Hepatitis C antibody detection in dried blood spots

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.

Laboratory-based testing for hepatitis C infection using dried blood spot samples: A systematic review and meta-analysis of diagnostic accuracy

The use of dried blood spot (DBS) samples can facilitate the implementation of reflex testing by circumventing the need for centrifugation and freezing of venous blood samples. This systematic review assessed the accuracy of using DBS samples to diagnose chronic hepatitis C virus (HCV) infection. A comprehensive search was undertaken to identify articles published up to July 2020 evaluating the diagnostic accuracy of anti-HCV, HCV-RNA and HCV core antigen tests using DBS. Screening, data extraction, quality appraisal and Grading of Recommendations, Assessment, Development and Evaluations certainty of the evidence assessment were performed independently by two reviewers. Meta-analysis, meta-regression and sensitivity analyses were conducted. The evidence demonstrates that laboratory-based anti-HCV and HCV-RNA tests using DBS samples have high diagnostic accuracy. All comparisons were between DBS and venous samples. For the detection of anti-HCV, sensitivity was 95% (95% CI: 92%-97%) and specificity was 99% ([95% CI: 98%-99%]; n = 25; I²  = 81%; moderate certainty). For the detection of HCV-RNA, the sensitivity was 95% (95% CI: 93%-97%) and specificity was 97% ([95% CI: 94%-98%]; n = 20; I²  = 52%; moderate certainty). The sensitivity of HCV core antigen tests was 86% (95% CI: 79%-91%) and specificity was 98% ([95% CI: 94%-99%]; n = 5; I²  = 37%; low certainty) compared with HCV-RNA (the gold standard for detecting chronic HCV). DBS samples could facilitate diagnosis of chronic HCV infection as the necessary sequential tests (anti-HCV and then HCV-RNA or HCV core antigen) can be undertaken using the same blood sample. This could reduce loss of patient follow-up and support international efforts towards HCV elimination in both high and low prevalence settings.

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.

Evaluation of the diagnostic accuracy of laboratory-based screening for hepatitis C in dried blood spot samples: A systematic review and meta-analysis

The dried blood spot (DBS) is increasingly used for the hepatitis C virus (HCV) screening. Our objective was to perform a meta-analysis of the methodology for HCV screening in DBS samples, particularly in the type of diagnostic assay used. We performed a meta-analysis of all eligible studies published to date (March 2018). The literature search revealed 26 studies: 21 for detection of anti-HCV antibodies and 10 for detection of HCV-RNA. Statistical analyses were performed using Meta-DiSc and STATA (MIDAS module). For detection of HCV antibodies, pooled diagnostic accuracy measures were as follows: sensitivity 96.1%, specificity 99.2%, positive likelihood ratio (PLR) 105, negative likelihood ratio (NLR) 0.04, diagnostic odds ratio (DOR) 2692.9, and summary receiver operating characteristic (SROC) 0.997 ± 0.001. For detection of HCV-RNA, the pooled diagnostic accuracy measures were as follows: sensitivity 97.8%, specificity 99.2%, PLR 44.8, NLR 0.04, DOR 1966.9, and SROC 0.996 ± 0.013. Similar values of pooled diagnostic accuracy measures were found according to the type of anti-HCV antibody detection assay (enzyme-linked immunosorbent assay, rapid diagnostic test, and chemiluminescence assays) and HCV-RNA detection assay (real-time polymerase chain reaction and transcription-mediated amplification). The analysis of external validity showed a high negative predicted value (NPV) for both approaches, but a low positive predicted value (PPV) when prevalence was < 10%, particularly in HCV-RNA tests. Finally, this meta-analysis is subject to limitations, especially publication bias and significant heterogeneity between studies. In conclusion, HCV screening in DBS samples has an outstanding diagnostic performance, with no relevant differences between the techniques used. However, external validity may be limited when the HCV prevalence is low.

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.

