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High level of susceptibility to human TRIM5? conferred by HIV-2 capsid sequences.

ABSTRACT: BACKGROUND:HIV-2, which was transmitted to humans from a distant primate species (sooty mangabey), differs remarkably from HIV-1 in its infectivity, transmissibility and pathogenicity. We have tested the possibility that a greater susceptibility of HIV-2 capsid (CA) to the human restriction factor TRIM5? (hTRIM5?) could contribute to these differences. RESULTS:We constructed recombinant clones expressing CA from a variety of HIV-2 viruses in the context of HIV-1 NL4-3-luciferase. CA sequences were amplified from the plasma of HIV-2 infected patients, including 8 subtype A and 7 subtype B viruses. CA from 6 non-epidemic HIV-2 subtypes, 3 HIV-2 CRF01_AB recombinants and 4 SIVsmm viruses were also tested. Susceptibility to hTRIM5? was measured by comparing single-cycle infectivity in human target cells expressing hTRIM5? to that measured in cells in which hTRIM5? activity was inhibited by overexpression of hTRIM5?.The insertion of HIV-2 CA sequences in the context of HIV-1 did not affect expression and maturation of the HIV-2 CA protein. The level of susceptibility hTRIM5? expressed by viruses carrying HIV-2 CA sequences was up to 9-fold higher than that of HIV-1 NL4-3 and markedly higher than a panel of primary HIV-1 CA sequences. This phenotype was found both for viruses carrying CA from primary HIV-2 sequences and viruses carrying CA from laboratory-adapted HIV-2 clones. High hTRIM5? susceptibility was found in all HIV-2 subtypes. In this series of viruses, susceptibility to hTRIM5? was not significantly affected by the presence of a proline at position 119 or by the number of prolines at positions 119, 159 or 178 in HIV-2 CA. No significant correlation was found between HIV-2 viremia and sensitivity to hTRIM5?. CONCLUSIONS:HIV-2 capsid sequences expressed high levels of susceptibility to hTRIM5?. This property, common to all HIV-2 sequences tested, may contribute in part to the lower replication and pathogenicity of this virus in humans.

SUBMITTER: Takeuchi JS

PROVIDER: S-EPMC3691696 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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High level of susceptibility to human TRIM5α conferred by HIV-2 capsid sequences.

Takeuchi Junko S JS Perche Benjamin B Migraine Julie J Mercier-Delarue Séverine S Ponscarme Diane D Simon François F Clavel François F Labrosse Béatrice B

Retrovirology 20130506

<h4>Background</h4>HIV-2, which was transmitted to humans from a distant primate species (sooty mangabey), differs remarkably from HIV-1 in its infectivity, transmissibility and pathogenicity. We have tested the possibility that a greater susceptibility of HIV-2 capsid (CA) to the human restriction factor TRIM5α (hTRIM5α) could contribute to these differences.<h4>Results</h4>We constructed recombinant clones expressing CA from a variety of HIV-2 viruses in the context of HIV-1 NL4-3-luciferase. ...[more]

PMID: 23647667

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Project description:Rhesus TRIM5? (rhTRIM5?) potently restricts replication of human immunodeficiency virus type 1 (HIV-1). Restriction is mediated through direct binding of the C-terminal B30.2 domain of TRIM5? to the assembled HIV-1 capsid core. This host-pathogen interaction involves multiple capsid molecules within the hexagonal HIV-1 capsid lattice. However, the molecular details of this interaction and the precise site at which the B30.2 domain binds remain largely unknown. The human orthologue of TRIM5? (hsTRIM5?) fails to block infection by HIV-1 both in vivo and in vitro This is thought to be due to differences in binding to the capsid lattice. To map the species-specific binding surface on the HIV-1 capsid lattice, we used microscale thermophoresis and dual-focus fluorescence correlation spectroscopy to measure binding affinity of rhesus and human TRIM5? B30.2 domains to a series of HIV-1 capsid variants that mimic distinct capsid arrangements at each of the symmetry axes of the HIV-1 capsid lattice. These surrogates include previously characterized capsid oligomers, as well as a novel chemically cross-linked capsid trimer that contains cysteine substitutions near the 3-fold axis of symmetry. The results demonstrate that TRIM5? binding involves multiple capsid molecules along the 2-fold and 3-fold interfaces between hexamers and indicate that the binding interface at the 3-fold axis contributes to the well-established differences in restriction potency between TRIM5? orthologues.IMPORTANCE TRIM5? is a cellular protein that fends off infection by retroviruses through binding to the viruses' protein shell surrounding its genetic material. This shell is composed of several hundred capsid proteins arranged in a honeycomb-like hexagonal pattern that is conserved across retroviruses. By binding to the complex lattice formed by multiple capsid proteins, rather than to a single capsid monomer, TRIM5? restriction activity persists despite the high mutation rate in retroviruses such as HIV-1. In rhesus monkeys, but not in humans, TRIM5? confers resistance to HIV-1. By measuring the binding of human and rhesus TRIM5? to a series of engineered HIV-1 capsid mimics of distinct capsid lattice interfaces, we reveal the HIV-1 capsid surface critical for species-specific binding by TRIM5?.

