Evaluation of dried blood spot specimens for HIV-1 drug-resistance testing using the Trugene® HIV-1 genotyping assay

HIV-1 drug resistance genotyping success rates and correlates of Dried-blood spots and plasma specimen genotyping failure in a resource-limited setting

BACKGROUND

HIV-1 drug resistance genotyping is critical to the monitoring of antiretroviral treatment. Data on HIV-1 genotyping success rates of different laboratory specimen types from multiple sources is still scarce.

METHODS

In this cross-sectional study, we determined the laboratory genotyping success rates (GSR) and assessed the correlates of genotyping failure of 6837 unpaired dried blood spot (DBS) and plasma specimens. Specimens from multiple studies in a resource-constrained setting were analysed in our laboratory between 2016 and 2019.

RESULTS

We noted an overall GSR of 65.7% and specific overall GSR for DBS and plasma of 49.8% and 85.9% respectively. The correlates of genotyping failure were viral load (VL) < 10,000 copies/mL (aOR 0.3 95% CI: 0.24-0.38; p < 0.0001), lack of viral load testing prior to genotyping (OR 0.85 95% CI: 0.77-0.94; p = 0.002), use of DBS specimens (aOR 0.10 95% CI: 0.08-0.14; p < 0.0001) and specimens from routine clinical diagnosis (aOR 1.4 95% CI: 1.10-1.75; p = 0.005).

CONCLUSIONS

We report rapidly decreasing HIV-1 genotyping success rates between 2016 and 2019 with increased use of DBS specimens for genotyping and note decreasing median viral loads over the years. We recommend improvement in DBS handling, pre-genotyping viral load testing to screen samples to enhance genotyping success and the development of more sensitive assays with well-designed primers to genotype specimens with low or undetectable viral load, especially in this era where virological suppression rates are rising due to increased antiretroviral therapy roll-out.

HIV-2 Drug Resistance Genotyping from Dried Blood Spots

The treatment of HIV-2 in resource-limited settings (RLS) is complicated by the limited availability of HIV-2-active antiretroviral drugs and inadequate access to HIV-2 viral load and drug resistance testing. Dried blood spots (DBS)-based drug resistance testing, widely studied for HIV-1, has not been reported for HIV-2 and could present an opportunity to improve care for HIV-2-infected individuals. We selected 150 DBS specimens from ongoing studies of antiretroviral therapy (ART) for HIV-2 infection in Senegal and subjected them to genotypic drug resistance testing. Total nucleic acid was extracted from DBS, reverse transcribed, PCR amplified, and analyzed by population-based Sanger sequencing, and major drug resistance-associated mutations (RAM) were identified. Parallel samples from plasma and peripheral blood mononuclear cells (PBMC) were also genotyped. We obtained 58 protease/reverse transcriptase genotypes. Plasma viral load was significantly correlated with genotyping success (P < 0.001); DBS samples with corresponding plasma viral load >250 copies/ml had a success rate of 86.8%. In paired DBS-plasma genotypes, 83.8% of RAM found in plasma were also found in DBS, and replicate DBS genotyping revealed that a single test detected 86.7% of known RAM. These findings demonstrate that DBS-based genotypic drug resistance testing for HIV-2 is feasible and can be deployed in RLS with limited infrastructure.

Next-Generation Sequencing for HIV Drug Resistance Testing: Laboratory, Clinical, and Implementation Considerations

Higher accessibility and decreasing costs of next generation sequencing (NGS), availability of commercial kits, and development of dedicated analysis pipelines, have allowed an increasing number of laboratories to adopt this technology for HIV drug resistance (HIVDR) genotyping. Conventional HIVDR genotyping is traditionally carried out using population-based Sanger sequencing, which has a limited capacity for reliable detection of variants present at intra-host frequencies below a threshold of approximately 20%. NGS has the potential to improve sensitivity and quantitatively identify low-abundance variants, improving efficiency and lowering costs. However, some challenges exist for the standardization and quality assurance of NGS-based HIVDR genotyping. In this paper, we highlight considerations of these challenges as related to laboratory, clinical, and implementation of NGS for HIV drug resistance testing. Several sources of variation and bias occur in each step of the general NGS workflow, i.e., starting material, sample type, PCR amplification, library preparation method, instrument and sequencing chemistry-inherent errors, and data analysis options and limitations. Additionally, adoption of NGS-based HIVDR genotyping, especially for clinical care, poses pressing challenges, especially for resource-poor settings, including infrastructure and equipment requirements and cost, logistic and supply chains, instrument service availability, personnel training, validated laboratory protocols, and standardized analysis outputs. The establishment of external quality assessment programs may help to address some of these challenges and is needed to proceed with NGS-based HIVDR genotyping adoption.

Prevalence of HIV-1 Drug Resistance among Patients with Antiretroviral Therapy Failure in Sichuan, China, 2010-2016

Antiretroviral therapy (ART) has been introduced recently and has significantly impacted morbidity and mortality, but can also engender drug resistance. To identify the prevalence of HIV-1 drug resistance (HIVDR) among patients with antiretroviral therapy failure in Sichuan during the period from 2010 to 2016, we carried out a longitudinal study in Sichuan, a province with the highest HIV/AIDS prevalence in China. The data and blood samples were collected from HIV/AIDS patients who received ART for more than half a year. Overall 5,512 sequences were completed from 7,059 ART-failure patients, and 2,499 individuals were identified as drug resistant. Among those with HIVDR mutations identified, 25.37% were against non-nucleoside reverse transcriptase inhibitors (NNRTIs), and 1.60% was against nucleoside reverse transcriptase inhibitors (NRTIs). NRTI-resistant drugs were mainly lamivudine (3TC) (57.77%) and emtricitabine (FTC), while NNRTI-resistant drugs were mainly nevirapine (NVP) (91.13%) and efavirenz (EFV) (72.81%). The most common recombination subtypes of HIV-1 in sequenced samples were CRF07_BC (circulating recombinant form, CRF) (41.42%), followed by CRF01_AE (40.77%). Moreover, drug resistance rate increased with the prolongation of treatment time (χ² = 14.758, P < 0.05). The overall prevalence of acquired drug resistance in HIV-1 infected patients in Sichuan was 5.47%, which has remained relatively stable from 2010 to 2016. HIV-1 CRF01_AE and CRF07_BC subtypes were the main epidemic strains, and the possibility of resistance was higher in CRF01_AE subtypes. The current study highlights the importance of acquired drug resistance surveillance over a long period.

