The use of real-time PCR to detect hepatitis C virus RNA in dried blood spots from Brazilian patients infected chronically

Dried blood spot sampling for hepatitis B virus quantification, sequencing and mutation detection

Hepatitis B virus (HBV) diagnosis is performed on serum samples, but the access to this diagnosis is difficult in low-income regions. The use of dried blood spot (DBS) samples does not require special structure for collection, storage or transport. This study evaluates the use of DBS for detection, quantification and sequencing of HBV DNA using in-house techniques. Two study groups were included: 92 HBsAg + individuals and 49 negative controls. Serum and DBS samples were submitted to quantitative and qualitative in-house PCR for S/pol genes, sequencing and phylogenetic analyses. Total of 84 serum samples were successfully amplified. Of them, 63 paired DBS were also positive in qualitative PCR. Qualitative PCR in DBS presented a sensitivity of 75% and specificity of 100% (Kappa = 0.689). Quantitative PCR in DBS presented a detection limit of 852.5 copies/mL (250 IU/mL), sensitivity of 77.63% and specificity of 100% (Kappa = 0.731). A total of 63 serum samples and 36 DBS samples were submitted to sequencing, revealing the circulation of genotypes A (65.08%), D (4.8%), E (3.2%) and F (27%) with 100% of correspondence between serum and DBS. All sequenced samples displayed polymorphisms in HBsAg gene. An HIV-coinfected patient presented the rtM204V/I-rtL180M double resistance mutation in serum and DBS. In conclusion, DBS is an alternative to detect, quantify and characterize HBV DNA, being a possibility of increasing diagnosis in low-income settings, closing gaps in HBV control.

Dried blood spots perform well to identify patients with active HCV infection in Vietnam

Recently, treatment advances in direct-acting antivirals have radically changed the management of HCV patients. However, in resource-limited countries, identification of patients with active HCV infection is still challenging in remote settings due to the limited access to laboratories able to measure HCV viral load. This study evaluated whether dried blood spots (DBS) transferred to a central laboratory could overcome this challenge. A total of 315 HCV-infected patients, naïve to anti-HCV treatment, provided each three type of samples: plasma, DBS with calibrated quantities of venous blood and DBS with uncalibrated quantities of capillary blood. Qualitative comparison was conducted in terms of detection of HCV viral load on DBS as opposed to plasma to estimate sensitivity and specificity. Quantitative comparisons were conducted by means of correlation estimation. Of the 250 patients with detected plasma HCV viral load, 245 also had detectable DBS HCV viral load (capillary or venous) leading to a sensitivity of 98.0% (95% confidence interval (CI): 95.4%-99.3%); importantly, all measurements with a plasma HCV viral load >118 IU/mL were also detected in DBS. When HCV was not detected in plasma, it was also not detected in DBS resulting in 100% specificity (95% CI: 94.5%-100%). Quantitative HCV viral load results were very similar when utilizing plasma or DBS sample types as illustrated by correlations >0.99. In conclusion, DBS sample types, with either uncalibrated capillary blood or calibrated venous blood, performed well to distinguish patients with active HCV infection, and who therefore need treatment, from other patients.

Evaluation of the efficiency of dried blood spot-based measurement of hepatitis B and hepatitis C virus seromarkers

