Comparison of an in-house 'home-brew' and commercial ViroSeq integrase genotyping assays on HIV-1 subtype C samples

Higher Genotyping Performance of the Applied Biosystems TaqPath Seq HIV-1 Genotyping Kit Against ViroSeq HIV-1 Genotyping Kit in HIV Protease, Reverse Transcriptase, and Integrase Regions

Purpose

We assessed the performance of Applied Biosystems TaqPath Seq HIV-1 Genotyping Kit (CE-IVD) (TaqPath Kit) against the ViroSeq HIV-1 Genotyping Assays in genotyping HIV protease (PR), reverse transcriptase (RT), and integrase (INI) regions.

Methods

The study included 43 HIV-1 plasma specimens: 20 from people living with HIV-1C and 23 well-characterized HIV-positive Virology Quality Assurance (VQA) samples with PR-, RT-, and INI mutations. VQA samples included HIV-1 subtypes A, B, C, D, F, G, CRFO2_AG and URF. HIV-1 RNA extracted from all specimens was tested with both genotyping assays. Known HIV drug resistance mutations (DRMs) were identified using the Stanford HIV drug resistance database. Sequencing success rates, nucleotide identity, and DRMs from the two commercial assays were compared.

Results

Of 43 samples, TaqPath Kit amplified 93.0% (40) for HIV PR/RT and 97.7% (42) for HIV INI regions, compared to ViroSeq Assays, which amplified 69.8% (30) and 72.1% (31) for PR/RT and INI, respectively. The TaqPath Kit successfully sequenced 90.0% (36/40) PR/RT and 97.6% (41/42) INI amplicons, while ViroSeq Assays sequenced 53.3% (16/30) PR/RT and 87.1% (27/31) INI amplicons. The mean nucleotide similarity was 98.8% (SD ± 1.30), 99.6% (SD ± 1.32) and 99.2% (SD ± 0.72) for paired RT, PR and INI sequences, respectively. The TaqPath Kit detected 97.2% (35/36) of DRMs identified by the ViroSeq Assays and an additional 83 mutations and polymorphisms in samples that failed genotyping with the ViroSeq Assays. Among these, 85.5% (71/83) were confirmed by the reference sequence, including 39 major DRMs.

Conclusion

The TaqPath Kit demonstrated higher genotyping performance compared to the ViroSeq assays. The TaqPath Kit was able to detect DRMs in the PR, RT and INI regions of various HIV-1 subtypes, offering a critical tool to identify and monitor HIV drug resistance to new and existing antiretroviral drugs targeting these regions.

High prevalence of reverse transcriptase inhibitors associated resistance mutations among people living with HIV on dolutegravir-based antiretroviral therapy in Francistown, Botswana

OBJECTIVES

We assessed HIV-1 drug resistance profiles among people living with HIV (PLWH) with detectable viral load (VL) and on dolutegravir-based antiretroviral therapy (ART) in Botswana.

METHODS

The study utilised available 100 residual HIV-1 VL samples from unique PLWH in Francistown who had viraemia at-least 6 months after initiating ART in Botswana's national ART program from November 2023 to January 2024. Viraemia was categorized as low-level viraemia (LLV) (VL: 200-999 copies/mL) or virologic failure (VF) (VL ≥1000 copies/mL). HIV-1 protease, reverse transcriptase and integrase genes were sequenced using an in-house next-generation sequencing Oxford nanopore technology. HIV-1 drug resistance mutations (DRMs) were identified using the HIVdb Program in the Stanford HIV drug resistance database and compared between VL groups.

RESULTS

Among 100 participants, 83.0% were on dolutegravir-based, 10.0% were on non-dolutegravir-based ART and 7.0% had unknown/undocumented ART regimens. Thirty (30%) participants had LLV and 70 (70%) had VF. Among 58 successfully sequenced, 32.8% [95% Confidence Interval (CI): 21.8-46.0] had DRMs to any drug class, 33.3% (4/12) in the LLV group and 32.6% (15/46) in the VF group. Among individuals on dolutegravir-based ART, the overall HIV DRMs were 34.8% (95% CI: 22.7-49.2). By VL groups, 40.0% (95% CI: 16.8-68.7) and 33.3% (95% CI: 20.2-50.0) had DRMs at LLV and VF, respectively.