Evaluation of dried blood spot samples for screening of hepatitis C and human immunodeficiency virus in a real-world setting

Both hepatitis C virus (HCV) infection and human immunodeficiency virus (HIV) infection are underdiagnosed, particularly in low-income countries and in difficult-to-access populations. Our aim was to develop and evaluate a methodology for the detection of HCV and HIV infection based on capillary dry blood spot (DBS) samples taken under real-world conditions. We carried out a cross-sectional study of 139 individuals (31 healthy controls, 68 HCV-monoinfected patients, and 40 HCV/HIV-coinfected patients). ELISA was used for anti-HCV and anti-HIV antibody detection; and SYBR Green RT-PCR was used for HCV-RNA detection. The HIV serological analysis revealed 100% sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The HCV serological analysis revealed a sensitivity of 92.6%, specificity of 100%, PPV of 100%, and NPV of 79.5%. Finally, the HCV-RNA detection test revealed a detection limit of 5 copies/µl with an efficiency of 100% and sensitivity of 99.1%, specificity of 100%, PPV of 100%, and NPV of 96.9%. In conclusion, our methodology was able to detect both HCV infection and HIV infection from the same DBS sample with good diagnostic performance. Screening for HCV and HIV using DBS might be a key strategy in the implementation of national programs for the control of both infections.

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.

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.

Who to test and how to test for chronic hepatitis C infection - 2016 WHO testing guidance for low- and middle-income countries

Testing and diagnosis of hepatitis C virus (HCV) infection is the gateway for access to both treatment and prevention services, and crucial for an effective hepatitis epidemic response. In contrast to HIV, a systematic approach to hepatitis C testing has been fragmented and limited to a few countries, and there remains a large burden of undiagnosed cases globally. Key challenges in the current hepatitis testing response, include lack of simple, reliable, and low cost diagnostic tests, laboratory capacity, and testing facilities; inadequate data to guide country-specific hepatitis testing approaches and who to test; stigmatization and social marginalization of some groups with or at risk of viral hepatitis; and lack of international or national guidelines on hepatitis testing for resource-limited settings. New tools to support the hepatitis global response include the 2016 Global Hepatitis Health Sector Strategy which include targets for testing and diagnosis, and World Health Organization (WHO) 2016 hepatitis testing guidelines for adults, adolescents, and children in low- and middle-income countries. The testing guidance complements recent published WHO guidance on the prevention, care and treatment of chronic hepatitis C and hepatitis B infection. These testing guidelines outline the public health approach to strengthening and expanding current testing practices for HCV and HBV and address what serological and virological assays to use, and who to test, as well as interventions to promote linkage to prevention and care after testing. They are intended for use across all age groups and populations. See boxes for key recommendations. Future directions and innovations in viral hepatitis testing include use of point-of-care assays for nucleic acid testing (NAT) and core antigen; validation of dried blood spots specimens with different commercial serological and NAT assays; multiplex and polyvalent platforms for integrated testing of HIV, HBV and HCV; and potential for self-testing.

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.

Surveillance for Hepatitis C

Hepatitis C is a global public health problem. Globally, an estimated 170 million persons (3 % of the world’s population) have been infected with the hepatitis C virus, and an estimated 350,000 persons die annually from complications of chronic hepatitis C. Furthermore, an increasing trend in hepatitis C mortality in the USA was observed over the last decade; in 2007, mortality associated with hepatitis C surpassed mortality associated with HIV. As the hepatitis C epidemic continues, it is increasingly important to accurately measure hepatitis C-related morbidity and mortality in order to inform public health programs and policies and prioritize and evaluate prevention efforts. This chapter provides an overview of hepatitis C surveillance and methods used in the USA with some examples from other countries.

Low incidence of hepatitis C virus among prisoners in Scotland

AIMS

To estimate hepatitis C virus (HCV) incidence and HCV risk among Scottish prisoners.

DESIGN

National sero-behavioural survey; dried blood spots were collected in order to identify recent HCV infections (i.e. HCV antibody-negative and HCV polymerase chain reaction (PCR)-positive).

SETTING

All 14 closed prisons in Scotland.

