Transmitted HIV Drug Resistance Research Articles

HIV-1 Transmitted Drug Resistance Mutations in Recently Diagnosed Antiretroviral-Naive Patients in Belém, Pará, Northern Brazil

HIV-1 Transmitted Drug Resistance Mutations in Recently Diagnosed Antiretroviral-Naive Patients in Belém, Pará, Northern Brazil

Patient-Related Factors Influencing Adherence to ART, A Case of Chivuna, Southern Province of Zambia

Despite the roll out of free life prolonging HIV and AIDS drugs in many public clinics in Zambia and the well documented effects of Anti Retrovirals (ARVs) in reducing mortality among people living with HIV, some people living with HIV still abandon treatment. This study explores patient-related factors that influence adherence to the life prolonging drugs. It is hoped that such information would be useful in enhancing adherence so as to achieve the goal of ART. This information is critical considering irrefutable evidence that non-adherence to Anti-Retroviral Therapy (ART) can lead to drug resistance and consequently, transmission of drug resistant HIV. Drug resistant HIV is not only expensive to handle, but can lead to increased morbidity, mortality and increased incidence of HIV cases particularly, for a low income country like Zambia. Methods: This paper uses data from a large mixed method study which was conducted in a rural setting. The study explored how patient-related factors influence people living with HIV in continuing taking of medication. The paper, therefore, discusses the major reasons reported by HIV infected people on ART for either being able to consistently take their medication or failing to do so. Results: Both limiting and facilitating factors were identified as influencing adherence. Among the facilitators identified were one having a reminder, feeling better after being on ART, seeing someone on ART recover, desire to live longer and disclosure of one’s positive status. The limiting factors included forgetting to take medication, non-recovery while on treatment for some time and drug fatigue. A significant association was found between adherence treatment and one having a reminder, desire to live longer and seeing someone on ART get better. Conclusion: While facilitators enhanced adherence, the barriers prevented or discouraged people on ART from continuing taking AIDS medicines as prescribed by their health care providers. In order to avoid drug resistance and other public health implications, such as transmission of drug resistant HIV virus and deaths, there is need to address these patient-related barriers.

Prevalence of HIV-1 transmitted drug resistance and viral suppression among recently diagnosed adults in São Paulo, Brazil.

HIV-1 transmitted drug resistance (TDR) mutations may reduce the efficacy of antiretroviral therapy (ART), but pre-treatment testing to determine the virus genotype can improve the efficacy of ART. Unfortunately, issues related to cost and logistics of pre-treatment testing limit its use in resource-limited settings. We studied 596 ART-naive individuals who were newly diagnosed from 2014 to 2016 in São Paulo, Brazil, to evaluate TDR and virological outcome after 48weeks of genotype-guided therapy. One or more TDR (based on the WHO surveillance list) was observed in 10.9% (CI 95%, 8.6-13.6) of the sequences, the most common of which was the K103N mutation, which confers resistance to first-generation drugs of the non-nucleoside reverse transcriptase inhibitor (NNRTI) antiretroviral drug class. Dual-class (1%, 6/596) and triple-class (0.34%, 2/596) resistance were uncommon. After 48weeks of treatment with ART, infection was suppressed to below 200 copies/mL in most patients (95%), with full suppression (RNA target not detected) in 65%. The following characteristics at patient enrollment were independently associated with a lack of full suppression: CD4 T cell counts below 500 cells/µL, viremia above 100,000 copies/mL, older age, and TDR to NNRTI. The rates of resistance were intermediate, but genotype-guided therapy resulted in high rates of viral suppression. The observed resistance profile should not be an obstacle to the use of the dolutegravir-based regimen now recommended in Brazil, but genotype testing may be warranted before initiating first-generation NNRTI-based regimens.