Although hepatitis B (HBV) and C (HCV) virus infections are still global health issues, measuring sero-markers by standard venipuncture is challenging in areas limited with the adequate human resources and basic infrastructure. This study aimed to inform the usefulness of dried blood spot (DBS) sampling technique for epidemiological study of HBV and HCV in the resources limited areas. We compared specimen recovery rate expressed as analytical sensitivity ratio of HBsAg, HBcAb and anti-HCV between serum specimens and DBS samples (HemaSpot vs Whatman903). Sensitivity ratio was calculated as the ratio of the measured value from DBS to the measured value from serum. Then both the qualitative and quantitative comparisons of HBsAg detection by DBS were done using Cambodian samples. HBsAg, HBcAb and anti-HCV sensitivity ratios for the highest sample dilution (8-fold) were 31.2:1, 38.9:1 and 32.0:1 for Whatman903 card and 17.6:1, 23.5:1 and 26.3:1 for HemaSpot respectively. Detection efficacy of HemaSpot (80%) was not inferior to Whatman903 (60%) after 1 month storage, and no significant difference in any hepatitis virus sero-markers was observed in HemaSpot-spotted patient samples stored for 2 weeks at −25 °C and 29 °C. All reference HemaSpot -spotted 400 HBsAg sero-negative samples showed negative. Sensitivity and specificity of HBsAg in HemaSpot were 92.3% and 100%. The recovery expressed as analytical sensitivity ratio of HBsAg, HBcAb and anti-HCV of HemaSpot specimen were not inferior to Whatman903. Therefore, DBS with its usefulness proved as an acceptable tool for large epidemiological study of HBV and HCV in resources limited remote area.

Comparison of two immunoassays for concurrent detection of HCV antigen and antibodies among HIV/HCV co-infected patients in dried serum/plasma spots

Hepatitis C virus (HCV) antigen/antibody (Ag/Ab) assays offer the benefit of reducing the window period compared to assays that detect only HCV-Ab. In this study the performance of the Murex Ag/Ab (Murex, Abbott) and Monolisa Ag/Ab Ultra (Monolisa, Bio-Rad) ELISAs was compared for the use of filter dried serum/plasma spots (DS/PS) with a focus on the sensitivity and the percentage of correct positive test results. Correct positive ELISA results were assumed for samples that subsequently tested positive for HCV RNA by RT-qPCR, or RNA negative samples that tested positive in a Western blot (confirmed ELISA results). Sensitivity was evaluated from DS/PS eluates using HCV seroconversion panels [plasma samples of subtypes-(St) 1a, 2b)] and longitudinal HCV antibody positive serum panels (St 1b, 2b, 3a, and 4d). The proportion of correct positive test results was evaluated using 1102 newly diagnosed HIV positive clinical dried serum spots (DSS) eluates for screening of potential HCV co-infection. For the plasma HCV seroconversion samples, which were used as a reference for DSS eluates, the Murex became reactive earlier for antigen positive bleeds. However, for the HCV antibody positive eluates and dilutions thereof, the Monolisa demonstrated a superior sensitivity. Of the clinical DSS 22.8 % (28/123) of samples reactive in the Murex were negative in a subsequent RT-qPCR and Western blot, while only 1.9 % (2/105) of the samples reactive in the Monolisa were negative in these confirmatory assays. Our results indicate that the Monolisa provides fewer false positive results for HCV detection in DSS, whereas for undiluted plasma or serum samples, the Murex can serve as an additional diagnostic tool to narrow the window period.

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.

Evaluation of the Aptima HCV Quant Dx Assay Using Serum and Dried Blood Spots

Hepatitis C virus (HCV) RNA quantitation is the primary method by which active HCV infections are identified and the response to direct-acting antiviral therapy is monitored. This study describes the evaluation of the Aptima HCV Quant Dx assay (Aptima HCV) performed on the Panther system. The clinical performance of Aptima HCV was compared to that of the Cobas AmpliPrep/Cobas TaqMan HCV test v2.0 (CAP/CTM). Overall agreement was 84.9% (186/219) with a kappa statistic of 0.755 (standard error, 0.037; 95% confidence interval [CI], 0.682 to 0.828). Passing-Bablok regression of log₁₀ IU/ml values revealed a regression line of Y = 1.163 × X - 0.991 (95% CI of the slope, 1.103 to 1.221, and intercept, -1.341 to -0.642). The 95% lower limit of detection (LLOD) for Aptima HCV on dried blood spot (DBS) samples was calculated to be 2.43 log₁₀ IU/ml (267 IU/ml; 95% CI, 2.31 to 2.73 log₁₀ IU/ml [204 to 540 IU/ml]). A comparison of Aptima HCV testing on paired DBS and serum specimens collected from patients at the time of routine blood collection for CAP/CTM demonstrated an overall agreement of 90.1% (82/91) with a kappa statistic of 0.657 (standard error, 0.101; 95% CI, 0.458 to 0.855). In conclusion, Aptima HCV provides a suitable alternative for HCV RNA testing on serum and DBS samples.

