Assessment of dried blood spot samples as a simple method for detection of hepatitis B virus markers

Validity of dried blood spot testing for sexually transmitted and blood-borne infections: A narrative systematic review

Testing for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) using dried blood spot (DBS) specimens has been an integral part of bio-behavioural surveillance in Canada for almost two decades, though less is known regarding the use of DBS in surveillance of other sexually transmitted and blood-borne infections (STBBI). A systematic review was conducted using a peer-reviewed search strategy to assess the current evidence regarding the validity of STBBI testing using DBS specimens. Eligibility criteria included studies reporting use of DBS specimens for STBBI testing with either commercially available or "in-house" tests in populations 15 years of age or older. Studies reporting a measure of validity such as sensitivity, specificity, positive and negative predictive values were eligible for inclusion. Quality of studies and risk of bias were assessed using the QUADAS-2 tool. A total of 7,132 records were identified. Of these, 174 met the criteria for inclusion. Among the studies that reported validity measures, a substantial proportion demonstrated high sensitivity (≥90%) in 62.5% of cases (N = 334/534 sensitivity measurements), and high specificity (≥90%) was observed in 84.9% of instances (N = 383/451 specificity measurements). However, the quality of the studies varied greatly. Our findings support the validity of the use of DBS specimens in STBBI testing where sufficient evidence was available, but validity is highly dependent on thorough method development and validation.

The role of dried blood spot tests in the detection of hepatitis B infection: A systematic review

Hepatitis B remains a public health problem worldwide despite vaccine availability. Although the existing diagnostic tools help detect the infection, logistics support and limited resources and technologies affect their usefulness and reliability in developing countries. This systematic review evaluated the performance of dried blood spots (DBS) as a collection and storage tool for diagnosing an hepatitis B virus (HBV) infection. A comprehensive search using OVID, Scopus and CINAHL databases was performed to collate articles published up to April 2023 that detected Hepatitis B infections using DBS. Five reviewers independently performed identification, screening, quality assessment and data extraction. A qualitative synthesis of the included studies was conducted. Of the 402 articles, 78 met the inclusion criteria. The results show that most studies focused on populations with known HBV, HCV and/or HIV status. Approximately half (49%) of the included studies utilized the Whatman Protein Saver Card for DBS collection. The DBS samples were then predominantly stored in room temperature conditions. In line with this, storage conditions influenced the concentration and stability of the analyte from the DBS samples, affecting the accuracy of downstream diagnostic methods. ELISA methods, using hepatitis B surface antigen (HBsAg) as an HBV marker, were the most widely used diagnostic tool for detecting HBV infection in DBS samples. The simplicity and cost-effectiveness of the ELISA technique highlight its potential to be used in low-resource settings. In line with this, the detection of HBsAg using an ELISA immunoassay had higher sensitivity (85.6%-100%), and specificity (95%-100%) ranges as compared to other target molecules and methods. Although this review only performed a qualitative analysis, DBS offers a promising method for collecting and storing blood samples; however, the standardization of sampling, storing conditions and diagnostic techniques is required to ensure sustainable application.

Applications of SARS-CoV-2 serological testing: impact of test performance, sample matrices, and patient characteristics

Laboratory testing has been a key tool in managing the SARS-CoV-2 global pandemic. While rapid antigen and PCR testing has proven useful for diagnosing acute SARS-CoV-2 infections, additional testing methods are required to understand the long-term impact of SARS-CoV-2 infections on immune response. Serological testing, a well-documented laboratory practice, measures the presence of antibodies in a sample to uncover information about host immunity. Although proposed applications of serological testing for clinical use have previously been limited, current research into SARS-CoV-2 has shown growing utility for serological methods in these settings. To name a few, serological testing has been used to identify patients with past infections and long-term active disease and to monitor vaccine efficacy. Test utility and result interpretation, however, are often complicated by factors that include poor test sensitivity early in infection, lack of immune response in some individuals, overlying infection and vaccination responses, lack of standardization of antibody titers/levels between instruments, unknown titers that confer immune protection, and large between-individual biological variation following infection or vaccination. Thus, the three major components of this review will examine (1) factors that affect serological test utility: test performance, testing matrices, seroprevalence concerns and viral variants, (2) patient factors that affect serological response: timing of sampling, age, sex, body mass index, immunosuppression and vaccination, and (3) informative applications of serological testing: identifying past infection, immune surveillance to guide health practices, and examination of protective immunity. SARS-CoV-2 serological testing should be beneficial for clinical care if it is implemented appropriately. However, as with other laboratory developed tests, use of SARS-CoV-2 serology as a testing modality warrants careful consideration of testing limitations and evaluation of its clinical utility.

Development and evaluation of serological screening based on one dried plasma spot for HIV, syphilis, and HCV

BACKGROUND

In the effort to prevent and control HIV/AIDS, China has established a national sentinel surveillance system. However, some sentinel sites face limitations in environmental resources and accessibility, prompting the exploration of alternative sample strategies. Dried plasma spots (DPS) samples are viewed as promising alternatives to traditional plasma samples due to their advantages, including sample stability, easy storage, and convenient transport. This study aims to develop a method for screening HIV, Treponema pallidum (TP), and Hepatitis C Virus (HCV) using DPS samples and assess their performance.

METHODS

Based on existing commercial assay kits, a detection method was established through the optimization of experimental parameters, including the amount of plasma on filter paper, the volume of elution solution applied to dried plasma spots, the size of dried plasma spots, elution solution volume, elution solution components, elution temperature, and elution time. A series of laboratory evaluation panels were constructed for laboratory assessments, including the laboratory basic panel, laboratory interference panel, and laboratory precision panel. Additionally, clinical samples were used for evaluation.

RESULTS

Optimal conditions for DPS sample extraction were: plasma volume, 100 µL; DPS size, whole spot; eluent volume, 500 µL; eluent, PBS with 1‰ Tween20; elution time, 2 h; elution temperature, room temperature. A total of 619 paired plasma/DPS samples were tested by both methods. The DPS-based ELISA method exhibited 100% sensitivity/specificity for HIV, 98.6%/100% for TP, and 99.6%/100% for HCV. Kappa values between the plasma samples and DPS samples were 100% for HIV, 99% for TP, and 100% for HCV. The DPS-based ELISA method failed to detect 1 HCV mono-infected sample and TP in 1 HIV/HCV/TP co-infected sample. For the HIV/HCV/TP co-infected sample, the S/CO in the plasma sample was 2.143 and in the DPS sample was 0.5. For HCV, the S/CO (sample OD/cut-off) was 3.049 in the plasma sample and 0.878 in the DPS sample.

CONCLUSIONS

A single DPS, following one-time standardized processing, can be used to detect HIV, HCV, and TP. Researching and establishing laboratory testing methods better suited for China's sentinel surveillance have significant practical applications in improving HIV testing in resource-constrained environments.

Evaluating the sensitivity and specificity of dried blood spots for serological testing of HIV, syphilis, hepatitis B and C Elecsys assays on the Roche Cobas system

This study was performed to validate a dried blood spot (DBS) method for the serological screening of HIV, syphilis, hepatitis B and C. It included 250 paired DBS and serum samples and 116 unpaired DBS samples from 366 unique patients from two laboratories between 8 October and 2 November 2021. As determined by original test request, these were tested using a DBS method for HIV Ag/Ab (n=216), anti-treponemal Ab (n=166), hepatitis B sAg (n=100), and hepatitis C Ab (n=100) Elecsys assays on the Roche Cobas automated platform. Using the manufacturer's (serum) cut-off for reactivity ('positivity'), the sensitivity and specificity of DBS testing compared with serum were: for HIV Ag/Ab 100% and 100%, for anti-treponemal Ab 68.3% and 100%, for hepatitis B sAg 95.9% and 100%, and for hepatitis C Ab 84.0% and 100%, respectively. Adjusting the assay cut-off using receiver operator curve analysis increased sensitivity of DBS testing for anti-treponemal Ab to 90.0%, hepatitis B sAg to 97.9% and hepatitis C Ab to 94.0% whilst maintaining specificity of 98.8%, 100% and 100%, respectively. With optimisation of assay cut-off, DBS can perform comparably with serum for serological testing for HIV, syphilis, hepatitis B and C and may be a valuable tool in increasing access to testing in New Zealand.