1283. Pretreatment HIV-1 Drug Resistance in Transmission Clusters of the Cologne-Bonn Region, Germany

BackgroundIn Germany, previous reports have demonstrated transmitted HIV-1 drug resistance mutations (DRM) in 10% of newly diagnosed individuals, affecting treatment failure and the choice of antiretroviral therapy (ART). Here, we sought to understand the molecular epidemiology of HIV DRM transmission throughout the Cologne-Bonn region, an area with one of the highest rate of new HIV infections in Europe (13.7 per 100,000 habitants).MethodsWe analyzed 714 HIV-1 ART naïve infected individuals diagnosed at the University Hospitals Cologne and Bonn between 2001 and 2016. Screening for DRM was performed according to the Stanford University Genotypic Resistance Interpretation. Shared DRM were defined as any DRM present in genetically linked individuals (<1.5% genetic distance). Phylogenetic and network analyses were performed to infer putative relationships and shared DRMs.ResultsWe detected 123 DRMs in our study population (17.2% of all sequences). Prevalence of any DRM was comparable among risk groups and was highest among people from an endemic area (i.e., country with HIV prevalence >1%) (11/51, 21.6%). Nucleoside-and non-nucleoside reverse transcriptase inhibitor (NRTI/NNNRTI) resistance mutations were detected in 49 (7%) and 97 (13.6%) individuals, with the E138A in 29 (4.1%) and K103N in 11 (1.5%) being the most frequent. Frequency of DRM was comparable in clustering and not clustering individuals (17.1% vs. 17.5%). Transmission network analysis indicated that the frequency of DRM in clustering individuals was the highest in PWID (3/7, 42.9%) (Figure 1A). Genetically linked individuals harboring shared DRMs were more likely to live in suburban areas than in Central Cologne (18.8% vs. 8% of clustering sequences with DRM; Figure 1B).ConclusionThe rate of DRMs was exceptionally high in the Cologne/Bonn area. Network analysis elucidated frequent cases of shared DRMs among genetically linked individuals, revealing the potential spread of DRMs and the need to prevent onward transmission of DRM in the Cologne-Bonn area. Disclosures M. Hoenigl, Gilead, Basilea, Merck: Speaker’s Bureau, Research grant and Speaker honorarium.

1282. Detection of HIV Transmitted Drug Resistance by Next-Generation Sequencing in a CRF01_AE Predominant Epidemic

BackgroundThe Philippines has the fastest growing HIV epidemic in the Asia-Pacific. Concurrent with this is a subtype shift from B to CRF01_AE. We have previously documented transmitted drug resistance (TDR) locally. However, the lack of drug pressure and the insensitivity of Sanger-based sequencing (SBS) may leave archived drug-resistance mutations (DRMs) undetected. To better detect TDR, we performed next-generation sequencing (NGS) on treatment-naïve patients and compared this with SBS.MethodsFollowing ethics approval, newly-diagnosed adult Filipino HIV patients were recruited from the Philippine General Hospital HIV treatment hub. Demographic data were collected, and blood samples underwent SBS with a WHO-approved protocol. Whole-genome NGS was performed using Illumina HiSeq through a commercial provider (Macrogen, Korea). Genotype and DRMs were analyzed and scored using the Stanford HIV Drug Resistance Database.Results113 patients were analyzed. Median age was 29 years (range 19–68), mean CD4 count was 147 cells/µL (range 0–556) and median viral load was 2.8 × 106 copies/mL. Genotype distribution was: CRF01_AE (93), B (13), possible CRF01_AE/B recombinants (5), CRF02_AG (1), possible URF (1). TDR prevalence by SBS and NGS at different minority variant cutoffs are shown in Table 1. All DRMs on SBS were found on NGS. Some samples had multiple DRMs. No factors were significantly associated with TDR, genotype, viral load or baseline CD4 count.ConclusionNGS is a more sensitive tool for detecting TDR compared with SBS. Nearly double the DRMs were found at an NGS cutoff of ≥5%, including INSTI DRMs. With increasing HIV drug resistance worldwide, switching to NGS may help decrease rates of initial treatment failure, especially in settings with limited repertoires of ARVs.Table 1. TDR Prevalence by SBS and NGS (N = 113).MethodAll (%)NRTI (%)NNRTI (%)PI (%)INSTI (%)SBS11 (9.7)2 (1.8)7 (6.2)3 (2.7)0 (0)*NGS≥1%59 (52.2)15 (13.3)29 (25.7)19 (16.8)17 (15.0)≥2%39 (34.5)7 (6.2)19 (16.8)9 (8.0)10 (8.8)≥5%22 (19.5)3 (2.7)15 (13.3)5 (4.4)2 (1.8)≥10%19 (16.8)1 (0.9)14 (12.4)4 (3.5)2 (1.8)≥15%15 (13.3)1 (0.9)12 (10.6)3 (2.7)1 (0.9)≥20%13 (11.5)1 (0.9)10(8.8)2 (1.8)1 (0.9)*SBS for INSTI only done for those with INSTI DRM on NGS ≥ 1% minority variantDisclosures All authors: No reported disclosures.