PARTICIPANTS

A total of 5187 prisoners responded to the survey (79% of available prisoners on survey days) comprising 5076 individuals (after removing incomplete returns and participants surveyed in more than one prison); 95% men, 32% (1625) reported an injecting history (PWID) and median sentence of 9.5 months. HCV antibody samples were available for 4904 participants; there was sufficient sera for HCV PCR for 2446 prisoners who had been in prison for at least 75 days.

MEASUREMENTS

The estimate of in-prison recent infections is based on prisoners incarcerated for a sufficient period, i.e. at least 75 days, so that recent infections could be attributed to prison.

FINDINGS

Overall HCV prevalence was 19%; 53% among people who reported an injecting history and 3% among other prisoners. Three recent infections probably acquired in prison were detected. None of the cases reported injecting during their current sentence or any other potential exposure. Estimated incidence was 0.6-0.9% overall and 3.0-4.3% among PWID (assuming all infections acquired through injecting). Fifty-seven per cent (929) of PWID were receiving opiate substitution treatment (OST) at the time of the survey. Of all prisoners, 2.5% and 8% of PWID reported injecting during their current period of incarceration.

CONCLUSION

The low incidence of HCV infections in Scottish prisons is due most probably to the low occurrence of in-prison injecting and high coverage of OST. Low HCV risk can be achieved in prisons without necessarily introducing needle exchange programmes, but close monitoring of risk behaviours is essential. If risk increases, provision of needle exchange should be considered.

Simultaneous detection of hepatitis C virus antigen and antibodies in dried blood spots

BACKGROUND

Enzyme immunoassays (EIA) designed to detect hepatitis C virus (HCV) core antigen and anti-HCV antibodies (HCV AgAb) simultaneously can improve the early detection of HCV infection when molecular diagnostic methods are not widely available.

OBJECTIVES

To evaluate the suitability of dried blood spot (DBS) samples for detecting HCV AgAb using commercial EIAs.

STUDY DESIGN

Paired serum and DBS samples were assayed using two commercial EIAs for HCV AgAb (Monolisa™ HCV AgAb ULTRA and Murex HCV AgAb). Manufacturer's recommendations were followed for sera while sample volume, incubation time and cut-off (CO) determination were evaluated for the DBS samples. The values of sensitivity, specificity, inter-rater agreement, detection limit, assay precision and stability of DBS samples at different conditions (22-26°C, 2-8°C and -20°C) were determined.

RESULTS

It was necessary to increase the DBS sample volume fourfold compared to the sera samples to approximate the DBS Optical Density (OD) values to the sera OD values. Using ROC curve to recalculate CO values for the DBS samples, sensitivity was 97.5% for both EIAs, while the specificity was 99.71% for Monolisa™ HCV AgAb ULTRA and 95.95% for Murex HCV AgAb. Accurate testing results were obtained with DBS samples for 60 days at all conditions evaluated; storage at -20°C resulted in low OD variation. Both EIAs demonstrated the same limit of detection among DBS samples [estimated viral load of 3.1 International Units per millilitre (IU/mL)] and low OD value variability in repetitivity and reproducibility studies.

CONCLUSION

DBS samples can be used for the detection of HCV AgAb by EIA as they present comparable performance characteristics and excellent stability among various storage conditions.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Dried blood spot samples: optimization of commercial EIAs for hepatitis C antibody detection and stability under different storage conditions

This study was undertaken to optimize and compare the efficiency of two commercial EIAs for anti-HCV detection (HCV Ab Radim, Pomezzia, Italy and ETI-AB-HCVK-4 DiaSorin, Vercelli, Italy), in dried blood spot (DBS) samples. The long-term stability of anti-HCV on DBS samples stored at three environmental conditions was also evaluated at: 2-8 °C, 20-25 °C, and -20 °C. Paired DBS and serum samples were obtained from individuals with or without anti-HCV. The type of elution buffer, sample and conjugate volume, sample incubation time and cut-off values were evaluated. For both EIAs, a larger sample volume was used, and the cut-off value determined by the manufacturer was employed for Radim EIA; however, ROC curve analysis was used for the DiaSorin EIA. The sensitivity and specificity of Radim EIA on DBS were 97.5% and 99.5%, respectively, and of DiaSorin EIA were 88.9% and 98.9%, respectively. Accurate results were obtained for a period of 117 days using DBS samples stored at all storage conditions, but storage at -20 °C resulted in the lowest variation among the absorbance values. Both EIAs demonstrated the same limit of detection (until dilution of 1:10(4) with estimated viral load of 3.1 × 10(-1) UI/ml), but the Radim EIA was associated with the best performance because a low coefficient of variation was observed in the repetition and reproducibility studies. In conclusion, commercial EIAs can be optimized for anti-HCV detection in DBS samples that are extremely stable at different conditions for more than 100 days.

