Quality control and external quality assessment for the independent clinic-based evaluation of point-of-care testing to detect Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis in eight countries.

BACKGROUND: Sexually transmitted infections caused by Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV) remain significant global health problems. The World Health Organization (WHO) has recently conducted a multi-faceted, multi-country validation study (ProSPeRo), which included an evaluation of the Xpert CT/NG and Xpert TV assays on the GeneXpert system (Cepheid, Sunnyvale, Ca., USA) in clinic-based settings across eight countries. To support the study, a training and quality management system was implemented and evaluated. METHODS: A comprehensive training program for the study was developed. Quality control (QC) and external quality assessment (EQA) samples were provided by an accredited quality assurance provider. QC testing was conducted at 14 point-of-care testing (POCT) clinics, while EQA samples were tested by the POCT sites and a reference laboratory supporting each clinic. RESULTS: For QC testing, concordance with the expected results for CT and NG was > 99% and rates of unsuccessful tests were < 4%. For TV testing, concordance was similar (97%), but rates of unsuccessful tests were high (18%), particularly in the 'TV negative' sample. For EQA testing initially conducted in 2018, concordance was 100% for CT and NG, and 90% for TV for the reference laboratory group (which used non-GeneXpert systems). Concordance for the POCT group was also high (> 94%) for all analytes, but this cohort (which used GeneXpert systems) exhibited a high rate of unsuccessful TV tests. All but one of these unsuccessful tests was subcategorised as 'invalid'. CONCLUSIONS: The high level of concordance for QC and EQA testing confirm that the trained operators at the POC clinical sites were competent to conduct POC testing and that the training and quality systems implemented for the ProSPeRo study were effective. The quality materials used were satisfactory for CT and NG but exhibited poor performance for TV testing on the GeneXpert system. The WHO should continue to work with industry and EQA providers to provide improved materials that are reliable, stable and cost effective for quality management, as it seeks to rollout molecular-based STI POCT in non-laboratory-based settings. TRIAL REGISTRATION: Ethics approval to conduct the ProSPeRo study was granted by the WHO Ethics Review Committee.

Characterization of Hepatitis B Precore/Core-Related Antigens.

Current therapies rarely cure chronic hepatitis B virus (HBV) infection due to the persistence of the viral episome, the covalently closed circular DNA (cccDNA), in hepatocytes. The hepatitis B virus core-related antigen (HBcrAg), a mixture of the viral precore/core gene products, has emerged as one potential marker to monitor the levels and activities of intrahepatic cccDNA. In this study, a comprehensive characterization of precore/core gene products revealed that HBcrAg components included the classical hepatitis B virus core antigen (HBc) and e antigen (HBeAg) and, additionally, the precore-related antigen, PreC, retaining the N-terminal signal peptide. Both HBeAg and PreC antigens displayed heterogeneous proteolytic processing at their C termini resulting in multiple species, which varied with viral genotypes. HBeAg was the predominant form of HBcrAg in HBeAg-positive patients. Positive correlations were found between HBcrAg and PreC, between HBcrAg and HBeAg, and between PreC and HBeAg but not between HBcrAg and HBc. Serum HBeAg and PreC shared similar buoyant density and size distributions, and both displayed density and size heterogeneity. HBc, but not HBeAg or PreC antigen, was found as the main component of capsids in DNA-containing or empty virions. Neither HBeAg nor PreC protein was able to form capsids in cells or in vitro under physiological conditions. In conclusion, our study provides important new quantitative information on levels of each component of precore/core gene products as well as their biochemical and biophysical characteristics, implying that each component may have distinct functions and applications in reflecting intrahepatic viral activities.IMPORTANCE Chronic hepatitis B virus (HBV) infection afflicts approximately 257 million people, who are at high risk of progressing to chronic liver diseases, including fibrosis, cirrhosis, and hepatocellular carcinoma. Current therapies rarely achieve cure of HBV infection due to the persistence of the HBV episome, the covalently closed circular DNA (cccDNA), in the nuclei of infected hepatocytes. Peripheral markers of cccDNA levels and transcriptional activities are urgently required to guide antiviral therapy and drug development. Serum hepatitis B core-related antigen (HBcrAg) is one such emerging peripheral marker. We have characterized the components of HBcrAg in HBV-infected patients as well as in cell cultures. Our results provide important new quantitative information on levels of each HBcrAg component, as well as their biochemical and biophysical characteristics. Our findings suggest that each HBcrAg component may have distinct functions and applications in reflecting intrahepatic viral activities.