Validation of dried blood spots samples for the screening of hepatitis B virus surface by enzyme immunoassay method

Dried Blood Spots (DBS) are blood collection carriers that facilitate the storage and transport of samples. Used for quality control during sero-epidemiological investigations, DBS eluate are not the conventional specimen indicated by manufacturers for enzyme immunoassay method (EIA) for hepatitis B virus surface (HBs antigen). The aim of our study was to evaluate DBS eluates used as a matrix for EIA of HBs antigen in a reference laboratory. This study took place from August 2016 to November 2017 at the Centre for Diagnosis and Research on AIDS and other infectious diseases (CeDReS) in Abidjan, Côte d'Ivoire. We used a panel of 149 whole blood samples from blood donors. The DBS performed with these samples were analyzed after elution with the HBsAg (version ULTRA) ELISA, Dia.Pro Diagnostic Bioprobes S.R.L., Sesto San Giovanni, Italy. The technical performance (sensitivity and specificity and kappa coefficient) of the test performed on DBS was determined for different ratios (optical density/threshold value) compared to the results obtained on the plasma used as reference. We obtained a sensitivity of 100% with DBS for all ratios. The specificity increased according to the ratio of optical density of the individual EIA reaction to the threshold value, with 6.09%, 47.0%, and 83.0%, respectively, for ratios of 1.0, 3.0, and 5.0. Best performance was observed at ratio of 10.0 with a sensitivity and specificity of 100%. In conclusion, DBS eluate can be used for the diagnosis of viral hepatitis B and would be useful for conducting sero-epidemiological investigations. However, ratio giving best performance must be determined for each enzyme immunoassay method kits.

Current Challenges and Future Perspectives of Diagnosis of Hepatitis B Virus

It is estimated that approximately 260 million people worldwide are infected with the hepatitis B virus (HBV), which is one of the leading causes of liver disease and liver cancer throughout the world. Compared with developed countries, low-income and middle-income countries have limited access to resources and advanced technologies that require highly specialized staff for HBV diagnosis. In spite of the heavy burden caused by hepatitis B virus, 90% of people are still undiagnosed. The World Health Organization (WHO) goal of eliminating hepatitis B by 2030 seems very difficult to achieve due to the existing diagnostic infrastructure in low-resource regions. The majority of diagnostic laboratories still use hepatitis B surface antigen (HBsAg)-based tests. WHO's elimination plan is at risk of derailment due to phases like the window period, immune control, and occult HBV infection (OBI) not being detected by standard tests. Here, in this article, we are focusing on various diagnostic platforms for the better diagnosis of HBV. The aim of the elimination of HBV can only be achieved by detecting all phases of HBV infection, which can be executed by a combined approach of using new marker assays along with advanced pretesting and testing methods.

Feasibility of dried blood spot for hepatitis C diagnosis in vulnerable subjects and people living in remote areas from Brazil

Background

Agile, accessible and cheap diagnosis of hepatitis C virus (HCV) infection is essential to achieve the elimination of this infection, worldwide, as mandated by the World Health Organzation as part of its strategy for 2030. Dried blood spots (DBS) can be an attractive alternative for sample collection among people living in remote areas and vulnerable populations due to the less invasive collection, its biosafety, and storage & transportation of samples at room temperature.

Design

This study aims to estimate the usefulness of dried blood spot samples for the diagnosis and the assessment of HCV infection rates in three different settings in Brazil. Cross-sectional analysis of a sample collection from different populations, aiming to assess the performance of the testing algorithms and respective procedures among different populations with diverse background infection rates.

Methods

We reported the evaluation of DBS as alternative samples for detecting anti-HCV in different groups in real life conditions: (I) Vulnerable subjects living in remote areas of Southeast, North and Northeast Brazil (n = 1464); (II) Beauticians (n = 288); (III) People who use non-injectable drugs (n = 201); (IV) patients referred to outpatient care (n = 275).

Results

General assay accuracy was 99%, with a weighted kappa value of 0.9, showing an excellent performance. Sensitivities ranged from 87.5% to 100.0% between groups and specificities were above 99.2%. A total of 194 individuals had HCV RNA in serum and concordance of anti-HCV detection in DBS was 98.4%.

Conclusions

DBS samples could be used for anti-HCV detection in different populations recruited in real life conditions and ambulatory settings, with a high overall sensitivity and specificity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07717-4.

Dried blood spot is the feasible matrix for detection of some but not all hepatitis B virus markers of infection

Objective

Use of dried blood spots (DBS) for detection of hepatitis B virus (HBV) markers of infection has the potential to facilitate diagnosis of HBV infection especially in resource-limited countries. The aim of this study was to evaluate the feasibility of DBS for detection of various markers of HBV infections.

Results

Fifty-four DBS samples were engineered from well-characterized plasma samples. All DBS samples were tested for HBsAg, total anti-HBc and HBV DNA, 20 of 54 samples were also tested for HBeAg using commercially available assays. HBsAg was detected in 24 of 25 (96%), HBV DNA in 22 of 25 (88%), total anti-HBc in all 9 (100%), and HBeAg in all 7 (100%) DBS samples. The average difference in HBV DNA levels between DBS eluates and corresponding plasma samples was 2.7 log₁₀ IU/mL. Fifteen DBS eluates positive for HBV DNA were sequenced and all of them belonged to HBV genotype A. Thirteen samples which were negative for all HBV markers showed HBeAg false positivity. Therefore, DBS is a reliable sample matrix for detection of HBsAg, total anti-HBc and HBV DNA, but not HBeAg. Further feasibility studies of DBS for diagnostic purposes and epidemiologic studies are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06178-x.

Evaluation of the bioMérieux VIDAS HIV Duo Quick and Anti-HCV assays for dried blood spot based serosurveillance

Serosurveillance is central to monitoring our progress towards HIV and HCV elimination targets proposed for 2030. However, serosurveillance systems are ineffective without reliable serological assays for the detection of HIV and HCV antibodies. Assays should also be compatible with dried blood spot (DBS) samples to facilitate biological sample collection. The VIDAS HIV Duo Quick and Anti-HCV assays are sold as reagents strips and processed by the automated VIDAS benchtop immunoanalyser. While both assays have shown excellent performance in serum and plasma, performance data in DBS samples is lacking. In our study, we evaluate the performance of the VIDAS HIV Duo Quick and Anti-HCV assays in DBS (n = 725) collected during a cross-sectional serosurvey (the Transitions study). The VIDAS HIV Duo quick had a sensitivity and specificity of 94.5% (95% CI 85.1%, 98.5%) and 95.7% (95% CI 93.9%, 97.0%) respectively. Likewise, the VIDAS Anti-HCV had a sensitivity and specificity of 95.6% (95% CI 91.6%, 97.8%) and 95.6% (95% CI 93.5%, 97.0%) respectively. These assays are unlikely to be helpful in low-prevalence settings due to sub-optimal performance, but their performance could likely be improved by optimizing DBS elution protocols which was, unfortunately, not possible during our study.

Decreased hepatitis B virus vaccine response among HIV-positive infants compared with HIV-negative infants in Botswana

OBJECTIVES

We sought to determine vaccine antibody titres and the prevalence of hepatitis B surface antigen (HBsAg) in both HIV-positive and HIV-negative infants born to HIV-positive mothers in Botswana.

DESIGN

This was a retrospective cross-sectional study using 449 archived dried blood spot samples from both HIV-positive and HIV-negative infants collected between 2016 and 2018.

METHODS

We screened dried blood spot samples for HBsAg and determined hepatitis B surface antibody titres. We determined hepatitis B virus (HBV) genotypes by amplifying 415 base-pairs of the surface region.

RESULTS

HIV-positive infants mounted a significantly lower immune response to the HBV vaccine (P  < 0.001). Furthermore, a lower proportion of HIV-positive infants had protective hepatitis B surface antibody titres (74.5%) than HIV-negative infants (89.2%) (P < 0.001). HIV-positive infants were older and 50.9% of them had completed vaccination (P = 0.018). Of the 449 infant samples tested, three (0.67%) were positive for HBsAg. Of the three HBsAg-positive infants, two had protective titres (>10 mIU/ml). Two of the three HBV-positive infants were infected with genotype D3 and had no drug-resistance or escape mutations.

CONCLUSION

Vaccine response was lower among HIV-positive infants compared with HIV-negative infants. HBV infections were observed in both HIV-positive and HIV-negative infants in Botswana. Studies to investigate additional preventive strategies to reduce HBV mother-to-child transmission are recommended.

The use of dried blood spot cards to assess serologic responses of individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster

Traditional blood sampling by venipuncture is cumbersome and relatively expensive. Dried blood spot (DBS) sampling is desirable because of its ease of sample collection, transportation and storage. It has been used in clinical diagnosis but not been thoroughly studied for the potential use to assess the immune status of individuals following natural infection or preventive vaccination. The goal of this study was to compare DBS to traditional blood samplings in detection of antibodies in individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster. Enzyme linked immunosorbent assay (ELISA) was used to test DBS eluates and serum samples for antibodies against measles, varicella, tetanus and hepatitis A. Sensitivities, specificities, and correlation coefficients were evaluated to compare optical density (OD) values of paired serum and DBS samples. The long-term stability of DBS samples at different temperatures was assessed using simulated immune measles blood. DBS OD was highly correlated with serum OD for antibodies to measles (r = 0.93), varicella (r = 0.82), and tetanus (r = 0.91). Sensitivities of DBS OD ranged from 86-99% and specificities ranged from 96-100% using cut-offs established by each assay. By contrast, the hepatitis A data showed a low sensitivity (31%) and weak correlation (r = 0.14) between DBS and serum samples. Antibody titers in serum samples for anti-influenza A (H1N1 and H3N1) failed to correlate in DBS eluates in HAI and MN assays. DBS samples were stable for 4 weeks when stored at room temperature and for 6 months at 4°C. DBS sampling was sensitive, specific, and highly correlated with traditional venipuncture sampling in detection of antibodies against measles, tetanus and varicella zoster, but not hepatitis A and influenza. Thus, the success of using DBS sampling to assess the antibody levels in immunized individuals may be dependent on the pathogens and the development of the assay used.

