Development and Optimization of Oligonucleotide Ligation Assay (OLA) Probes for Detection of HIV-1 Resistance to Dolutegravir.

The WHO currently recommends dolutegravir (DTG)-based ART for persons living with HIV infection in resource-limited-settings (RLS). To expand access to testing for HIV drug resistance (DR) to DTG in RLS, we developed probes for use in the oligonucleotide ligation assay (OLA)-Simple, a near-point of care HIV DR kit. Genotypic data from clinical trials and case reports were used to determine the mutations in HIV-1 integrase critical to identifying individuals with DTG-resistance at virologic failure of DTG-based ART. Probes to detect G118R, Q148H/K/R, N155H and R263K in HIV-1 subtypes A, B, C, D and CRF01_AE were designed using sequence alignments from the Los Alamos database and validated using 61 clinical samples of HIV-1 subtypes A, B, C, D, CRF01_AE genotyped by PacBio (n = 15) or Sanger (n = 46). Initial OLA probes failed to ligate for 16/244 (6.5%) codons (9 at G118R and 7 at Q148H/K/R). Probes revised to accommodate polymorphisms interfering with ligation at codons G118R and Q148R reduced indeterminates to 3.7% (5 at G118R and 4 at Q148H/K/R) and detected DTG-mutations with a sensitivity of 96.5% and 100% specificity. These OLA DTG resistance probes appear highly sensitive and specific across HIV-1 subtypes common in RLS with high burden of HIV infection.

Rapid Near Point-of-Care Assay for HLA-B*57:01 Genotype Associated with Severe Hypersensitivity Reaction to Abacavir.

The nucleoside reverse transcriptase inhibitor abacavir (ABC) is used commonly to treat young children with HIV infection and is a component of the fixed-dose-combination Triumeq®. ABC can trigger a severe hypersensitivity reaction in people who are homozygous or heterozygous for HLA-B*57:01. Testing for HLA-B*57:01 before ABC initiation is standard-of-care in high-resource settings, but current tests are costly or difficult to access in resource-limited settings. To address these gaps, we developed an inexpensive simple-to-use rapid assay to detect HLA-B*57:01. We designed and optimized a multiplexed polymerase chain reaction (PCR) to amplify HLA-B*57 subtypes and the human beta-globin gene; employed probes and ligation to specifically tag the HLA-B*57:01 allele with biotin. Tagged-ligated products were detected by immunocapture in an enzyme-linked immunosorbent assay plate or lateral flow strip. Cell lines with known HLA genotypes were used to optimize the assay. The optimized assay was then compared with genotypes of clinical specimens (n = 60) determined by sequencing, with specimens enriched for individuals with HLA-B*57:01. The optimized assay utilizes 40-min 35-cycle multiplex PCR for B*57 and beta-globin; 20-min ligation reaction; and 15-min detection. Evaluation of the HLA-B*57:01 oligonucleotide ligation assay using clinical specimens had a sensitivity of 100% (n = 27/27 typed as B*57:01) and specificity of 100% (n = 33/33 typed as non-B*57:01) by visual interpretation of lateral flow strips. The cost is US$5.96/specimen. This rapid and economical assay accurately detects HLA-B*57:01 in clinical specimens. Use of this assay could expand access to HLA-B*57:01 genotyping and facilitate safe same-day initiation of ABC-based treatment.

Genotypic Methods for HIV Drug Resistance Monitoring: The Opportunities and Challenges Faced by China.

AIDS is a globalized infectious disease. In 2014, UNAIDS launched a global project of "90-90-90" to end the HIV epidemic by 2030. The second and third 90 require 90% of HIV-1 infected individuals receiving antiretroviral therapy (ART) and durable virological suppression. However, wide use of ART will greatly increase the emergence and spreading of HIV drug resistance and current HIV drug resistance test (DRT) assays in China are seriously lagging behind, hindering to achieve virological suppression. Therefore, recommending an appropriate HIV DRT method is critical for HIV routine surveillance and prevention in China. In this review, we summarized the current existing HIV drug resistance genotypic testing methods around the world and discussed the advantages and disadvantages of these methods.

Pretreatment HIV Drug Resistance and Virologic Outcomes to First-Line Antiretroviral Therapy in Peru.

Access to nucleoside reverse transcriptase inhibitor (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) first-line antiretroviral therapy (ART) for HIV has been increasing in Peru since a national ART program was initiated in 2004. Between 2007 and 2009, we found a 1% prevalence of pre-ART HIV drug resistance (PDR) among antiretroviral (ARV)-naive Peruvians. Given that PDR has been associated with virologic failure (VF) of ART, in 2014-2015 we enrolled a follow-up cohort at the same institution to determine whether the rate of transmitted resistance had increased and compared virologic outcomes of those with and without PDR. Blood specimens from ARV-naive individuals were assessed for PDR to NNRTI-based ART by an oligonucleotide ligation assay (OLA) sensitive to 2% mutant within an individual's HIV quasispecies at reverse transcriptase codons M41L, K65R, K103N, Y181C, M184V, and G190A, and by Sanger consensus sequencing (CS). Rates of VF (plasma HIV RNA >200 copies/mL) were compared between those with and without PDR. Among 122 ARV-naive adults, PDR was detected by OLA in 17 (13.9%) adults. Compared with the 2007-2009 cohort, the proportion with PDR at OLA codons was significantly increased (p < .001). A total of 11 of 19 OLA mutations conferring high-level drug resistance were also detected by CS, and 8 additional participants had mutations encoding low-level resistance detected by CS for a total of 25 participants (20.5%). VF at month 6 of NNRTI-ART appeared greater in participants with versus without PDR [4/18 (22.2%) vs. 3/71 (4.2%); p = .03]. An increasing prevalence of PDR was detected among ARV-naive Peruvians. Studies are needed to determine risks of specific PDR mutations.

