2014 “Towards an HIV Cure” symposium Melbourne A novel assay that precisely measures the size of the latent HIV reservoir reveals that ART- nave individuals harbour a large pool of latently infected CD4+ T cells Nicolas Chomont, PhD
Jan 07, 2016
2014 “Towards an HIV Cure” symposiumMelbourne
A novel assay that precisely measures the size of the latent HIV reservoir reveals that ART-naive individuals harbour a large pool
of latently infected CD4+ T cells
Nicolas Chomont, PhD
Measuring the size of the reservoir
There is a need to develop sensitive, reproducible and clinical trial scalable methods to measure the size of the latent HIV reservoir
There is currently no gold standard method to measure the size of the latent HIV reservoir (frequency of latently infected cells)
•The quantitative viral outgrowth assay measures replication-competent HIV but may largely underestimate the size of the reservoir (Ho, Cell 2013)
•PCR based assays are reproducible, relatively easy to perform but may overestimate the size of the reservoir (Eriksson, Plos Pathogens 2013)
Defective viral genomes
Ho et al. Cell 2013
Principle of TILDA
TILDA: “Tat/Rev Induced Limiting Dilution Assay”
Nested RT-PCRfor msHIV RNA(24+40 cycles)
Maximum likelihood
methodFrequency of
cells with inducible msHIV
RNA
10-20 mL whole blood
PBMCs
Ficoll gradient centrifugation
CD4+
T cells
Negative selection
12h PMA+ionomycin
Distribute in limiting dilutions
Frequency of cells with msHIV
RNA baseline
TILDA in CD4 T cells from ART subjects
The majority of cells with inducible virus are latently infected in ART subjects
TILDA and other assays
TILDA gives a reservoir size in between Q-VOA and DNA
Adapted from Eriksson et al. 2013
TILDA and other assays
Total DNA in PBMCs Total DNA in resting CD4 Integrated DNA in resting CD4Integrated DNA in PBMCs
Total DNA in rectal CD4 Q-VOA SCA
TILDA correlates with several assays measuring HIV persistence
ART in Acute and Chronic infection
TILDA distinguishes between subjects who have started ART during acute and chronic infection
TILDA in viremic subjects (no ART)
The majority of cells with inducible virus are latently infected in ART naive subjects
TILDA in viremic subjects (no ART)
75% of the cells with inducible HIV are latently infected in untreated HIV infected subjects
ART VIR
Pre-integration latency?
Pre-integration latency
Post-integration latency
Entry Uncoating
Reverse transcription
Integration
Viral transcription
Viral production
Pre-integration latency?
Pre-integration latency
Post-integration latency
PMA+ionomycin
PMA+ionomycin
TILDA
+
+
RALTEGRAVIR(4h) PMA+ionomycin
+ RALTEGRAVIR
RALTEGRAVIR(4h) PMA+ionomycin
+ RALTEGRAVIR
+
-
TILDA with raltegravir
VIR1 VIR9 VIR11
Post-integration latency is already established in untreated HIV-infected subjects
Conclusions
TILDA is:• sensitive (1.4 cells/million)• reproducible (coefficient of variation <0.2)• fast (<2 days)• relatively inexpensive ($300)• easily transferable (basic culture set up + real time PCR) • Clinical trial transferable (requires only 10mL of blood)
The median frequency of “reservoir” cells measured by TILDA is 24 cells/million, which is 48 times more than Q-VOA and 6 to 27 times less than PCR-based assays
In untreated disease, the frequency of latently infected cells largely exceeds the frequency of productively infected cells suggesting that the majority of infected cells are transcriptionally silent even in the absence of ART
This provides a rationale for the use of shock and kill strategies at the time of ART initiation
Shock and kill at ART initiation
shock
HIV-specific CD8 T cells
Latent reservoir
HIV viral load
ART
ART
Acknowledgements
VGTI Florida
Francesco Procopio
Remi Fromentin
Deanna Kulpa
Amanda McNulty
Anne-Gaelle Blackwell
Lydie Trautmann
Rafick-Pierre Sekaly
Merck and Co
Daria Hazuda
Mike Miller
Richard Barnard
UCSF
Steven Deeks
Rick Hecht
Westmead Institute
Sarah Palmer
Karolinska Institutet
Susanne Eriksson
University of Pennsylvania
Una O’Doherty
Johns Hopkins
Robert Siliciano
Janet Siliciano
UCSD
Doug Richman
Matt Strain
The study participants!
U19AI096109 R21AI113096
ARCHE 108687-54