Diagnosis of Human Immunodeficiency Virus Infection

HIV diagnostics have played a central role in the remarkable progress in identifying, staging, initiating, and monitoring infected individuals on life-saving antiretroviral therapy. They are also useful in surveillance and outbreak responses, allowing for assessment of disease burden and identification of vulnerable populations and transmission "hot spots," thus enabling planning, appropriate interventions, and allocation of appropriate funding. HIV diagnostics are critical in achieving epidemic control and require a hybrid of conventional laboratory-based diagnostic tests and new technologies, including point-of-care (POC) testing, to expand coverage, increase access, and positively impact patient management. In this review, we provide (i) a historical perspective on the evolution of HIV diagnostics (serologic and molecular) and their interplay with WHO normative guidelines, (ii) a description of the role of conventional and POC testing within the tiered laboratory diagnostic network, (iii) information on the evaluations and selection of appropriate diagnostics, (iv) a description of the quality management systems needed to ensure reliability of testing, and (v) strategies to increase access while reducing the time to return results to patients. Maintaining the central role of HIV diagnostics in programs requires periodic monitoring and optimization with quality assurance in order to inform adjustments or alignment to achieve epidemic control.

Robust and sensitive subtype-generic HIV-1 pol genotyping for use with dried serum spots in epidemiological studies

HIV-1 genotyping of larger pol-fragments from dried serum/plasma spots (DSS/DPS) is often hindered by RNA-degradation during transportation at ambient temperature. We evaluated an in-house HIV-1 DSS/DPS-genotyping assay designed in two shorter overlapping fragments covering all resistance mutations in protease and reverse transcriptase. Validation criteria such as specificity, detection limit, accuracy, reproducibility and storage conditions were assessed using reference plasma samples prepared as DPS and clinical DSS from the German molecular HIV-1 surveillance processed under real-life transportation conditions. The specificity was 100% for both samples types, and the experimental DPS detection limit of 1000 copies/ml yielded a 98.7% (3,329/3373) success rate for DSS (including all subtypes) above this detection limit. Accuracy for DPS compared to the gold standard was 99.1% and the reproducibility was 100% for DPS replicates and 99.9% for DSS pairs. Storage of DPS at room temperature was possible for 90 or 30 days and at -20 °C for at least 180 or 90 days at viral loads of 10,000 or 1000 copies/ml, respectively. The HIV-1 pol-genotyping assay presented here is a sensitive, robust and subtype generic tool for a large-scale population-based HIV-1 drug resistance surveillance for the use of DSS/DPS.

Improved prediction of gestational hypertension by inclusion of placental growth factor and pregnancy associated plasma protein-a in a sample of Ghanaian women

BACKGROUND

We assessed whether adding the biomarkers Pregnancy Associated Plasma Protein-A (PAPP-A) and Placental Growth Factor (PlGF) to maternal clinical characteristics improved the prediction of a previously developed model for gestational hypertension in a cohort of Ghanaian pregnant women.

METHODS

This study was nested in a prospective cohort of 1010 pregnant women attending antenatal clinics in two public hospitals in Accra, Ghana. Pregnant women who were normotensive, at a gestational age at recruitment of between 8 and 13 weeks and provided a blood sample for biomarker analysis were eligible for inclusion. From serum, biomarkers PAPP-A and PlGF concentrations were measured by the AutoDELFIA immunoassay method and multiple of the median (MoM) values corrected for gestational age (PAPP-A and PlGF) and maternal weight (PAPP-A) were calculated. To obtain prediction models, these biomarkers were included with clinical predictors maternal weight, height, diastolic blood pressure, a previous history of gestational hypertension, history of hypertension in parents and parity in a logistic regression to obtain prediction models. The Area Under the Receiver Operating Characteristic Curve (AUC) was used to assess the predictive ability of the models.

RESULTS

Three hundred and seventy three women participated in this study. The area under the curve (AUC) of the model with only maternal clinical characteristics was 0.75 (0.64-0.86) and 0.89(0.73-1.00) for multiparous and primigravid women respectively. The AUCs after inclusion of both PAPP-A and PlGF were 0.82 (0.74-0.89) and 0.95 (0.87-1.00) for multiparous and primigravid women respectively.

CONCLUSION

Adding the biomarkers PAPP-A and PlGF to maternal characteristics to a prediction model for gestational hypertension in a cohort of Ghanaian pregnant women improved predictive ability. Further research using larger sample sizes in similar settings to validate these findings is recommended.

High Levels of Dual-Class Drug Resistance in HIV-Infected Children Failing First-Line Antiretroviral Therapy in Southern Ethiopia

Clinical monitoring of pediatric HIV treatment remains a major challenge in settings where drug resistance genotyping is not routinely available. As a result, our understanding of drug resistance, and its impact on subsequent therapeutic regimens available in these settings, remains limited. We investigate the prevalence and correlates of HIV-1 drug resistance among 94 participants of the Ethiopia Pediatric HIV Cohort failing first-line combination antiretroviral therapy (cART) using dried blood spot-based genotyping. Overall, 81% (73/90) of successfully genotyped participants harbored resistance mutations, including 69% (62/90) who harbored resistance to both Nucleoside Reverse Transcriptase Inhibitors (NRTIs) and Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs). Strikingly, 42% of resistant participants harbored resistance to all four NRTIs recommended for second-line use in this setting, meaning that there are effectively no remaining cART options for these children. Longer cART duration and prior regimen changes were significantly associated with detection of drug resistance mutations. Replicate genotyping increased the breadth of drug resistance detected in 34% of cases, and thus is recommended for consideration when typing from blood spots. Implementation of timely drug resistance testing and access to newer antiretrovirals and drug classes are urgently needed to guide clinical decision-making and improve outcomes for HIV-infected children on first-line cART in Ethiopia.

Alternative Sample Types for HIV-1 Antiretroviral Drug Resistance Testing

Monitoring human immunodeficiency virus type 1 (HIV-1) drug resistance is critical for assessing ART effectiveness and treatment outcomes for HIV-1-infected individuals, including children, worldwide. Traditionally, testing for HIV-1 drug resistance has primarily been performed on plasma samples, and with commercially available, clinically validated assays that are costly and difficult to access. While plasma is the preferred sample for HIV-1 drug resistance genotyping, plasma analysis requires sophisticated laboratory equipment, personnel, space, and stringent storage conditions for maintenance of sample integrity and transport. With the limitations in feasibility and affordability of providing these ideal conditions for plasma genotyping in resource-constrained settings, the field has gained substantial experience with the dried blood spot (DBS) technique as an alternative. Moreover, DBS analysis can be used to comprehensively monitor the spread of the epidemic with applications to more-sensitive and quantitative technologies to assess HIV-1 globally.