Dried blood sample analysis by antibody array across the total testing process

Dried blood samples (DBSs) have many advantages; yet, impediments have limited the clinical utilization of DBSs. We developed a novel volumetric sampling device that collects a precise volume of blood, which overcomes the heterogeneity and hematocrit issues commonly encountered in a traditional DBS card collection as well as allowing for more efficient extraction and processing procedures and thus, more efficient quantitation, by using the entire sample. We also provided a thorough procedure validation using this volumetric DBS collection device with an established quantitative proteomics analysis method, and then analyzed 1000 proteins using this approach in DBSs concomitantly with serum for future consideration of utility in clinical applications. Our data provide a first step in the establishment of a DBS database for the broad application of this sample type for widespread use in clinical proteomic and other analyses applications.

Evaluation of Dried Blood Spot Testing for SARS-CoV-2 Serology Using a Quantitative Commercial Assay

Dried blood spots (DBS) are commonly used for serologic testing for viruses and provide an alternative collection method when phlebotomy and/or conventional laboratory testing are not readily available. DBS collection could be used to facilitate widespread testing for SARS-CoV-2 antibodies to document past infection, vaccination, and potentially immunity. We investigated the characteristics of Roche's Anti-SARS-CoV-2 (S) assay, a quantitative commercial assay for antibodies against the spike glycoprotein. Antibody levels were reduced relative to plasma following elution from DBS. Quantitative results from DBS samples were highly correlated with values from plasma (r2 = 0.98), allowing for extrapolation using DBS results to accurately estimate plasma antibody levels. High concordance between plasma and fingerpick DBS was observed in PCR-confirmed COVID-19 patients tested 90 days or more after the diagnosis (45/46 matched; 1/46 mismatched plasma vs. DBS). The assessment of antibody responses to SARS-CoV-2 using DBS may be feasible using a quantitative anti-S assay, although false negatives may rarely occur in those with very low antibody levels.

Comparison of four extraction methods for the detection of hepatitis B virus DNA in dried blood spot samples

The dried blood spot (DBS) samples are a useful resource for viral DNA isolation and important in increasing access to HBV diagnosis. However, the choice of the DNA extraction method is crucial for reliable results. We compared the reliability of four DNA extraction methods using DBS samples for the qualitative and quantitative detection of HBV. A panel of serially diluted HBV DNA in whole blood was spotted onto filter paper (Whatman 903 paper and Whatman FTA cards). Four methods were used to extract DNA: QIAamp^® DNA Blood Mini Kit (Qiagen); High Pure Viral Nucleic Acid Kit (Roche); Invisorb Spin Blood Midi Kit (Invitek), and DBS Genomic DNA Isolation Kit (Norgen Biotek). Two qualitative PCRs for the core and surface gene regions of HBV were used, and in‐house real‐time PCR was also evaluated. It was possible to detect HBV DNA using all extraction and PCR protocols. The lowest limit of detection was found using Whatman 903 paper, Roche extraction, and qualitative PCR (20 copies of HBV DNA per ml) for the surface/polymerase HBV region. In the case of in‐house real‐time PCR, the lowest limit of detection was found using both Roche and Qiagen assays (estimated 2 × 10³ copies per ml). These results suggest the importance of both the extraction method and PCR protocol in detecting HBV DNA in DBS. This study provides insights into the utility of DBS samples in HBV molecular diagnosis and their feasibility in low resource areas where cold storage and transportation may be difficult.

Dried blood spot sampling as an alternative for the improvement of hepatitis B and C diagnosis in key populations

BACKGROUND

To achieve the elimination of hepatitis B and C, there is an urgent need to develop alternative strategies to increase the access of diagnosis, particularly among key populations such as people living with human immunodeficiency virus (HIV), individuals with coagulopathies and chronic kidney disease (CKD) patients.

AIM

To evaluate the use of dried blood spot (DBS) in the detection of hepatitis B virus (HBV) and hepatitis C virus (HCV) markers.

METHODS

A total of 430 individuals comprised of people living with HIV, coagulopathies and CKD provided paired serum and DBS samples. HBsAg, anti-HBc and anti-HCV were tested in those samples using a commercial electrochemiluminescence. Demographic and selected behavioral variables were evaluated to assess possible association with HBV and HCV positivity.

RESULTS

Using DBS, HBsAg prevalence varied from 3.9% to 22.1%, anti-HBc rates varied from 25.5% to 45.6% and anti-HCV positivity ranged from 15.9% to 41.2% in key populations. Specificities of HBV and HCV tests using DBS varied from 88.9% to 100%. The HBsAg assay demonstrated the best performance in CKD and coagulopathy individuals and the anti-HCV test had a sensitivity and specificity of 100% in people living with HIV. Accuracy of HBV and HCV detection in DBS varied from 90.2% to 100%. In the CKD group, HBsAg positivity was associated with infrequent use of condoms, and anti-HBc positivity was associated with sharing nail cutters/razors/toothbrushes. Anti-HCV reactivity was positively associated with a history of transplantation and length of time using hemodialysis in both specimens. In people living with HIV, only the male gender was associated with anti-HBc positivity in serum and DBS.

CONCLUSION

DBS with electrochemiluminescence are useful tools for the diagnosis and prevalence studies of hepatitis B and C among key populations and may increase the opportunity to foster prevention and treatment.

Reliability of dried blood spot (DBS) cards in antibody measurement: A systematic review

BACKGROUND

Increasingly, vaccine efficacy studies are being recommended in low-and-middle-income countries (LMIC), yet often facilities are unavailable to take and store infant blood samples correctly. Dried blood spots (DBS), are useful for collecting blood from infants for diagnostic purposes, especially in low-income settings, as the amount of blood required is miniscule and no refrigeration is required. Little is known about their utility for antibody studies in children. This systematic review aims to investigate the correlation of antibody concentrations against infectious diseases in DBS in comparison to serum or plasma samples that might inform their use in vaccine clinical trials.

METHODS AND FINDINGS

We searched MEDLINE, Embase and the Cochrane library for relevant studies between January 1990 to October 2020 with no language restriction, using PRISMA guidelines, investigating the correlation between antibody concentrations in DBS and serum or plasma samples, and the effect of storage temperature on DBS diagnostic performance. We included 40 studies in this systematic review. The antibody concentration in DBS and serum/plasma samples reported a good pooled correlation, (r2 = 0.86 (ranged 0.43 to 1.00)). Ten studies described a decline of antibody after 28 days at room temperature compared to optimal storage at -20°C, where antibodies were stable for up to 200 days. There were only five studies of anti-bacterial antibodies.

CONCLUSIONS

There is a good correlation between antibody concentrations in DBS and serum/plasma samples, supporting the wider use of DBS in vaccine and sero-epidemiological studies, but there is limited data on anti-bacterial antibodies. The correct storage of DBS is critical and may be a consideration for longer term storage.

Point-of-Care Tests for Hepatitis B: An Overview

Despite the heavy disease burden posed by hepatitis B, around 90% of people living with hepatitis B are not diagnosed globally. Many of the affected populations still have limited or no access to essential blood tests for hepatitis B. Compared to conventional blood tests which heavily rely on centralised laboratory facilities, point-of-care testing for hepatitis B has the potential to broaden testing access in low-resource settings and to engage hard-to-reach populations. Few hepatitis B point-of-care tests have been ratified for clinical use by international and regional regulatory bodies, and countries have been slow to adopt point-of-care testing into hepatitis B programs. This review presents currently available point-of-care tests for hepatitis B and their roles in the care cascade, reviewing evidence for testing performance, utility, acceptability, costs and cost-effectiveness when integrated into hepatitis B diagnosis and monitoring programs. We further discuss challenges and future directions in aspects of technology, implementation, and regulation when adopting point-of-care testing in hepatitis B programs.

[Detection of markers of hepatitis B and D virus infection in biological media and dried blood spots.]