CONCLUSIONS

A high but similar prevalence of any DRMs was observed among individuals with LLV and those with VF on dolutegravir-based therapy. Monitoring DRMs in individuals with detectable VL is crucial for preserving dolutegravir-based ART.

A validated in-house assay for HIV drug resistance mutation surveillance from dried blood spot specimens

Despite increasing scale-up of antiretroviral therapy (ART) coverage, challenges related to adherence and HIV drug resistance (HIVDR) remain. The high cost of HIVDR surveillance is a persistent challenge with implementation in resource-constrained settings. Dried blood spot (DBS) specimens have been demonstrated to be a feasible alternative to plasma or serum for HIVDR genotyping and are more suitable for lower resource settings. There is a need for affordable HIVDR genotyping assays which can amplify HIV-1 sequences from DBS specimens, particularly those with low viral loads, at a low cost. Here, we present an in-house assay capable of reliably amplifying HIV-1 protease and partial reverse transcriptase genes from DBS specimens, which covers the complete World Health Organization 2009 list of drug resistance mutations under surveillance. DBS specimens were prepared using whole blood spiked with HIV-1 at concentrations of 10,000, 5000, 1000, and 500 copies/mL (n=30 for each concentration). Specimens were tested in triplicate. A two-step approach was used consisting of cDNA synthesis followed by nested PCR. The limit of detection of the assay was calculated to be approximately 5000 (95% CI: 3200-10,700) copies/mL for the protease gene and 3600 (95% CI: 2200-10,000) copies/mL for reverse transcriptase. The assay was observed to be most sensitive with higher viral load specimens (97.8% [95% CI: 92.2-99.7]) for both protease and reverse transcriptase at 10,000 copies/mL with performance decreasing with the use of specimens with lower viral loads (46.7% [36.1-57.5] and 60.0% [49.1-70.2] at 500 copies/mL for protease and reverse transcriptase, respectively). Ultimately, this assay presents a promising opportunity for use in resource-constrained settings. Future work should involve validation under field conditions including sub-optimal storage conditions and preparation of DBS with fingerprick blood in order to accurately reflect real-world collection scenarios.

High prevalence of pre-treatment and acquired HIV-1 drug resistance mutations among non-citizens living with HIV in Botswana

Background

Approximately 30,000 non-citizens are living with HIV in Botswana, all of whom as of 2020 are eligible to receive free antiretroviral treatment (ART) within the country. We assessed the prevalence of HIV-1 mutational profiles [pre-treatment drug resistance (PDR) and acquired drug resistance (ADR)] among treatment-experienced (TE) and treatment-naïve (TN) non-citizens living with HIV in Botswana.

Methods

A total of 152 non-citizens living with HIV were enrolled from a migrant HIV clinic at Independence Surgery, a private practice in Botswana from 2019-2021. Viral RNA isolated from plasma samples were genotyped for HIV drug resistance (HIVDR) using Sanger sequencing. Major known HIV drug resistance mutations (DRMs) in the pol region were determined using the Stanford HIV Drug Resistance Database. The proportions of HIV DRMs amongst TE and TN non-citizens were estimated with 95% confidence intervals (95% CI) and compared between the two groups.

Results

A total of 60/152 (39.5%) participants had a detectable viral load (VL) >40 copies/mL and these were included in the subsequent analyses. The median age at enrollment was 43 years (Q1, Q3: 38-48). Among individuals with VL > 40 copies/mL, 60% (36/60) were treatment-experienced with 53% (19/36) of them on Atripla. Genotyping had a 62% (37/60) success rate - 24 were TE, and 13 were TN. A total of 29 participants (78.4, 95% CI: 0.12-0.35) had major HIV DRMs, including at least one non-nucleoside reverse transcriptase inhibitor (NNRTI) associated DRM. In TE individuals, ADR to any antiretroviral drug was 83.3% (20/24), while for PDR was 69.2% (9/13). The most frequent DRMs were nucleoside reverse transcriptase inhibitors (NRTIs) M184V (62.1%, 18/29), NNRTIs V106M (41.4%, 12/29), and K103N (34.4%, 10/29). No integrase strand transfer inhibitor-associated DRMs were reported.