Use of Dried Plasma Spots for HIV-1 Viral Load Determination and Drug Resistance Genotyping in Mexican Patients

Monitoring antiretroviral therapy using measurements of viral load (VL) and the genotyping of resistance mutations is not routinely performed in low- to middle-income countries because of the high costs of the commercial assays that are used. The analysis of dried plasma spot (DPS) samples on filter paper may represent an alternative for resource-limited settings. Therefore, we evaluated the usefulness of analyzing DPS samples to determine VL and identify drug resistance mutations (DRM) in a group of HIV-1 patients. The VL was measured from 22 paired plasma and DPS samples. In these samples, the average VL was 4.7 log₁₀ copies/mL in liquid plasma and 4.1 log₁₀ copies/mL in DPS, with a correlation coefficient of R = 0.83. A 1.1 kb fragment of HIV pol could be amplified in 14/22 (63.6%) of the DPS samples and the same value was amplified in plasma samples. A collection of ten paired DPS and liquid plasma samples was evaluated for the presence of DRM; an excellent correlation was found in the identification of DRM between the paired samples. All HIV-1 pol sequences that were obtained corresponded to HIV subtype B. The analysis of DPS samples offers an attractive alternative for monitoring ARV therapy in resource-limited settings.

HemaSpot, a Novel Blood Storage Device for HIV-1 Drug Resistance Testing

HemaSpot, a novel dried-blood storage filter device, was used for HIV-1 pol resistance testing in 30 fresh United States blood samples and 54 previously frozen Kenyan blood samples. Genotyping succeeded in 79% and 58% of samples, respectively, improved with shorter storage and higher viral load, and had good (86%) resistance mutation concordance to plasma.

Stability of HIV-1 Nucleic Acids in Dried Blood Spot Samples for HIV-1 Drug Resistance Genotyping

Dried blood spots (DBS) are an easy to collect sample-type that can stabilize biological material at ambient temperature for transport and storage, making them ideal for use in resource-limited settings (RLS). We investigated the effect of storage temperature and duration on ability to detect mixed HIV-1 viral RNA populations, and subsequently viral RNA populations in a background of proviral DNA. Part one of the study used DBS samples of whole blood spiked with specific quantities of HIV-1 subtype-B and -C RNA to study mixed virus population detection. Part two used DBS comprising of HIV-1 subtype-B proviral DNA containing U1 cells combined with HIV-1 subtype-C RNA to mimic HIV-1 infected clinical samples as a model system to study the relative stability of HIV-1 RNA and DNA in DBS. Prepared DBS were stored at -20 °C and +30 °C for periods of one day, one, two, and four weeks. Samples were genotyped to determine changes in the detection of mixtures in the sample over time. From two weeks onwards, storage at +30 °C resulted in gradual, time-related reduction in the detection of mixed virus population at log10 VL 4.0 but not at log10 5.0. Proviral DNA and viral RNA were both stable for at least 52 weeks when stored at -20 °C, compared to progressive RNA decay over time at +30 °C. DBS storage conditions and duration had a significant effect on HIV-1 RNA amplification. Our results demonstrate that DBS storage at ambient temperature (+30 °C) should not exceed two weeks, with long-term storage at -20 °C or lower.

Field study of dried blood spot specimens for HIV-1 drug resistance genotyping

Dried blood spots (DBS) are an alternative specimen type for HIV drug resistance genotyping in resource-limited settings. Data relating to the impact of DBS storage and shipment conditions on genotyping efficiency under field conditions are limited. We compared the genotyping efficiencies and resistance profiles of DBS stored and shipped at different temperatures to those of plasma specimens collected in parallel from patients receiving antiretroviral therapy in Uganda. Plasma and four DBS cards from anti-coagulated venous blood and a fifth card from finger-prick blood were prepared from 103 HIV patients with a median viral load (VL) of 57,062 copies/ml (range, 1,081 to 2,964,191). DBS were stored at ambient temperature for 2 or 4 weeks or frozen at -80 °C and shipped from Uganda to the United States at ambient temperature or frozen on dry ice for genotyping using a broadly sensitive in-house method. Plasma (97.1%) and DBS (98.1%) stored and shipped frozen had similar genotyping efficiencies. DBS stored frozen (97.1%) or at ambient temperature for 2 weeks (93.2%) and shipped at ambient temperature also had similar genotyping efficiencies. Genotyping efficiency was reduced for DBS stored at ambient temperature for 4 weeks (89.3%, P = 0.03) or prepared from finger-prick blood and stored at ambient temperature for 2 weeks (77.7%, P < 0.001) compared to DBS prepared from venous blood and handled similarly. Resistance profiles were similar between plasma and DBS specimens. This report delineates the optimal DBS collection, storage, and shipping conditions and opens a new avenue for cost-saving ambient-temperature DBS specimen shipments for HIV drug resistance (HIVDR) surveillances in resource-limited settings.

Evaluation of a dried blood and plasma collection device, SampleTanker(®), for HIV type 1 drug resistance genotyping in patients receiving antiretroviral therapy

Whatman 903 filter paper is the only filter paper that has been used for HIV drug resistance (HIVDR) genotyping in resource-limited settings. In this study, we evaluated another dried blood specimen collection device, termed SampleTanker(®) (ST), for HIVDR genotyping. Blood specimens from 123 antiretroviral therapy (ART)-experienced patients were used to prepare ST whole blood and ST plasma specimens; they were then stored at ambient temperature for 2 or 4 weeks. The remaining plasma specimens were stored at -80°C and used as frozen plasma controls. Frozen plasma viral load (VL) was determined using the Roche Amplicor HIV-1 Monitor test, v.1.5 and 50 specimens with VL ≥3.00 log10 copies/ml were genotyped using the broadly sensitive genotyping assay. The medium VL for the 50 frozen plasma specimens with VL ≥3.00 log10 was 3.58 log10 copies/ml (IQR: 3.32-4.11) and 96.0% (48/50) of them were genotyped. Comparing to frozen plasma specimens, significantly lower genotyping rates were obtained from ST whole blood (48.98% and 42.85%) and ST plasma specimens (36.0% and 36.0%) stored at ambient temperature for 2 and 4 weeks, respectively (p<0.001). Nucleotide sequence identity and resistance profile analyses between the matched frozen plasma and ST whole blood or ST plasma specimens revealed high nucleotide sequence identities and concordant resistance profiles (98.1% and 99.0%, and 96.6% and 98.9%, respectively). Our results indicate that with the current design, the ST may not be the ideal dried blood specimen collection device for HIVDR monitoring for ART patients in resource-limited settings.