The aim of this study was to assess the rates of detection of the major markers of infection with hepatitis B and Delta (D) viruses in serum, saliva and dry blood dots (DBS) as a possible option for serological studies among the population of the endemic region in conditions of limited laboratory resources. For this purpose, paired samples of blood serum and DBS, blood serum and saliva from patients with chronic hepatitis B with Delta agent living in the Republic of Tyva, which is endemic for this disease. HBsAg was detected in 289 (100%) serum samples, in 88/92 (95.7%) saliva samples, in 60/80 (75%) DBS samples, stored three years at room temperature, and in 111/117 (94.9%) DBS stored one year at the same conditions. Anti-HBcore was detected in 209 (100%) serum samples, while in saliva and DBS samples this marker was detected in only 13.04% (12/92) and 19.7% (23/117), respectively. Anti-HDV antibodies in serum were detected in 209 (100%) samples collected from patients in 2017-2018. In saliva and DBS anti-HDV were not detected in any sample. This difference in the detection rates of anti-HBcore and anti-HDV might be accounted for the fact that the HBV core protein is a very strong immunogen, indusing the production of anti-HBcore in high concentrations. Probably, the concentration of anti-HDV is much lower, which explains its absence in saliva and DBS in patients with hepatitis B+D. Samples of biological media (saliva), as well as DBS can serve as an alternative material for the detection of HBsAg in screening and research prevalence studies. Meanwhile, the definition of anti-HDV in such media is not possible due to the false negative results. Due to the high probability of superinfection with HDV in patients with HBV in endemic areas, the detection of HBsAg in alternative media (saliva or DBS) should be followed by testing for anti-HDV in serum samples.

Evaluation of the Aptima™ HBV Quant Dx assay for semi-quantitative HBV viral load from dried blood spots

BACKGROUND

The detection and quantification of hepatitis B virus (HBV) DNA from dried blood spots (DBS) is a major tool for chronic hepatitis B management in resource-limited settings. This strategy fits in perfectly with the hepatitis control plan promoted by the World Health Organization. However, few commercial methods are validated for viral load (VL) measurement on DBS.

OBJECTIVES

Our objective was to evaluate the performance of the HBV VL measurement of the Aptima™ HBV Quant Dx assay on DBS compared to plasma samples on the Panther® platform (Hologic).

STUDY DESIGN

266 whole blood samples for routine measurement were included. Five spots of 75 μL of whole blood were loaded onto a card before centrifugation and plasma settling.

RESULTS

149 samples were quantifiable and 117 were not detected. We achieved excellent linearity (r² = 0.994) over a wide range of measurements suitable for clinical practice, and a 95 % lower limit of detection (LLOD-95 %) at 2.65 log₁₀ IU/mL (445 IU/mL). A good performance of this assay was observed for samples with HBV VL > LLOD-95 % and 100 % of samples were detected if HBV VL was above 2.95 log₁₀ IU/mL. The correlation between the two matrices for quantitative VLs was good (r² = 0.978) with a very low bias (-0.002 log₁₀ IU/mL).

CONCLUSION

The Aptima™ assay can properly detect and quantify HBV DNA in DBS, providing a satisfactory use in clinical monitoring and therapeutic decisions. DBS represents an excellent alternative to plasma, especially in resource-limited countries, while maintaining the performance and advantages of an automated technique.

Epidemiology of hepatitis B and C virus infection in Central West Argentina

Little information is available regarding the prevalence of viral hepatitis in Central West Argentina. This study aims to give new information regarding HBV and HCV prevalence, genotypes, and risk factors in Central West Argentina and the suitability of dried blood spot (DBS) sampling for HBV and HCV screening.

METHODS

A total of 622 individuals were included; the mean age was 36.6 ± 14.3 years and 55.4% were females. HBV and HCV markers were detected using serological and molecular analysis, and risk factors were evaluated using statistical analysis.

RESULTS

Using serum samples, the HBsAg prevalence was 1.8%, the rate of HBV exposure (anti-HBc positivity) was 5.3%, and the rate of HBV immunity was 34.9%. HBV DNA was found in four out of 11 HBsAg⁺ samples, and the viruses in three of these samples were classified as genotypes A1, A2 and F2a. Multivariate analysis showed that anti-HBs positivity was associated with the level of schooling and history of HBV vaccination. The anti-HCV prevalence was 2.6%, and HCV RNA was found in 11 samples, seven of which contained viruses of genotypes 1a (n = 2), 1b (n = 3) and 2 (n = 2). The sensitivity of the DBS assay for HBsAg, anti-HBc, and anti-HCV was 100%, 66.6%, and 75%, respectively, and the specificity was above 98% for all markers when compared to serum.

CONCLUSION

A low rate of HBV immunity was observed, demonstrating the importance of HBV vaccination. High HCV prevalence was found, and HCV 1b was closely related to other Argentinian isolates. Finally, the performance of DBS testing in this population needs more optimization to increase its sensitivity and specificity.

Evaluation of the cobas® HCV test for quantifying HCV RNA in dried plasma spots collected using the cobas® Plasma Separation Card

OBJECTIVE

This study evaluated the performance of the cobas® hepatitis C virus (HCV) Test for use on the cobas® 6800/8800 Systems for the detection and quantification of HCV RNA collected using the cobas® Plasma Separation Card (PSC) compared with plasma samples.

METHODS

Whole EDTA-venous blood was collected from 50 HCV-positive donors and 140 μL from each donor was spotted onto a PSC and stored either frozen or at ambient temperature. These were compared with matched EDTA-plasma samples. The limit of detection (LoD) of the assay for PSC samples was determined using serial dilutions of the Roche HCV secondary calibration standard. The stability of the PSC samples across a range of timepoints was also assessed.

RESULTS

The mean titer difference between ambient and -10 °C storage of PSC samples was 0.04 log10 IU/mL (95% CI: 0.00, 0.07). The mean titer difference between frozen PSC samples and EDTA plasma samples was -1.59 log10 IU/mL (95% CI: -1.66, -1.53) and between ambient PSC samples and EDTA samples was -1.64 log10 IU/mL (95% CI: -1.70, -1.57). Correlation between PSC samples and EDTA plasma was linear in both cases (frozen: slope = 1.039, intercept=-1.839, R² = 0.89; ambient: slope = 1.012, intercept=-1.712, R² = 0.88). The LoD of the cobas® HCV Test using the PSC was 866 IU/mL (95% CI: 698, 1153 IU/mL) and 408 IU/mL (95% CI: 336, 544 IU/mL) using an optimized Assay Specific Analysis Package.

CONCLUSIONS

PSC samples correlate well with plasma viral load and demonstrate a LoD below 1000 IU/mL and good stability at ambient temperature for 28 days. A correction factor would allow quantification of HCV viral RNA load from samples collected using a PSC.

Evaluation of accuracy of hepatitis B virus antigen and antibody detection and relationship between epidemiological factors using dried blood spot

Dried blood spots (DBS) testing might increase the access for Hepatitis B virus (HBV) diagnosis, but little is known about the performance of these assays in real life conditions. This study aims to evaluate the diagnostic accuracy of HBsAg, anti-HBc and anti-HBs detection in DBS in clinical settings and field studies and to evaluate demographic and risk behaviour according the presence of HBsAg and anti-HBc. Paired sera and DBS samples were obtained from 2309 individuals from 3 groups, defined as follows: G1: clinical setting (n = 5-19), G2: general population (n = 1305) and G3: vulnerable individuals that could be more exposed to blood contact (n = 485). Sera and DBS were tested using commercial enzyme immunoassay (EIA), with some modifications added. Using DBS samples, the specificity values were above 90 % for HBsAg and anti-HBc in all groups and for anti-HBs range from 58.6%-85%. HBsAg testing had the best performance in GI (sensitivity = 84.4 %) and among those samples that the paired serum also presented anti-HBc marker (sensitivity = 91.6 %). High sensitivity of anti-HBc testing in DBS samples was observed in GI (80.8 %) and among HBV active cases (HBsAg+/anti-HBc+) (98.4 %). Testing of anti-HBs in DBS showed the highest sensitivity in GIII (65.5 %), in previous HBV exposed and cured individuals and when serum titers were above 100 IU/mL (86.7 %). DBS samples could be used for screening and prevalence studies for HBsAg and anti-HBc, particularly in clinical settings and among HBV active cases in field studies.

Usefulness of automated assays for detecting hepatitis B and C markers in dried blood spot samples

Objective

Dried blood spots (DBSs) can be used as an alternative to serum samples because they are easily collected and can be transported without refrigeration to reference laboratories for diagnosis. The present study was performed to evaluate the utility of electrochemiluminescence immunoassay “ECLIA” for anti-HCV, HBsAg and anti-HBc detection from DBS samples.

Results

Anti-HCV was detected in 103 DBS samples from 108 paired, positive serum and undetected in 364 DBS samples from 366 paired, negative specimens, giving a sensitivity of 95.4% and a specificity of 99.4%. HBsAg was detected in 67 DBS samples out of 71 positive, paired serum and was undetected among 295 DBS samples from 298 paired, negative specimens, giving a sensitivity and specificity of 94.4% and 99%, respectively. Anti-HBc was detected in 160 DBS samples from 185 paired, positive serum specimens and undetected in 349 DBS samples from 357 paired, negative serum specimens, giving a sensitivity of 86.5% and a specificity of 97.8%. Overall, the Kappa index indicated a high agreement between results obtained for the serum and DBS samples (k: 0.95, 0.93 and 0.86 for anti-HCV, HBsAg, anti-HBc, respectively). In conclusion, the ECLIA test could be used for detecting hepatitis B and C markers in DBS.

