Early infant human immunodeficiency virus type 1 detection suitable for resource-limited settings with multiple circulating subtypes by use of nested three-monoplex DNA PCR and dried blood spots

A Rapid and Sensitive Detection of HIV-1 with a One-Pot Two-Stage Reverse Transcription Recombinase Aided Real-Time PCR Assay

Human immunodeficiency virus 1 (HIV-1) attacks the immune system, making people susceptible to various diseases, thus increasing their risk of death. Comprehensive detection of major HIV-1 strains circulating in China is vital for effective HIV-1 infection prevention and treatment. HIV-1 nucleic acid detection is considered effective for HIV-1 diagnosis since traditional immunological testing may fail to detect HIV-1 infection during the window period. This work demonstrates a one-pot two-stage amplification assay (RT-RAP), a combination of reverse transcription recombinase (RT- RAA), and quantitative real-time polymerase chain reaction (qRT-PCR). The turn-around time of the assay is only 50 min and can be performed with commonly available laboratory equipment, the qPCR devices. The RT-RAP assay could detect approximately 5 and 14 copies/reaction of HIV-1 DNA and RNA using recombinant plasmids and standard reference strains, respectively. Additionally, we found that the clinical performance of RT-RAP (detected 169 samples out of 170 specimens) was consistent with that of qRT-PCR. The sensitivity and specificity of RT-RAP were 100.00% (99/99) and 98.59% (70/71), respectively, while its positive and negative predictive values were 99.00% (99/100) and 100.00% (70/70), respectively. The total coincidence rate of the RT-RAP was 99.41% (169/170), with a kappa value of 0.988 (p < 0.05). We demonstrated that RT-RAP could rapidly detect the common HIV-1 subtypes commonly circulating in China with comparable sensitivity and specificity to qRT-PCR.

Advances in Directly Amplifying Nucleic Acids from Complex Samples

Advances in nucleic acid amplification technologies have revolutionized diagnostics for systemic, inherited, and infectious diseases. Current assays and platforms, however, often require lengthy experimental procedures and multiple instruments to remove contaminants and inhibitors from clinically-relevant, complex samples. This requirement of sample preparation has been a bottleneck for using nucleic acid amplification tests (NAATs) at the point of care (POC), though advances in “lab-on-chip” platforms that integrate sample preparation and NAATs have made great strides in this space. Alternatively, direct NAATs—techniques that minimize or even bypass sample preparation—present promising strategies for developing POC diagnostic tools for analyzing real-world samples. In this review, we discuss the current status of direct NAATs. Specifically, we surveyed potential testing systems published from 1989 to 2017, and analyzed their performances in terms of robustness, sensitivity, clinical relevance, and suitability for POC diagnostics. We introduce bubble plots to facilitate our analysis, as bubble plots enable effective visualization of the performances of these direct NAATs. Through our review, we hope to initiate an in-depth examination of direct NAATs and their potential for realizing POC diagnostics, and ultimately transformative technologies that can further enhance healthcare.

Adjusting for time-dependent sensitivity in an illness-death model, with application to mother-to-child transmission of HIV

In mother-to-child transmission of HIV, identifying infected infants relies on a diagnostic test with imperfect sensitivity that is administered at scheduled visits. Under this scenario, a participant's true state may be unknown at the start and end times of the study, and the detection of transitions into illness may be delayed or missed altogether. This could lead to biased estimates of the risk of transmission and covariate associations. When a test has imperfect sensitivity, but perfect specificity, the additional uncertainty can be captured as a random variable measuring delay in detection. The cumulative distribution then defines a time-dependent sensitivity function that increases over time. We present a maximum likelihood based illness-death model that accounts for imperfect sensitivity by including the delay as an exponential distribution. We specify transition rates as penalized B-splines to allow for nonhomogeneity of risk and discuss the model under Markov and semi-Markov assumptions. We apply this method to our motivating data set, a study of 1499 mother and infant pairs at three sites in Africa.

Determinant and outcome of early diagnosis of HIV infection among HIV-exposed infants in southwest Ethiopia

BACKGROUND

Preventing mother-to-child transmission (PMTCT) of human immunodeficiency virus infection (HIV) has been a fundamental advancement in the acquired immunodeficiency syndrome (AIDS) response for the past decade. Several countries have made great strides in the efforts to prevent HIV through mother-to-child transmission. The objective of this study is to assess the determinant and outcome of early diagnosis of HIV infection among HIV-exposed infants in southwest Ethiopia.

