Avances en investigación básicaAvances en investigación básicaJavier Martinez-Picado
19th Conference on Retroviruses and Opportunistic Infections
Seattle, March 5-8, 2012
Javier Martinez-Picado19th Conference on Retroviruses and Opportunistic Infections
Seattle, March 5-8, 2012
Barcelona, 13/03/12
Restrictions FactorsTowards a HIV-1 Cure
Highligthed Topics Highligthed Topics
Restriction factors: a defense against retroviral infection
SAMHD1 is a myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx
Restriction factors: a defense against retroviral infection
SAMHD1 is a myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx
Barcelona, 13/03/12
Restriction Factors Restriction Factors
Benkirane #63Lieberman #64
Luban #65Kewal Ramani #66
Barcelona, 13/03/12
Host defenses against retroviruses
Host defenses against retroviruses
Modified from Kirchhoff, 2010 Host Cell Microb
Laguette & Benkirane, 2012. Trends in Immunology
Barcelona, 13/03/12
Dendritic Cells Dendritic Cells
DCs coordinate immune responses to invading pathogens
DCs can carry HIV-1 to target CD4+ T cells, amplifying the cytopathic effects of the virus
SAMHD1 is responsible for blocking replication of HIV within dendritic cells, although it functions in other myeloid cells as well
SAMHD1 can be antagonized by vpx
Benkirane #63
Barcelona, 13/03/12
What does make DC refractory to HIV-1 ?
What does make DC refractory to HIV-1 ?
Modified from emulenews
Proteosomal Degradation
REVERSETRANSCRIPTION
RESTRICTIVE INFECTION PERMISSIVE INFECTION
Barcelona, 13/03/12
What does make DC refractory to HIV-1 ?
What does make DC refractory to HIV-1 ? Vpx addition or Silencing of SAMHD1 increases the
susceptibility of monocytic-derived DCs to infection
Laguette et al. Nature 2011
MDDC
siRNAVLP-Vpx
THP-1
Barcelona, 13/03/12
SAMHD1SAMHD1 SAM domain and HD domain form a dimer that in humans is encoded by the SAMHD1 gene.
Chr 20sterile alpha motif
It belongs to a family of proteins that have been involved in a rare genetic disorder, the Aicardi-Goutières Syndrome, an inflammatory encephalopathy that resembles congenital viral infection, such as vertically acquired HIV.
Laguette & Benkirane, 2012. Trends in Immunology
Barcelona, 13/03/12
SAMHD1 cuts the power for HIV-1SAMHD1 cuts the power for HIV-1
SAMHD1 is a potent dGTP-stimulated triphosphohydrolase that restricts the availability of dNTPs, the building blocks of genetic material, in macrophages and dendritic cells.
dNTP → dN + Pi The molecule cuts off the supply line of dNTP available for cDNA synthesis by RT and so prevents viral replication
SAMHD1 is the only HIV-1 restriction factor against which the virus has not evolved a neutralizing strategy. Its discovery opens new possibilities to understand the intricacies of the relation between lentiviral evolution and primate hosts.
Lahouassa et 1l 2012 Nat ImmunolJermi 2012 Nat Rev Microbiol
Laguette et al. 2012 Hist Cell Microb
Barcelona, 13/03/12
SAMHD1 is a restriction factor that blocks HIV-1 replication in myeloid cells.
SAMHD1 is antagonized by vpx, a molecule present in HIV-2 and SIV but not in HIV-1.
Modulating SAMHD1 function could render human hosts more prone to develop appropriate innate and adaptive immune responses.
Therapies that mimic the effect of SAMHD1 or otherwise deplete the intracellular supply of dNTPs could represent a new approach to HIV treatment and cure.
Potential role in the development of dendritic-cell-targeted vaccines against HIV/AIDS.
ImplicationsImplications
Barcelona, 13/03/12
If HIV-1 does not have vpx but HIV-2 does, why HIV-1 is more pathogenic than HIV-2?
ParadoxParadox
vpx
HIV Reservoirs and Cure Research
HIV Reservoirs and Cure Research
Pathways toward a Cure: Viral Latency and Reservoirs
Barcelona, 13/03/12
HIV Cure HIV Cure
Barcelona, 13/03/12
HAART is effectiveHAART is effective
Suppression to below detectable HIV-1 RNA levels is rapid and durable.