Applicability of Oral Fluid and Dried Blood Spot for Hepatitis B Virus Diagnosis

Hepatitis B virus (HBV) is one of the major causes of chronic liver disease worldwide; however most of individuals are not aware about the infection. Oral fluid and dried blood spot (DBS) samples may be an alternative to serum to HBV diagnosis to increase the access to diagnosis in remote areas or high-risk groups. The main objective of this review is to give an insight about the usefulness of oral fluid and DBS for detecting HBV markers. Several groups have evaluated the detection of HBsAg, anti-HBc, and anti-HBs markers in oral fluid and DBS samples demonstrating 13 to 100% of sensitivity and specificity according different groups, sample collectors, and diagnosis assays. In the same way, HBV DNA detection using oral fluid and DBS samples demonstrate different values of sensitivity according type of collection, studied group, extraction, and detection methods. Thus, serological and molecular diagnostic tests demonstrated good performance for detecting HBV using oral fluid and DBS according some characteristics and could be useful to increase the access to the diagnosis of HBV.

Analysis of Inflammatory Mediators in Newborn Dried Blood Spot Samples by Chip-Based Immunoaffinity Capillary Electrophoresis

A chip-based immunoaffinity capillary electrophoresis (ICE) system has been developed for measuring inflammatory mediators in dried blood samples routinely taken from newborn babies. A defined area of each dried blood spot was removed from the sample card and its contents eluted. The recovered eluates were injected into the chip and the analytes of interest isolated by the immunoaffinity disk within the chip. The captured analytes were labeled in-situ with a red light-emitting laser dye and electro-eluted into the chip separation channel. Electrophoretic separation of all of the analytes was achieved within 2.0 min with quantification of each peak being performed by online LIF detection and integration of each peak area. The degree of accuracy and precision achieved by the chip-based system is comparable to conventional immunoassays and the system is robust enough to be applied to the analysis of clinical samples.

Using dried blood spot for the detection of HBsAg and anti-HCV antibodies in Cameroon

Objective

Dried blood spots (DBS) offer multiple benefits for collecting, storing and shipping whole blood samples. Our objective was to compare, for the first time in Africa, the performance of DBS with respect to plasma in the detection of Hepatitis B surface antigen (HBsAg) and antibodies to Hepatitis C Virus (anti-HCV) using Architect, Abbott Diagnostics.

Results

DBS had a sensitivity of 99%, a specificity of 100%, a positive predictive value of 99%, a negative predictive value of 100% and a kappa index of 0.99 for the detection of HBsAg. For anti-HCV detection, the sensitivity, specificity, positive predictive value, negative predictive value and kappa index were 99%, 98%, 98%, 99%, and 0.97, respectively. This study confirms that DBS may be a reliable alternative specimen type for HBV and HCV diagnosis.

New virological tools for screening, diagnosis and monitoring of hepatitis B and C in resource-limited settings

Worldwide, the increasingly dominant model of laboratory testing is the centralised laboratory, in which automation of analytical processes increases, enabling the analysis of large numbers of samples at a relatively low cost. However, this trend does not fulfil the requirements for care of patients with chronic hepatitis B and C in resource-limited settings. Alternative models using point-of-care (POC) tests and dried blood spots (DBSs) are increasingly being considered for viral hepatitis screening, diagnosis and monitoring. POC tests are small devices providing qualitative and/or quantitative determination of viral antibodies and/or antigens. They can use original specimen matrices, such as oral fluid or blood collected from a fingerstick. POC tests are particularly useful for large-scale screening, and to improve access to care in regions where laboratory access is limited. New POC devices that detect and quantify viral nucleic acids are at the developmental stage. DBSs offer the main advantage of enabling storage of desiccated blood that can be easily transported to reference centres, where state-of-the-art molecular and serological diagnostic tests are available. However, standardisation and better automation of DBS handling are needed. Herein, we review alternatives to classical hepatitis B and C virological tests, examining POC tests and DBSs, as well as alternatives to nucleic acid testing. Innovations in testing approaches resulting from the availability of these new assays are also discussed.

Assessing hepatitis B immunity using dried blood spot samples from HIV+ individuals

This study aims to evaluate the utility of an optimized enzyme immunoassay (EIA) to detect and quantify antibodies against hepatitis B surface antibody (anti-HBs) in dried blood spots (DBSs) within the context of human immunodeficiency virus (HIV) status. Serum and DBS samples were obtained from 56 HIV+ and 99 HIV- patients and subjected to EIA for the detection of anti-HBs, where sample volume and cut off value were modified for DBS testing. Sensitivities of anti-HBs detection in DBS were 79.8% and 76.8% in HIV- and HIV+ subjects, respectively. Concordant results for anti-HBs in serum and DBS presented high mean CD8 cell counts, HIV viral load and optical density (OD) values of anti-HBs. Anti-HBs titers were significantly higher in serum, whether or not anti-HBs titers were detected in DBS. It was possible to detect anti-HBs in DBS as low as 17.4 and 27.3 IU/mL among HIV+ and HIV- subjects, respectively. In conclusion, DBS can be used to detect and quantify anti-HBs in HIV-infected individuals, which could increase access to diagnosis and vaccination.

Dried Blood Spots for Global Health Diagnostics and Surveillance: Opportunities and Challenges

There is increasing interest in using dried blood spot (DBS) cards to extend the reach of global health and disease surveillance programs to hard-to-reach populations. Conceptually, DBS offers a cost-effective solution for multiple use cases by simplifying logistics for collecting, preserving, and transporting blood specimens in settings with minimal infrastructure. This review describes methods to determine both the reliability of DBS-based bioanalysis for a defined use case and the optimal conditions that minimize pre-analytical sources of data variability. Examples by the newborn screening, drug development, and global health communities are provided in this review of published literature. Sources of variability are linked in most cases, emphasizing the importance of field-to-laboratory standard operating procedures that are evidence based and consider both stability and efficiency of recovery for a specified analyte in defining the type of DBS card, accessories, handling procedures, and storage conditions. Also included in this review are reports where DBS was determined to not be feasible because of technology limitations or physiological properties of a targeted analyte.

Comparison of the performance of enzyme immunoassays for hepatitis B and C detection in dried blood spot

Dried blood spots (DBSs) could be an alternative to serum for hepatitis B virus (HBV) and hepatitis C virus (HCV) diagnosis. This study aims to evaluate two enzyme immunoassays (EIAs) for HBsAg and anti-HCV detection using DBS. Serum was tested using commercial EIA. DBS was tested using optimized EIA developed for serum and commercial EIA developed for DBS (Imunoscreen). Concordances between DBS and serum samples for both markers and EIAs were higher than 97%. Both EIAs demonstrated good performance for HBsAg and anti-HCV detection using DBS, and these methods could be used unchangeably increasing the access for HBV and HCV diagnosis.

Diagnostic accuracy of serological diagnosis of hepatitis C and B using dried blood spot samples (DBS): two systematic reviews and meta-analyses

BACKGROUND

Dried blood spots (DBS) are a convenient tool to enable diagnostic testing for viral diseases due to transport, handling and logistical advantages over conventional venous blood sampling. A better understanding of the performance of serological testing for hepatitis C (HCV) and hepatitis B virus (HBV) from DBS is important to enable more widespread use of this sampling approach in resource limited settings, and to inform the 2017 World Health Organization (WHO) guidance on testing for HBV/HCV.

METHODS

We conducted two systematic reviews and meta-analyses on the diagnostic accuracy of HCV antibody (HCV-Ab) and HBV surface antigen (HBsAg) from DBS samples compared to venous blood samples. MEDLINE, EMBASE, Global Health and Cochrane library were searched for studies that assessed diagnostic accuracy with DBS and agreement between DBS and venous sampling. Heterogeneity of results was assessed and where possible a pooled analysis of sensitivity and specificity was performed using a bivariate analysis with maximum likelihood estimate and 95% confidence intervals (95%CI). We conducted a narrative review on the impact of varying storage conditions or limits of detection in subsets of samples. The QUADAS-2 tool was used to assess risk of bias.

RESULTS

For the diagnostic accuracy of HBsAg from DBS compared to venous blood, 19 studies were included in a quantitative meta-analysis, and 23 in a narrative review. Pooled sensitivity and specificity were 98% (95%CI:95%-99%) and 100% (95%CI:99-100%), respectively. For the diagnostic accuracy of HCV-Ab from DBS, 19 studies were included in a pooled quantitative meta-analysis, and 23 studies were included in a narrative review. Pooled estimates of sensitivity and specificity were 98% (CI95%:95-99) and 99% (CI95%:98-100), respectively. Overall quality of studies and heterogeneity were rated as moderate in both systematic reviews.

