine, ≥99.0% (HPLC)
Supelco
Zidovudine, Pharmaceutical Secondary Standard; Certified Reference Material
USP
Zidovudine, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Anti-SAMHD1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution
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Monoclonal Anti-SAMHD1 antibody produced in mouse, ~1.0 mg/mL, clone SM1.1, purified immunoglobulin
Zidovudine, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Anti-SAMHD1 antibody produced in rabbit, purified immunoglobulin, buffered aqueous solution
Sigma-Aldrich
Anti-SAMHD1 antibody produced in mouse, IgG fraction of antiserum, buffered aqueous solution