Does a change in quality control results influence the sensitivity of an anti-HCV test?

Background Laboratories use quality control (QC) testing to monitor the extent of normal variation. Assay lot number changes contribute the greatest amount of variation in infectious disease serology testing. An unexpected change in six lots of an anti-HCV assay allowed the determination of the effect these lot changes made to the assay's clinical sensitivity. Methods Two sets of seroconversion samples comprising of 44 individual samples and 9 external quality assessment scheme (EQAS) samples, all positive to anti-HCV, were tested in affected and unaffected assay lots, and the difference in the quantitative and qualitative results of the samples was analyzed. Results Of 44 low-positive seroconversion samples tested in affected and unaffected assay lots, only three samples had results reported below the assay cutoff when tested on two of the six affected assay lot. A further sample had results below the cutoff for only one affected lot. None of the EQAS samples reported false-negative results. Samples having a signal to cutoff value of less than 6.0 generally had lower results in the affected lots compared with the unaffected lots. Conclusions Unexpected changes in QC reactivity related to variation, in particular assay lot changes, may affect patient results. This study demonstrated that QConnect Limits facilitated the detection of an unexpectedly large variation in QC test results, allowed for the identification of the root cause of the change, and showed that the risk associated with the change was low but credible. The use of evidence-based QC program is essential to detect changes in test systems.

In vitro replication phenotype of a novel (-1G) hepatitis B virus variant associated with HIV co-infection.

The -1G mutant HBV is more prevalent in individuals co-infected with HIV/HBV than in individuals infected with HBV alone and in some cases is the dominant virus in circulation. This mutant is created by the deletion of a dGMP (-1G) from the guanine rich homopolymer sequence located at nts 2,085-2,090 (numbering from EcoRI site as position 1) in the HBV core gene. This deletion causes a frameshift generating a premature stop codon at (64) Asn in the HBV core gene (codon 93 in the precore gene), that truncates the precore protein, precursor of the secreted hepatitis B "e" antigen (HBeAg), and the core protein which forms the viral nucleocapsid. However, the replication phenotype of the -1G mutant HBV is unknown. An in vitro cell culture model in which hepatoma cells were transiently transfected with infectious cDNAs was used to show that the -1G mutant HBV is incapable of autonomous replication and, as expected, replication was restored to wild-type (wt) levels by supplying HBV core protein in trans. Although the -1G mutation had no deleterious effect on intracellular HBV-DNA levels, high levels of -1G mutant HBV relative to wt HBV reduced virus secretion and HBeAg secretion relative to empty vector controls. Importantly, the -1G mutant HBV also caused intracellular retention of truncated precore protein in the endoplasmic reticulum (ER) and Golgi apparatus. Together, these effects may be contributing to the increased pathology observed in the setting of HIV/HBV co-infection.

Implementation of Novel Quality Assurance Program for Hepatitis C Viral Load Point of Care Testing.

All patients should have access to accurate and timely test results. The introduction of point of care testing (PoCT) for infectious diseases has facilitated access to those unable to access traditional laboratory-based medical testing, including those living in remote and regional locations, or individuals who are marginalized or incarcerated individuals. In many countries, laboratory testing for infectious diseases, such as hepatitis C virus (HCV), is performed in a highly regulated environment. However, this is not the case for PoCT, where testing is performed by non-laboratory staff and quality controls are often lacking. An assessment of the provision of laboratory-based quality assurance to PoCT for infectious disease was conducted and the barriers to participation identified. A novel approach to providing quality assurance to PoCT sites, in particular those testing for HCV, was designed and piloted. This novel approach incudes identifying and validating sample types that are inactivated and stable at ambient temperature, creating cost-effective supply chains to facilitate logistics of samples, and the development of a smart phone-enabled portal for data entry and analyses. The creation and validation of this approach to quality assurance of PoCT removes the barriers to participation and acts to improve the quality and accuracy of testing, reduce errors and waste, and improve patient outcomes.