CONCLUSION

HCV-Ab and HBsAg testing using DBS compared to venous blood sampling was associated with excellent diagnostic accuracy. However, generalizability is limited as no uniform protocol was applied and most studies did not use fresh samples. Future studies on diagnostic accuracy should include an assessment of impact of environmental conditions common in low resource field settings. Manufacturers also need to formally validate their assays for DBS for use with their commercial assays.

Screening for HIV, hepatitis B and syphilis on dried blood spots: A promising method to better reach hidden high-risk populations with self-collected sampling

Introduction

Many people at high risk for sexually transmitted infections (STIs), e.g., men who have sex with men (MSM), are not optimally reached by current sexual health care systems with testing. To facilitate testing by home-based sampling or sampling in outreach setting we evaluated dried blood spots (DBS), a method for self-collected blood sampling for serological screening of HIV, hepatitis B (HBV) and syphilis. The aims of this study were to assess the acceptability and feasibility of self-collected DBS and to compare the test results for screening of HIV, HBV and syphilis from DBS with blood drawn by venous puncture.

Methods

DBS were collected from men who have sex with men (MSM), visiting the STI clinic of the public health service South Limburg (n = 183) and HIV positive and HBV positive patients (n = 34), visiting the outpatient clinics of the Maastricht University Medical Centre in the period January 2012–April 2015. The 93 first participating MSM visiting the STI clinic were asked to fill in a questionnaire about the feasibility and acceptability about self-collection of DBS in a setting without going to a health care facility and were asked to collect the DBS themselves. Serological screening tests for HIV (HIV combi PT, Roche), HBV (HBsAg, Roche) and syphilis (Treponema pallidum Ig, Biokit 3.0) were performed on DBS and on blood drawn by venous puncture, which was routinely taken for screening.

Results

In total 217 participants were included in the study with a median age of 40 years (range between 17–80). Of MSM 84% agreed that it was clear and easy to do the finger-prick, while 53% agreed that it was clear and easy to apply the blood onto the DBS card. Also, 80% of MSM would use the bloodspot test again. In 91% (198) of DBS, sufficient material was collected to perform the three tests. No difference was observed in DBS quality between self-collected DBS and health care worker collected DBS. For HIV (n = 195 DBS-serum pairs) sensitivity and specificity were 100%. For HBV the sensitivity for HBsAg (n = 202) was 90% and specificity was 99%. For syphilis (n = 191) the sensitivity of the DBS was 93% with a specificity of 99%. Analysis of the DBS of HIV positive participants (n = 38) did show similar test performance for HBV and syphilis as in HIV negatives.

Conclusion

DBS is an acceptable self-sampling method for MSM, as there was no difference in DBS quality in self-collected and health care worker collected DBS. Test performance, i.e., its high sensitivity (>90%) and specificity (>99%) measures show that DBS is a valid alternative for venous blood puncture. Especially when DBS is combined with home-collected sampling for Chlamydia trachomatis and Neisseria gonorrhoeae, complete STI screening can be done in outreach setting and/or home-collected sampling in MSM.

Evaluation of the COBAS® AmpliPrep/COBAS® TaqMan® HCV Test v2.0 for HCV viral load monitoring using dried blood spot specimens

This study evaluated the use of dried blood spot (DBS) for HCV viral load quantification using the COBAS^® AmpliPrep/COBAS^® Taqman^® HCV Quantitative Test v2.0 (CAP/CTM HCV v2), and compared two different procedures for preparation of DBS samples with a Specimen Pre-Extraction (SPEX) reagent (either heated [SPEX with SH] for 10min at 56°C on a thermomixer, or incubated for 1h at room temperature [SPEX at RT]) against the standard plasma input. Whole blood specimens from 48 patients with chronic HCV infection and Whatman^® 903 Protein Saver Cards were used to prepare 35μL DBS. An aliquot of plasma was spun and frozen from each draw. Mean DBS viral load results were compared to the corresponding results from plasma. Correlation between DBS to plasma was linear for both SPEX with SH (R²=0.96) and SPEX at RT (R²=0.97) procedures, with a constant negative offset of approximately 2.0log₁₀IU/mL between whole blood DBS without any adjustments and plasma results. After volume corrections, the mean offset to plasma decreased to -0.39 and -0.36 for the two procedures, respectively. The study demonstrated the use of DBS for HCV viral load correlates well with plasma with a constant offset.

Evaluation of HBsAg and anti-HBc assays in saliva and dried blood spot samples according HIV status

Influence of HIV status in HBV markers detection in saliva and dried blood spots (DBS) was not well established. This study aims to evaluate the performance of optimized commercial immunoassay for identifying HBsAg and anti-HBc in saliva and DBS according HIV status. A sum of 535 individuals grouped as HIV⁺, HBV⁺, HIV/HBV⁺ and HIV/HBV- were recruited where 347 and 188 were included for HBsAg and anti-HBc evaluation, respectively. Serum, DBS collected in Whatman 903 paper and saliva obtained using salivette device were analyzed using EIA. Increased sample volume and ROC curve analysis for cut off determination were used for DBS and saliva testing. HBsAg detection in saliva and DBS exhibited sensitivities of 80.9% and 85.6% and specificities of 86.8% and 96.3%. Sensitivity of anti-HBc in saliva and DBS were 82.4% and 76.9% and specificities in saliva and DBS were 96.9% and 91.7%. Low sensitivities were observed for HBsAg (62%) and anti-HBc (47%) detection in saliva of HIV/HBV+ individuals. OD values were also lower for HBsAg detection in DBS and saliva of HIV/HBV+ individuals compared to their serum samples. Statistical significance was found for sensitivities in HBsAg detection between saliva and DBS demonstrating high sensitivity for DBS specimens. In conclusion, HIV status or antiretroviral treatment appears to interfere in the performance of HBsAg and anti-HBc detection in DBS and saliva samples using the adapted commercial EIA.

Performance of ANTI-HCV testing in dried blood spots and saliva according to HIV status

The use of saliva and dried blood spots (DBS) could increase access to HCV diagnosis for high-risk populations, such as HIV-infected individuals, but the performance of these assays has not been well established in this group. This study aims to evaluate HIV status, particularly TCD4⁺ cell count and viral load, in the performance of anti-HCV testing using DBS and saliva. A total of 961 individuals classified as HCV+, HIV+, or HIV/HCV+, as well as negative controls, donated serum, DBS, and saliva samples for anti-HCV testing using a commercial enzyme immunoassay. Sample volume was modified for DBS and saliva, and an ROC curve was used for cut-off determination in saliva. Anti-HCV sensitivities were greater than 93% using DBS and saliva in the HCV+ group, while they were 83.3% and 95.6% for HCV/HIV+ individuals for DBS and saliva assays, respectively. Specificity varied from 91.7% to 100% using saliva and DBS in HIV monoinfected and control subjects. When only anti-HCV/HCV RNA+ serum samples, that is, true positives, were considered, the sensitivities were 98.3% and 100% for DBS and saliva, respectively, in the HCV+ group and 91.6% and 94.8% for DBS and saliva, respectively, in the HIV/HCV+ group. High absorbance values were observed among those presenting with HCV RNA in serum and low HIV viral load (less than 50 copies/mL). In conclusion, DBS and saliva samples could be used for anti-HCV detection, particularly to identify active HCV cases, but low sensitivity was observed for anti-HCV testing using DBS in the HIV/HCV+ group.

Novel applications for a noninvasive sampling method of the nasal mucosa

Reliable methods for sampling the nasal mucosa provide clinical researchers with key information regarding respiratory biomarkers of exposure and disease. For quick and noninvasive sampling of the nasal mucosa, nasal lavage (NL) collection has been widely used as a clinical tool; however, limitations including volume variability, sample dilution, and storage prevent NL collection from being used in nonlaboratory settings and analysis of low abundance biomarkers. In this study, we optimize and validate a novel methodology using absorbent Leukosorb paper cut to fit the nasal passage to extract epithelial lining fluid (ELF) from the nasal mucosa. The ELF sampling method limits the dilution of soluble mediators, allowing quantification of both high- and low-abundance soluble biomarkers such as IL-1β, IL-8, IL-6, interferon gamma-induced protein 10 (IP-10), and neutrophil elastase. Additionally, we demonstrate that this method can successfully detect the presence of respiratory pathogens such as influenza virus and markers of antibiotic-resistant bacteria in the nasal mucosa. Efficacy of ELF collection by this method is not diminished in consecutive-day sampling, and percent recovery of both recombinant IL-8 and soluble mediators are not changed despite freezing or room temperature storage for 24 h. Our results indicate that ELF collection using Leukosorb paper sampling of ELF provides a sensitive, easy-to-use, and reproducible methodology to collect concentrated amounts of soluble biomarkers from the nasal mucosa. Moreover, the methodology described herein improves upon the standard NL collection method and provides researchers with a novel tool to assess changes in nasal mucosal host defense status.