Detection of anti-hepatitis C virus and hepatitis C virus RNA in dried blood spot specimens using Whatman No. 1 filter paper

Purpose

Dried blood spot (DBS) specimen simplifies blood collection, processing, storage and shipment and may reduce the cost of testing for hepatitis C virus (HCV) infection. We wanted to see if DBS using a cheap filter paper is reliable alternative to serum for detection of anti-HCV and HCV RNA.

Materials and Methods

At a tertiary care hospital in Northeast India, we collected 91 paired DBS and serum specimens from patients at risk of HCV infection from July 2014 to June 2015. DBS was collected on Whatman No. 1 filter paper. After processing, the specimens were subjected to anti-HCV detection by a third-generation Enzyme-Linked Immunosorbent Assay (ELISA). The reactive DBS and serum specimens were further subjected to HCV RNA detection by polymerase chain reaction. The results were analysed in paired screen-positive study design.

Results

Anti-HCV was detected in 9 (9.9%) DBS specimens and 10 (10.9%) serum specimens. There was statistically significant (P < 0.0001) correlation between the optical density values of DBS and serum specimens (Pearson r = 0.9181, 95% confidence interval: 0.8781-0.9453). HCV RNA was detected in 5/9 (55.6%) reactive DBS and 9/10 (90.0%) reactive serum specimens. There was no correlation between HCV RNA levels in the DBS and the serum specimens. The relative sensitivity rate and the relative false-positive rate of DBS anti-HCV ELISA were 0.89 and 1.00, respectively.

Conclusions

DBS using Whatman No. 1 filter paper is quite reliable as serum for detection of anti-HCV. It can be useful in effective surveillance. However, it is not suitable for confirmation of chronic HCV infection.

Determination of anti-HCV and quantification of HCV-RNA and IP-10 from dried blood spots sent by regular mail

BACKGROUND

With the introduction of direct acting antivirals, treatment of hepatitis C virus (HCV) in hard-to-reach populations is now feasible. Therefore, new cost-effective and reliable test methods are needed. Determination of HCV antibodies and HCV-RNA from dried blood spots samples could represent one such method. Here we examined whether anti-HCV could be detected-and HCV-RNA quantified-from dried blood spots, sent by regular mail. We also investigated, if IP-10 determined from dried blood spots correlated with fibrosis progression appraised by transient elastography.

METHOD

Forty chronic HCV infected patients were consecutively enrolled. At baseline and after six months, dried blood spots were prepared from blood collected by venous puncture, dried for 4-6 hours, then stored in gas-impermeable plastic bags with a desiccator, before being sent by regular mail. At each visit, approximately six months apart, paired venous samples was obtained and analyzed for anti-HCV, HCV-RNA and IP-10.

RESULTS

Anti-HCV was found in 66/67 of the dried blood spots. Sixty-six paired samples were available for HCV-RNA analysis. A statistically significant correlation was found between log HCV-RNA concentrations in plasma, and log HCV-RNA obtained from (P < 0.0001, Pearson's R 0.6788, R2 0.4607). HCV-RNA, derived from DBS samples, was lower than the corresponding plasma concentration, reflected by a Bland-Altman bias of 3 with SD of bias ± 0.6472. We found no correlation between IP-10 and fibrosis progression.

CONCLUSIONS

We identified anti-HCV in 66/67samples, and quantified IP-10 and HCV-RNA from dried blood spots, dried at room temperature and sent by regular mail. HCV-RNA concentrations from the dried blood spots were lower than corresponding plasma values; a probable result of heparin coated test tubes. We found no correlation between IP-10 and fibrosis progression. Overall, dried blood spots could be a cost-effective and easy-to-use alternative to standard tests for the diagnosis of HCV infections.