Assessment of Transmitted HIV-1 Drug Resistance Mutations Using Ultra- Deep Pyrosequencing in a Turkish Cohort.

Antiretroviral treatment (ART) reduces morbidity and mortality caused by human immunodeficiency virus (HIV) infection; however, the emergence of drug-resistant strains poses an important obstacle to treatment success. Using conventional sequencing methods to determine antiretroviral resistance, mutations present in ≥20% of quasispecies can be identified, but drug-resistant minority variants can lead to virologic failure. We aimed to assess transmitted drug resistance mutations (TDRMs) within minority variants using ultra-deep pyrosequencing (UDPS). Treatment-naive adult patients were included in this observational study. Surveillance TDRMs were classified as ≥20% or at minority variant level (≥2% - <20%). Genotypic sensitivity score calculated by using all pre-treatment drug resistance mutations (PDRMs) was also evaluated. Thirty-six patients were analyzed. Any TDRM at ≥20% level was detected in 8.3% of the patients (n=3). This prevalence increased to 30.6% (n=11) with the inclusion of minority variants. All non-nucleoside reverse transcriptase inhibitor and protease inhibitor-related TDRMs were within minority variants. The genotypic sensitivity score of rilpivirine-based regimens was considerably diminished when minority variants were included in the PDRM analysis. UDPS was used for the first time to assess TDRM in a Turkish HIV cohort and uncovered several mutations hidden within minority variants. UDPS may be preferred to detect PDRMs for avoiding virologic failure with rilpivirine-based ART regimens.

Prevalence of pretreatment HIV drug resistance in Mwanza, Tanzania.

In a 2008-10 study, we found a pretreatment HIV drug resistance (PDR) prevalence of 18.2% in patients at Bugando Medical Centre (BMC) in Mwanza, Tanzania. To determine the prevalence of PDR and transmitted HIV drug resistance (TDR) in patients visiting the BMC from 2013 to 2015. Adult outpatients were sequentially enrolled into two groups, separated by whether they were initiating ART. Previous exposure to antiretroviral drugs, except for prevention of mother-to-child transmission, was an exclusion criterion. HIV pol sequences were analysed according to WHO guidelines for surveillance of PDR and TDR. Two hundred and thirty-five sequences were analysed (138 ART initiators, 97 non-initiators). The prevalence of PDR was 4.7% (95% CI 2.6%-8.2%) overall, 3.1% (95% CI 1.1%-8.7%) for non-initiators and 5.8% (95% CI 3.0%-11.0%) for ART initiators. PDR to NNRTIs and nucleoside or nucelotide reverse transcriptase inhibitors was found in 3.0% (95% CI 1.5%-6.0%) and 1.7% (95% CI 0.7%-4.3%) of patients, respectively. Resistance to PIs was not observed. The prevalence of TDR was 6.0% (95% CI 3.6%-9.8%). Prevalence of PDR significantly decreased compared with 2008-10 and was below the WHO-defined threshold for triggering a public health response. National and systematic surveillance is needed to inform Tanzania's public health strategy.