Pyrosequencing dried blood spots reveals differences in HIV drug resistance between treatment naïve and experienced patients

Dried blood spots (DBS) are an alternative specimen collection format for HIV-1 genotyping. DBS produce HIV genotyping results that are robust and equivalent to plasma when using conventional sequencing methods. However, using tagged, pooled pyrosequencing, we demonstrate that concordance between plasma and DBS is not absolute and varies according to viral load (VL), duration of HIV infection and antiretroviral therapy (ART) status. The plasma/DBS concordance is the highest when VL is ≥5,000 copies/ml and/or the patient has no ART exposure and/or when the duration of HIV infection is ≤2 years. Stepwise regression analysis revealed that VL is most important independent predictor for concordance of DBS with plasma genotypes. This is the first study to use next generation sequencing to identify discordance between DBS and plasma genotypes. Consideration should be given to VL, duration of infection, and ART exposure when interpreting DBS genotypes produced using next generation sequencing. These findings are of particular significance when DBS are to be used for clinical monitoring purposes.

Field evaluation of a broadly sensitive HIV-1 in-house genotyping assay for use with both plasma and dried blood spot specimens in a resource-limited country

HIV-1 drug resistance (HIVDR) assays are important tools in clinical management of HIV-infected patients on antiretroviral therapy (ART) and surveillance of drug-resistant variants at population levels. The high cost associated with commercial assays hinders their use in resource-limited settings. We adopted and validated a low-cost in-house assay using 68 matched plasma and dried blood spot (DBS) samples with a median viral load (VL) of 58,187 copies/ml, ranging from 253 to 3,264,850 against the commercial assay ViroSeq. Results indicated that the in-house assay not only had a higher plasma genotyping rate than did ViroSeq (94% versus 78%) but also was able to genotype 89.5% (51/57) of the matched DBS samples with VLs of ≥ 1,000 copies/ml. The sensitivity in detecting DR mutations by the in-house assay was 98.29% (95% confidence interval [CI], 97.86 to 98.72) on plasma and 96.54 (95% CI, 95.93 to 97.15) on DBS, and the specificity was 99.97% (95% CI, 99.91 to 100.00) for both sample types compared to ViroSeq. The minor DR mutation differences detected by the in-house assay against ViroSeq did not result in clinical significance. In addition, cost analysis showed that the in-house assay could reduce the genotyping cost by about 60% for both plasma and DBS compared to ViroSeq. This field condition evaluation highlights the potential utility of a cost-effective, subtype-independent, in-house genotyping assay using both plasma and DBS specimens for HIVDR clinical monitoring and population-based surveillance in resource-limited settings.

Genotyping external quality assurance in the World Health Organization HIV drug resistance laboratory network during 2007-2010

The World Health Organization (WHO) has developed a global laboratory network to support human immunodeficiency virus drug resistance genotyping for public health surveillance in resource-limited countries. Blinded proficiency panels are an essential part of a genotyping quality-assurance program and are used to monitor the reliability of genotyping data in the WHO laboratory network. Laboratories in Europe, North America, Asia, Africa, and the Caribbean have tested panels annually since 2007; 103 of 131 submissions (79%) had >99% nucleotide sequence identity and resistance mutation concordance, compared with consensus. Most errors were associated with mixtures in the test specimen, leading to subjectivity in base-calling or amplification bias. Overall, genotyping assays used by the WHO laboratory network are reliable.

Comparison of Ahlstrom grade 226, Munktell TFN, and Whatman 903 filter papers for dried blood spot specimen collection and subsequent HIV-1 load and drug resistance genotyping analysis

Dried blood spots (DBS) collected onto filter paper have eased the difficulty of blood collection in resource-limited settings. Currently, Whatman 903 (W-903) filter paper is the only filter paper that has been used for HIV load and HIV drug resistance (HIVDR) testing. We therefore evaluated two additional commercially available filter papers, Ahlstrom grade 226 (A-226) and Munktell TFN (M-TFN), for viral load (VL) testing and HIVDR genotyping using W-903 filter paper as a comparison group. DBS specimens were generated from 344 adult patients on antiretroviral therapy (ART) in Botswana. The VL was measured with NucliSENS EasyQ HIV-1 v2.0, and genotyping was performed for those specimens with a detectable VL (≥ 2.90 log(10) copies/ml) using an in-house method. Bland-Altman analysis revealed a strong concordance in quantitative VL analysis between W-903 and A-226 (bias = -0.034 ± 0.246 log(10) copies/ml [mean difference ± standard deviation]) and W-903 and M-TFN (bias = -0.028 ± 0.186 log(10) copies/ml) filter papers, while qualitative VL analysis for virological failure determination, defined as a VL of ≥ 3.00 log(10) copies/ml, showed low sensitivities for A-266 (71.54%) and M-TFN (65.71%) filter papers compared to W-903 filter paper. DBS collected on M-TFN filter paper had the highest genotyping efficiency (100%) compared to W-903 and A-226 filter papers (91.7%) and appeared more sensitive in detecting major HIVDR mutations. DBS collected on A-226 and M-TFN filter papers performed similarly to DBS collected on W-903 filter paper for quantitative VL analysis and HIVDR detection. Together, the encouraging genotyping results and the variability observed in determining virological failure from this small pilot study warrant further investigation of A-226 and M-TFN filter papers as specimen collection devices for HIVDR monitoring surveys.

Characterization of HIV-1 subtypes and drug resistance mutations among individuals infected with HIV in Georgia

In order to describe HIV-1 subtypes and drug resistance mutations in Georgia, blood samples from 153 patients infected with HIV-1 collected from 2006 to 2008 were genotyped. Of these, 126 samples were from newly diagnosed, antiretroviral (ARV)-naïve patients and 27 from ARV-treated patients. Partial pol region sequences were used to identify drug resistance mutations and to conduct phylogenetic analysis for subtype determination. The results indicated that 138 (90.2%) patients harbored subtype A viruses, 11 (7.2%) carried subtype B virus, two subtype G (1.3%), one (0.6%) subtype F and one (0.6%) 03_AB recombinant. All subtype A strains clustered with the Former Soviet Union A (A FSU) subtype. Among patients with no prior exposure to ARVs, mutations associated with resistance were detected in five patients: three (2.4%) patients had reverse transcriptase (RT) inhibitor mutations and two other patients had the protease (PI) inhibitor associated mutation M46I. PI mutation V77I was found in 42 of subtype A isolates. Of 27 ARV-treated patients, 22 (81.5%) harbored at least one nucleoside reverse transcriptase inhibitors (NRTI), a non-NRTI (NNRTI) and/or a PI mutation. The most common NRTI resistance mutation was M184V/I (74.1%). Frequency of thymidine analog mutations was relatively low (25.9%). With regard to NNRTI mutations, G190S/A was the most frequent mutation, which might be a preferred mutations for subtype A. Georgia's HIV epidemic continues to be dominated by Subtype A FSU. The prevalence of transmitted drug resistance is low, but has the potential to increase with increasing use of ARVs.