Detection of hepatitis C virus RNA in dried blood spots

BACKGROUND

An estimated 130-170 million people worldwide are chronically infected with HCV.(1) In Europe the highest prevalence of HCV infections is in the IDU population.(2) As traditional HCV screening relies on the detection of HCV antibody or HCV RNA in blood, screening in high-risk groups such as IDU is difficult due to poor venous access caused by damaged veins.

OBJECTIVES

In this study DBS was evaluated as an alternative sample type to blood for the detection of HCV RNA.

STUDY DESIGN

The endpoint detection limit, inter-assay and intra-assay variability of the method were determined. The DBS method was compared to our routine frontline assay using a panel of paired DBS and blood samples. The effect of different storage temperatures and length of storage time on the stability of HCV RNA in DBS was also assessed.

RESULTS

The endpoint detection limit of the method based on results from mock DBS was 250 IU/ml. The method was shown to be precise and robust. The sensitivity and specificity of the method was found to be 100% and 95.8%, respectively. No significant variation in the stability of HCV RNA in DBS over a 1 year period at a range of different temperatures was observed.

CONCLUSIONS

A sensitive and stable method was developed for the detection of HCV RNA in DBS. Screening high-risk populations using DBS as a sample type may improve uptake of HCV testing by increasing opportunity for patients to be tested and consequently increasing access to treatment.

The use of dried blood spots for assessing antibody response to hepatitis A virus after natural infection and vaccination

During recent years, vaccination against hepatitis A has been implemented in several countries. It is expected that the increase in mass vaccination against hepatitis A will eventually result in a decreased prevalence of anti-HAV antibodies in the general population. For this reason, a suitable clinical sample for diagnosis of hepatitis A must be sufficiently sensitive to enable detection of lower antibodies titers. In this study, the feasibility of using dried blood spots (DBS) was assessed for the detection of anti-HAV antibodies after a natural infection and vaccination. Seventy-four DBS and paired plasma samples were obtained from a group of college students for a cross-sectional hepatitis A seroepidemiological study. Forty-six students seronegative for anti-HAV were selected randomly and immunized with an inactivated hepatitis A vaccine using an 0-6 month schedule. Seroconversion was monitored in paired plasma and DBS samples 6 months after the first dose followed by a period of 8 and 24 months after the second dose. A strong correlation between OD/CO rates of paired plasma and DBS samples for the detection of anti-HAV was observed. The sensitivity and specificity of the DBS compared with plasma for the detection of anti-HAV antibodies after natural infection was 100%. The sensitivity of DBS in samples collected 24 months after the second dose of hepatitis A vaccine was 95.4%. The results showed that DBS samples can be used for the detection of anti-HAV antibodies both after natural infection or vaccination.

Dried blood spot for hepatitis C virus serology and molecular testing

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

CONCLUSION

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

Use of dried serum spots for serological and molecular detection of hepatitis a virus