Prevalence of Transmitted HIV drug resistance in antiretroviral treatment na\xefve newly diagnosed individuals in China

To investigate the prevalence and temporal trend of transmitted drug resistance (TDR), a nationwide cross-sectional survey was conducted among 5627 ART naïve newly diagnosed HIV-infected individuals in 2015 in China. Totally 4704 partial pol sequences were obtained. Among them, the most common HIV-1 circulating recombinant form (CRF) or subtype was CRF01_AE (39.0%), followed by CRF07_BC (35.6%), CRF08_BC (8.9%), and subtype B (5.5%). TDR mutations were found in 3.6% of the cases, with 1.1% harboring TDR to protease inhibitors (PIs), 1.3% having TDR to nucleoside reverse transcriptase inhibitors (NRTIs), and 1.6% to non-nucleoside reverse transcriptase inhibitors (NNRTIs). No significant difference was found in the prevalence of TDR, as compared with the results of another nationwide survey performed among ART naïve HIV-infected people in between 2004 and 2005, except in the 16–25 year-old group. In addition, four drug-resistant transmission clusters were identified in phylogenetic trees, accounting for 6.2% (9/145) of the individuals with TDR. Although the rate of TDR remained relatively low in the past 10 years in China, surveillance is still needed to monitor the trend of TDR and to optimize the first-line regimens.

Evolution of HIV-1 transmitted drug resistance in Italy in the 2007–2014 period: A weighted analysis

BackgroundRecent studies suggest that transmitted drug resistance (TDR) may be decreasing in latest years, likely because of the reduced frequency of acquired resistance. However, specific risk factors, geographical areas and special HIV-infected populations may be disproportionally affected by TDR. ObjectivesCorrelates of TDR and time trends were evaluated from 2007 to 2014. Study designWe evaluated the genotypic results of 2155 naïve patients enrolled in the I.Co.N.A cohort at 23 clinical Centers in Italy between 2007 and 2014. A weighted analysis was performed to account for the patients enrolled in the cohort in each clinical Centre at each biennium (total number of patients: 3737). ResultsOverall prevalence of TDR was 10.7%. Independent predictors of TDR were sexual risk factor (OR 2.315, p = 0.020) and non-Italian geographical origin (OR 1.57, p = 0.038). The weighted prevalence of TDR was 10.5% with a stable proportion over calendar years. Generally, TDR prevalence was numerically higher, although not significantly, in clinical Centers of metropolitan areas with more than 3 millions of residents as compared to others (11.3% vs. 9.2%). The difference in TDR prevalence between these Centers decreased in more recent years. ConclusionsA stable frequency of TDR was observed during the most recent years in Italy, with opposite and converging trends in large metropolitan areas as compared to the rest of the country, suggesting a more homogeneous spread of TDR across the country in latest years. Concerns remain for sexual route of infection and non-Italian origin, reinforcing the need for specific prevention strategies prioritizing specific populations.

Prevalence and Transmission Dynamics of HIV-1 Transmitted Drug Resistance in a Southeastern Cohort.

BackgroundTransmitted drug resistance (TDR) compromises clinical management and outcomes. Transmitted drug resistance surveillance and identification of growing transmission clusters are needed in the Southeast, the epicenter of the US HIV epidemic. Our study investigated prevalence and transmission dynamics in North Carolina.MethodsWe analyzed surveillance drug resistance mutations (SDRMs) using partial pol sequences from patients presenting to 2 large HIV outpatient clinics from 1997 to 2014. Transmitted drug resistance prevalence was defined as ≥1 SDRMs among antiretroviral therapy (ART)–naïve patients. Binomial regression was used to characterize prevalence by calendar year, drug class, and demographic and clinical factors. We assessed the transmission networks of patients with TDR with maximum likelihood trees and Bayesian methods including background pol sequences (n = 15 246).ResultsAmong 1658 patients with pretherapy resistance testing, ≥1 SDRMs was identified in 199 patients, with an aggregate TDR prevalence of 12% (95% confidence interval, 10% to 14%) increasing over time (P = .02). Resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs; 8%) was common, followed by nucleoside reverse transcriptase inhibitors (4%) and protease inhibitors (2%). Factors associated with TDR were being a man reporting sex with men, white race, young age, higher CD4 cell count, and being a member of a transmission cluster. Transmitted drug resistance was identified in 106 clusters ranging from 2 to 26 members. Cluster resistance was primarily NNRTI and dominated by ART-naïve patients or those with unknown ART initiation.ConclusionsModerate TDR prevalence persists in North Carolina, predominantly driven by NNRTI resistance. Most TDR cases were identified in transmission clusters, signifying multiple local transmission networks and TDR circulation among ART-naïve persons. Transmitted drug resistance surveillance can detect transmission networks and identify patients for enhanced services to promote early treatment.