METHODS

An institutional based retrospective cohort study was conducted in a hospital. Medical records of HIV-exposed infants and their mothers enrolled into the program were reviewed. Data entry and analysis was carried out using SPSS version 20 for Windows.

RESULTS

A total of 426 HIV exposed infant-mother pairs where both mother and infants received a minimum ARV intervention for PMTCT were included in the study. Two hundred fifty-four (59.6%) of mothers had attended antenatal care (ANC). Of all participants, 234(54.9%) mothers did not receive any PMTCT prophylaxis during ANC, while only 104(24.4) received antiretroviral (ART) as PMTCT prophylaxis and 163(38.3%) claimed that did not observe any infant PMTCT interventions while 135(31.7%) of the infants received single-dose NVP + AZT. About 385(90.4%) infants were not infected at their final infection status. Those mothers who did not attended ANC follow-up, infants on mixed and complementary feeding and infants weaned off and mothers who were in WHO clinical stage III and IV were more likely to have HIV sero positive infant.

CONCLUSION

This study showed that 385(90.4%) of the infants were not infected at their final infection status. Therefore, encouraging pregnant women to visit health facilities during their course of pregnancy, focusing on exclusive breast feeding counseling and promotion, and early initiation of antiretroviral treatment to HIV infected pregnant women are recommend.

Past, present and future molecular diagnosis and characterization of human immunodeficiency virus infections

Substantive and significant advances have been made in the last two decades in the characterization of human immunodeficiency virus (HIV) infections using molecular techniques. These advances include the use of real-time measurements, isothermal amplification, the inclusion of internal quality assurance protocols, device miniaturization and the automation of specimen processing. The result has been a significant increase in the availability of results to a high level of accuracy and quality. Molecular assays are currently widely used for diagnostics, antiretroviral monitoring and drug resistance characterization in developed countries. Simple and cost-effective point-of-care versions are also being vigorously developed with the eventual goal of providing timely healthcare services to patients residing in remote areas and those in resource-constrained countries. In this review, we discuss the evolution of these molecular technologies, not only in the context of the virus, but also in the context of tests focused on human genomics and transcriptomics.

[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.

Guidelines for the qualitative detection of viral genomes in dried blood spots

Dried blood spots (DBSs) are a useful alternative to blood sampling especially in children or for screening high-risk populations in developing countries. DBS blood collection can be employed in the diagnosis of viral infections by PCR or RT-PCR and also in viral genome sequencing. In addition, the advent of multiplex PCR approaches has led to further diagnostic and methodological improvements allowing simultaneous detection of two or more different viral genomes in the same sample and amplification reaction. This chapter describes general guidelines for the qualitative viral genome amplification and detection in DBS providing an example application of a qualitative real-time SYBR Green-based multiplex RT-PCR assay targeting two major viral pathogens, HIV-1 and HCV.

Diagnosis of HIV-1 infection in infants using dried blood spots in Tamil Nadu, South India

INTRODUCTION

Diagnosis of HIV infection in infants is difficult due to the presence of maternal antibodies; only nucleic acid assays are very helpful in early detection. Filter papers are especially useful for blood collection in resource-poor settings with limited access to diagnostic facilities. MATERIALS #ENTITYSTARTX00026;

METHODS

DBS samples were collected from the infants born to HIV seropositive mothers who had received single dose nevirapine at onset of labor. The samples were directly spotted onto the Whatman 903 cards from heel, big toe or finger prick depending on the age of the infants. A total of 766 infant samples were collected on dried blood spots (DBS) and transported to the Department of Experimental Medicine (DEM), Chennai, for testing from different government hospitals of rural and urban parts of Tamil Nadu, South India. According to National AIDS Control Organization's (NACO) protocol DNA was extracted from all these DBS and PCR was performed using the Roche kit version 1.5.

RESULTS

Fifteen infants were found to be HIV positive and 751 were HIV negative; all these 15 positive infants and 49 negative infants who were in the age group between 10 and 18 months were repeated with another DBS and compared with whole blood. The DBS results were concordant with the whole blood method and the sensitivity and specificity were 100%.