We assessed the feasibility of using dried serum spots (DSS) for the serological and molecular diagnosis of hepatitis A virus (HAV) infection. Sixty-eight sera spotted onto filter papers (Whatman International Ltd., United Kingdom) were used for detection of total anti-HAV antibodies, and 64 sera were used for detection of immunoglobulin M antibody to HAV. DSS were stored at 4 degrees C, room temperature, and 37 degrees C for 1, 2, and 4 weeks. Sensitivity and specificity of the serological assays were 100% regardless of temperature and storage duration. To assess the stability of HAV RNA, we performed qualitative and quantitative reverse transcription-PCRs (RT-PCRs) with human plasma spiked with serial dilutions of cultured HAV spotted on Flinders Technology Associates filter paper cards (Whatman International Ltd.). Filter papers were stored at room temperature and processed for RT-PCR assays. No reduction of viral load was observed after 5, 15, and 30 days of storage. The approximately 10-fold reduction of sensitivity from DSS was attributable to a smaller sample input in DSS samples. This method was further evaluated using 35 frozen sera. HAV RNA amplification showed 100% specificity and 92.3% sensitivity, and sequence analysis from DSS and sera provided identical results. HAV RNA can be accurately recovered from DSS for molecular epidemiology purposes, and we confirm the reliability of blotted samples in the serological diagnosis of HAV infection. The DSS method facilitates storage and shipment of samples from routine laboratories to reference centers for further investigations and large epidemiological studies.

What a drop can do: dried blood spots as a minimally invasive method for integrating biomarkers into population-based research

Logistical constraints associated with the collection and analysis of biological samples in community-based settings have been a significant impediment to integrative, multilevel bio-demographic and biobehavioral research. However recent methodological developments have overcome many of these constraints and have also expanded the options for incorporating biomarkers into population-based health research in international as well as domestic contexts. In particular using dried blood spot (DBS) samples-drops of whole blood collected on filter paper from a simple finger prick-provides a minimally invasive method for collecting blood samples in nonclinical settings. After a brief discussion of biomarkers more generally, we review procedures for collecting, handling, and analyzing DBS samples. Advantages of using DBS samples-compared with venipuncture include the relative ease and low cost of sample collection, transport, and storage. Disadvantages include requirements for assay development and validation as well as the relatively small volumes of sample. We present the results of a comprehensive literature review of published protocols for analysis of DBS samples, and we provide more detailed analysis of protocols for 45 analytes likely to be of particular relevance to population-level health research. Our objective is to provide investigators with the information they need to make informed decisions regarding the appropriateness of blood spot methods for their research interests.

Routine practice HCV infection screening with saliva samples: multicentric study in an intravenous drug user population

OBJECTIVE

The purpose of this randomized multicentric study was to evaluate the diagnostic contribution of screening for HCV infection on saliva samples in day-to-day practice in the intravenous drug-user (IVDU) population.

METHODS

Between January and May 2004, 274 presumably HCV-negative IVDU were screened for HCV infection in 15 centers in France (median age 29 years). After centralized randomization, screening tests were performed on blood samples (arm A) or saliva samples (arm B). Screening tests were performed in 78 subjects (28%) had never been screened before and in 196 subjects (72%) who had had a negative HCV screening test on average 12 months prior to the beginning of the study. In the event of a positive saliva test for anti-HCV Ab, a serum test for anti-HCV Ab was performed. In the event of a positive serum test for anti-HCV Ab, PCR was performed on serum to measure HCV-RNA.

RESULTS

Fourteen individuals were positive for HCV RNA (7 in each arm). Six of these cases had not been detected before. In eight cases, the median time between the last negative screening test and study inclusion was 11 months (range 6-94 months).

CONCLUSIONS

Viremia tests were positive in 5% percent of the target population, although one-third of the individuals in arm A (blood samples) were not tested. The saliva test may be a useful alternative in the event of refusal of a blood test or when poor venous conditions compromise venous puncture. A confirmatory blood test still remains difficult to obtain in nearly half of patients.

Use of dried spots of whole blood, plasma, and mother's milk collected on filter paper for measurement of human immunodeficiency virus type 1 burden