Impact of transmitted HIV-1 drug resistance on the efficacy of first-line antiretroviral therapy with two nucleos(t)ide reverse transcriptase inhibitors plus an integrase inhibitor or a protease inhibitor.

To examine the impact of transmitted drug resistance (TDR) on response to first-line regimens with integrase strand transfer inhibitors (INSTIs) or boosted protease inhibitors (bPIs). From an Italian observational database (ARCA) we selected HIV-1-infected drug-naive patients starting two NRTIs and either an INSTI or a bPI, with an available pre-ART resistance genotype. The endpoint was virological failure (VF; plasma HIV-1 RNA >200 copies/mL after week 24). WHO surveillance drug resistance mutations and the Stanford algorithm were used to classify patients into three resistance categories: no TDR (A), TDR but fully-active ART prescribed (B), TDR and at least low-level resistance to one or more prescribed drug (C). We included 1365 patients with a median follow-up of 96 weeks (IQR 54-110): 1205 (88.3%) starting bPI and 160 (11.7%) INSTI. Prevalence of TDR was 6.1%, 12.5%, 2.6% and 0% for NRTI, NNRTI, bPI and INSTI, respectively. Cumulative Kaplan-Meier estimates for VF at 48 weeks were 11% (95% CI 10.1%-11.9%) for the bPI group and 7.7% (95% CI 5.4%-10%) for the INSTI group. In the INSTI group, cumulative estimates for VF at 48 weeks were 6% (95% CI 4%-8%) in resistance category A, 5% (95% CI 1%-10%) in B and 50% (95% CI 30%-70%) in C (P < 0.001). Resistance category C [versus A, adjusted hazard ratio (aHR) 12.6, 95% CI 3.2-49.8, P < 0.001] and nadir CD4 (+100 cells/mm3, aHR 0.6, 95% CI 0.4-0.9, P = 0.03) predicted VF. In the bPI group, VF rates were not influenced by baseline resistance. Our data support the need for NRTI resistance genotyping in patients starting an INSTI-based first-line ART.

Evolution of transmitted HIV‐1 drug resistance and viral subtypes circulation in Italy from 2006 to 2016

The aim was to evaluate the evolution of transmitted HIV-1 drug resistance (TDR) prevalence in antiretroviral therapy (ART)-naïve patients from 2006 to 2016. HIV-1 sequences were retrieved from the Antiviral Response Cohort Analysis (ARCA) database and TDR was defined as detection of at least one mutation from the World Health Organization (WHO) surveillance list. We included protease/reverse transcriptase sequences from 3573 patients; 455 had also integrase sequences. Overall, 68.1% of the patients were Italian, the median CD4 count was 348 cells/μL [interquartile range (IQR) 169-521 cells/μL], and the median viral load was 4.7 log10 HIV-1 RNA copies/mL (IQR 4.1-5.3 log10 copies/mL). TDR was detected in 10.3% of patients: 6% carried mutations to nucleos(t)ide reverse transcriptase inhibitors (NRTIs), 4.4% to nonnucleos(t)ide reverse transcriptase inhibitors (NNRTIs), 2.3% to protease inhibitors (PIs), 0.2% to integrase strand transfer inhibitors (INSTIs) and 2.1% to at least two drug classes. TDR declined from 14.5% in 2006 to 7.3% in 2016 (P=0.003): TDR to NRTIs from 9.9 to 2.9% (P=0.003) and TDR to NNRTIs from 5.1 to 3.7% (P=0.028); PI TDR remained stable. The proportion carrying subtype B virus declined from 76.5 to 50% (P<0.001). The prevalence of TDR was higher in subtype B vs. non-B (12.6 vs. 4.9%, respectively; P<0.001) and declined significantly in subtype B (from 17.1 to 8.8%; P=0.04) but not in non-B subtypes (from 6.1 to 5.8%; P=0.44). Adjusting for country of origin, predictors of TDR were subtype B [adjusted odds ratio (AOR) for subtype B vs. non-B 2.91; 95% confidence interval (CI) 1.93-4.39; P<0.001], lower viral load (per log10 higher: AOR 0.86; 95% CI 0.75-0.99; P=0.03), site in northern Italy (AOR for southern Italy/island vs. northern Italy, 0.61; 95% CI 0.40-0.91; P=0.01), and earlier calendar year (per 1year more recent: AOR 0.95; 95% CI 0.91-0.99; P=0.02). The prevalence of HIV-1 TDR has declined during the last 10years in Italy.