Evaluation of dried blood spot as an alternative sample collection method for hepatitis C virus RNA quantitation and genotyping using a commercial system

Dried blood spot (DBS) is a minimally invasive sampling method suitable for sample collection, storage and transportation in resource limited areas. Aim of this study was to compare the diagnostic utility of DBS with plasma sample for HCV RNA quantitation and genotyping using commercial systems. Plasma and DBS card spotted samples were collected from 95 HCV seropositive patients. Both types of samples were subjected to HCV RNA by real-time PCR (Abbott m2000rt, USA). Genotyping was performed using Abbott HCV genotype II kit (Abbott diagnostics, USA) in samples with viral load > 3 log10 IU/ml. In both plasma and DBS, 14 (14.7%) samples were negative and 81 (85.3%) were positive for HCV RNA. Median viral load in plasma (3.78; range 0-7.43) log10 IU/ml was comparable to DBS (3.93; range 0-7.24) log10 IU/ml. DBS demonstrated sensitivity and specificity of 97.5 and 85.7% respectively, with positive predictive value (PPV) of 97.5% and negative predictive value (NPV) of 85.7%. DBS showed good correlation (r2 = 0.866) and agreement (93.5%) with plasma. Genotyping in 20 patients showed 100% concordance between DBS and plasma samples. DBS showed good sensitivity and specificity as a sampling method for HCV RNA quantitation and genotyping.

Diagnostic accuracy of detection and quantification of HBV-DNA and HCV-RNA using dried blood spot (DBS) samples - a systematic review and meta-analysis

BACKGROUND

The detection and quantification of hepatitis B (HBV) DNA and hepatitis C (HCV) RNA in whole blood collected on dried blood spots (DBS) may facilitate access to diagnosis and treatment of HBV and HCV infection in resource-poor settings. We evaluated the diagnostic performance of DBS compared to venous blood samples for detection and quantification of HBV-DNA and HCV-RNA in two systematic reviews and meta-analyses on the diagnostic accuracy of HBV DNA and HCV RNA from DBS compared to venous blood samples.

METHODS

We searched MEDLINE, Embase, Global Health, Web of Science, LILAC and Cochrane library for studies that assessed diagnostic accuracy with DBS. Heterogeneity was assessed and where appropriate pooled estimates of sensitivity and specificity were generated using bivariate analyses with maximum likelihood estimates and 95% confidence intervals. We also conducted a narrative review on the impact of varying storage conditions or different cut-offs for detection from studies that undertook this in a subset of samples. The QUADAS-2 tool was used to assess risk of bias.

RESULTS

In the quantitative synthesis for diagnostic accuracy of HBV-DNA using DBS, 521 citations were identified, and 12 studies met the inclusion criteria. Overall quality of studies was rated as low. The pooled estimate of sensitivity and specificity for HBV-DNA was 95% (95% CI: 83-99) and 99% (95% CI: 53-100), respectively. In the two studies that reported on cut-offs and limit of detection (LoD) - one reported a sensitivity of 98% for a cut-off of ≥2000 IU/ml and another reported a LoD of 914 IU/ml using a commercial assay. Varying storage conditions for individual samples did not result in a significant variation of results. In the synthesis for diagnostic accuracy of HCV-RNA using DBS, 15 studies met the inclusion criteria, and this included six additional studies to a previously published review. The pooled sensitivity and specificity was 98% (95% CI:95-99) and 98% (95% CI:95-99.0), respectively. Varying storage conditions resulted in a decrease in accuracy for quantification but not for reported positivity.

CONCLUSIONS

These findings show a high level of diagnostic performance for the use of DBS for HBV-DNA and HCV-RNA detection. However, this was based on a limited number and quality of studies. There is a need for development of standardized protocols by manufacturers on the use of DBS with their assays, as well as for larger studies on use of DBS conducted in different settings and with varying storage conditions.

Dry Blood Spots a Reliable Method for Measurement of Hepatitis B Viral Load in Resource-Limited Settings

Background & Aims

Hepatitis B virus (HBV) quantification is essential in the management of chronic hepatitis B, both to determine treatment eligibility and in the monitoring of treatment effect. This test, however, is rarely available in resource-limited settings due to high costs and stringent requirements for shipment and storage of plasma. Dried Blood Spots (DBS) can be a convenient alternative to plasma, but its use for HBV monitoring has not been investigated under real-life conditions in Africa.

