Friday, 22nd September 2017

Virology and Microbiology

  Human immunodeficiency virus reverse transcriptase and antiretroviral therapy



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Luis Menéndez-Arias








Research summary

The human immunodeficiency virus (HIV) is a retrovirus that infects cells of the immune system, and is the etiological agent of AIDS. Nowadays, treatment of HIV-infection involves the use of inhibitors of retroviral enzymes such as the reverse transcriptase (RT), protease and integrase; as well as drugs targeting viral entry. Combination therapies including two or three RT inhibitors have been rather successful in the clinic, and play a key role in the management of HIV-infected individuals. However, the emergence of resistant viruses, the observed cross-reactivity between the inhibitors, and unwanted secondary effects are major hurdles towards their long-term efficacy.

We are interested in therapeutic targets for HIV, emphasizing on the role of the viral RT. HIV RT plays a pivotal role in the replication of the viral genomic RNA. Recently, our efforts have been directed towards two major goals: (1) understanding the role of different amino acids in the nucleotide specificity of the enzyme, as well as in its fidelity of DNA synthesis; and (2) the elucidation of molecular mechanisms involved in RT inhibitor resistance and the analysis of the contribution of different amino acid substitutions in the acquisition of drug resistance.

Nucleotide specificity studies are relevant in drug resistance but are also important to develop useful tools in molecular biology. Thus, we are trying to obtain more stable and faithful RTs, with biotechnological applications (for example, in the analysis of gene expression). Understanding the role of different residues in RT function (both on DNA polymerase activity, but also in modulating RNase H function and reverse transcription initiation) should help us to design novel strategies for treating HIV infection.

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Amino acid residues in the HIV-1 RT thumb-connection subdomains and the RNase H domain can modulate resistance to AZT and other nucleoside inhibitors by altering the balance between excision and template RNA degradation (Menéndez-Arias, 2013; Antiviral Res. 98, 93).         RT-PCR assays showing the effect of the temperature on the cDNA synthesis catalyzed by engineered recombinant HIV-1 group O RT variants (Matamoros et al. 2013; Biochemistry 52, 9318).


Relevant publications:

  • Barrioluengo, V., Álvarez, M., Barbieri, D., Menéndez-Arias, L. (2011) Thermostable HIV-1 group O reverse transcriptase variants with the same fidelity as murine leukaemia virus reverse transcriptase. Biochem. J. 436, 599-607
  • Kisic, M., Matamoros, T., Nevot, M., Mendieta, J., Martinez-Picado, J., Martínez, M.A., Menéndez-Arias, L. (2011) Thymidine analogue excision and discrimination modulated by mutational complexes including single amino acid deletions of Asp-67 or Thr-69 in HIV-1 reverse transcriptase. J. Biol. Chem. 286, 20615-20624
  • Betancor, G., Garriga, C., Puertas, M.C., Nevot, M., Anta, L., Blanco, J.L., Pérez-Elías, M.J., de Mendoza, C., Martínez, M.A., Martinez-Picado, J., Menéndez-Arias, L., for the Resistance Platform of the Spanish AIDS Research Network (ResRIS) (2012) Clinical, virological and biochemical evidence supporting the association of HIV-1 reverse transcriptase polymorphism R284K and thymidine analogue resistance mutations M41L, L210W and T215Y in patients failing tenofovir/emtricitabine therapy. Retrovirology 9, 68. 
  • Álvarez, M., Barrioluengo, V., Afonso-Lehmann, R., Menéndez-Arias, L. (2013) Altered error specificity of RNase H-deficient HIV-1 reverse transcriptases during DNA-dependent DNA synthesis. Nucleic Acids Res. 41, 4601-4612.   
  • Betancor, G., Álvarez, M., Marcelli, B., Andrés, C., Martínez, M.A., Menéndez-Arias, L. (2015) Effects of HIV-1 reverse transcriptase connection subdomain mutations on polypurine tract removal and initiation of (+)-strand DNA synthesis. Nucleic Acids Res. 43, 2259-2270.