Quality assurance in the HIV/AIDS laboratory network of China

Background In 2009, there were 8273 local screening laboratories, 254 confirmatory laboratories, 35 provincial confirmatory central laboratories and 1 National AIDS Reference Laboratory (NARL) in China. These laboratories were located in Center for Disease Control and Prevention (CDC) facilities, hospitals, blood donation clinics, maternal and child health (MCH) hospitals and border health quarantine health-care facilities.

Methods The NARL and provincial laboratories provide quality assurance through technical, bio-safety and managerial training; periodic proficiency testing; on-site supervisory inspections; and commercial serologic kit evaluations.

Results From 2002 to 2009, more than 220 million HIV antibody tests were performed at screening laboratories, and all reactive and indeterminate samples were confirmed at confirmatory laboratories. The use of highly technically complex tests, including CD4 cell enumeration, viral load, dried blood spot (DBS)-based early infant diagnosis (EID), drug resistance (DR) genotyping, HIV-1 subtyping and incidence assays, have increased in recent years and their performance quality is closely monitored.

Conclusion China has made significant progress in establishing a well-coordinated HIV laboratory network and QA systems. However, the coverage and intensity of HIV testing and quality assurance programmes need to be strengthened so as to ensure that more infected persons are diagnosed and that they receive timely prevention and treatment services.

Diagnosis of HIV-1 infection in infants using dried blood spots in Tamil Nadu, South India

INTRODUCTION

Diagnosis of HIV infection in infants is difficult due to the presence of maternal antibodies; only nucleic acid assays are very helpful in early detection. Filter papers are especially useful for blood collection in resource-poor settings with limited access to diagnostic facilities. MATERIALS #ENTITYSTARTX00026;

METHODS

DBS samples were collected from the infants born to HIV seropositive mothers who had received single dose nevirapine at onset of labor. The samples were directly spotted onto the Whatman 903 cards from heel, big toe or finger prick depending on the age of the infants. A total of 766 infant samples were collected on dried blood spots (DBS) and transported to the Department of Experimental Medicine (DEM), Chennai, for testing from different government hospitals of rural and urban parts of Tamil Nadu, South India. According to National AIDS Control Organization's (NACO) protocol DNA was extracted from all these DBS and PCR was performed using the Roche kit version 1.5.

RESULTS

Fifteen infants were found to be HIV positive and 751 were HIV negative; all these 15 positive infants and 49 negative infants who were in the age group between 10 and 18 months were repeated with another DBS and compared with whole blood. The DBS results were concordant with the whole blood method and the sensitivity and specificity were 100%.

Quantitative recovery of proviral HIV-1 DNA from leukocytes by the Dried Buffy Coat Spot method for real-time PCR determination

The current recommended method for diagnosing HIV-1 in newborns infected vertically and in adults, during the "window period", is the detection of proviral HIV-1 DNA within leukocytes (buffy coat). This study describes a new portable Dried Buffy Coat Spot (DBCS) assay able to provide a quantitative proviral HIV-1 DNA recovery from the buffy coat. Fifty blood samples were collected from HIV-positive children and processed for DBCSs. Total DNA and proviral DNA were normalised to β-globin and HIV-1 pol genes. Assay sensitivity and specificity were evaluated against the whole blood dried blood spot (DBS) method. Both procedures, using automatic DNA extraction, were compared to a standard whole blood DNA manual extraction. DNA recovery from whole blood was nearly equivalent to that of the DBCS-based extraction, while DBS-based extraction was 10-fold less sensitive. The detection rate of proviral HIV-1 DNA with DBCS assay was equivalent to whole blood manual extraction (100% concordance), but DBS-extracted samples showed limited concordance (44%). The DBCS assay may prove to be more feasible in resource-limited settings. It may represent a simple and robust point-of-care assay for HIV screening of children, for whom a reference test is still lacking.