Conclusion

We report high rates of PDR and ADR in ART-experienced and ART-naïve non-citizens, respectively, in Botswana. Given the uncertainty of time of HIV acquisition and treatment adherence levels in this population, routine HIV-1C VL monitoring coupled with HIVDR genotyping is crucial for long-term ART success.

Affordable drug resistance genotyping of HIV-1 reverse transcriptase, protease and integrase genes, for resource limited settings

BACKGROUND

As use of dolutegravir (DTG) becomes more common in resource limited settings (RLS), the demand for integrase resistance testing is increasing. Affordable methods for genotyping all relevant HIV-1 pol genes (i.e., protease (PR), reverse transcriptase (RT) and integrase (IN)) are required to guide choice of future antiretroviral therapy (ART). We designed an in-house HIV-1 drug resistance (HIVDR) genotyping method that is affordable and suitable for use in RLS.

METHODS

We obtained remnant plasma samples from CAPRISA 103 study and amplified HIV-1 PR, RT and IN genes, using an innovative PCR assay. We validated the assay using remnant plasma samples from an external quality assessment (EQA) programme. We genotyped samples by Sanger sequencing and assessed HIVDR mutations using the Stanford HIV drug resistance database. We compared drug resistance mutations with previous genotypes and calculated method cost-estimates.

RESULTS

From 96 samples processed, we obtained sequence data for 78 (81%), of which 75 (96%) had a least one HIVDR mutation, with no major-IN mutations observed. Only one sample had an E157Q INSTI-accessory mutation. When compared to previous genotypes, 18/78 (23%) had at least one discordant mutation, but only 2/78 (3%) resulted in different phenotypic predictions that could affect choice of subsequent regimen. All CAPRISA 103 study sequences were HIV-1C as confirmed by phylogenetic analysis. Of the 7 EQA samples, 4 were HIV-1C, 2 were HIV-1D, and 1 was HIV-1A. Genotypic resistance data generated using the IDR method were 100% concordant with EQA panel results. Overall genotyping cost per sample was estimated at ~ US$43-$US49, with a processing time of ~ 2 working days.

CONCLUSIONS

We successfully designed an in-house HIVDR method that is suitable for genotyping HIV-1 PR, RT and IN genes, at an affordable cost and shorter turnaround time. This HIVDR genotyping method accommodates changes in ART regimens and will help to guide HIV-1 treatment decisions in RLS.

A Partially Multiplexed HIV Drug Resistance (HIVDR) Assay for Monitoring HIVDR Mutations of the Protease, Reverse-Transcriptase (PRRT), and Integrase (INT)

As dolutegravir (DTG)-containing HIV regimens are scaled up globally, monitoring for HIV drug resistance (HIVDR) will become increasingly important. We designed a partially multiplexed HIVDR assay using Sanger sequencing technology to monitor HIVDR mutations in the protease, reverse-transcriptase (PRRT), and integrase (INT). A total of 213 clinical and analytical plasma and dried blood spot (DBS) samples were used in the evaluation. The assay detected a wide range of known HIV-1 subtypes and circulating recombinant forms (CRFs) of group M from 139 samples. INT accuracy showed that the average nucleotide (nt) sequence concordance was 99.8% for 75 plasma samples and 99.5% for 11 DBS samples compared with the reference sequences. The PRRT accuracy also demonstrated the average nucleotide sequence concordance was 99.5% for 57 plasma samples and 99.2% for 33 DBS samples. The major PRRT and INT DR mutations of all samples tested were concordant with those of the reference sequences using the Stanford HIV database (db). Amplification sensitivity of samples with viral load (VL) >5000 copies/mL showed plasma exceeded 95% of positivity, and DBS exceeded 90% for PRRT and INT. Samples with VL (1000 to 5000 copies/mL) showed plasma exceeded 90%, and DBS reached 88% positivity for PRRT and INT. Assay precision and reproducibility showed >99% nucleotide sequence concordance in each set of replicates for PRRT and INT. In conclusion, this HIVDR assay met WHO HIVDR assay performance criteria for surveillance, worked for plasma and DBS, used minimal sample volume, was sensitive, and was a potentially cost-effective tool to monitor HIVDR mutations in PRRT and INT. IMPORTANCE This HIVDR genotyping assay works for both plasma and DBS samples, requires low sample input, and is sensitive. This assay has the potential to be a user-friendly and cost-effective HIVDR assay because of its partially multiplexed design. Application of this genotyping assay will help HIVDR monitoring in HIV high-burdened countries using a DGT-based HIV drug regimen recommended by the U.S. President's Emergency Plan for AIDS Relief and the WHO.

