1088. A Five Residue Insertion between Codons 28 and 29 of the HIV-1 Protease Gene Reduces the Replicative Capacity of the Virus
Session: Poster Abstract Session: HIV: Resistance
Friday, October 9, 2015
Room: Poster Hall
Posters
  • A five residue insertion beetween codons 28 and 29 of the HIV-1 protease gene reduces replicative capacity of the virus.pdf (1.4 MB)
  • Background: Antiretroviral therapy is highly effective in inhibiting viral replication; however, virologic failure is not uncommon defined as plasma viral load above 1000 copies/ml on two consecutive viral load measurements after 3 months. A 5-residue insertion sequence at codon 28 of HIV-1 protease gene was detected from a patient who was poorly adherent to ART with a 10-year history of multi-drug resistant HIV-1 developing a viral load of 164,110 copies per µL. This is the first report of a five residue insertion at codon 28. Our study aims to analyze the structure of the HIV-1 protease insertion mutant and to further characterize the impact on resistance from this rare insertion sequence causing a reduced replicative capacity

    Methods: A sequence of homology modeling using Schrödinger PRIME software, docking experiments using PYMOL then repeated with the nine Gag and Gag-Pol cleavage peptides, and molecular dynamics (MD) simulations using the Wayne State University Grid Nano Molecular Dynamics (NAMD) v. 2.9 were carried out

    Results:  Genotypic results (ViroSeq test) indicate that the isolate is resistant to indinavir, lopinavir/r, nelfinavir, fosamprenavir and possibly resistant to tipranavir, darunavir, and atazanavir without evidence of resistance to saquinavir. The phenotypic test indicates resistance to atazanavir, atazanavir/r, fosamprenavir/r, and nelfinavir and partial sensitivity to darunavir/r, lopinavir/r, and tipranavir/r. The isolate is sensitive to saquinavir based on both the phenotypic and genotypic test results. Surprisingly, the virus replicative capacity for the codon 28 insertion mutant is only 28% relative to the wild-type (100% reference). To evaluate changes in molecular recognition of the protease inhibitors and the nine substrate peptides we performed a series of 40 ns MD simulations as described in the Methods section. These results indicate major changes in both inhibitor and substrate binding when compared to the wild-type HIV-1 protease.

    Conclusion: The five residue insertion mutation exhibits altered binding properties of both the Gag and GagPol substrates and the nine protease inhibitors. MD experiments indicate that the active site cleft insertion mutation also reduces inhibitor binding as observed earlier based on genotypic and phenotypic tests. 

    Eunice Ann Wong, MD1, Cathy Mcleod, BS2, Bradley Keusch, BS2, Benjamin Kuiper, BS3, Iulia Kovari, PhD2, Hossein Salimnia, Ph.D.4, Jennifer Veltman, MD5 and Ladislau Kovari, Ph.D.6, (1)Infectious Diseases, Detroit Medical Center-Wayne State University, Detroit, MI, (2)Biochemistry, Wayne State University, Detroit, MI, (3)Wayne State University, Detroit, MI, (4)Dept. of Pathology, Wayne St. Univ. Sch. of Med., Detroit, MI, (5)Detroit Medical Center/Wayne State University, Detroit, MI, (6)Department of Biochemistry and Molecular Biology, Wayne State University, Detroit, MI

    Disclosures:

    E. A. Wong, None

    C. Mcleod, None

    B. Keusch, None

    B. Kuiper, None

    I. Kovari, None

    H. Salimnia, Nanosphere: Grant Investigator , Grant recipient and Research grant
    BioFire: Grant Investigator , Grant recipient and Research grant
    GenMark: Grant Investigator , Grant recipient and Research grant
    Accelerate: Grant Investigator , Grant recipient and Research grant
    AdvanDx: Grant Investigator , Grant recipient and Research grant

    J. Veltman, None

    L. Kovari, None

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