Screening and diagnosis of HBV in low-income and middle-income countries

HBV testing and diagnosis of HBV-related liver disease in low-income and middle-income countries differs substantially from that in developed countries in terms of access to resources and expensive technologies requiring highly specialized staff. For identification and classification of HBV infection, genomic amplification methods to detect and quantify HBV DNA are often nonexistent or available only in central laboratories of major cities. When samples from peripheral locations do arrive, delays in receiving results generate loss to follow-up. Testing is often limited to measurement of hepatitis B surface antigen (HBsAg), alanine aminotransferase levels, aspartate aminotransferase to platelet ratio index and hepatitis B e antigen (HBeAg) to determine indications for antiviral therapy (AVT). Utilization of AVT is limited by cost and availability, particularly when patients are not covered by health insurance. The natural history of HBV infection is influenced by genotypes B and C in East Asia, where decades of immune tolerance have led to mostly vertical transmission; in sub-Saharan Africa, where genotypes A1 and E predominate, infection is transmitted horizontally between young children, followed by a nonreplicative phase. In both regions, cirrhosis and hepatocellular carcinoma are common and would be considerably ameliorated by AVT. Implementation of the HBV vaccine since the 1990s in Asia and 2000s in Africa has decreased the incidence of HBV, but vaccine failure and insufficiently effective prevention remain concerning issues.

Dried blood spots, valid screening for viral hepatitis and human immunodeficiency virus in real-life

AIM

To detect chronic hepatitis B (CHB), chronic hepatitis C (CHC) and human immunodeficiency virus (HIV) infections in dried blood spot (DBS) and compare these samples to venous blood sampling in real-life.

METHODS

We included prospective patients with known viral infections from drug treatment centers, a prison and outpatient clinics and included blood donors as negative controls. Five drops of finger capillary blood were spotted on filter paper, and a venous blood sample was obtained. The samples were analyzed for HBsAg, anti-HBc, anti-HBs, anti-HCV, and anti-HIV levels as well as subjected to a combined nucleic acid test (NAT) for HBV DNA, HCV RNA and HIV RNA.

RESULTS

Samples from 404 subjects were screened (85 CHB, 116 CHC, 114 HIV and 99 blood donors). DBS had a sensitivity of > 96% and a specificity of > 98% for the detection of all three infections. NAT testing did not improve sensitivity, but correctly classified 95% of the anti-HCV-positive patients with chronic and past infections. Anti-HBc and anti-HBS showed low sensitivity in DBS (68% and 42%).

CONCLUSION

DBS sampling, combined with an automated analysis system, is a feasible screening method to diagnose chronic viral hepatitis and HIV infections outside of the health care system.

Innovations in health and demographic surveillance systems to establish the causal impacts of HIV policies

PURPOSE OF REVIEW

Health and demographic surveillance systems (HDSS), in conjunction with HIV treatment cohorts, have made important contributions to our understanding of the impact of HIV treatment and treatment-related interventions in sub-Saharan Africa. The purpose of this review is to describe and discuss innovations in data collection and data linkage that will create new opportunities to establish the impacts of HIV treatment, as well as policies affecting the treatment cascade, on population health and economic and social outcomes.

RECENT FINDINGS

Novel approaches to routine collection of biomarkers, behavioural data, spatial data, social network information, migration events and mobile phone records can significantly strengthen the potential of HDSS to generate exposure and outcome data for causal analysis of HIV treatment impact and policies affecting the HIV treatment cascade. Additionally, by linking HDSS data to health service administration, education and welfare service records, researchers can substantially broaden opportunities to establish how HIV treatment affects health and economic outcomes when delivered through public sector health systems and at scale.

SUMMARY

As the HIV treatment scaleup in sub-Saharan Africa enters its second decade, it is becoming increasingly important to understand the long-term causal impacts of large-scale HIV treatment and related policies on broader population health outcomes, such as noncommunicable diseases, as well as on economic and social outcomes, such as family welfare and children's educational attainment. By collecting novel data and linking existing data to public sector records, HDSS can create near-unique opportunities to contribute to this research agenda.

The prevalence of hepatitis B virus infection in HIV-positive and HIV-negative infants: KwaZulu-Natal, South Africa

Background

The prevalence of hepatitis B virus (HBV) amongst South African infants and children has been reported in the pre-HIV era. Despite the reported high prevalence of HIV in the general population of South Africa, the rate of HIV/HBV co-infection amongst infants and children remains poorly reported.

Objectives

We describe the prevalence of HBV infection amongst HIV-positive and HIV-negative infants by molecular methods of diagnosis using dried blood spot samples.

Methods

This retrospective cross-sectional study was conducted between July 2011 and December 2011 in an academic referral laboratory offering viral diagnostic services to the entire KwaZulu-Natal province of South Africa. A total of 322 study samples were collected from discarded residual dried blood spot samples following routine infant diagnosis of HIV. Equal proportions of HIV-positive and HIV-negative infant specimens were studied. Statistical differences in the prevalence of HBV between the HIV-positive and HIV-negative samples were calculated using the Pearson chi-square test, and a p-value < 0.05 was considered statistically significant. Further testing for HBV DNA using a nested polymerase chain reaction method was performed.

Results

The overall prevalence of HBV was 10%. In the HIV-positive group, 21 of 161 infants tested positive for HBV compared with 12 of 161 HIV-negative infants who tested positive for HBV. The proportion of infants infected with HBV was marginally higher amongst HIV-positive infants (13.0%; 95% CI 6.8–19.9) compared with HIV-negative infants (7.5%; 95% CI 2.5–13.7; P = 0.098), though not statistically significant.

Conclusion

The finding of a 10% HBV prevalence in this infant cohort is clinically significant. The non-statistically significant difference in HBV prevalence between the HIV-positive and HIV-negative infants suggests that high prevalence of HBV infection in children may be a problem independent of HIV.

Update on hepatitis B and C virus diagnosis

Viral hepatitis B and C virus (HBV and HCV) are responsible for the most of chronic liver disease worldwide and are transmitted by parenteral route, sexual and vertical transmission. One important measure to reduce the burden of these infections is the diagnosis of acute and chronic cases of HBV and HCV. In order to provide an effective diagnosis and monitoring of antiviral treatment, it is important to choose sensitive, rapid, inexpensive, and robust analytical methods. Primary diagnosis of HBV and HCV infection is made by using serological tests for detecting antigens and antibodies against these viruses. In order to confirm primary diagnosis, to quantify viral load, to determine genotypes and resistance mutants for antiviral treatment, qualitative and quantitative molecular tests are used. In this manuscript, we review the current serological and molecular methods for the diagnosis of hepatitis B and C.

Hepatitis B viral load in dried blood spots: A validation study in Zambia

BACKGROUND

Access to hepatitis B viral load (VL) testing is poor in sub-Saharan Africa (SSA) due to economic and logistical reasons.

OBJECTIVES

To demonstrate the feasibility of testing dried blood spots (DBS) for hepatitis B virus (HBV) VL in a laboratory in Lusaka, Zambia, and to compare HBV VLs between DBS and plasma samples.

STUDY DESIGN

Paired plasma and DBS samples from HIV-HBV co-infected Zambian adults were analyzed for HBV VL using the COBAS AmpliPrep/COBAS TaqMan HBV test (Version 2.0) and for HBV genotype by direct sequencing. We used Bland-Altman analysis to compare VLs between sample types and by genotype. Logistic regression analysis was conducted to assess the probability of an undetectable DBS result by plasma VL.

RESULTS

Among 68 participants, median age was 34 years, 61.8% were men, and median plasma HBV VL was 3.98logIU/ml (interquartile range, 2.04-5.95). Among sequenced viruses, 28 were genotype A1 and 27 were genotype E. Bland-Altman plots suggested strong agreement between DBS and plasma VLs. DBS VLs were on average 1.59logIU/ml lower than plasma with 95% limits of agreement of -2.40 to -0.83log IU/ml. At a plasma VL ≥2,000IU/ml, the probability of an undetectable DBS result was 1.8% (95% CI: 0.5-6.6). At plasma VL ≥20,000IU/ml this probability reduced to 0.2% (95% CI: 0.03-1.7).

CONCLUSIONS

In a Zambian laboratory, we observed strong agreement between DBS and plasma VLs and high sensitivity in DBS at plasma VL ≥2,000IU/ml. As HBV treatment expands, DBS could increase access to HBV VL testing and care in SSA settings.

Long term stability of HBsAg, anti-HBc and anti-HCV in dried blood spot samples and eluates

BACKGROUND

Dried blood spots (DBS) are a useful specimen collection tool in situations where venous access is problematic, however, detection of biomarkers from this specimen type is subject to variation depending on storage conditions and storage time.

OBJECTIVES

The objective of this study is to assess the detection of HBsAg, anti-HBc and anti-HCV from DBS after storage.