We studied the use of dried spots of bodily fluids (plasma, whole blood, and mother's milk) on filter paper as a means of sample collection and storage for human immunodeficiency virus type 1 (HIV-1) viral load testing under stringent field conditions. Plasma placed directly in lysis buffer, which is customarily used for viral load assays, was used for comparison in all our experiments. Utilizing reconstruction experiments, we demonstrate no statistical differences between viral loads determined for plasma and mother's milk spotted on filter paper and those for the same fluids placed directly in lysis buffer. We found that the addition of whole blood directly to lysis buffer was unreliable and could not be considered a feasible option. However, viral load measurements for whole blood spotted onto filter paper correlated with plasma viral load values for both filter spots and lysis buffer (Pearson correlation coefficients, 0.7706 and 0.8155, respectively). In conclusion, dried spots of plasma, whole blood, or mother's milk provide a feasible means for the collection, storage, and shipment of samples for subsequent viral load measurement and monitoring. Virus material spotted and dried on filter paper is a good inexpensive alternative for collecting patient material to monitor the HIV-1 viral load. Measuring the HIV-1 burden from whole blood dried on filter paper provides a suitable alternative for low-technology settings with limited access to refrigeration, as can be found in sub-Saharan Africa.

Anonymous pilot study of hepatitis C virus prevalence in liver transplant surgeons

The risk of hepatitis C virus (HCV) transmission to surgeons is related to the HCV prevalence in the surgical patient population. As HCV-related cirrhosis is the commonest indication for liver transplantation in Europe and North America, liver transplant surgeons are at particular risk. The prevalence of HCV infection in liver transplant surgeons is unknown. The aim of this study was to estimate the prevalence of HCV infection in liver transplant surgeons attending the 9th Congress of the International Liver Transplantation Society using unlinked anonymous testing for HCV. Surgeons attending the conference were invited to complete an anonymised questionnaire regarding their surgical and transplant practice and provide an unlinked anonymised blood spot sample by finger prick. Samples were screened for antibodies to HCV (enzyme-linked immunosorbent assay III, Ortho Diagnostics, Raritan, NJ). Polymerase chain reaction testing for HCV RNA was performed on reactive samples.A total of 117 liver transplant surgeons (79 European, 16 North American, 10 Asian, 9 South American, 3 Australasian) provided a blood spot sample. Two (1.7%) surgeons had antibodies to HCV, 1 (0.8%) had detectable HCV RNA (genotype 1a). Assuming that both infections were acquired during surgery, the estimated maximum rate of HCV transmission is 1 per 743 to 1,045 years of surgical (0.96 to 1.35 HCV transmissions per 1,000 years of general surgical practice) and 449 to 683 years of liver transplant practice (1.46 to 2.23 HCV transmissions per 1,000 years of liver transplantation practice). In conclusion, risk of HCV transmission to liver transplant surgeons appears to be low despite the particular risks associated with frequently operating on HCV infected patients.

Commercial enzyme immunoassay adapted for the detection of antibodies to hepatitis C virus in dried blood spots

BACKGROUND

Dried blood spots (DBS) provide a convenient method for blood sample collection in many settings where the prevalence of infection with hepatitis C virus (HCV) is increasing. Consequently, HCV assays are required that produce reliable results using samples derived from DBS.

OBJECTIVES AND STUDY DESIGN

The optimum buffer for the elution of samples from DBS was selected and the performance of a commercial enzyme immunoassay (EIA) was evaluated using these DBS eluates and paired plasma samples.

RESULTS

DBS with paired plasma samples were compared using this modified commercial EIA, which was found to have an estimated sensitivity and specificity of approximately 100% for detecting anti-HCV antibodies in DBS.

CONCLUSION

A DBS-based assay for the detection of antibodies to HCV will prove valuable for collecting epidemiological data in the field or in under resourced settings.

Dried blood spots are an acceptable and useful HIV surveillance tool in a remote developing world setting

Enzyme-linked immunosorbent assay and Western blot analysis of dried blood spots (DBS) on filter paper have been shown to be as sensitive and specific as analysis of serum, and therefore may be a cost-effective and culturally appropriate HIV seroprevalence tool in remote areas. This study examines the acceptability of DBS in a tropical, rural population from an outpatient clinic in Andhra Pradesh, India, where participation was offered to every fifth patient seeking general medical care between March and April 2001. All 1413 patients approached for the study agreed to participate and provide a DBS for examination. The overall HIV seroprevalence in this sample was 2.8%. Of the participants, 51.7% were male, 93.2% were between the ages of 18 and 40, 85.3% were married, 29.7% were employed, 47.6% had no education and 73.1% resided in a rural setting. In the univariate analysis, history of genital warts (P = 0.01), sexually transmitted disease (P = 0.001), premarital sexual intercourse (P = 0.002), sexual contact with a commercial sex worker (P = 0.003), being employed (P = 0.011) and having more than 10 injections for medical purposes (P = 0.006) all correlated with being HIV-infected. Given the uniform willingness of these clinic attendees to be tested, we conclude that DBS is a useful, cost-effective tool in HIV serosurveillance in a rural, tropical setting.

