Genotypic Drug Resistance Assays Research Articles

Molecular epidemiological characteristics of newly diagnosed HIV-1 cases in Fujian Province in 2020

To investigate the HIV-1 genotype and distribution of newly diagnosed HIV-1 cases in Fujian Province in 2020, so as to provide insights into formulation of the precise AIDS control strategy in the province. Newly diagnosed HIV-1 cases without antiretroviral therapy (excluding AIDS patients) were randomly sampled from each city of Fujian Province in 2020 at a proportion of 50% of the mean number of HIV-infected cases reported across 9 cities of Fujian Province during the past three years. Subjects' demographic and epidemiological data were collected and blood samples were collected. The HIV-1 pol gene was amplified using nested reverse-transcription PCR assay, and the gene sequences were used for HIV-1 genotyping and phylogenetic analysis. The gene sequences were uploaded to the HIV Drug Resistance Database (http://hivdb.stanford.edu) for genotypic drug resistance assays, and the scores and level of HIV drug resistance were estimated using the HIVDB Algorithm version 9.5. A total of 1 043 newly diagnosed HIV-1 cases were reported in Fujian Province in 2020, and 936 gene sequences were successfully obtained following sequencing of blood samples. There were 9 HIV-1 genotypes characterized in blood samples from 936 newly diagnosed HIV-1 cases, with CRF07_BC (52.1%) and CRF01_AE (30.4%) as predominant subtypes, followed by CRF08_BC (4.9%), CRF55_01B (3.0%), subtype C (2.5%), subtype B (2.1%), CRF85_BC (1.7%), CRF59_01B (0.3%) and CRF65_CPX (0.1%), and unidentified subtypes were found in 26 blood samples. HIV-1 drug resistance was detected in 43 out of the 936 newly diagnosed HIV-1 cases, with 4.6% prevalence of HIV-1 drug resistance prior to therapy, and the highest drug resistance was found in the HIV CRF59_01B subtype, followed by in CRF08_BC, B, C, CRF01_AE, CRF07_BC and other subtypes, with a significant difference in the genotype-specific prevalence of HIV-1 drug resistance (χ2 = 45.002, P < 0.05). There was a HIV-1 genotype diversity in Fujian Province in 2020, and emerging recombinant and drug-resistant HIV-1 strains were detected and spread across patients and regions. Monitoring of HIV-1 genotypes is recommended to be reinforced for timely understanding of the transmission and spread of novel recombinant and drug-resistant HIV-1 strains.

Minority and majority pretreatment HIV-1 drug resistance associated with failure of first-line nonnucleoside reverse-transcriptase inhibitor antiretroviral therapy in Kenyan women.

Among women initiating first-line nonnucleoside reverse-transcriptase inhibitor (NNRTI)-based-ART with and without a history of single-dose nevirapine (sdNVP) with or without zidovudine with or without lamivudine (ZDV with and without 3TC) for prevention of mother-to-child HIV transmission (PMTCT), we hypothesized that pre-ART HIV-drug resistance would be associated with virologic failure DESIGN/METHODS:: In a prospectively enrolled study, three genotypic drug-resistance assays [oligonucleotide-ligation-assay (OLA), consensus sequencing, and next-generation sequencing by Illumina] were retrospectively performed to detect pre-ART drug resistance. Minority or majority drug-resistant variants identified in pre-ART RNA and/or DNA, a history of antiretrovirals for PMTCT, and other risk factors were assessed for association with virologic failure. Failure occurred in 38/169 (22.5%) women, and was associated with pre-ART drug resistance detected by any assay (OLA of plasma or PBMC, consensus sequencing of PBMC and/or plasma, and next-generation sequencing of PBMC at frequencies of at least 10% and as minority variants; all P < 0.0001). Failure was also associated with PMTCT using sdNVP and ZDV with or without 3TC, but not sdNVP only; however, the longer time-interval between PMTCT and ART initiation observed for sdNVP-only women showed no interaction with failure. Viral loads and OLA of PBMC in longitudinal specimens demonstrated rapid failure and emergence of drug resistance, particularly among sdNVP and ZDV with or without 3TC-experienced women with pre-ART drug-resistant minority variants by next-generation sequencing but without drug resistance by OLA or consensus sequencing. Pre-ART drug resistance was detected similarly by OLA of PBMC or plasma and by consensus sequencing, and was associated with virologic failure soon after initiation of first-line NVP-based ART. A history of sdNVP and ZDV with or without 3TC for PMTCT or minority variants detected by next-generation sequencing identified additional women with failure. These findings emphasize the value of assessing individual antiretroviral history, particularly nonsuppressive antiretrovirals with at least two drug classes, and testing for pre-ART drug resistance, including minority variants.