[Dried blood spots for monitoring HIV infection in Public Health Programs in developing countries]

As access to antiretroviral treatment increases in the developing countries, efforts towards making it easier and less costly to collect, store, and deliver the biological samples to reference laboratories, where the serological and genetic diagnosis techniques are performed, have become a high priority. Blood sampling on filter papers is an inexpensive and practical alternative to plasma for antiretroviral treatment monitoring in countries with limited resources and no access to cold chains or refrigeration. The main clinical applications and uses of blood-sampling onto filter papers (dried blood spots [DBS]) are reviewed, focusing on how these can be applied in monitoring HIV infection, particularly for use in National Health Programs in developing countries, or in resource-limited settings. A review is presented of studies that have used the DBS technique for quantifying viral load, analysis of antiretroviral drug-resistance mutations, early infant diagnosis, adult serological diagnosis, detection of viral p24 antigen, and molecular epidemiology of HIV-1, in different geographical locations. Those variables that could affect the use of DBS, particularly in the HIV field, as well as explaining how these procedures can be optimised to increase their sensitivity are also reviewed. The aim of this study was to review the advantages of implementing the DBS technique in the HIV field, especially in resource-constrained regions.

Dried blood spot specimens are a suitable alternative sample type for HIV-1 viral load measurement and drug resistance genotyping in patients receiving first-line antiretroviral therapy

BACKGROUND

Antiretroviral therapy (ART) is being administered in developing nations at unprecedented numbers following the World Health Organization's (WHO) development of standardized first-line drug regimens. To ensure continued efficacy of these drug regimens, WHO recommends monitoring virological responses and development of human immunodeficiency virus (HIV) drug resistance (HIVDR) in HIV-infected patients in a prospective cohort. The current study compared dried fluid spot specimens with the reference standard plasma specimens as a practical tool for viral load (VL) and HIVDR genotyping in resource-limited settings.

METHODS

Dried blood spot (DBS), dried plasma spot (DPS), and plasma specimens were collected from 173 -patients receiving ART at 2 hospital sites in Abuja, Nigeria. HIV-1 VL analysis was performed using NucliSENS EasyQ HIV-1 v1.1 RUO test kits. Genotyping of the HIV-1 pol gene was performed using a broadly sensitive in-house assay.

RESULTS

Direct comparison of VL levels showed that DBS specimens, and not DPS specimens, gave results comparable to those of plasma specimens (P = .0619 and .0007, respectively); however, both DBS and DPS specimens had excellent correlation with plasma specimens in predicting virological failure (VL, ≥1000 copies/mL) in patients (κ = 0.78 and 0.83, respectively). Of the 18 specimens with a plasma VL ≥1000 copies/mL, HIVDR genotyping rates were 100% in DBS and 38.9% in DPS specimens, and DBS specimens identified 61 of 65 HIVDR mutations (93.8%) identified in plasma specimens.

CONCLUSIONS

Our results indicate that DBS specimens could be used for surveys to monitor HIVDR prevention failure in resource-limited settings.

Development and evaluation of an assay for HIV-1 protease and reverse transcriptase drug resistance genotyping of all major group-M subtypes

BACKGROUND

High cost and varying sensitivity for non-B HIV-1 subtypes limits application of current commercial kits for HIV-1 drug resistance genotyping of all major HIV-1 group-M subtypes.

OBJECTIVES

Our research aimed to develop and validate an assay specific for all major HIV-1 group-M subtypes for use as an alternative to commercial assays for HIV-1 protease (PR) and reverse transcriptase (RT) drug resistance genotyping.

STUDY DESIGN

A nested RT-PCR encompassing the entire PR and RT up to amino acid 321 of HIV-1 was designed to detect HIV-1 group-M subtypes. Primers compatible with group-M subtypes were defined and analytical sensitivity of the assay evaluated using a panel of reference viruses for subtypes A-H and CRF01_AE. The assay was subsequently evaluated on 246 plasma samples from HIV-1 infected individuals harboring various group-M subtypes and viral loads (VLs).

RESULTS

All major group-M HIV-1 subtypes were detected with an overall analytical sensitivity of 1.00E+03 RNA copies/ml. Application of the genotyping assay on 246 primarily African clinical samples comprising subtypes A (n=52; 21.7%), B (n=12; 5.0%), C (n=127; 52.9%), D (n=25; 10.4%), CRF01_AE (n=10; 4.2%), and CRF02_AG (n=10; 4.2%), and unassigned variants (n=10; 4.2%), VL range 4.32E+02-8.63E+06 (median 2.66E+04) RNA copies/ml, was ∼98% successful.

CONCLUSIONS

A group-M subtype-independent genotyping assay for detection of HIV-1 drug resistance was developed. The described assay can serve as an alternative to commercial assays for HIV-1 drug resistance genotyping in routine diagnostics, and for surveillance and monitoring of drug resistance in resource-limited settings (RLS).

Description of two commercially available assays for genotyping of HIV-1

HIV-1 resistance testing is one important part in the diagnostics of antiretroviral treatment and is commonly done by genotyping. Currently, two systems are commercially available and, despite being far from easy to use, these have achieved a high degree of sophistication. Modifications of standard kit protocols might be necessary based on the clinical situation. Although resistance reports based on decision rules are a part of both systems, considerable knowledge and skills are nevertheless required by the user to establish useful clinical data out of detected resistance patterns. Both systems described here have their advantages and disadvantages; a decision for one or the other system needs to be based on individual requirements. The future might lie in so-called 'next-generation sequencing' systems based on pyrosequencing, which enable a high throughput and the detection of minor variants of less than 1%.