HIV-1 Genetic Diversity and Natural Polymorphisms of the Integrase Gene in Integrase Inhibitor-Naive Patients in Harare, Zimbabwe

Previously used as part of salvage therapy, integrase strand transfer inhibitors (INSTIs) have become part of the preferred antiretroviral therapy (ART) first-line regimen in most low- to middle-income countries. With the extensive use of dolutegravir in first-line ART, drug resistance mutations to INSTIs are inevitable. Therefore, active monitoring and surveillance of INSTI drug resistance is required. The aim of this study was to evaluate the genetic diversity of the integrase gene and determine pretreatment INSTI resistance in Harare, Zimbabwe. Forty-four HIV-1 Integrase sequences from 65 were obtained from treatment-naive individuals using a custom genotyping method. Drug resistance mutations were determined using the Stanford HIV Drug Resistance Interpretation program. Viral subtyping was done by phylogenetic analysis and the REGA HIV subtyping tool determined recombinants. Natural polymorphisms were evaluated relative to the global subtype B and C consensus sequences. One hundred ninety-two sequences from the region were accessed from GenBank to assess differences between the Zimbabwean sequences and those from neighboring countries. No major INSTI resistance mutations were detected; however, the L74I polymorphism was detected in three sequences of the 44 (6.8%). There was little genetic variability in the Integrase gene, with a mean genetic distance range of 0.053015. The subtype C consensus was identical to the global subtype C consensus and varied from the global subtype B consensus at five major positions: T124A, V201I, T218I, D278A, and S283G. This study has provided baseline sequence data on the presence of HIV-1 subtype C Integrase gene drug resistance mutations from Harare, Zimbabwe.

High performance of integrase genotyping on diverse HIV-1 clades circulating in Cameroon: toward a successful transition to dolutegravir-based regimens in low and middle-income countries

A successful transition to dolutegravir-based regimens in low and middle-income countries (LMICs) requires an integrase genotyping assay effective on diverse HIV-1 clades. We herein developed and validated an in-house integrase genotyping protocol on plasma samples from 195 HIV-infected patients in Cameroon. Median [IQR] viremia was 23,574 (518-109,235) copies/mL; 128/195 participants had ≥1000copies/mL (i.e., WHO-threshold for genotypic resistance testing in LMICs). A total of 18 viral clades were detected: 72(51.1%) CRF02_AG, 38(26.9%) pure subtypes and 31(22.0%) other recombinants. Following WHO-threshold (≥1000copies/ml), sequencing performance was 82.81%(106/128). Regarding viremia, performance was 85.00%(68/80) with ≥100,000copies/mL versus 76.67%(23/30) with 10,000 to 99,999copies/mL (P = 0.22); 83.33%(15/18) with 1,000 to 99,999copies/mL (P = 0.55); 73.68%(14/19) with 500 to 999copies/mL (P = 0.19); 50%(13/26) for 200 to 499copies/mL (P = 0.0005) and 36.36%(8/22) for <200copies/mL (P < 0.0001). The developed in-house integrase-genotyping is highly effective on both pure and recombinant viral clades, even at low-level viremia. This performance underscores its usefulness in monitoring integrase-resistance mutations and supporting the scale-up of dolutegravir-based regimens in LMICs.

Limited HIV-1 Subtype C nef 3'PPT Variation in Combination Antiretroviral Therapy Naïve and Experienced People Living with HIV in Botswana

