Short communication: antiretroviral therapy resistance mutations present in the HIV type 1 subtype C pol and env regions from therapy-naive patients in Zambia

Current ARTs, Virologic Failure, and Implications for AIDS Management: A Systematic Review

Antiretroviral therapies (ARTs) have revolutionized the management of human immunodeficiency virus (HIV) infection, significantly improved patient outcomes, and reduced the mortality rate and incidence of acquired immunodeficiency syndrome (AIDS). However, despite the remarkable efficacy of ART, virologic failure remains a challenge in the long-term management of HIV-infected individuals. Virologic failure refers to the persistent detectable viral load in patients receiving ART, indicating an incomplete suppression of HIV replication. It can occur due to various factors, including poor medication adherence, drug resistance, suboptimal drug concentrations, drug interactions, and viral factors such as the emergence of drug-resistant strains. In recent years, extensive efforts have been made to understand and address virologic failure in order to optimize treatment outcomes. Strategies to prevent and manage virologic failure include improving treatment adherence through patient education, counselling, and supportive interventions. In addition, the regular monitoring of viral load and resistance testing enables the early detection of treatment failure and facilitates timely adjustments in ART regimens. Thus, the development of novel antiretroviral agents with improved potency, tolerability, and resistance profiles offers new options for patients experiencing virologic failure. However, new treatment options would also face virologic failure if not managed appropriately. A solution to virologic failure requires a comprehensive approach that combines individualized patient care, robust monitoring, and access to a range of antiretroviral drugs.

High Virologic Failure Rates with Maraviroc-Based Salvage Regimens Among Indian Patients: A Preliminary Analysis-Maraviroc Effectiveness in HIV-1 Subtype C

BACKGROUND

There is no information on the clinical effectiveness of Maraviroc (MVC) amongst People Living with HIV (PLHIV) in India infected with HIV-1 Subtype C viruses.

METHODS

We conducted a retrospective chart review of adult PLHIV on MVC based Antiretroviral (ARV) regimens for at least 6 months. Maraviroc was initiated amongst PLHIV with documented R5 tropic viruses (determined by in-house population sequencing of the V3 loop in triplicate and interpreted using the Geno2Pheno algorithm) in combination with an Optimized Background regimen (designed using genotypic resistance testing and past ARV history). Plasma viral loads (PVL) are performed 6 months post-initiation and annually thereafter. Primary outcome d. Median duration on MVC treatment was 1.8 years (range 1-2.9 years) while median duration of ART prior to switching to MVC was 13 years. Maraviroc was combined with Darunavir/ritonavir (DRV/r) (n=10), Atazanavir/r (ATV/r) (n=2) and Lopinavir/r (LPV/r) (n=1). All PLHIV were infected with HIV-1 Subtype C. Only 23.3% PLHIV achieved virologic suppression at 6 months and sustained it for 2.3 years. Median CD4 count change from baseline was +117 (n=13), +228 (n=10), +253 (n=9), and +331 (n=4) at 6, 12, 18 and 24 months respectively. Repeat tropism among patients with virologic failure demonstrated R5 virus.

CONCLUSIONS

High rates of virologic failure was seen when MVC was used amongst treatment experienced PLHIV infected with HIV-1 Subtype C in India. was the proportion of PLHIV with virologic success (PVL<50 copies/ml) at last follow up visit.

RESULTS

Data on 13 PLHIV were analyze.

Definition of an 18-mer Synthetic Peptide Derived from the GB virus C E1 Protein as a New HIV-1 Entry Inhibitor

BACKGROUND

A slower progression of AIDS and increased survival in GBV-C positive individuals, compared with GBV-C negative individuals has been demonstrated; while the loss of GBV-C viremia was closely associated with a rise in mortality and increased progression of AIDS. Following on from the previous reported studies that support the thesis that GBV-C E2 interferes with HIV-1 entry, in this work we try to determine the role of the GBV-C E1 protein in HIV-1 inhibition.

METHODS

The present work involves the construction of several overlapping peptide libraries scanning the GBV-C E1 protein and the evaluation of their anti-HIV activity.

