Identification of Ongoing Human Immunodeficiency Virus Type 1 (HIV-1) Replication in Residual Viremia during Recombinant HIV-1 Poxvirus Immunizations in Patients with Clinically Undetectable Viral Loads on Durable Suppressive Highly Active Antiretroviral Therapy

Abstract

In most human immunodeficiency virus type 1 (HIV-1)-infected individuals who achieve viral loads of <50 copies/ml during highly active antiretroviral therapy (HAART), low levels of plasma virus remain detectable for years by ultrasensitive methods. The relative contributions of ongoing virus replication and virus production from HIV-1 reservoirs to persistent low-level viremia during HAART remain controversial. HIV-1 vaccination of HAART-treated individuals provides a model for examining low-level viremia, as immunizations may facilitate virus replication and sequence evolution. In a phase 1 trial of modified vaccinia virus Ankara/fowlpox virus-based HIV-1 vaccines in 20 HIV-infected young adults receiving HAART, we assessed the prevalence of low-level viremia and sequence evolution, using ultrasensitive viral load (<6.5 copies/ml) and genotyping (five-copy sensitivity) assays. Viral evolution, consisting of new drug resistance mutations and novel amino acid changes within a relevant HLA-restricted allele (e.g., methionine, isoleucine, glutamine, or arginine for leucine at position 205 of RT), was found in 1 and 3 of 20 subjects, respectively. Sequence evolution was significantly correlated with levels of viremia of between 6.5 and <50 copies/ml (P ‫؍‬ 0.03) and was more likely to occur within epitopes presented by relevant HLA alleles (P < 0.001). These findings suggest that ongoing virus replication contributes to low-level viremia in patients on HAART and that this ongoing replication is subject to CD8؉ T-cell selective pressures.Highly active antiretroviral therapy (HAART) inhibits human immunodeficiency virus type 1 (HIV-1) replication, decreasing plasma viremia below the detection limit (Ͻ50 copies/ ml) of clinically used viral load assays (32). Most patients receiving standard HAART, however, have low levels of viremia (median, 3.1 copies/ml) detectable by more sensitive assays (11,17,22,28,31,34), the source of which remains unclear and controversial. Low-level viremia may arise from viral expression from cellular reservoirs established before HAART (2, 21-23, 25, 29, 31, 34, 46) or from low levels of complete cycles of virus replication (7, 46). Evidence supporting the former includes the stable persistence of low-level viremia during long-term HAART (2,11,23,25,28,31,34), intermingling of HIV-1 sequences from free plasma virus with persistent replication-competent viral sequences in resting memory CD4 ϩ T cells or proviral DNA in peripheral blood mononuclear cells (PBMC) (2,23,34,46), and a lack of decay in low-level viremia with treatment intensification of standard three-drug HAART regimens (10, 24). The contribution of ongoing complete cycles of virus replication during long-term suppressive HAART is supported by findings of sequence evolution with new drugresistant variants in a subset of patients during seemingly effective HAART (7, 46), decreases in plasma viremia with treatment intensification (22), and transient increases in episomal cDNA following treatment intensification with an integrase ...

Standardization and performance evaluation of “modified” and “ultrasensitive” versions of the Abbott RealTime HIV-1 assay, adapted to quantify minimal residual viremia

“…4,5,7,9,11,12,[18][19][20][21][22][23][24] Numerous studies investigating the clinical significance of MVR and the origin of residual viruses circulating in blood are ongoing and all of them are based on ultrasensitive assays quantifying HIV-1 RNA levels below 50 cp/mL. Thanks to these pioneering studies, several interesting findings have been reported.…”

Monitoring of HIV Type 1 DNA Load and Drug Resistance in Peripheral Blood Mononuclear Cells During Suppressive Antiretroviral Therapy Does Not Predict Virologic Failure

“…[12][13][14][15][16][17] Given that low intracellular ARV concentrations allow viral replication and the selection of drug-resistant HIV-1, we hypothesized that the detection of new drug resistance mutations during suppressive ART would predict subsequent virologic failure.…”

Genetic Diversity of Simian Immunodeficiency Virus Encoding HIV-1 Reverse Transcriptase Persists in Macaques despite Antiretroviral Therapy

“…Recent studies have attempted to determine whether the source of persistent viremia during successful combination ART also results from incomplete suppression of virus replication or if residual plasma virus is produced by long-lived, chronically infected cells. Some studies indicate that low-level viral replication may occur in specific anatomical compartments despite suppression of plasma HIV-1 RNA to less than 75 copies per ml by ART (5,7,9,15,28,29,36,39), whereas others have found no evidence for ongoing HIV-1 replication during suppressive therapy (4,7,11,23,27,34,38,40). For example, studies by Dinoso et al, McMahon et al, and Gandhi et al showed no decrease in the level of persistent viremia in patients before, during, or after treatment intensi-fication with several different classes of antiretroviral compounds by using an assay with single RNA copy sensitivity, suggesting a lack of ongoing new rounds of infection during effective ART (11,14,31).…”