STUDY DESIGN

DBS specimens were stored at -70°C, -20°C, 4°C, 22 to 28°C and 37°C either with or without desiccant. Eluates were also prepared from DBS specimens and stored at -20°C and -70°C. DBS cards and eluates were tested for HBsAg, anti-HBc and anti-HCV at baseline on day 0 and thereafter at intervals of 14, 70 and 200 days.

RESULTS

Loss of detection of both HBsAg and anti-HBc was evident by the first time point (14 days) in all storage conditions except for the samples (DBS and eluates) stored at -20°C or -70°C. Both HBsAg and anti-HBc stored under these conditions showed minimal variation up to the final time point (200 days) of storage. The detection of anti-HCV did not differ between the 22 to 28°C, 4°C, -20°C and -70°C DBS nor the -20°C or the -70°C stored eluates over the 200 day time period.

CONCLUSION

We suggest that extended storage of DBS intended for downstream testing is best carried out by freezing either the DBS, or eluate, at -20°C or -70°C as soon as possible following collection for optimal detection of HBsAg, anti-HBc and anti-HCV.

Evaluation of nucleic acid stabilization products for ambient temperature shipping and storage of viral RNA and antibody in a dried whole blood format

Loss of sample integrity during specimen transport can lead to false-negative diagnostic results. In an effort to improve upon the status quo, we used dengue as a model RNA virus to evaluate the stabilization of RNA and antibodies in three commercially available sample stabilization products: Whatman FTA Micro Cards (GE Healthcare Life Sciences, Pittsburgh, PA), DNAstāble Blood tubes (Biomātrica, San Diego, CA), and ViveST tubes (ViveBio, Alpharetta, GA). Both contrived and clinical dengue-positive specimens were stored on these products at ambient temperature or 37°C for up to 1 month. Antibody and viral RNA levels were measured by enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays, respectively, and compared with frozen unloaded controls. We observed reduced RNA and antibody levels between stabilized contrived samples and frozen controls at our earliest time point, and this was particularly pronounced for the FTA cards. However, despite some time and temperature dependent loss, a 94.6-97.3% agreement was observed between stabilized clinical specimens and their frozen controls for all products. Additional considerations such as cost, sample volume, matrix, and ease of use should inform any decision to incorporate sample stabilization products into a diagnostic testing workflow. We conclude that DNAstāble Blood and ViveST tubes are useful alternatives to traditional filter paper for ambient temperature shipment of clinical specimens for downstream molecular and serological testing.

Validation of rapid point-of-care (POC) tests for detection of hepatitis B surface antigen in field and laboratory settings in the Gambia, Western Africa

Hepatitis B virus (HBV) infection is a leading cause of death in sub-Saharan Africa (SSA). Point-of-care tests for hepatitis B surface antigen (HBsAg) could be an ideal tool for a large-scale HBV screening/treatment program in SSA. Using data from the PROLIFICA (Prevention of Liver Fibrosis and Cancer in Africa) program, we conducted a cross-sectional study to assess the diagnostic accuracy of three point-of-care tests (Determine, Vikia, and Espline) for the detection of HBsAg in the field or a laboratory setting in the Gambia. In the field, we used finger-prick whole blood for the Determine and Vikia tests and dried blood spots for the reference standard test (AxSYM HBsAg enzyme-linked immunosorbent assay [ELISA]). In the laboratory we used serum for the Determine, Espline, and reference test (Architect chemiluminescent microparticle immunoassay). Of 773 participants recruited at the community and 227 known chronic HBV carriers (1,000 subjects in total), 293 were positive for HBsAg. The sensitivity and specificity of the Determine test were 88.5% and 100% in the field and 95.3% and 93.3% in the laboratory setting, respectively. The sensitivity and specificity were 90.0% and 99.8% for the Vikia test (in the field) and 93.9% and 94.7% for the Espline test (in the laboratory). There was no evidence that one kit was better than another. Most of the patients with false-negative results (18/19) were classified as inactive chronic carriers. In summary, the three point-of-care tests had acceptable ranges of diagnostic accuracy. These tests may represent accurate, rapid, and inexpensive alternatives to serology testing for the screening of HBV infection at field level in SSA.

Hepatitis B virus DNA stability in plasma samples under short-term storage at 42°C

We evaluated the stability of hepatitis B virus (HBV) DNA in plasma samples stored at 42°C for external quality assessment (EQA) panels of viral load. To assess the stability of plasma samples containing different concentrations of HBV DNA, serial dilutions of HBV-infected samples with a viral load of 6.40 log₍₁₀₎ IU/mL were made to yield viral loads of 5, 4, and 3 log₍₁₀₎ IU/mL. These were incubated at 42°C for up to 7 days and then frozen at -70°C. Viral load testing for HBV DNA was performed for all samples using COBAS^¯ AmpliPrep/COBAS^¯ TaqMan^¯ HBV Test (v.2.0, Roche, Switzerland). Results were compared with fresh frozen plasma samples as a benchmark to establish acceptable measurements on the days following sample collection. Although the results of this study demonstrated a decrease in HBV DNA viral load ranging from 0.005 to 0.30 log₍₁₀₎ IU/mL after storage at 42°C for up to 7 days, these values did not exceed 0.5 log₍₁₀₎, which is the estimated intra-assay variation for molecular tests. Thus, the insignificant decrease in viral load suggests that shipment of HBV in plasma samples at temperatures of up to 42°C is permissible if they are frozen within 7 days.

Dried blood spots--preparing and processing for use in immunoassays and in molecular techniques

The idea of collecting blood on a paper card and subsequently using the dried blood spots (DBS) for diagnostic purposes originated a century ago. Since then, DBS testing for decades has remained predominantly focused on the diagnosis of infectious diseases especially in resource-limited settings or the systematic screening of newborns for inherited metabolic disorders and only recently have a variety of new and innovative DBS applications begun to emerge. For many years, pre-analytical variables were only inappropriately considered in the field of DBS testing and even today, with the exception of newborn screening, the entire pre-analytical phase, which comprises the preparation and processing of DBS for their final analysis has not been standardized. Given this background, a comprehensive step-by-step protocol, which covers al the essential phases, is proposed, i.e., collection of blood; preparation of blood spots; drying of blood spots; storage and transportation of DBS; elution of DBS, and finally analyses of DBS eluates. The effectiveness of this protocol was first evaluated with 1,762 coupled serum/DBS pairs for detecting markers of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus infections on an automated analytical platform. In a second step, the protocol was utilized during a pilot study, which was conducted on active drug users in the German cities of Berlin and Essen.

Dried blood spot testing for the antenatal screening of HTLV, HIV, syphilis, toxoplasmosis and hepatitis B and C: prevalence, accuracy and operational aspects

INTRODUCTION

Screening for vertically transmitted infection is mandatory and must be conducted at the first prenatal consultation. The most vulnerable women's groups are those at the lowest socio-economic level. Dried blood spot testing on filter paper could represent a secure way to screen pregnant women in the prenatal period.

METHODS

A cross-sectional study was conducted between November 2009 and March 2010, in the Metropolitan Region of Salvador, Bahia, Brazil, to compare the accuracy of the dried blood spot in filter paper and venipuncture serological as screening methods for HIV, HTLV, VHB, VHC, Treponema pallidum, and Toxoplasma gondii during prenatal period. Results of the venous blood sample collected in tubes were considered the gold standard.

RESULTS

Serum samples and dried blood spot were obtained from 692 pregnant women aged between 14 and 42 years, with a median age of 26. Thirteen women were seropositive for T. gondii (1.88%; 95% CI: 0.60-2.71%), five for T. pallidum (0.72%; 95% CI: 0.15-1.61%), two for HBV (0.29%; 95% CI: 0.050.95%) and one for HTLV-1 (0.14%; 95% CI: 0.01-0.71%). No one was positive for HCV and HIV. The dried blood spot accuracy for syphilis and HTLV were 100% (95% CI: 99.25-100) and 100% (95% CI: 99.45-100%), respectively. The average time between blood collection and recording of the sample in the reference laboratory was 4.93 (3.82) days and between dried blood spot processing and active search for pregnant women was 3.44 (4.27) days.

CONCLUSIONS

The use of dried blood spot may represent a secure way to expedite access to results of vertically transmitted diseases in the prenatal period, particularly in regions with scarce healthcare resources.

Current and future use of "dried blood spot" analyses in clinical chemistry

The analysis of blood spotted and dried on a matrix (i.e., "dried blood spot" or DBS) has been used since the 1960s in clinical chemistry; mostly for neonatal screening. Since then, many clinical analytes, including nucleic acids, small molecules and lipids, have been successfully measured using DBS. Although this pre-analytical approach represents an interesting alternative to classical venous blood sampling, its routine use is limited. Here, we review the application of DBS technology in clinical chemistry, and evaluate its future role supported by new analytical methods such as mass spectrometry.