RESULTS

Specifically, an 18-mer synthetic peptide from the GBV-C E1 protein, E1(139-156), showed similar antiviral activity against HIVs from viruses from clades A, B, C, D and AE. Competitive ELISA using specific gp41-targeting mAbs, fluorescence resonance energy transfer as well as haemolysis assays demonstrated that this E1 peptide sequence interacts with the highly conserved N-terminal region of the HIV-1 gp41 (the fusion peptide) which is essential for viral entry.

CONCLUSIONS

We have defined a novel peptide lead compound and described the inhibitory role of a highly conserved fragment of the E1 protein.

GENERAL SIGNIFICANCE

The results together allow us to consider the non-pathogenic E1 GBV-C protein as an attractive source of peptides for the development of novel anti-HIV therapies.

Maraviroc: a review of its use in HIV infection and beyond

The human immunodeficiency virus-1 (HIV-1) enters target cells by binding its envelope glycoprotein gp120 to the CD4 receptor and/or coreceptors such as C-C chemokine receptor type 5 (CCR5; R5) and C-X-C chemokine receptor type 4 (CXCR4; X4), and R5-tropic viruses predominate during the early stages of infection. CCR5 antagonists bind to CCR5 to prevent viral entry. Maraviroc (MVC) is the only CCR5 antagonist currently approved by the United States Food and Drug Administration, the European Commission, Health Canada, and several other countries for the treatment of patients infected with R5-tropic HIV-1. MVC has been shown to be effective at inhibiting HIV-1 entry into cells and is well tolerated. With expanding MVC use by HIV-1-infected humans, different clinical outcomes post-approval have been observed with MVC monotherapy or combination therapy with other antiretroviral drugs, with MVC use in humans infected with dual-R5- and X4-tropic HIV-1, infected with different HIV-1 genotype or infected with HIV-2. This review discuss the role of CCR5 in HIV-1 infection, the development of the CCR5 antagonist MVC, its pharmacokinetics, pharmacodynamics, drug–drug interactions, and the implications of these interactions on treatment outcomes, including viral mutations and drug resistance, and the mechanisms associated with the development of resistance to MVC. This review also discusses available studies investigating the use of MVC in the treatment of other diseases such as cancer, graft-versus-host disease, and inflammatory diseases.

Characterization of HIV drug resistance mutations among patients failing first-line antiretroviral therapy from a tertiary referral center in Lusaka, Zambia

In settings of resource constraint, an understanding of HIV drug resistance can guide antiretroviral therapy (ART) at switch to second-line therapy. To determine the prevalence of such HIV drug resistance mutations (HIV DRM), we used an in-house sequencing assay in the pol gene (protease and partial reverse transcriptase) in a cohort of patients suspected of failing a first-line regimen, which in Zambia comprises two nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) and one non-nucleoside reverse transcriptase inhibitor (NNRTI). Our analysis cohort (n = 68) was referred to the University Teaching Hospital in Lusaka from November 2009 to October 2012. Median duration on first-line ART to suspected treatment failure was 3.2 years (IQR 1.7-4.7 years). The majority of patients (95%) harbored HIV-1 subtype C virus. Analysis of reverse transcriptase revealed M184V (88%), K103N/S (32%), and Y181C/I/V (41%) DRMs, with the latter conferring reduced susceptibility to the salvage therapy candidates etravirine and rilpivirine. Three patients (5%) had major protease inhibitor (PI) resistance mutations: all three had the V82A mutation, and one patient (Clade J virus) had a concurrent M46I, Q58E, and L76V DRM. HIV-1 genotyping revealed major and minor DRMs as well as high levels of polymorphisms in subtype C isolates from patients failing first-line antiretroviral therapy. Closer monitoring of DRM mutations at first-line failure can inform clinicians about future options for salvage therapy.

Limited increase in primary HIV-1C drug resistance mutations in treatment naïve individuals in Ethiopia