Evaluation of a modified commercial assay in detecting antibody to hepatitis C virus in oral fluids and dried blood spots

Oral fluid testing is an effective alternative to serum antibody testing for surveillance of human immunodeficiency virus (HIV) and hepatitis B infections, and is being extended to hepatitis C infections. The objective of this study was to determine and compare the sensitivity and specificity of a modified commercial assay for the detection of antibody to hepatitis C virus (anti-HCV) in oral fluids collected by two different oral fluid collection devices (the Epitope OraSure trade mark and Sarstedt Salivette ) and in dried fingerprick blood spots. In this study, 253 anti-HCV seropositive patients and 394 blood donors (all anti-HCV negative) were recruited between August 2000 and January 2001. Each participant provided oral fluid specimens by OraSure and Salivette, and at least one dried blood spot. Serum specimens were collected from the patients whenever possible. For those injecting drug users who did not provide a serum specimen, HCV status was established on the basis of previous testing. All the nonserum samples were tested for the presence of anti-HCV, using a modified Ortho HCV 3.0 SAVe enzyme-linked immunosorbent assay (ELISA) protocol. The recommended preliminary cutoffs for the modified ELISA were suboptimal. Further, the sensitivity, specificity, and positive and negative predictive values could be improved by varying the cutoff and taking into account the likely prevalence of HCV in the population under investigation. For instance, given a population with a 50% prevalence of anti-HCV, the optimal sensitivities of the modified assay on OraSure, Salivette, and dried blood spots were 92%, 83%, and virtually 100%, respectively, in contrast to 83%, 59%, and 99% using the preliminary cutoffs. The respective optimal specificities were 99%, 93%, and 100%. In conclusion, oral fluids collected by the OraSure device provide an extremely useful method to conduct public health surveillance of not only HIV, but also hepatitis C, among injecting drug users. In addition, dried blood spot specimens may be useful for surveillance and could be employed as a first line diagnostic specimen.

Use of a dry-plasma collection device to overcome problems with storage and transportation of blood samples for epidemiology studies in developing countries

Studies are difficult in areas lacking modern facilities due to the inability to reliably collect, store, and ship samples. Thus, we sought to evaluate the use of a dry plasma collection device for seroepidemiology studies. Plasma was obtained by fingerstick using a commercial dry plasma collection device (Chemcard Plasma Collection Device) and serum (venipuncture) from individuals in Kazakhstan. Plasma samples were air dried for 15 min and then stored desiccated in foil zip-lock pouches at 4 to 6 degrees C and subsequently shipped to the United States by air at ambient temperature. Serum samples remained frozen at -20 degrees C until assayed. Helicobacter pylori status was determined by enzyme-linked immunosorbent assay (HM-CAP EIA) for the dry plasma and the serum samples. The results were concordant in 250 of the 289 cases (86.5%). In 25 cases (8.6%), the dry plasma samples gave indeterminate results and could not be retested because only one sample was collected. Five serum samples were positive, and the corresponding dry plasma samples were negative; one serum sample was negative, and the corresponding plasma sample was positive. The relative sensitivity and specificity of the Chemcard samples to serum were 97.6 and 97.9%, respectively, excluding those with indeterminate results. Repeated freeze-thawing had no adverse effect on the accuracy of the test. We found the dry plasma collection device to provide an accurate and practical alternative to serum when venipuncture may be difficult or inconvenient and sample storage and handling present difficulties, especially for seroepidemiologic studies in rural areas or developing countries and where freeze-thawing may be unavoidable.