Comparison of HIV-1 RNA measurements obtained by using plasma and dried blood spots in the automated abbott real-time viral load assay

Dried blood spots (DBS) may be a promising alternative specimen type to plasma for measuring the viral load (VL) in HIV-infected individuals in resource-limited settings. However, characterization of assay performance using DBS is incomplete. In this prospective study, the VL was measured in parallel using plasma and DBS specimens collected at the same time from 157 HIV-1-infected individuals. DBS were prepared by dispensing 50 μl of blood onto filter paper cards and were stored desiccated at -20°C. Nucleic acid extraction from plasma and DBS was performed automatically using the Abbott m2000sp instrument, and the VL was measured using the RealTime HIV-1 VL assay, which has a lower limit of detection of 40 HIV RNA copies/ml. The correlation between plasma and DBS results was good (R = 0.91; P < 0.001). The mean difference in the VL (DBS minus plasma) was 0.35 log copies (standard deviation [SD], 0.47 log copies). A total of 40 (26%) paired specimens had a difference of >0.5 log copy, and in 12 (7.8%) it was >1 log copy. the VL from DBS was measurable in 95.7% of specimens with a plasma VL of >2.74 log copies (550 HIV RNA copies/ml). In summary, the VL can reliably be measured using DBS with the Abbott RealTime HIV-1 assay. The estimated lower limit of detection of this automated methodology on DBS is 550 copies/ml, a threshold that may be acceptable for periodic VL monitoring in patients on antiretroviral therapy in resource-limited settings, where early detection of virologic treatment failure is often problematic.

Optimization of a low cost and broadly sensitive genotyping assay for HIV-1 drug resistance surveillance and monitoring in resource-limited settings

Commercially available HIV-1 drug resistance (HIVDR) genotyping assays are expensive and have limitations in detecting non-B subtypes and circulating recombinant forms that are co-circulating in resource-limited settings (RLS). This study aimed to optimize a low cost and broadly sensitive in-house assay in detecting HIVDR mutations in the protease (PR) and reverse transcriptase (RT) regions of pol gene. The overall plasma genotyping sensitivity was 95.8% (N = 96). Compared to the original in-house assay and two commercially available genotyping systems, TRUGENE® and ViroSeq®, the optimized in-house assay showed a nucleotide sequence concordance of 99.3%, 99.6% and 99.1%, respectively. The optimized in-house assay was more sensitive in detecting mixture bases than the original in-house (N = 87, P<0.001) and TRUGENE® and ViroSeq® assays. When the optimized in-house assay was applied to genotype samples collected for HIVDR surveys (N = 230), all 72 (100%) plasma and 69 (95.8%) of the matched dried blood spots (DBS) in the Vietnam transmitted HIVDR survey were genotyped and nucleotide sequence concordance was 98.8%; Testing of treatment-experienced patient plasmas with viral load (VL) ≥ and <3 log10 copies/ml from the Nigeria and Malawi surveys yielded 100% (N = 46) and 78.6% (N = 14) genotyping rates, respectively. Furthermore, all 18 matched DBS stored at room temperature from the Nigeria survey were genotyped. Phylogenetic analysis of the 236 sequences revealed that 43.6% were CRF01_AE, 25.9% subtype C, 13.1% CRF02_AG, 5.1% subtype G, 4.2% subtype B, 2.5% subtype A, 2.1% each subtype F and unclassifiable, 0.4% each CRF06_CPX, CRF07_BC and CRF09_CPX.

Evaluation of the Dried Blood Spot (DBS) Collection Method as a Tool for Detection of HIV Ag/Ab, HBsAg, anti-HBs and anti-HCV in a Malaysian Tertiary Referral Hospital

Introduction: Dried blood spot (DBS) collection is an appealing alternative to whole blood or plasma sampling, as it has technical and economic advantages over the latter. Materials and Methods: A prospective cross-sectional study was conducted at a Malaysian tertiary referral hospital from November 2009 to March 2010. One hundred and fifty paired specimens of DBS and plasma were analysed by the standard assays for HIV Ag/Ab, HBsAg, anti-HBS and anti-HCV, separately (total 600 paired specimens). DBS sample titres were then compared to the results of plasma testing, which was used as the gold standard. Results: For the HIV Ag/Ab assay with a cut-off point of 0.35 Relative Light Units (RLUs), the sensitivity and specificity were both 100%. For the HBsAg assay, the sensitivity was 96.5% and the specificity was 97.8%, with a cut-off point of 1.72 RLUs. Sensitivity for the anti-HBs test was 74.2% and the specificity was 86.9%, using a cut-off point of 0.635 RLUs. For the anti-HCV assay, the sensitivity was 97.3% and the specificity was 100%, with a cut-off point of 0.10 RLUs. Conclusion: DBS is an ideal choice to be used as a screening tool for the detection of HIV, Hepatitis B and Hepatitis C virus infections. However, different cut-off values need to be used for the validation of test positivity in DBS samples because the small amount of blood in the DBS specimens leads to lower assay titres. Key words: Anti-HBs, Anti-HCV, dried blood spot (DBS), HBsAg, Human immunodeficiency virus (HIV), HIV Ag/Ab

Dried blood spots in HIV monitoring: applications in resource-limited settings

By the end of 2008, 4 million people were receiving antiretroviral treatment for HIV/AIDS in low- and middle-income countries. In industrialized countries, monitoring of treatment with viral load measurements and drug resistance testing is the standard of care to ensure early detection of treatment failure and a prompt switch to a fully active second-line regimen, before drug-resistant mutations accumulate. These tests, however, require highly specialized laboratories and stringent procedures for storage and shipment of plasma, and are rarely available in resource-limited settings. Therefore, treatment failure in such settings is usually not detected until patients develop severe immunodeficiency, at which stage widespread resistance is likely. Dried blood spots (DBS) are easy to collect and store, and can be a convenient alternative to plasma in settings with limited laboratory capacity. This review provides an overview of possible applications of DBS technologies in the monitoring of HIV treatment, with the main focus on viral load quantification and drug resistance testing.

Minority HIV mutation detection in dried blood spots indicates high specimen integrity and reveals hidden archived drug resistance

BACKGROUND

Dried blood spots (DBS) could serve as an attractive, cost-effective alternative to plasma for HIV drug resistance testing.

OBJECTIVES

To assess the utility and potential gain in genotypic information with sensitive testing of DBS compared to conventional bulk plasma genotyping, and examine the correlation of majority and minority-level resistance mutations in DBS with treatment history.