Antiretroviral drug resistance is a major challenge for management and control of HIV-1 infection worldwide and particularly in resource limited countries. The frequency of primary drug resistance mutations (DRMs) and of naturally occurring polymorphisms was determined in 83 antiretroviral treatment (ART) naïve Ethiopian individuals infected with HIV-1, consecutively enrolled in 2010. In all individuals HIV-1C was found. The median (interquartile range) of CD4(+) T-cell count and viral load were 100 (49-201) cells/μl and 44,640 (12,553-134,664) copies/ml, respectively. Protease (PR) and reverse transcriptase (RT) genes of HIV-1 RNA were amplified and sequenced. The proportion of primary DRM to any drug class, using the World Health Organization mutation lists, was 7.2% (6/83), thus exceeding the WHO threshold limit of 5%. Three individuals (3.6%) had non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations, two individuals (2.4%) had protease inhibitor mutations, and one (1.2%) had mutations associated with two drug classes (nucleoside reverse transcriptase inhibitor and NNRTI). In addition, the frequency of polymorphisms in the PR and RT genes was higher compared with previous studies in Ethiopian as well as worldwide isolates. Hence, genotypic drug resistance testing as part of routine management of individuals seems reasonable even in resource limited countries prior to treatment in order to allow proper choice of ART.

HIV-1 coreceptor tropism in India: increasing proportion of X4-tropism in subtype C strains over two decades

BACKGROUND

Recent studies show an increase in the frequency of X4-tropism in African HIV-1 subtype C (HIV-1C) strains and among Indian children with a longer duration of infection. There is limited availability of comprehensive data on HIV-1 tropism in Indian HIV-1C strains and impact on coreceptor antagonist drug susceptibility. We evaluated coreceptor tropism trends over 2 decades and maraviroc resistance-associated V3 loop substitutions among the Indian HIV-1C strains.

METHODS

We performed genotypic tropism testing using Geno2Pheno10% on primary samples from patients (n = 224) and on Indian HIV-1C sequences downloaded from the Los Alamos database (n = 528, 1991-2010). We also studied maraviroc resistance-associated substitutions in R5-tropic HIV-1C (n = 992) and subtype B sequences (n = 576).

RESULTS

Among primary samples, 88% belonged to HIV-1C and 11.2% was predicted as X4-tropic, with higher prevalence noted among patients from north-eastern India (19.1%) and significant association with intravenous drug users (P = 0.04). X4-tropism prevalence was higher among antiretroviral therapy-experienced (18.8%) compared with antiretroviral therapy-naive patients (9.1%). Indian database HIV-1C sequences showed X4-tropism at 4%. An increase in the X4 tropism frequency was seen over the years 1991 (1.6%) through 2012 (10%). We found a high frequency of 19T substitution (826/992; 83.3%) among HIV-1C V3 loop compared with subtype B.

CONCLUSIONS

The predominance of R5-tropism in Indian HIV-1C strains despite a marginal temporal increase in X4-tropism prevalence highlights the likely effectiveness of coreceptor antagonists in India. Our frequent observation of common maraviroc resistance-associated substitutions among Indian R5-tropic HIV-1C raises the possibility that they may be natural polymorphisms, indicating the need for further elucidation.

Analysis of primary resistance mutations to HIV-1 entry inhibitors in therapy naive subtype C HIV-1 infected mother-infant pairs from Zambia

BACKGROUND

Small molecular CCR5 inhibitors represent a new class of drugs for treating HIV-1 infection. The evaluation of the primary resistance mutations associated with entry inhibitors during HIV-1 perinatal transmission is required because they may have a profound impact on the clinical management in MTCT.

OBJECTIVES

To evaluate the primary resistance mutations to maraviroc and vicriviroc during perinatal transmission and analyze the sensitivity of Env derived from mother-infant pairs to maraviroc.

STUDY DESIGN

Nine MIPs infected by subtype C HIV-1 were recruited to analyze the prevalence and transmission of primary resistance mutations to maraviroc and vicriviroc. Moreover, Env derived from six MIPs were employed to construct provirus clones and to analyze the sensitivity to maraviroc.

RESULTS

Mutations A316T, conferring partial resistance to maraviroc, T307I and R315Q, both conferring partial resistance to vicriviroc are prevalent in mother and infant cohorts, indicating the transmission of primary resistance mutations during HIV-1 perinatal transmission. However, the mutations of acutely infected mothers seem to directly transmit to their corresponding infants, while some mutations at low frequency of chronically infected mothers would be lost during transmission. Moreover, provirus clones derived from acutely infected MIPs are less susceptible to maraviroc than those from chronically infected MIPs.

CONCLUSIONS

Our study suggests that the transmission mode of primary resistance mutations and the sensitivity to maraviroc are dependent on infection status of MIPs either acutely or chronically infected. These results may indicate that higher dose of maraviroc could be needed for treatment of acutely infected MIPs compared to chronically infected MIPs.