Paper-based detection of HIV-1 drug resistance using isothermal amplification and an oligonucleotide ligation assay.

Regular HIV-1 viral load monitoring is the standard of care to assess antiretroviral therapy effectiveness in resource-rich settings. Persistently elevated viral loads indicate virologic failure (VF), which warrants HIV drug resistance testing (HIVDRT) to allow individualized regimen switches. However, in settings lacking access to HIVDRT, clinical decisions are often made based on symptoms, leading to unnecessary therapy switches and increased costs of care. This work presents a proof-of-concept assay to detect M184V, the most common drug resistance mutation after first-line antiretroviral therapy failure, in a paper format. The first step isothermally amplifies a section of HIV-1 reverse transcriptase containing M184V using a recombinase polymerase amplification (RPA) assay. Then, an oligonucleotide ligation assay (OLA) is used to selectively label the mutant and wild type amplified sequences. Finally, a lateral flow enzyme-linked immunosorbent assay (ELISA) differentiates between OLA-labeled products with or without M184V. Our method shows 100% specificity and 100% sensitivity when tested with samples that contained 200 copies of mutant DNA and 800 copies of wild type DNA prior to amplification. When integrated with sample preparation, this method may detect HIV-1 drug resistance at a low cost and at a rural hospital laboratory.

Prevalence of Pre-antiretroviral-Treatment Drug Resistance by Gender, Age, and Other Factors in HIV-Infected Individuals Initiating Therapy in Kenya, 2013-2014.

Background: Pre-antiretroviral-treatment drug resistance (PDR) is a predictor of human immunodeficiency virus (HIV) treatment failure. We determined PDR prevalence and correlates in a Kenyan cohort. Methods: We conducted a cross-sectional analysis of antiretroviral (ARV) treatment-eligible HIV-infected participants. PDR was defined as ≥2% mutant frequency in a participant's HIV quasispecies at pol codons K103N, Y181C, G190A, M184 V, or K65R by oligonucleotide ligation assay and Illumina sequencing. PDR prevalence was calculated by demographics and codon, stratifying by prior ARV experience. Poisson regression was used to estimate prevalence ratios. Results: PDR prevalences (95% confidence interval [CI]) in 815 ARV-naive adults, 136 ARV-experienced adults, and 36 predominantly ARV-naive children were 9.4% (7.5%-11.7%), 12.5% (7.5%-19.3%), and 2.8% (0.1%-14.5%), respectively. Median mutant frequency within an individual's HIV quasispecies was 67%. PDR prevalence in ARV-naive women 18-24 years old was 21.9% (9.3%-40.0%). Only age in females associated with PDR: A 5-year age decrease was associated with adjusted PDR prevalence ratio 1.20 (95% CI, 1.06-1.36; P = .004). Conclusions: The high PDR prevalence may warrant resistance testing and/or alternative ARVs in high HIV prevalence settings, with attention to young women, likely to have recent infection and higher rates of resistance. Clinical Trials Registration: NCT01898754.

Development and validation of an oligonucleotide ligation assay to detect lamivudine resistance in hepatitis B virus.

Treatment of chronic hepatitis B virus (HBV) infection with lamivudine-monotherapy rapidly selects mutant variants in a high proportion of individuals. Monitoring lamivudine resistance by consensus sequencing is costly and insensitive for detection of minority variants. An oligonucleotide ligation assay (OLA) for HBV lamivudine-resistance was developed and compared to consensus sequencing. Both assays detected drug resistance mutations in 35/64 (54.7%) specimens evaluated, and OLA detected minority mutants in an additional six (9.4%). OLA may offer a sensitive and inexpensive alternative to consensus sequencing for detection of HBV drug resistance in resource-limited settings.

Optimization of the oligonucleotide ligation assay for the detection of nevirapine resistance mutations in Zimbabwean Human Immunodeficiency Virus type-1 subtype C.

An oligonucleotide ligation assay (OLA) designed to detect Human Immunodeficiency Virus type-1 (HIV)-drug-resistance to the nevirapine (NVP) selected mutations K103N, Y181C, V106M and G190A was used to evaluate 200 archived dried blood spots (DBS) from infected infants participating in the Zimbabwean Early Infant Diagnosis (EID) Program. Consensus sequencing of specimens with indeterminate OLA results was performed to identify genetic sequence polymorphisms that appeared to compromise performance of the OLA. When consistent patterns of polymorphisms were observed the probes were redesigned, and DBS specimens with indeterminate OLA results were retested with the new Zimbabwe-specific (ZW) probes. OLA results obtained in Zimbabwe were compared to repeat testing in a US reference laboratory. 188/200 (94%) DBS yielded polymerase chain reaction (PCR) amplification of HIV pol. ZW probes reduced indeterminate OLA results from 5.2% to 2.8% of codons evaluated (p=0.02), with 98.2% concordance between results obtained in the Zimbabwean and US laboratories. Optimization of OLA probes to accommodate polymorphisms in regional HIV variants improved OLA performance, and comparison to the USA results showed successful implementation of the OLA in Zimbabwe for detection of NVP resistance mutations in DBS specimens.