HIV-1 DNA decay dynamics in early treated individuals: practical considerations for clinical trial design

The build-up of stock of stable integrated proviruses overtime explains the difficulty in reducing HIV-1 DNA levels when treatment is initiated at the chronic stage of the infection

Background

Understanding factors affecting the size and the evolution of the HIV reservoir is essential for the development of curative strategies. This study aimed to assess the impact of antiretroviral therapy (ART) initiated during primary infection (PHI) vs chronic infection (CHI) on the levels and dynamics of integrated HIV-1 DNA, a biomarker of viral persistence.

Methods

Integrated and total HIV-1-DNA were measured in the blood of 92 patients treated during PHI (early group) and 41 during CHI (deferred group), at diagnosis, ART initiation, and 12-24 months on treatment.

Results

On ART, detectable (>1.78 log10 copies/106 PBMCs) integrated HIV-1 DNA levels were significantly lower in the early vs deferred group (2.99 log10vs 3.29 log10,p = 0.005). The proportion of undetectable integrated HIV-1 DNA tended to be higher in the early group vs deferred group (61 % vs 46 %; p = 0.133).

Conclusion

Treatment initiated at PHI limits the levels of integrated HIV-1 DNA in blood. However, initiating treatment at CHI does not allow reaching such low levels in most patients, probably because the stable proviruses at that stage are present in the less prone to elimination long-lived cells. Thus, early ART could provide an opportunity to preparing for functional cure and eradication strategies.

Genotypic Resistance Testing of HIV-1 DNA in Peripheral Blood Mononuclear Cells

HIV-1 DNA exists in nonintegrated linear and circular episomal forms and as integrated proviruses. In patients with plasma viremia, most peripheral blood mononuclear cell (PBMC) HIV-1 DNA consists of recently produced nonintegrated virus DNA while in patients with prolonged virological suppression (VS) on antiretroviral therapy (ART), most PBMC HIV-1 DNA consists of proviral DNA produced months to years earlier. Drug-resistance mutations (DRMs) in PBMCs are more likely to coexist with ancestral wild-type virus populations than they are in plasma, explaining why next-generation sequencing is particularly useful for the detection of PBMC-associated DRMs. In patients with ongoing high levels of active virus replication, the DRMs detected in PBMCs and in plasma are usually highly concordant. However, in patients with lower levels of virus replication, it may take several months for plasma virus DRMs to reach detectable levels in PBMCs. This time lag explains why, in patients with VS, PBMC genotypic resistance testing (GRT) is less sensitive than historical plasma virus GRT, if previous episodes of virological failure and emergent DRMs were either not prolonged or not associated with high levels of plasma viremia. Despite the increasing use of PBMC GRT in patients with VS, few studies have examined the predictive value of DRMs on the response to a simplified ART regimen. In this review, we summarize what is known about PBMC HIV-1 DNA dynamics, particularly in patients with suppressed plasma viremia, the methods used for PBMC HIV-1 GRT, and the scenarios in which PBMC GRT has been used clinically.

Clinical validation of a quantitative HIV-1 DNA droplet digital PCR assay: Applications for detecting occult HIV-1 infection and monitoring cell-associated HIV-1 dynamics across different subtypes in HIV-1 prevention and cure trials

BACKGROUND

In HIV-1-exposed infants, nucleic acid testing (NAT) is required to diagnose infection since passively transferred maternal antibodies preclude antibody testing. The sensitivity of clinical NAT assays is lowered with infant antiretroviral prophylaxis and, with empiric very early antiretroviral treatment of high-risk infants, thereby impacting early infant diagnosis. Similarly, adult HIV-1 infections acquired under pre-exposure prophylaxis may occur at low levels, with undetectable plasma viremia and indeterminate antibody tests, for which HIV-1 DNA testing maybe a useful adjunct. Cell-associated HIV-1 DNA concentrations are also used to monitor HIV-1 persistence in viral reservoirs with relevance to HIV-1 cure therapeutics, particularly in perinatal infections.

OBJECTIVES

We clinically validated an HIV-1 DNA quantitative assay using droplet digital PCR (ddPCR), across different HIV-1 subtypes.

STUDY DESIGN

The analytical sensitivity and specificity of an HIV-1 DNA ddPCR assay was determined using serial dilutions of a plasmid containing HIV-1 LTR-gag spiked into peripheral blood mononuclear cells (PBMCs), with MOLT-4 cells or PBMCs infected with different HIV-1 subtypes (A, B and C), and U1 cells spiked into PBMCs. Inter- and intra-run variability were used to determine assay precision.

RESULTS

The HIV-1 LTR-gag ddPCR assay was reliable and reproducible, and exhibited high analytical specificity with sensitivity to near single copy level, across multiple HIV-1 subtypes, and a limit of detection of 4.09 copies/million PBMCs.

CONCLUSIONS

This assay has applications for detecting occult HIV-1-infection in the setting of combination and long-acting regimens used for HIV-1 prevention, across different HIV-1 subtypes, in infants and adults, and in HIV-1 cure interventions.