Dolutegravir (DTG) is a potent anti-HIV drug that is used to treat HIV globally. There have been reports of mutations in the HIV-1 3'-polypurine tract (3'PPT) of the nef gene, contributing to DTG failure; however, there are limited 'real-world' data on this. In addition, there is a knowledge gap on the variability of 3'PPT residues in patients receiving combination antiretroviral therapy (cART) with and without viral load (VL) suppression. HIV-1 subtype C (HIV-1C) whole-genome sequences from cART naïve and experienced individuals were generated using next-generation sequencing. The nef gene sequences were trimmed from the generated whole-genome sequences using standard bioinformatics tools. In addition, we generated separate integrase and nef gene sequences by Sanger sequencing of plasma samples from individuals with virologic failure (VF) while on a DTG/raltegravir (RAL)-based cART. Analysis of 3'PPT residues was performed, and comparison of proportions computed using Pearson's chi-square test with p-values < 0.05 was considered statistically significant. A total of 6009 HIV-1C full genome sequences were generated and had a median log10 HIV-1 VL (Q1, Q3) copies/mL of 1.60 (1.60, 2.60). A total of 12 matching integrase and nef gene sequences from therapy-experienced participants failing DTG/ RAL-based cART were generated. HIV-1C 3'PPT nef gene sequences from therapy-experienced patients failing DTG cART (n = 12), cART naïve individuals (n = 1263), and individuals on cART with and without virological suppression (n = 4696) all had a highly conserved 3'PPT motif with no statistically significant differences identified. Our study confirms the high conservation of the HIV-1 nef gene 3'PPT motif in 'real-world' patients and showed no differences in the motif according to VL suppression or INSTI-based cART failure. Future studies should explore other HIV-1 regions outside of the pol gene for associations with DTG failure.

HIV-1 Drug Resistance Genotyping in Resource Limited Settings: Current and Future Perspectives in Sequencing Technologies

Affordable, sensitive, and scalable technologies are needed for monitoring antiretroviral treatment (ART) success with the goal of eradicating HIV-1 infection. This review discusses use of Sanger sequencing and next generation sequencing (NGS) methods for HIV-1 drug resistance (HIVDR) genotyping, focusing on their use in resource limited settings (RLS). Sanger sequencing remains the gold-standard method for detecting HIVDR mutations of clinical relevance but is mainly limited by high sequencing costs and low-throughput. NGS is becoming a more common sequencing method, with the ability to detect low-abundance drug-resistant variants and reduce per sample costs through sample pooling and massive parallel sequencing. However, use of NGS in RLS is mainly limited by infrastructure costs. Given these shortcomings, our review discusses sequencing technologies for HIVDR genotyping, focusing on common in-house and commercial assays, challenges with Sanger sequencing in keeping up with changes in HIV-1 treatment programs, as well as challenges with NGS that limit its implementation in RLS and in clinical diagnostics. We further discuss knowledge gaps and offer recommendations on how to overcome existing barriers for implementing HIVDR genotyping in RLS, to make informed clinical decisions that improve quality of life for people living with HIV.

Development of a new comprehensive HIV-1 genotypic drug resistance assay for all commercially available reverse transcriptase, protease and integrase inhibitors in patients infected with group M HIV-1 strains

Comprehensive PCR assays for the genotypic drug resistance analysis of all HIV-1 antiretroviral agents (reverse transcriptase, protease and integrase inhibitors) are increasingly in demand due to introduction of integrase inhibitors in the first line regimens and the increasing presence of non-B HIV-1 clades around the world. This study focused on the development and evaluation of a new PCR-based assay for the amplification and sequencing of the entire HIV-1 pol region of major circulating group M HIV-1 strains in Europe for genotypic drug resistance analysis. The comprehensive touchdown PCR assay developed in this study utilized HIV-1 RNA extracted from the plasma of blood samples of consenting HIV-1 infected patients in Cyprus, collected from 2017 to 2019. The HIV-1 pol region was amplified by touchdown PCR for both the primary RT-PCR and the secondary PCR steps. Successful PCR amplicons were determined by population DNA sequencing, using the Sanger method and the genotypic drug resistance analysis was performed with the Stanford University HIV Drug Resistance Database Program. The newly developed assay successfully amplified the entire HIV-1 pol region (2844 nucleotides long) of 141 out of 144 samples of group M HIV-1 subtypes and recombinant strains of the Cyprus HIV-1 Transmission Cohort Study (CHICS) isolated from 2017 to 2019 and genotypic analyses were conducted for all currently available HIV-1 reverse transcriptase, protease and integrase inhibitors. The drug resistance, epidemiological and demographic data of these study subjects will be expanded upon in the CHICS (L.G. Kostrikis et al., manuscript in preparation for publication). The newly developed HIV-1 genotypic drug resistance assay would benefit clinical settings, and research focusing on the world-wide spread of HIV-1 drug-resistant strains, especially in geographic regions characterized by polyphyletic HIV-1 infections.