STUDY DESIGN

Evaluate nucleic acids from the DBS of 33 antiretroviral-experienced subtype B-infected subjects for minority M41L, K65R, K70R, K103N, Y181C, M184V, and T215Y/F mutations by real-time PCR. Compare minority resistance mutations in DBS with bulk genotypes from the same DBS cards and available plasma specimens.

RESULTS

All but one (50/51, 98%) mutation from the original plasma bulk sequencing were still detectable in the DBS after three years of storage. The one mutation not identified in DBS was also no longer detectable by bulk sequencing. Furthermore, sensitive testing found 12 additional drug resistance mutations at minority levels in the DBS of 11 (33%) patients. Six minority mutations were in the RNA compartment and six were detected only in the DNA compartment. Resistance was detected in the DBS RNA compartment only in cases where the associated drug was in use within one year of sample collection.

CONCLUSIONS

Our ability to identify majority and additional minority-level resistance mutations demonstrated that DBS, if stored properly, is a high-integrity specimen type for conventional and sensitive drug resistance testing. Our data further support the global utility of DBS for drug resistance surveillance and clinical monitoring.

Development and application of a broadly sensitive dried-blood-spot-based genotyping assay for global surveillance of HIV-1 drug resistance

As antiretroviral therapy (ART) is scaled up in resource-limited countries, surveillance for HIV drug resistance (DR) is vital to ensure sustained effectiveness of first-line ART. We have developed and applied a broadly sensitive dried-blood-spot (DBS)-based genotyping assay for surveillance of HIV-1 DR in international settings. In 2005 and 2006, 171 DBS samples were collected under field conditions from newly diagnosed HIV-1-infected individuals from Malawi (n = 58), Tanzania (n = 60), and China (n =53). In addition, 30 DBS and 40 plasma specimens collected from ART patients in China and Cameroon, respectively, were also tested. Of the 171 DBS analyzed at the protease and RT regions, 149 (87.1%) could be genotyped, including 49 (81.7%) from Tanzania, 47 (88.7%) from China, and 53 (91.4%) from Malawi. Among the 70 ART patient samples analyzed, 100% (30/30) of the Chinese DBS and 90% (36/40) of the Cameroonian plasma specimens were genotyped, including 8 samples with a viral load of <400 copies/ml. The results of phylogenetic analyses indicated that the subtype, circulating recombinant form (CRF), and unique recombinant form (URF) distribution was as follows: 73 strains were subtype C (34%), 37 were subtype B (17.2%), 24 each were CRF01_AE or CRF02_AG (11.2% each), 22 were subtype A1 (10.2%), and 9 were unclassifiable (UC) (4.2%). The remaining samples were minor strains comprised of 6 that were CRF07_BC (2.8%), 5 that were CRF10_CD (2.3%), 3 each that were URF_A1C and CRF08_BC (1.4%), 2 each that were G, URF_BC, and URF_D/UC (0.9%), and 1 each that were subtype F1, subtype F2, and URF_A1D (0.5%). Our results indicate that this broadly sensitive genotyping assay can be used to genotype DBS collected from areas with diverse HIV-1 group M subtypes and CRFs. Thus, the assay is likely to become a useful screening tool in the global resistance surveillance and monitoring of HIV-1 where multiple subtypes and CRFs are found.

Dried blood spot for hepatitis C virus serology and molecular testing

We investigated the performance of dried blood spots (DBS) in hepatitis C virus (HCV) diagnosis using modified commercial tests. Paired DBS and serum samples were collected from 200 patients: 100 patients with anti-HCV antibodies (anti-HCV), including 62 patients with detectable serum HCV RNA, and 100 patients without anti-HCV. The DBS sample consisted of three drops of approximately 50 microL of whole blood applied to a paper card, which was then stored at -20 degrees C within 48 hours of collection. Using the Ortho HCV 3.0 enzyme-linked immunosorbent assay kit on DBS, we observed both a specificity and sensitivity of 99% in detecting anti-HCV. HCV RNA was detected on DBS in 60/62 (97%) patients with detectable serum HCV RNA, which was then successfully quantified in 55 samples (89%) using the Cobas TaqMan HCV test. A good correlation was observed between the DBS HCV RNA concentration and the serum level (r(2) = 0.95; P < 0.001). HCV genotyping was successfully performed on DBS samples, with a full concordance between the 14 paired DBS and serum samples (genotypes 1-4).

CONCLUSION

This study presents DBS as a reliable alternative to serum specimens for detecting anti-HCV, quantifying HCV RNA and genotyping HCV. DBS may increase the opportunities for HCV testing and treatment follow-up in hard-to-reach individuals.

HIV-1 and HCV detection in dried blood spots by SYBR Green multiplex real-time RT-PCR

Dried blood spot (DBS) is a reliable method of blood collection used for the diagnosis of several human diseases. DBS is particularly useful for diagnosing children and for the screening of high-risk populations especially in countries where health facilities are not readily accessible. This report describes a qualitative SYBR Green-based real-time multiplex RT-PCR for the simultaneous detection of hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) genomes in DBS. Specific viral amplicons were identified in the same sample by their distinctive melting temperatures. The analysis of scalar concentrations of the reference samples indicated that this multiplex procedure detects at least 2500 copies/ml of HCV and 400 copies/ml of HIV-1. HIV-1 and HCV viral loads in 20 patients infected with HIV-1 and/or HCV and in 5 healthy blood donors were also tested, confirming the sensitivity and specificity of the assay. This method may represent a reliable alternative for the detection of HIV-1/HCV co-infection, in rapid and relatively inexpensive screening programmes.

Dried Fluid Spots for HIV Type-1 Viral Load and Resistance Genotyping: A Systematic Review

Background

Dried spots on filter paper made of whole blood (dried blood spots; DBS), plasma (dried plasma spots; DPS) or serum (dried serum spots) hold promise as an affordable and practical alternative specimen source to liquid plasma for HIV type-1 (HIV-1) viral load determination and drug resistance genotyping in the context of the rapidly expanding access to antiretroviral therapy (ART) for HIV-1-infected individuals in low- and middle-income countries. This report reviews the current evidence for their utility.

Methods

We systematically searched the English language literature published before 2009 on Medline, the websites of the World Health Organization and US Centers for Disease Control and Prevention, abstracts presented at relevant international conferences and references from relevant articles.

Results

Data indicate that HIV-1 viral load determination and resistance genotyping from DBS and DPS is feasible, yielding comparable test performances, even after storage. Limitations include reduced analytical sensitivity resulting from small analyte volumes (approximately 3.5 log10 copies/ ml at 50 ml sample volume), nucleic acid degradation under extreme environmental conditions, impaired efficiency of nucleic acid extraction, potential interference of archived proviral DNA in genotypes obtained from DBS and the excision of spots from the filters in high-volume testing.