Clinical evaluation of a dried blood spot assay for atazanavir

Current procedures for obtaining and measuring plasma concentrations of HIV protease inhibitors (PIs) are technically challenging. Dried blood spot (DBS) assays offer a way to overcome many of the obstacles. We sought to develop a DBS assay for quantitation of the PI atazanavir (ATV) and to compare this method with a previously validated plasma assay. We prospectively enrolled 48 patients with well-controlled HIV disease who had been on ATV for at least 7 days. ATV was quantified from plasma by use of high-performance liquid chromatography (HPLC). A reversed-phase ultrahigh-performance liquid chromatography (UPLC) assay was utilized for DBS samples. The concentrations of ATV quantified in a DBS matrix showed very strong agreement with those measured in plasma (r(2) = 0.988). The mean difference in ATV concentration between the two methods was -10.8% (95% confidence interval [95% CI], -7.65% to -13.95%), indicating that the DBS method has a slight negative bias. A majority (97.8%) of the differences in concentration between the two assays fell within ±2 standard deviations. ATV concentrations were lower in subjects who had detectable HIV RNA in plasma (mean, 543 ng/ml) than in those with HIV RNA of <50 copies/ml (mean, 1,582 ng/ml) (P = 0.03, Wilcoxon rank-sum test). In conclusion, our study demonstrated that ATV quantitation in a DBS matrix is feasible and accurate. DBS use offers a convenient alternative for measuring plasma concentrations of ATV and may have utility in monitoring of drug concentrations in clinical practice and in future studies.

Nucleic acid assay system for tier II laboratories and moderately complex clinics to detect HIV in low-resource settings

There is a clear need for an instrument-free molecular diagnostic system for detecting human immunodeficiency virus type 1 (HIV-1) RNA or DNA that can be used in developing countries. Such a test could be used for early diagnosis of HIV-1 infection during infancy and could serve as a surrogate end point for vaccine trials. We developed the IsoAmp HIV-1 assay (BioHelix Corporation), which targets the HIV-1 gag gene with use of isothermal reverse-transcription helicase-dependent amplification chemistry. The IsoAmp HIV assay uses a disposable amplicon containment device with an embedded vertical-flow DNA detection strip to detect the presence of HIV-1 amplicons. The vertical-flow DNA detection strip has a control line to validate the performance of the device and a test line to detect the analyte. The analyte is detected by a sandwich immunoassay for reporter moieties on a capture probe and a detection probe. The control line consists of the detection probe reporter moiety conjugated to the vertical-flow DNA detection strip. The preliminary limit of detection of the IsoAmp HIV assay was evaluated by testing serial dilutions of HIV-1 armored RNA (Assuragen). We found that 21 (75%) of 28 assays yielded positive results when 50 copies of HIV-1 armored RNA were input into the IsoAmp HIV reaction.

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.

Detection of low levels of human immunodeficiency virus (HIV) may be critical for early diagnosis of pediatric HIV infection by use of dried blood spots

We compared a DNA-based assay with a total nucleic acid-based assay for early detection of infant human immunodeficiency virus (HIV) infection. The codetection of DNA and RNA did not result in an overall higher sensitivity compared to that of DNA alone. Discordant results were associated with low levels of HIV DNA, indicating that the sample amount may be critical.

Resistance mutations in HIV-1 infected pregnant women and their infants receiving antiretrovirals to prevent HIV-1 vertical transmission in China

The objective of this study was to assess the resistance baseline in HIV-1-infected pregnant women in China and the emergence of drug resistance (DR) among them and their infants after receiving single-dose nevirapine (sdNVP) or zidovudine plus sdNVP (ZDV-sdNVP) for the prevention of mother-to-child transmission (PMTCT). The prospective study followed 62 drug-naïve HIV-1-infected mothers and their infants who received sdNVP for PMTCT and 18 who received ZDV-sdNVP. Primary DR was detected in 8.8% (7/80) of pregnant women at baseline. Two (2.5%) women had mutations associated with nucleoside reverse transcriptase inhibitors (NRTI). Six (7.5%) women harboured mutations associated with non-nucleoside reverse transcriptase inhibitors (NNRTI). No protease inhibitor (PI) DR was detected. The DR rates in infected mothers selected by sdNVP and ZDV-sdNVP regimen were 16.3% and 0%, respectively. Women with the emergence of DR after sdNVP had lower CD4 cell counts at delivery than women without DR after sdNVP (178 vs.364 cells/mm(3), P < 0.05). The vertical transmission rate in women with baseline resistance was similar to that in women without baseline resistance (1/7 vs. 3/73, P > 0.05). The study indicates that NVP resistance after sdNVP was associated with CD4 cell count at delivery. ZDV-sdNVP regimen was of more significance in the prevention of the emergence of NNRTI-related DR than sdNVP.