HIV-1 diversity in the envelope glycoproteins: implications for viral entry inhibition

Entry of HIV-1 into a host cell is a multi-step process, with the viral envelope gp120 and gp41 acting sequentially to mediate the viral attachment, CD4 binding, coreceptor binding, and fusion of the viral and host membranes. The emerging class of antiretroviral agents, collectively known as entry inhibitors, interfere in some of these steps. However, viral diversity has implications for possible differential responses to entry inhibitors, since envelope is the most variable of all HIV genes. Different HIV genetic forms carry in their genomes genetic signatures and polymorphisms that could alter the structure of viral proteins which are targeted by drugs, thus impairing antiretroviral binding and efficacy. This review will examine current research that describes subtype differences in envelope at the genetic level and the effects of mutations on the efficacy of current entry inhibitors.

Low-abundance resistant mutations in HIV-1 subtype C antiretroviral therapy-naive individuals as revealed by pyrosequencing

Given the recent scale-up of antiretroviral therapy (ART) in sub-Saharan Africa, we sought to determine how often and at what levels do drug-resistant mutant variants exist in ART-naive HIV subtype C infected individuals. Samples from 10 ART-naive Zambian individuals were subjected to ultra-deep pyrosequencing (UDPS) to characterize the frequency of low-abundance drug resistance mutations in the pol gene. Low-abundance clinically relevant variants were detected for nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) in eight of the ten subjects. Intermediate to high-level resistance was predicted for the majority of NRTIs. Mutations conferring resistance to most first-line and some second-line therapy drugs were also observed. UDPS detected a number of additional major resistant mutations suggesting that these individuals may have an increased risk of virological failure after initiating ART. Moreover, the effectiveness of first-line and even some secondline ART may be compromised in this setting.

The increasing prevalence of HIV-1 subtype C in Southern Brazil and its dispersion through the continent

The HIV-1 has evolved swiftly and the scenario of HIV-1 genetic diversity is constantly changing. In South America, recombinant forms of subtypes B, F1, and BF1 have historically driven the HIV-1 epidemic. In recent years, however, infection with subtype C has gained prominence as its prevalence increased in Southern Brazil as well as neighboring countries. Current studies point to a single introduction of closely related strains as the beginning of the Brazilian subtype C epidemic. However, the place of origin of these strains, date, and route of introduction are under continuous debate as well as the clinical outcomes of the emergence of subtype C. Therefore, this paper reviews the history of the HIV-1 subtype C in Brazil, particularly in the Southern region, covering its demographic and evolutionary history and the possible implications to the Brazilian AIDS epidemic as well as to neighboring countries.

Naturally occurring resistance mutations to HIV-1 entry inhibitors in subtypes B, C, and CRF31_BC

BACKGROUND

Entry inhibitors are a class of antiretroviral (ARV) drugs that prevent HIV replication by blocking viral entry into the host cell. The investigation of naturally occurring mutations associated with entry inhibitors across subtypes is required because genetic differences between HIV-1 variants may influence the emergence of drug resistance. Despite the importance of subtype C, which predominates globally, the majority of studies include only subtype B strains.

OBJECTIVES

To investigate the presence of natural resistance mutations to entry inhibitors in HIV-1 subtypes B, C, and CRF31_BC strains.

STUDY DESIGN

Eighty samples were collected from antiretroviral-naïve patients. The gp41 gene from 67 patients and the gp120 gene from 65 patients were partially sequenced. Resistance mutations to entry inhibitors Enfuvirtide, Maraviroc, and Vicriviroc were screened.

RESULTS

ENF resistance-associated mutations of HR1 and HR2 on gp41 were not associated with any subtype. However, the major polymorphisms detected in HR1: N42S, L54M, and A67T were most prevalent in subtype C (p<0.001). Mutations A316T and R315Q in gp120, which are related to MVC and VCV reduced susceptibility respectively, were predominant in subtype C (p<0.05).

CONCLUSIONS

This study shows that many more resistance-associated mutations to entry inhibitors in ARV-naïve patients occur in subtype C compared with subtype B strains. However, further studies will be necessary to elucidate if the differential genetic background of HIV subtypes can affect the efficacy of treatment with entry inhibitors.