Project description:Restriction factors are intrinsic cellular defense proteins that have evolved to block microbial infections. Retroviruses such as HIV-1 are restricted by TRIM5 proteins, which recognize the viral capsid shell that surrounds, organizes, and protects the viral genome. TRIM5α uses a SPRY domain to bind capsids with low intrinsic affinity (KD of >1 mM) and therefore requires higher-order assembly into a hexagonal lattice to generate sufficient avidity for productive capsid recognition. TRIMCyp, on the other hand, binds HIV-1 capsids through a cyclophilin A domain, which has a well-defined binding site and higher affinity (KD of ∼10 μM) for isolated capsid subunits. Therefore, it has been argued that TRIMCyp proteins have dispensed with the need for higher-order assembly to function as antiviral factors. Here, we show that, consistent with its high degree of sequence similarity with TRIM5α, the TRIMCyp B-box 2 domain shares the same ability to self-associate and facilitate assembly of a TRIMCyp hexagonal lattice that can wrap about the HIV-1 capsid. We also show that under stringent experimental conditions, TRIMCyp-mediated restriction of HIV-1 is indeed dependent on higher-order assembly. Both forms of TRIM5 therefore use the same mechanism of avidity-driven capsid pattern recognition.IMPORTANCE Rhesus macaques and owl monkeys are highly resistant to HIV-1 infection due to the activity of TRIM5 restriction factors. The rhesus macaque TRIM5α protein blocks HIV-1 through a mechanism that requires self-assembly of a hexagonal TRIM5α lattice around the invading viral core. Lattice assembly amplifies very weak interactions between the TRIM5α SPRY domain and the HIV-1 capsid. Assembly also promotes dimerization of the TRIM5α RING E3 ligase domain, resulting in synthesis of polyubiquitin chains that mediate downstream steps of restriction. In contrast to rhesus TRIM5α, the owl monkey TRIM5 homolog, TRIMCyp, binds isolated HIV-1 CA subunits much more tightly through its cyclophilin A domain and therefore was thought to act independently of higher-order assembly. Here, we show that TRIMCyp shares the assembly properties of TRIM5α and that both forms of TRIM5 use the same mechanism of hexagonal lattice formation to promote viral recognition and restriction.

Project description:Current HIV-1 gene therapy approaches aim at stopping the viral life cycle at its earliest steps, such as entry or immediate postentry events. Among the most widely adopted strategies are CCR5 downregulation/knockout and the use of broadly neutralizing antibodies. However, the long-term efficacy and side effects are still unclear. TRIM5? is an interferon-stimulated restriction factor that can intercept incoming retroviruses within one hour of cytosolic entry and potently inhibit the infectivity of restriction-sensitive viruses. The human TRIM5? (TRIM5?hu) generally does not efficiently target HIV-1, but point mutations in its capsid-binding domain can confer anti-HIV-1 activity. Although the mechanisms by which TRIM5?hu mutants inhibit HIV-1 are relatively well understood, their characterization as potential transgenes for gene therapy is lacking. Additionally, previous reports of general immune activation by overexpression of TRIM5? have hindered its broad adoption as a potential transgene. Here we demonstrate the ability of the R332G-R335G TRIM5?hu mutant to efficiently restrict highly divergent HIV-1 strains, including Group O, as well as clinical isolates bearing cytotoxic T lymphocyte escape mutations. R332G-R335G TRIM5?hu efficiently protected human lymphocytes against HIV-1 infection, even when expressed at relatively low levels following lentiviral transduction. Most importantly, under these conditions Rhesus macaque TRIM5? (TRIM5?Rh) and TRIM5?hu (wild-type or mutated) had no major effects on the NF-?B pathway. Transgenic TRIM5? did not modulate the kinetics of I?B?, JunB, and TNFAIP3 expression following TNF-? treatment. Finally, we show that human lymphocytes expressing R332G-R335G TRIM5?hu have clear survival advantages over unmodified parental cells in the presence of pathogenic, replication-competent HIV-1. These results support the relevance of R332G-R335G and other mutants of TRIM5?hu as candidate effectors for HIV-1 gene therapy.

Dataset Information

High level of susceptibility to human TRIM5? conferred by HIV-2 capsid sequences.

Publications

High level of susceptibility to human TRIM5α conferred by HIV-2 capsid sequences.

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