Low-cost HIV-1 diagnosis and quantification in dried blood spots by real time PCR

Background

Rapid and cost-effective methods for HIV-1 diagnosis and viral load monitoring would greatly enhance the clinical management of HIV-1 infected adults and children in limited-resource settings. Recent recommendations to treat perinatally infected infants within the first year of life are feasible only if early diagnosis is routinely available. Dried blood spots (DBS) on filter paper are an easy and convenient way to collect and transport blood samples. A rapid and cost effective method to diagnose and quantify HIV-1 from DBS is urgently needed to facilitate early diagnosis of HIV-1 infection and monitoring of antiretroviral therapy.

Methods and Findings

We have developed a real-time LightCycler (rtLC) PCR assay to detect and quantify HIV-1 from DBS. HIV-1 RNA extracted from DBS was amplified in a one-step, single-tube system using primers specific for long-terminal repeat sequences that are conserved across all HIV-1 clades. SYBR Green dye was used to quantify PCR amplicons and HIV-1 RNA copy numbers were determined from a standard curve generated using serially diluted known copies of HIV-1 RNA. This assay detected samples across clades, has a dynamic range of 5 log₁₀, and %CV <8% up to 4 log₁₀ dilution. Plasma HIV-1 RNA copy numbers obtained using this method correlated well with the Roche Ultrasensitive (r = 0.91) and branched DNA (r = 0.89) assays. The lower limit of detection (95%) was estimated to be 136 copies. The rtLC DBS assay was 2.5 fold rapid as well as 40-fold cheaper when compared to commercial assays. Adaptation of the assay into other real-time systems demonstrated similar performance.

Conclusions

The accuracy, reliability, genotype inclusivity and affordability, along with the small volumes of blood required for the assay suggest that the rtLC DBS assay will be useful for early diagnosis and monitoring of pediatric HIV-1 infection in resource-limited settings.

LTR real-time PCR for HIV-1 DNA quantitation in blood cells for early diagnosis in infants born to seropositive mothers treated in HAART area (ANRS CO 01)

HIV-1 diagnosis in babies born to seropositive mothers is one of the challenges of HIV epidemics in children. A simple, rapid protocol was developed for quantifying HIV-1 DNA in whole blood samples and was used in the ANRS French pediatric cohort in conditions of prevention of mother-to-child transmission. A quantitative HIV-1 DNA protocol (LTR real-time PCR) requiring small blood volumes was developed. First, analytical reproducibility was evaluated on 172 samples. Results obtained on blood cell pellets and Ficoll-Hypaque separated mononuclear cells were compared in 48 adult HIV-1 samples. Second, the protocol was applied to HIV-1 diagnosis in infants in parallel with plasma HIV-RNA quantitation. This prospective study was performed in children born between May 2005 and April 2007 included in the ANRS cohort. The assay showed good reproducibility. The 95% detection cut-off value was 6 copies/PCR, that is, 40 copies/10(6) leukocytes. HIV-DNA levels in whole blood were highly correlated with those obtained after Ficoll-Hypaque separation (r = 0.900, P < 0.0001). A total of 3,002 specimens from 1,135 infants were tested. The specificity of HIV-DNA and HIV-RNA assays was 100%. HIV-1 infection was diagnosed in nine infants before age 60 days. HIV-DNA levels were low, underlining the need for sensitive assays when highly active antiretroviral therapy (HAART) has been given. The performances of this HIV-DNA assay showed that it is adapted to early diagnosis in children. The results were equivalent to those of HIV-RNA assay. HIV-DNA may be used even in masked primary infection in newborns whose mothers have received HAART.

Update on successes and challenges regarding mother-to-child transmission of HIV

PURPOSE OF REVIEW

There is an unprecedented global commitment to reverse the pediatric HIV epidemic by making prevention of mother-to-child transmission (PMTCT) services accessible in all countries. This review outlines the successes made and the challenges that remain.

RECENT FINDINGS

In resource-rich countries, mother-to-child transmission rates of HIV as low as 1% have been achieved. The efficacy of short-course antiretrovirals for PMTCT in Africa is estimated at 50%. Coinfections with herpes simplex virus type 2, other sexually transmitted infections resulting in genital ulcers, and endemic infectious diseases (e.g., malaria) may increase the risk of mother-to-child transmission of HIV. Vertical transmission of drug-resistant viruses has been reported; the prevalence and effect of transmitted resistant virus on treatment outcomes are under investigation. Obstacles facing PMTCT in resource-limited countries include the lack of healthcare infrastructure, limited manpower, and competing public health priorities with the limited healthcare budget.