Methods

The performance of DBS in HBV quantification was investigated using a modified commercial test (Abbott RealTime HBV assay). Paired DBS and plasma samples were collected from an HBV positive cohort in Addis Ababa, Ethiopia. DBS were stored at ambient temperature for 4–39 days before shipment to the laboratory.

Results

Twenty-six paired samples were selected covering the total range of quantification, from 2.14 log IU/ml to >7 log IU/ml. HBV was detected in 21 of 21 (100%) DBS from patients with a corresponding plasma viral load above 2.70 log IU/ml. The mean difference between plasma and DBS was 0.59 log IU/ml, and the correlation was strong (R2 = 0.92). In stability studies there was no significant change in DBS viral load after storage at room temperature for up to 12 weeks.

Conclusions

This study suggests that DBS can be a feasible and reliable alternative to plasma for quantification of HBV in resource-limited settings. DBS can expand access to antiviral treatment for patients in low- and middle-income countries.

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.

Evaluation of dried blood spot samples for hepatitis C virus detection and quantification

BACKGROUND

Dried blood spots (DBS) could be an excellent alternative for HCV diagnosis, since it is less invasive and can be stored and transported without refrigeration.

OBJECTIVES

The aim of this study was to optimize quantitative and qualitative methods for HCV detection in DBS.

STUDY DESIGN

DBS and serum samples were collected from 99 subjects (59 anti-HCV/HCV RNA positive and 40 seronegative samples). Seven extraction methods and different PCR parameters were evaluated in DBS samples in the quantitative RT-PCR (qRT-PCR) developed to amplify the 5' noncoding region of HCV. A qualitative PCR for amplification of NS5B region of HCV was also valued and the nested-PCR sequenced.

RESULTS

The qRT-PCR showed good correlation to commercial assay for HCV viral measurement in serum. To quantify HCV RNA in DBS, it was necessary to increase reverse transcriptase and cDNA concentration. HCV RNA quantification in DBS demonstrated sensitivity of 65.9%, 100% of specificity and kappa statistic of 0.65. The median viral load of DBS samples was 5.38 log10 copies/ml (minimum value=1.76 and maximum value=10.48 log10 copies/ml). HCV RNA was detected in NS5B regions and nucleotide sequences obtained in 43 serum and 11 DBS samples. The presence of the same subtype was observed in paired serum and DBS samples.

CONCLUSIONS

In this study, it was possible to demonstrate that, despite the low sensitivity, the optimized protocol was able to determine the viral load, as well as, the infecting HCV genotype, validating the usefulness of DBS for viral load determination and molecular epidemiology studies of HCV.

Real-time polymerase chain reaction optimised for hepatitis C virus detection in dried blood spots from HIV-exposed infants, KwaZulu-Natal, South Africa

Background

There is a paucity of data on the prevalence of hepatitis C virus (HCV) in children, particularly in sub-Saharan Africa. A major obstacle in resource-limited settings for polymerase chain reaction (PCR) testing is the necessity for specimen transportation and storage at low temperatures. There are numerous recent studies of using real-time HCV PCR for diagnosis and screening of plasma and serum, but few have looked at using dried blood spot (DBS) specimens.

Objectives

The aim of this study was to optimise a real-time HCV PCR method to detect HCV RNA from infant DBS specimens for use as a tool for HCV surveillance in KwaZulu-Natal, South Africa.

Method

The LightCycler^® 2.0 instrument was used for the HCV PCR using the LightCycler^® RNA Master SYBR Green I kit. Template volume, primer concentration and primer annealing temperatures were optimised and the method was used on 179 DBS specimens from HIV-exposed infants in KwaZulu-Natal.

Results

Primer concentrations adjusted to 0.25 µM and a template volume of 10 µL improved the PCR amplification. Primer annealing temperatures lowered from 65 °C to 58 °C resulted in higher quantities of amplified PCR product. The limit of detection of the optimised HCV PCR assay was between 1200 IU/mL and 3580 IU/mL of HCV RNA. HCV was not detected in any of the 179 DBS specimens.