Epidemiological surveillance of HIV-1 transmitted drug resistance among newly diagnosed individuals in Shijiazhuang, northern China, 2014-2015.

BackgroundThe widespread use of antiretroviral therapy (ART) has led to considerable concerns about the prevalence of transmitted drug resistance (TDR). Sexual contact, particularly men who have sex with men (MSM) was the most prevalent form of HIV transmission in Shijiazhuang. Hence, we conducted an epidemiological surveillance study on TDR among newly diagnosed individuals who infected-HIV through sexual contact in from 2014–2015.MethodsGenotypic resistance mutations were defined using the WHO-2009 surveillance list. Potential impact on antiretroviral drug was predicted according to the Stanford HIV db program version 7.0. The role of transmission clusters in drug resistant strains was evaluated by phylogenetic and network analyses.ResultsIn this study, 589 individuals were recruited and 542 samples were amplified and sequenced successfully. The over prevalence of TDR was 6.1%: 1.8% to nucleoside reverse transcriptase inhibitors (NRTIs), 2.0% to non- NRTIs (NNRTIs) and 2.4% to protease inhibitors (PIs), respectively. We did not find significant differences in the TDR prevalence by demographic and clinical characteristics (p > 0.05). Using network and phylogenetic analysis, almost 60.0% sequences were clustered together. Of these clusters, 2 included at least two individuals carrying the same resistance mutation, accounting for 21.2% (7/33) individuals with TDR. No significant difference was observed in the clustering rate between the individuals with and without TDR.ConclusionsWe obtained a moderate level TDR rate in studied region. These findings enhance our understanding of HIV-1 drug resistance prevalence in Shijiazhuang, and may be helpful for the comprehensive prevention and control of HIV-1.

Transmitted drug resistance among HIV infected men who have sex with men in Tianjin, 2014-2017

Objective: To understand prevalence and transmission of transmitted drug resistance (TDR) among HIV infected men who have sex with men (MSM) in Tianjin from 2014 to 2017. Methods: A total of 225 blood samples were collected from HIV infected MSM in Tianjin from 2014 to 2017. Pol gene fragments were obtained by viral RNA extraction and nested PCR amplification. Phylogenetic and drug resistance analyses were conducted. Results: A total of 205 samples were successfully sequenced and analyzed. Based on pol sequences, 53.2% (109/205), 28.8% (59/205), 10.2% (21/205), 4.9% (10/205) and 2.9% (6/205) of the samples were positive for HIV subtypes CRF01_AE, CRF07_BC, B, CRF55_01B and unique recombinant forms (URFs). Twenty transmission clusters, including 75 sequences, were identified and 62.5% (10/16) of sequences with TDR were in 5 clusters. The prevalence of TDR was 7.8% between 2014 and 2017. The annual prevalence rate increased from 3.9% (2/51) in 2014, 5.7% (3/53) in 2015, 9.6% (5/52) in 2016 to 12.2%(6/49) in 2017, the difference was not significant (χ(2)=2.504, P=0.127). CRF01_AE and B strains had high TDR prevalence (3.4%, 7/205) and (2.9%, 6/205), respectively. The TDR mutation was mainly NNRTIs, the TDR prevalence was 6.3% (13/205). In contract, the TDR prevalence of NRTIs and PIs were 1.5% (3/205) and 1.0% (2/205) respectively. Conclusion: Results from this study suggested that the prevalence of HIV-1 TDR strains in MSM was serious in Tianjin. It is necessary to take effective prevention and control measures.