Importance of minor variants and their detection (ultra‐deep sequencing) in the management of HIV infection

Sanger genotypic drug resistance assays currently used for routine HIV management often miss low‐frequency drug‐resistant HIV variants, potentially posing patients at risk of antiretroviral treatment failure. Next‐generation sequencing (NGS) technologies allow detection of such minority variants down to approximately 0.5%–1% frequency. They also facilitate interrogating “other” HIV genomic regions like Gag or the RT connection domain, which modulate HIV resistance and are not usually addressed in routine care. Due to the capacity and scalability of NGS platforms, it is even feasible to envision full HIV genome sequencing to inform treatment design at relatively low cost and workload. Although the equipment for NGS remains rather expensive and accurate analysis of NGS still requires comprehensive bioinformatics support, even these barriers are being reduced. The steadfast evolution of NGS platforms is dramatically reducing the cost of genotyping. Open‐source and commercial bioinformatic solutions are automatizing and streamlining analyses and NGS drug resistance data interpretation to the extent that lab technicians without bioinformatics knowledge will soon be able to generate reliable estimates of drug resistance from NGS data on their own. However, despite such impressive advances, the main question remains open: do we need NGS for HIV management? In this presentation, we will review the evidence supporting (or not) NGS for HIV clinical management. We will argue that, on one hand, detection of minority variants may further improve the outcomes of first‐line efavirenz or nevirapine‐based ART, may help design more effective salvage ART regimens, and may improve clinical outcomes to CCR5 antagonists. On the other hand, although well‐powered studies are generally lacking, detection of minority variants does not seem to modify the outcomes of first‐line ART including higher genetic barrier drugs such as second‐generation NNRTIs, protease or integrase inhibitors. We will then discuss the relationship between minority variants and ART adherence and will end by summarizing the main challenges faced by NGS to reach routine HIV clinical management.

HBV virological assessment

Management of hepatitis B virus (HBV) infected patients involves serological diagnosis, quantitation of HBV-DNA and measurement of HBV drug resistance. Different serological markers such as HBsAg, anti-HBs, anti-HBc (total and IgM), HBeAg and anti-HBe are assessed by immunoassays in order to define the infection status. The emergence of surface mutants however is a continuous challenge to design more effective immunoassays. Commercially available quantitative HBV-DNA assays with increased sensitivity and wider linear range give a more accurate estimate of viral replication and contribute decisively in the initiation and the monitoring of the response to HBV therapy. Genotypic drug resistance assays are important diagnostic tools, since the administration of nucleoside/nucleotide analogues to HBV infected patients leads to the development of drug resistance patterns very much dependent on the treatment regimen. Special issues have to be taken into consideration regarding HBV/HIV-1 co-infected patients, since concominant HIV and HBV replication results in higher rates of HBV replication. Current efforts are focused on the standardization of HBV-DNA assays (qualitative and quantitative), of HBV drug resistance assays as well as in the development of new assays and markers that will help in the prognosis and management of HBV infection (quantitative detection of pre-core mutants and HBV ccc-DNA assays).

Genotypic analysis of Mycobacterium tuberculosis in two distinct populations using molecular beacons: implications for rapid susceptibility testing.

Past genotypic studies of Mycobacterium tuberculosis may have incorrectly estimated the importance of specific drug resistance mutations due to a number of sampling biases including an overrepresentation of multidrug-resistant (MDR) isolates. An accurate assessment of resistance mutations is crucial for understanding basic resistance mechanisms and designing genotypic drug resistance assays. We developed a rapid closed-tube PCR assay using fluorogenic reporter molecules called molecular beacons to detect reportedly common M. tuberculosis mutations associated with resistance to isoniazid and rifampin. The assay was used in a comparative genotypic investigation of two different study populations to determine whether these known mutations account for most cases of clinical drug resistance. We analyzed samples from a reference laboratory in Madrid, Spain, which receives an overrepresentation of MDR isolates similar to prior studies and from a community medical center in New York where almost all of the resistant isolates and an equal number of susceptible controls were available. The ability of the molecular beacon assay to predict resistance to isoniazid and rifampin was also assessed. The overall sensitivity and specificity of the assay for isoniazid resistance were 85 and 100%, respectively, and those for rifampin resistance were 98 and 100%, respectively. Rifampin resistance mutations were detected equally well in isolates from both study populations; however, isoniazid resistance mutations were detected in 94% of the isolates from Madrid but in only 76% of the isolates from New York (P = 0.02). In New York, isoniazid resistance mutations were significantly more common in the MDR isolates (94%) than in single-drug-resistant isolates (44%; P < 0.001). No association between previously described mutations in the kasA gene and isoniazid resistance was found. The first mutations that cause isoniazid resistance may often occur in sequences that have not been commonly associated with isoniazid resistance, possibly in other as yet uncharacterized genes. The molecular beacon assay was simple, rapid, and highly sensitive for the detection of rifampin-resistant M. tuberculosis isolates and for the detection of isoniazid resistance in MDR isolates.