Barcelona, 13/03/12
However, despite prolonged HAART …
However, despite prolonged HAART …
Replication competent viruses can be rescued ex vivo from resting CD4+ T cells
Low level plasma viremia (< 50 copies) persists Immune activation diminishes but does not normalize Plasma viremia rebounds after treatment interruption
Barcelona, 13/03/12
What sustains HIV-1 despite HAART?
What sustains HIV-1 despite HAART?
Ongoing HIV-1 replication cycles in cells located in sanctuary sites where drug levels are suboptimal
Latently infected cells (resting central memory T cells): Might produce virus upon reactivation.
Might proliferate
Lewin #106
Barcelona, 13/03/12
New markersNew markers
Plasma: HIV RNA Ultrasensitive HIV RNA
Cell-associated: Total HIV DNA Integrated cell HIV DNA Episomal HIV DNA HIV RNA
Cell-activation markers
Inflammation
Lewin #106
Barcelona, 13/03/12
Viral replication in pharmacologic sanctuaries
Viral replication in pharmacologic sanctuaries
Quantitation of intracellular ARV concentrations, including NRTI-triphosphates in PMBC, LN and GALT.
Pharmacokinetic data suggest drug-specific compartmentalization
Fletcher #108
104
103
102
101
1
ATV
(ng/
mL)
PBMC LN Ileal Rectal
EFV
(ng/
mL)
105
103
102
101
1
104
PBMC LN Ileal Rectal
Barcelona, 13/03/12
Viral replication in pharmacologic sanctuaries
Viral replication in pharmacologic sanctuaries
Hypothesis: inadequate drug penetration may contribute to cryptic replication of HIV, which sustains HIV infection.
Mechanisms: Physiochemical characteristics Susceptibility for and distribution of influx and efflux
transporters (Minuesa #590; P-gp in primary CD4+ T cells and raltegravir intracellular concentrations)
Drug metabolizing enzymes Expression of phosphorylating enzymes Activation state of the compartment Host genetic traits.
Fletcher #108
Barcelona, 13/03/12
Reservoirs,does time of treatment initiation
matter?
Reservoirs,does time of treatment initiation
matter? Treatment of early HIV infection reduces viral reservoir to levels found in elite controllers
Buzon et al. #151
Tota
l HIV
-1 D
NA
Chronic
Acute
Elite C Acute Chronic
Barcelona, 13/03/12
New chemotherapy against latencyNew chemotherapy against latency Transcriptional activators: reactivation of the latent HIV-1
without inducing T cell activation
Barcelona, 13/03/12
Chromatin Reconfiguration for Purging HIV-1 from the Latent Reservoir
Chromatin Reconfiguration for Purging HIV-1 from the Latent Reservoir
Johnstone, Nat Rev Drug Discov, 2002
Barcelona, 13/03/12
Vorinostat Disrupts HIV-1 Latency in Patients on ART
Vorinostat Disrupts HIV-1 Latency in Patients on ART
n=5; CD4 count 562 cells/µL; 4 years of ART; 400 mg single dose of voronistat; no AE
👍 PBMC cellular histone acetylation
👍HIV RNA levels increased significantly (5-fold) in pools of resting CD4+ cells obtained after SAHA dosing compared to BL
Proof-of-concept for HDAC inhibitors as a therapeutic class to directly attack and potentially eradicate latent HIV infection
No demonstration of viral production
Similar study suggested in NHP without data (Lifson #107)
Archin #157LB
Barcelona, 13/03/12
Autologous ZFN CCR5-disrupted CD4+ T cells
Autologous ZFN CCR5-disrupted CD4+ T cells
June #155
Barcelona, 13/03/12
Autologous ZFN CCR5-disrupted CD4+ T cells
Autologous ZFN CCR5-disrupted CD4+ T cells
SB-728-T infusion increases CD4 counts that persist over time.
SB-728-T expands rapidly and home to the gut.
3/6 subjects with >11 months follow up had an ~1-log decrease in total HIV-1 DNA over time: SB-728-T may decrease proviral DNA.
In one subject with the highest level of CCR5 modification, pVL was controlled (< limit of detection) without HAART.
These data suggest that in addition to the previously documented increases in CD4 cell, SB-728-T may also suppress HIV replication
June #155
Barcelona, 13/03/12
SummarySummary
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