Conclusion

The optimised real-time HCV PCR on infant DBS specimens performed well, but HCV was not found in this surveillance study. HIV infection may have little impact on the vertical transmission of HCV in this region.

Dried blood spot in the genotyping, quantification and storage of HCV RNA: a systematic literature review

The entry of new all-oral direct acting antiviral therapy for hepatitis C provides an opportunity to scale up HCV care in low- and middle-income countries. In HIV, use of dried blood spots (DBS) has facilitated the diagnosis and management of HIV in resource-poor settings. DBS may be used in a similar way to facilitate diagnosis and management of HCV. Here, we present a systematic review of the literature of DBS for HCV RNA detection and genotyping. Using an a priori review protocol, three databases were searched for studies published up to August 2013 that reported the use of dried blood and serum spots in genotyping, detection and measurement of HCV RNA, as well as the rate of degradation of HCV RNA when stored in DBS at room temperature. Nine papers were eligible for inclusion; eight studied DBS and one dried serum. Two studies measured concordance between genotype and subtype determined by DBS and whole plasma and both found 100% concordance. Four studies measured endpoint detection limits of HCV RNA-positive samples by DBS and found positive predictive values of 100% down to 250, 334, 2500 and 24160 IU/mL. Two studies found deterioration of HCV RNA in DBS samples stored at room temperature, while two others failed to detect such deterioration. These results support the potential use of DBS for genotyping and HCV RNA detection. Studies of the use of DBS for HCV RNA viral load measurement and of the rate of degradation of HCV RNA when stored in DBS at ambient temperatures remain inconclusive.

Disparate detection outcomes for anti-HCV IgG and HCV RNA in dried blood spots

Dried blood spots (DBS) expedite the collection, storage and shipping of blood samples, thereby facilitating large-scale serologic studies. We evaluated the sensitivity of anti-HCV IgG testing and HCV-RNA quantitation using freshly prepared and stored DBS derived from HCV-infected patients. Protocols for elution were optimized using DBS prepared from plasma of 52 HCV-infected persons and 51 uninfected persons (control DBS), then applied to DBS from 33 chronic hepatitis C patients that had been stored at -20°C for 5 years (stored DBS). Control and stored DBS, and their corresponding plasma, were processed for anti-HCV IgG testing using the VITROS chemiluminescence assay (CIA) and the HCV 3.0 enzyme immunoassay (EIA) (Ortho-Clinical Diagnostics), and for HCV RNA quantitation by quantitative (q) RT-PCR. HCV genotyping was conducted by nucleotide sequencing. The sensitivity of CIA and EIA in control DBS was 92% and 90%, respectively, compared to 100% and 97%, respectively, in stored DBS. The sensitivity of HCV RNA detection was 88% in control DBS, compared to 36% in stored DBS. Specificity was 100% for all the assays in both control and stored DBS. Genotypes 1, 2 and 3 were detected in 16 (62%), 6 (23.1%), and 4 (15.3%) samples, respectively. Sequences generated from DBS and their corresponding plasma samples were identical. Whereas the sensitivity of anti-HCV IgG detection in stored DBS was equivalent to that in recently prepared DBS, the sensitivity of HCV RNA detection was markedly lower in stored DBS compared to recently prepared DBS. Stored DBS may be reliably used for anti-HCV detection but for HCV-RNA-based testing freshly prepared DBS is preferable to stored DBS.

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.

Interleukin-28B polymorphisms and response of chronic hepatitis C patients from Indonesia to pegylated interferon/ribavirin treatment

This study demonstrated that Indonesian patients with chronic hepatitis C (mostly ethnic Java people) mostly were infected with hepatitis C virus (HCV) genotype 1; however, they carried mainly the major genotypes of interleukin 28B (IL-28B) single nucleotide polymorphisms (SNPs) (rs12979860 CC, rs11881222 TT, rs8103142 AA, and rs8099917 TT), and they mostly achieved sustained virological responses to pegylated interferon/ribavirin treatment.