HIV-1 transmitted drug resistance in Slovenia and its impact on predicted treatment effectiveness: 2011-2016 update.

HIV-positive individuals that have a detected transmitted drug resistance (TDR) at baseline have a higher risk of virological failure with antiretroviral therapy (ART). This study offers an update on the prevalence of TDR in Slovenia, looks for onward transmission of TDR, and reassesses the need for baseline drug resistance testing. Blinded questionnaires and partial pol sequences were obtained from 54.5% (168/308) of all of the patients diagnosed with HIV-1 from 2011 to 2016. Subtype B was detected in 82.7% (139/168) of patients, followed by subtype A (8.3%), subtype C (2.4%), and CRF01_AE (1.8%). Surveillance drug resistance mutations (SDRMs) were found in four individuals (2.4%), all of them men who have sex with men (MSM) and infected with subtype B. K103N was detected in two patients and T68D and T215D in one person each, corresponding to a prevalence of 0%, 1.2%, and 1.2% of TDR to protease inhibitors (PIs), nucleoside reverse transcriptase inhibitors (NRTIs), and non-NRTIs (NNRTIs), respectively. The impact of mutations on drug susceptibility was found to be most pronounced for NNRTIs. No forward spread of TDR within the country was observed; however, phylogenetic analysis revealed several new introductions of HIV into Slovenia in recent years, possibly due to increased risky behavior by MSM. This was indirectly confirmed by a substantial increase in syphilis cases and HIV-1 non-B subtypes during the study period. A drug-resistant HIV variant with good transmission fitness is thus more likely to be imported into Slovenia in the near future, and so TDR should be closely monitored.

Low prevalence of transmitted HIV-1 drug resistance detected by a dried blood spot (DBS)-based next-generation sequencing (NGS) method in newly diagnosed individuals in Cameroon in the years 2015-16.

To determine the most recent prevalence, transmission patterns and risk factors of transmitted drug-resistance mutations (TDRMs) in Cameroon, we initiated a multicentre study monitoring HIV-1 drug resistance in newly HIV-1-diagnosed individuals using a novel next-generation sequencing (NGS) assay applicable to fingerprick dried blood spot (DBS) samples. Fingerprick DBS samples and questionnaires were collected from 360 newly HIV-1-diagnosed individuals in four hospitals in urban areas in Cameroon in the years 2015-16. We developed an HIV-1 protease and reverse transcriptase drug resistance genotyping assay applicable to DBS samples and HIV-1 genomes of groups M, N and O. The WHO 2009 list of mutations for surveillance of transmitted drug-resistant HIV strains was used to analyse TDRMs. Applying our 'DBS-NGS-genotypic resistance test', baseline HIV-1 drug resistance data were successfully obtained from 82.8% (298/360) of newly diagnosed individuals. At nucleotide frequencies >15%, TDRMs to NRTIs were observed in 3.0% (9/298), to NNRTIs in 4.0% (12/298) and to PIs in 1.3% (3/240). The NNRTI mutation K103N was most commonly detected (2.7%). Expanding the analysis to low-abundance TDRMs, i.e. 3%-15%, 12 additional individuals (4.0%) harbouring TDRMs were identified. Having unprotected sex with a known HIV-1-positive person was significantly associated with the transmission of DRMs (adjusted OR 9.6; 95% CI 1.79-51.3). The prevalence of transmitted HIV-1 drug resistance is currently low in the study sites in Cameroon. Evidence of some risky sexual behaviours depicts a public health problem with possible implications for the prevention of new HIV-1 infections.

Provincial and national prevalence estimates of transmitted HIV-1 drug resistance in South Africa measured using two WHO-recommended methods.

