HIV cure research: Why are single cells harbouring HIV latent?

SY07

Symposium

Track A - Basic science

CME accreditation

M4/Channel 6

24 July 14:45 - 15:45

Moderators

Miles DAVENPORT
The Kirby Institute, UNSW, Australia
Deanna KULPA
Emory University, United States

Despite the success of antiretroviral therapy (ART) in suppressing viral replication and preventing disease progression, HIV-1 persists in a long-lived reservoir of latently infected cells. The previous conception of the reservoir as a static viral archive has given way to a more dynamic view: the reservoir is maintained and sometimes dominated by expansion of infected-cell clones, including those harbouring intact proviruses. This symposium will highlight advances in our understanding of HIV persistence that have been possible through the development of single-cell methods allowing the analysis of proviruses, integration sites and gene expression of infected cells that can persist despite ongoing immunologic pressure.

14:45 5 min	Introduction Deanna KULPA Emory University, United States Miles DAVENPORT The Kirby Institute, UNSW, Australia

14:50 10 min	Beyond peripheral blood: New insights on CNS reservoirs Melissa CHURCHILL RMIT University, Australia

15:00 10 min	The immunology of HIV persistence: Immune dysregulation, escape and resistance to CTL or NK cell killing Michael BETTS University of Pennsylvania, United States

15:10 10 min	Beyond peripheral blood: Impact of host tissue environment on HIV persistence Jacob ESTES Oregon Health & Science University, United States

15:20 25 min	Live Q&A Miles DAVENPORT The Kirby Institute, UNSW, Australia Deanna KULPA Emory University, United States Jacob ESTES Oregon Health & Science University, United States Michael BETTS University of Pennsylvania, United States Melissa CHURCHILL RMIT University, Australia

AUTHOR

Ernest Tee

SUMMARY

This session reviewed the single-cell methodologies to characterize the HIV-infected cellular reservoir. The topics covered were the description of central nervous system (CNS) HIV reservoirs using droplet digital PCR technology, interrogation of the HIV reservoir using the ASAP-seq single-cell method, and elucidating the host tissue environment’s role on HIV persistence.

HIGHLIGHTS

Melissa Churchill used droplet digital PCR technology to demonstrate that the brain is a HIV reservoir site, containing intact proviruses. Churchill illustrated that CNS myeloid cells harbor the HIV reservoir and also showed that in non-virally suppressed patients, HIV provirus promoter activity in CNS is lower than non-CNS sites, whereas there is no compartmentalization of HIV provirus promoter activity in virally-suppressed patients. Michael Betts applied the single-cell transposase accessible chromatin (scATAC) and select antigen profiling (scSAP) assays to detect and characterize the HIV reservoir respectively. There were no unique cell surface markers identified on infected CD4 T-cell subsets. Furthermore, beyond CCR5, there was minimal commonality of cell surface markers between different HIV-infected CD4 T cell subsets. Betts also emphasized that HIV-infected cells are poised for reactivation due to heightened gene accessibility of AP-1 family transcription factors. Jacob Estes examined the role of spatial phenotyping, regional spatial transcriptomics and single-cell targeted spatial transcriptomic techniques in elucidating the transcriptomic and proteomic landscapes within the vicinity of HIV-infected cells in tissue. This includes the emerging role of IL-10 signaling in driving HIV reservoir persistence. Furthermore, there is a gradient in chemokine expression influenced by distance from HIV-infected cells.

CRITICAL ASSESSMENT

These talks provide further clues in the biology of the HIV reservoir, paving the way for the development of reservoir-specific interventions in the quest for HIV cure. Further research should be done to probe the HIV reservoir in brain tissue, in terms of elucidating their transcriptional and translational activity and controls, as well as the potential for CNS HIV proviral DNA to be reactivated. The transcriptional and translational milieu surrounding HIV-infected reservoir cells contribute to the persistence of the reservoir. Specifically, the role of IL-10 in relation to the perpetuation of the HIV reservoir needs to be further explored.