Nested-quantitative PCR approach with improved sensitivity for the detection of low titer levels of Candidatus Liberibacter asiaticus in the Asian citrus psyllid, Diaphorina citri Kuwayama

Candidatus Liberibacter asiaticus (CLas) is a phloem-limited bacterium transmitted by the Asian citrus psyllid, Diaphorina citri, and the presumptive causal agent of citrus greening disease. The current method of detection for CLas within plant and insect samples is by a presence/absence qPCR assay using the CLas 16S rDNA gene target. Although qPCR is highly sensitive, low bacterial titers or suboptimal qPCR conditions can result in false-negatives. Using a nested qPCR assay, we determined the false-negative rate of the 16S presence/absence qPCR assay was greater than 50%. Studies to determine the performance parameters of the qPCR assays for CLas 16S and Wingless (Wg), the D. citri endogenous gene, using plasmid and psyllid DNA, revealed suboptimal and variable performance of the 16S assay in psyllid samples. Average efficiencies and sensitivity limits of the plasmid assays were 99.0% and 2.7 copies of template for Wg, respectively, and 98.5% and 2.2-22.1 copies for 16S, respectively. Variability in efficiency was significantly greater in psyllid samples for both gene targets compared to the corresponding plasmid assays, and efficiencies as low as 76% were obtained for 16S. A secondary structure analysis revealed the formation of two stem-loop structures that block the forward and probe binding sites in the 16S template, which could hinder amplification. In summary, our results suggest that suboptimal qPCR efficiency is not uncommon for the 16S presence/absence qPCR assay, which combined with lowCLas titers in some samples, could contribute significantly to the under-reporting of CLas infection in psyllid and plant samples.

Detection of Streptococcus pneumoniae and Haemophilus influenzae type B by real-time PCR from dried blood spot samples among children with pneumonia: a useful approach for developing countries

Background

Dried blood spot (DBS) is a reliable blood collection method for storing samples at room temperature and easily transporting them. We have previously validated a Real-Time PCR for detection of Streptococcus pneumoniae in DBS. The objective of this study was to apply this methodology for the diagnosis of S. pneumoniae and Haemophilus influenzae b (Hib) in DBS samples of children with pneumonia admitted to two hospitals in Mozambique and Morocco.

Methods

Ply and wzg genes of S. pneumoniae and bexA gene of Hib, were used as targets of Real-Time PCR. 329 DBS samples of children hospitalized with clinical diagnosis of pneumonia were tested.

Results

Real-Time PCR in DBS allowed for a significant increase in microbiological diagnosis of S. pneumoniae and Hib. When performing blood bacterial culture, only ten isolates of S. pneumoniae and none of Hib were detected (3·0% positivity rate, IC95% 1·4-5·5%). Real-Time PCR from DBS samples increased the detection yield by 4x fold, as 30 S. pneumoniae and 11 Hib cases were detected (12·4% positivity rate, IC95% 9·0-16·5%; P<0·001).

Conclusion

Real-Time PCR applied in DBS may be a valuable tool for improving diagnosis and surveillance of pneumonia caused by S. pneumoniae or Hib in developing countries.

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.

IP-10 can be measured in dried plasma spots in patients with chronic hepatitis C infection

The chemokine IP-10 (CXCL10) is a candidate marker for hepatitis C virus (HCV) fibrosis monitoring. The aim of this proof-of-concept study is to assess if IP-10 measurements from dried plasma spots (DPS) are accurate in HCV-infected patients with either minimal or significant fibrosis. We measured IP-10 levels in plasma and DPS of 21 HCV-infected patients with cirrhosis and 19 patients with no/little fibrosis (determined with FibroScan). Cirrhotic patients had significantly higher levels of IP-10 compared to patients with minimal fibrosis. DPS and plasma measurements of IP-10 are comparable and the correlation was excellent (r(2) = 0.97, p<0.0001). The DPS based method for IP-10 detection performs well in HCV-infected patients with either minimal or significant fibrosis.