Assessment of the Cavidi ExaVir Load Assay for Monitoring Plasma Viral Load in HIV-2-Infected Patients

Antiretroviral Treatment of HIV-2 Infection: Available Drugs, Resistance Pathways, and Promising New Compounds

Currently, it is estimated that 1-2 million people worldwide are infected with HIV-2, accounting for 3-5% of the global burden of HIV. The course of HIV-2 infection is longer compared to HIV-1 infection, but without effective antiretroviral therapy (ART), a substantial proportion of infected patients will progress to AIDS and die. Antiretroviral drugs in clinical use were designed for HIV-1 and, unfortunately, some do not work as well, or do not work at all, for HIV-2. This is the case for non-nucleoside reverse transcriptase inhibitors (NNRTIs), the fusion inhibitor enfuvirtide (T-20), most protease inhibitors (PIs), the attachment inhibitor fostemsavir and most broadly neutralizing antibodies. Integrase inhibitors work well against HIV-2 and are included in first-line therapeutic regimens for HIV-2-infected patients. However, rapid emergence of drug resistance and cross-resistance within each drug class dramatically reduces second-line treatment options. New drugs are needed to treat infection with drug-resistant isolates. Here, we review the therapeutic armamentarium available to treat HIV-2-infected patients, as well as promising drugs in development. We also review HIV-2 drug resistance mutations and resistance pathways that develop in HIV-2-infected patients under treatment.

Can In-house HIV-2 Viral Load Assay be a Reliable Alternative to Commercial Assays for Clinical and Therapeutic Monitoring?

BACKGROUND

Currently, there is a global contemplation to end the AIDS epidemic by 2030. HIV-2 poses unique challenges to this end. The burden of HIV-2 is higher in resource-limited countries, and it is intrinsically resistant to NNRTI drugs. In addition, there is no FDA-approved plasma viral load assay to monitor disease progression and therapeutic efficacy. To overcome these challenges, we have developed and evaluated an in-house quantitative HIV-2 viral load assay.

METHODS

Blood samples were collected from 28 HIV-2 treatment-naïve monoinfected individuals and tested using an in-house qPCR HIV-2 viral load assay. The extracted RNA was amplified using Quantifast pathogen + IC kit.

RESULTS

The in-house qPCR has a limit of detection of 695 copies/ml. The intra- and inter-assay variation (% CV) of the assay was 0.61 and 0.95, respectively. The in-house assay quantified HIV-2 NIBSC accurately (1000 IU) with a mean of 1952 copies/mL. Among the 28 samples tested by in-house qPCR assay, 11 (39.2%) samples were quantified, whereas 17 (60.7%) samples were not detected. In comparison with Altona RealStar HIV-2 RT PCR and Exavir Load RT assay, the results were 96.4% and 69.6% concordant, respectively. No significant (p = 0.99 and p = 0.13) difference in quantifying viral load between the three assays. Based on clinical and immunological (CD4) staging, the performance characteristics were comparable.

CONCLUSION

To the best of our knowledge, this is the first in-house qPCR developed in India. The performance characteristics of the in-house assay are comparable to the commercial assays, and they can be used assertively to monitor HIV-2 patients.

Genotypic resistance profiles of HIV-2-infected patients from Cape Verde failing first-line antiretroviral therapy

: The pol gene from HIV-2-infected patients from Cape Verde experiencing virologic failure was sequenced and drug resistance mutations were determined. Most patients were taking a first-line regimen of zidovudine (AZT), lamivudine (3TC) and lopinavir/ritonavir (LPV/r). Resistance mutations were found in most patients (11/17; 64.7%) especially I82F (4/7; 57.1%) and M184V (10/17; 58.8%). Resistance to all reverse transcriptase and protease inhibitors was found in 58.8% (10/17) of the patients. Integrase inhibitors are warranted to treat these patients.

Interaction of human immunodeficiency virus-1 and human immunodeficiency virus-2 capsid amino acid variants with human tripartite motif 5α protein SPRY domain and its association with pathogenesis

Purpose

The sequence variation of human immunodeficiency virus (HIV) capsid region may influence and alter the susceptibility to human tripartite motif 5α protein (huTRIM5α).

Materials and Methods

Molecular docking was carried out with huTRIM5α SPRY domain by the use of ClusPro and Hex docking program for HIV-1 and HIV-2 capsid sequences.

Results

The sequence analysis on HIV-1 and HIV-2 capsid gag gene identified 35 (19.7%) single-nucleotide polymorphisms (SNPs) in HIV-1 and 8 (4.5%) SNPs in HIV-2. The variations observed in the HIV-2 capsid region were significantly lower than HIV-1 (P < 0.001). The molecular docking analysis showed that HIV-1 wild type used V1 loop, while HIV-2 used V3 loop of huTRIM5α for interaction. HIV-1 with A116T SNP and HIV-2 with V81A SNP use V3 and V1 loop of huTRIM5α for interaction respectively. The reduced huTRIM5α inhibition may lead to a faster progression of disease among HIV-1-infected individuals. However, in case of HIV-2, increased inhibition by huTRIM5α slows down the disease progression.

Conclusion

Polymorphisms in the capsid protein with both HIV-1- and HIV-2-monoinfected individuals showed the difference in the docking energy from the wild type. This is the first study which documents the difference in the usage of loop between the two HIV types for interaction with huTRIM5α. Variations in the capsid protein result in alteration in the binding to the restriction factor huTRIM5α.