Sentinel surveillance of transmitted HIV drug resistance (TDR) among recently infected populations within a country was recommended by the World Health Organization from 2004 to 2015. Serum specimens collected as part of the 2010, 2011 and 2012 National Antenatal Sentinel HIV Prevalence Surveys were used to estimate provincial and national TDR prevalence in South Africa. Moderate (5-15%) levels of transmitted non-nucleoside reverse transcriptase inhibitor (NNRTI) drug class resistance were detected in three of five provinces surveyed in 2010 and 2011 (Eastern Cape, Free State and KwaZulu-Natal). Inclusion of all nine of South Africa's provinces in the 2012 survey enabled calculation of a national TDR point prevalence estimate: TDR to the NNRTI drug class was 5.4% (95% CI 3.7, 7.8%), with K103N and V106M being the most frequently detected mutations. TDR estimates for the nucleoside reverse transcriptase inhibitor (NRTI) drug class were 1.1% (95% CI 0.5, 2.4%) and 0.6% (95% CI 0.1, 1.6%) for protease inhibitors (PI). These data provide national TDR estimates for South Africa in 2012 and indicate that levels of TDR were low to moderate for the NNRTI drug class and low for NRTIs and PIs in the population surveyed.

Prevalence of transmitted drug resistance among HIV-1 treatment-naive patients in Beijing.

To optimise patients' outcomes and gain insight into transmitted drug resistance (TDR) among human immunodeficiency virus (HIV)-1 treatment-naive patients in Beijing, the prevalence of TDR was assessed. Demographic and clinical data of 1241 treatment-naive patients diagnosed between April 2014 and February 2015 were collected. TDR was defined using the Stanford University HIV drug resistance mutations database. The risk factors were evaluated by multi-logistic regression analysis. Among 932 successfully amplified cases, most were male (96.78%) and infected through men having sex with men (91.74%). Genotype were CRF01_AE (56.44%), B (20.60%), CRF07_BC (19.96%), C (1.61%) and other genotypes (1.39%). The overall prevalence of TDR was 6.12%. Most frequent mutations occurred in non-nucleoside reverse transcriptase inhibitors (NNRTIs) (3.11%), followed by protease inhibitors (PIs) (2.25%) and nucleoside reverse transcriptase inhibitors (NRTIs) (1.32%). Furthermore, HIV-1 genotype was associated with high risk of resistance, in which genotype C and other genotype may have higher risk for resistance. The prevalence among treatment-naive patients in Beijing was low. Resistance to NNRTIs was higher than with PIs or NRTIs. Continuous monitoring of regional levels of HIV-1 TDRs would contribute to improve treatment outcomes and prevent failures.

Temporal trends of transmitted HIV drug resistance in a multinational seroconversion cohort.

The rate of transmitted drug resistance (TDR) may increase with wider use of antiretroviral therapy and can contribute to therapeutic failure. We analysed time trends in TDR among HIV seroconverters. Using CASCADE data of individuals with well estimated dates of HIV seroconversion, we examined HIV nucleotide sequences collected prior to antiretroviral therapy use from 1996-2012. All samples were taken within 12 months of testing HIV positive. Using logistic regression, we examined the association between TDR and year of seroconversion, adjusting for confounders. Of 4717 individuals seroconverting between 1996 and 2012, median (IQR) age at seroconversion was 33 (27, 39) years. The majority (3839; 92%) were male, mainly exposed through MSM (3767; 80%), and infected with subtype B (3464; 73%). Overall, 515 (11%) individuals had at least one drug resistance-related mutation; 280 individuals with nucleoside reverse transcriptase, 185 with nonnucleoside reverse transcriptase, and 144 with protease inhibitor mutations. Estimated TDR prevalence was 19.4% (8.2, 36.0) in 1996, significantly decreasing to 8.5% (5.9, 11.9) in 2012 [odds ratio (OR; 95% confidence interval (CI)) = 0.92 (0.90, 0.95) per year increase]. Individuals exposed through sex between men and women were significantly less likely to have been infected with a drug-resistant strain [OR (95% CI) = 0.59 (0.41, 0.87) compared with MSM], and there was marginal evidence that sampling during acute infection was associated with higher odds of resistance [OR (95% CI) = 1.20 (0.97, 1.7), P = 0.093] compared with later sampling. TDR has decreased over calendar time although a significant proportion of new infections still carry resistance-related mutations.

Prevalence and transmission dynamics of HIV-1 transmitted drug resistance in a southeastern cohort

Prevalence and transmission dynamics of HIV-1 transmitted drug resistance in a southeastern cohort