Validation of Dried Tube Sample Format Quality Controls for the Monitoring of Viral Load and Blood Screening Assays.

HIV viral load (VL) and donor screening assays experience variation and require quaity assurance (QA). NRL sought to confirm a dried tube sample format (HIVDTS) sample type for use in quality control (QC) programs for HIV molecular testing. 50 µL of HIV supernatant at 1 × 105 copies per millilitre (copies/mL)) was dried for 48 hours at room temperature. Post-production and shipped integrity studies were undertaken. Dried HIVDTS was reconstituted in PBS buffer and tested in HIV VL (six participants) or blood screening assays (four participants). Results were entered into NRL's QC monitoring software (EDCNet™) for analysis. The mean of 224 VL results when HIVDTS QCs were tested in Biocentric HIV GENERIC Charge Virale assay was 4.54 log10 copies/mL, with the percentage coefficient of variation (CV%) ranging from 1.75 to 13.20%. The mean Ct value for HIVDTS QCs tested on Roche Cobas MPX assay results was 28.71 (range 28.33 to 29.14), with CV% ranging from 1.56 to 3.98%. The study confirms HIVDTS QCs can effectively monitor the performance of HIV molecular testing and offers a cheaper alternative to commercial QC samples that require cold-chain shipping on dry ice and UN3373 conditions.

Results of cytomegalovirus DNA viral loads expressed in copies per millilitre and international units per millilitre are equivalent.

Quantification of Cytomegalovirus (CMV) DNA is required for the initiation and monitoring of anti-viral treatment and the detection of viral resistance. However, due to the lack of standardisation of CMV DNA nucleic acid tests, it is difficult to set universal thresholds. In 2010, the 1st WHO International Standard for Human Cytomegalovirus for Nucleic Acid Amplification Techniques was released. Since then CMV DNA viral load assays have been calibrated using this standard. Three external quality assessment (EQA) providers sent the same five samples to their participants and analysed the results to determine the equivalence of reporting CMV DNA results in international units per millilitre (IU/mL), and compared the difference in results reported in IU/mL with those reported in copies per millilitre (c/mL), and to determine the rate of adoption of IU/mL. About 78% of participants continue to report results in c/mL even though six of the 12 commercial assays are calibrated against the standard. The range of the results reported in IU/mL was less than those reported in c/mL indicating that the adoption of the WHO standard successfully improved the reporting of the CMV viral load. The variation in individual sample results reported by different assays, irrespective of whether in IU/mL or c/mL, is still great and therefore more standardisation of the assays is needed to allow the setting of treatment and monitoring thresholds. This study can act as a bench mark to determine rate of future adoption if reporting CMV DNA viral load results in IU/mL.

Targeting the hepatitis B virus precore antigen with a novel IgNAR single variable domain intrabody.

The Hepatitis B virus precore protein is processed in the endoplasmic reticulum (ER) into secreted hepatitis B e antigen (HBeAg), which acts as an immune tolerogen to establish chronic infection. Downregulation of secreted HBeAg should improve clinical outcome, as patients who effectively respond to current treatments (IFN-α) have significantly lower serum HBeAg levels. Here, we describe a novel reagent, a single variable domain (V(NAR)) of the shark immunoglobulin new antigen receptor (IgNAR) antibodies. V(NAR)s possess advantages in stability, size (~14 kDa) and cryptic epitope recognition compared to conventional antibodies. The V(NAR) domain displayed biologically useful affinity for recombinant and native HBeAg, and recognised a unique conformational epitope. To assess therapeutic potential in targeting intracellular precore protein to reduce secreted HBeAg, the V(NAR) was engineered for ER-targeted in vitro delivery to function as an intracellular antibody (intrabody). In vitro data from HBV/precore hepatocyte cell lines demonstrated effective intrabody regulation of precore/HBeAg.