SUMMARY

Although the birth of an HIV-infected child in a resource-rich country is now a sentinel health event, in most resource-limited countries the birth of an HIV-infected child continues to be the status quo. Comprehensive PMTCT, including antiretroviral treatment for HIV-infected women and children, should be paramount in resource-limited countries.

Qualitative human immunodeficiency virus RNA analysis of dried blood spots for diagnosis of infections in infants

The Gen-Probe Aptima human immunodeficiency virus type 1 (HIV-1) RNA assay was adapted for the diagnosis of HIV infection in infants by using dried blood spots. The assay was 99% sensitive (128/129) and 100% specific (162/162). This may prove useful in resource-limited settings, since it precludes the need for a phlebotomist and maintenance of a cold chain.

Overseas processing of dried blood spots for timely diagnosis of HIV in Haitian infants

OBJECTIVE

To determine the feasibility of sending dried blood spots (DBS) to an overseas processing center for the diagnosis of HIV infection in infants in rural Haiti.

METHODS

The program took place in the Central Department of Haiti. Children under 18 months of age who were born to an HIV-infected mother or who had a positive HIV antibody test had blood collected on filter paper. Once dry, specimens were labeled with a unique identifying number, placed in sealed gas-impermeable envelopes containing a desiccant, stored at room temperature, and mailed to a commercial laboratory in The Netherlands, where blood was eluted from the filter paper and analyzed by the Retina(trade mark) rainbow HIV-1 RNA assay. Infants were tested at 1 month of age and again at 4 months of age.

RESULTS

The DBS protocol was easily scaled up. During the study period, 138 infants had HIV status confirmed; 15 of them were found to be HIV infected and were enrolled in appropriate HIV care, and 123 were confirmed to be HIV uninfected, avoiding unnecessary prophylactic antibiotics and providing reassurance to caregivers.

CONCLUSION

Central, overseas processing of DBS is a feasible solution for the timely diagnosis of HIV infection in infants where local capacity is unavailable. Regional processing centers for DBS could improve the access of millions of children in Latin America and the Caribbean to timely diagnosis of HIV infection.

Development and optimization of an internally controlled dried blood spot assay for surveillance of human immunodeficiency virus type-1 drug resistance

OBJECTIVES

We present the evaluation of a methodology for the genotypic assessment of human immunodeficiency virus type-1 (HIV-1) drug resistance, optimized for use with dried blood spots (DBS).

METHODS

The ability to generate HIV-1 protease (PR) and reverse transcriptase (RT) contiguous amplicons and nucleotide sequences from DBS was evaluated. Different collection matrices and extraction methodologies were compared. The relative subtype sensitivity of the amplification strategy was assessed using a comprehensive panel of plasmids representing A-H subtypes. A panel of DBS and plasma specimens was subjected to HIV genotyping. Sequences generated from each sample type were compared.

RESULTS

Extensive replicate testing revealed most sensitivity with the use of 903 filter paper and silica/guanidine extraction, which had an estimated 95% inclusivity endpoint of 1542 proviral copies/mL, as compared with 21 573 proviral copies/mL for the FTA system. All HIV-1 group M subtypes analysed-with the exception of subtypes A2, AE, AG, F and H-had a relative sensitivity of </=10 plasmid copies/PCR reaction. The PCR was multiplexed to include amplification of a human housekeeping gene to monitor the integrity of the human genomic DNA. Using a panel of clinical samples, we demonstrated the ability to amplify and sequence from 83% (n = 10) in the PR region and 100% (n = 12) in the RT region, of samples with detectable viral load. All specimens with an HIV-1 RNA load >/=1000 copies/mL were successfully amplified and sequenced. Twelve specimens had pol genotyping from both plasma and DBS samples. Sequence analysis and drug resistance interpretation revealed that 10 (83%) provided concordant drug resistance interpretation.

CONCLUSIONS

Our results demonstrate that the technique is appropriate for surveillance of drug resistance in untreated individuals and those with virological failure on therapy.