Conclusions

This technology offers the advantages of a stable specimen matrix, ease of sample collection and shipment. The current sensitivity in drug resistance testing is appropriate for public health surveillance among pretreatment populations. However, consistently improved analytical sensitivity is needed for their routine application in the therapeutic monitoring of individuals receiving ART, particularly at the onset of treatment failure.

Nevirapine resistance in human immunodeficiency virus type 1-positive infants determined using dried blood spots stored for up to six years at room temperature

Dried blood spots that had been stored ambiently for 3 to 6 years lost approximately 1 log(10) of human immunodeficiency virus type 1 (HIV-1) RNA, but the majority could still be genotyped for resistance. Nevirapine resistance was found in 7/16 (43.5%) HIV-1-positive HIVNET 024 infants at 4 to 6 weeks, but no resistance was found at other time points.

Correlation between human immunodeficiency virus type 1 (HIV-1) RNA measurements obtained with dried blood spots and those obtained with plasma by use of Nuclisens EasyQ HIV-1 and Abbott RealTime HIV load tests

The plasma human immunodeficiency virus (HIV) RNA load is used in the clinical routine for the monitoring of HIV infection and the patient's response to antiretroviral therapy. Other body fluids or dried blood spots (DBS) can be used, however, to assess the level of viremia. The use of DBS may be especially helpful for the monitoring of HIV-infected patients in resource-poor settings, where access to adequate laboratory facilities is often difficult. However, the correlation between the HIV RNA levels in plasma and those in DBSs has not been well established. Paired plasma and DBS samples obtained from HIV type 1 (HIV-1)-infected patients were tested for HIV RNA copy numbers by using two different commercial assays, the Nuclisens EasyQ HIV-1 (version 1.1) test (the Nuclisens test; Biomerieux) and the m2000rt RealTime HIV test (the m2000rt test; Abbott). Nucleic acid extraction was performed manually by using either the Nuclisens isolation kit (which uses the Boom methodology) or the m2000rt sample preparation kit (an iron particle-based method). A total of 103 paired plasma and DBS samples were tested. Viral load results were obtained for 97 (94.2%) samples with the Nuclisens isolation kit and 81 (78.6%) samples with the m2000rt kit. The overall correlation between the RNA loads in plasma and DBS was good, although better results were obtained by the Nuclisens test (R(2) = 0.87, P < 0.001) than by the m2000rt test (R(2) = 0.70, P < 0.001). While the specificities were excellent and similar for both the Nuclisens and the m2000rt tests (97.1% and 100%, respectively), the sensitivity was greater by the Nuclisens test than by the m2000rt test (75.8% and 56.6%, respectively). Overall, the viral loads in DBS tended to be lower than those in plasma, with mean differences of 0.3 log unit (standard deviation, 0.5 log unit) and 0.76 log unit (standard deviation, 0.8 log unit) for the Nuclisens and the m2000rt tests, respectively. The levels of agreement between the measurements in plasma and DBS were assessed by using the Bland-Altman plot for each assay. The Nuclisens test gave results within its defined limits (-0.65 to 1.26) for 95.9% of the samples, while the m2000rt test gave results within its limits (-0.83 to 2.33) for 100% of the samples. In summary, the HIV-1 load can accurately be quantified by testing DBS by either the Nuclisens or the m2000rt test, although the Nuclisens test may outperform the m2000rt test when nucleic acids are extracted manually.

Evaluation of different RNA extraction methods and storage conditions of dried plasma or blood spots for human immunodeficiency virus type 1 RNA quantification and PCR amplification for drug resistance testing

The development and validation of dried sample spots as a method of specimen collection are urgently needed in developing countries for monitoring of human immunodeficiency virus (HIV) infection. Our aim was to test some crucial steps in the use of dried spots, i.e., viral recovery and storage over time. Moreover, we investigated whether dried plasma and blood spots (DPS and DBS, respectively) give comparable viral load (VL) results. Four manual RNA extraction methods from commercial HIV type 1 (HIV-1) VL assays--a QIAamp minikit (Qiagen), the Abbott Molecular sample preparation system, the Nuclisens assay (bioMarieux), and High Pure viral nucleic acid kit (Roche Applied Science)--were compared for VL quantification and PCR amplification for genotypic drug resistance testing on dried spots from spiked plasma and residual samples from HIV-1 patients (n = 47; median VL, 4.13 log(10) copies/ml). RNA recovery from DPS was efficient using Nuclisens extraction (median difference, 0.03 log(10) copies/ml) and slightly underestimated using the Abbott Molecular sample preparation system (median difference, 0.35 log(10) copies/ml). PCR amplification results were in concordance. Measurements from DBS overestimated VL for plasma, with VL results showing <3.7 log(10) copies/ml. VL was stable for up to 3 months in spiked DPS stored at 20 degrees C but for only 1 month at 37 degrees C. A faster decline was observed in PCR efficiency: DPS could be stored for 1 week at 37 degrees C and for 1 month at 20 degrees C. In conclusion, the RNA extraction method is an important factor in obtaining reliable RNA quantification and PCR amplification of HIV-1 on DPS/DBS. DBS could be used as an alternative for DPS depending on HIV RNA cutoffs for virological failure. VL measurements remain stable over a longer period than do PCR amplification results.

New methods for the surveillance of HIV drug resistance in the resource poor world

PURPOSE OF REVIEW

As antiretroviral therapy scale-up proceeds in developing countries, simple and inexpensive procedures are required to monitor the prevalence and transmission of drug-resistant HIV strains to ensure optimal use of antiviral therapy. This article reviews new surveillance methods and practices used to monitor drug resistance in the developing world.

RECENT FINDINGS

Several recently published studies report the successful development of methods using dried blood spots, collected on filter paper, for HIV drug resistance genotyping tests. In concert to antiretroviral therapy rollout, the WHO has developed a laboratory network and sought to implement surveillance of transmitted drug resistance in developing countries. A small number of developing world prevalence studies have thus far been published using dried blood spots. These studies reveal low rates of transmitted drug resistance. Other studies indicate that the use of dried blood spots for HIV drug resistance surveillance may possibly lead to overestimates.

SUMMARY

The use of dried blood spots as a method of specimen collection and storage is simple, inexpensive and is an appropriate technique for the surveillance of transmitted HIV drug resistance.