Laboratory evaluation of the Liat HIV Quant (IQuum) whole-blood and plasma HIV-1 viral load assays for point-of-care testing in South Africa.

Point-of-care (POC) HIV viral load (VL) testing offers the potential to reduce turnaround times for antiretroviral therapy monitoring, offer near-patient acute HIV diagnosis in adults, extend existing centralized VL services, screen women in labor, and prompt pediatrics to early treatment. The Liat HIV Quant plasma and whole-blood assays, prerelease version, were evaluated in South Africa. The precision, accuracy, linearity, and agreement of the Liat HIV Quant whole-blood and plasma assays were compared to those of reference technologies (Roche CAP CTMv2.0 and Abbott RealTime HIV-1) on an HIV verification plasma panel (n = 42) and HIV clinical specimens (n = 163). HIV Quant plasma assay showed good performance, with a 2.7% similarity coefficient of variation (CV) compared to the Abbott assay and a 1.8% similarity CV compared to the Roche test on the verification panel, and 100% specificity. HIV Quant plasma had substantial agreement (pc [concordance correlation] = 0.96) with Roche on clinical specimens and increased variability (pc = 0.73) in the range of <3.0 log copies/ml range with the HIV Quant whole-blood assay. HIV Quant plasma assay had good linearity (2.0 to 5.0 log copies/ml; R(2) = 0.99). Clinical sensitivity at a viral load of 1,000 copies/ml of the HIV Quant plasma and whole-blood assays compared to that of the Roche assay (n = 94) was 100% (confidence interval [CI], 95.3% to 100%). The specificity of HIV Quant plasma was 88.2% (CI, 63.6% to 98.5%), and that for whole blood was 41.2% (CI, 18.4% to 67.1%). No virological failure (downward misclassification) was missed. Liat HIV Quant plasma assay can be interchanged with existing VL technology in South Africa. Liat HIV Quant whole-blood assay would be advantageous for POC early infant diagnosis at birth and adult adherence monitoring and needs to be evaluated further in this clinical context. LIAT cartridges currently require cold storage, but the technology is user-friendly and robust. Clinical cost and implementation modeling is required.

Feasibility of HIV point-of-care tests for resource-limited settings: challenges and solutions.

Improved access to anti-retroviral therapy increases the need for affordable monitoring using assays such as CD4 and/or viral load in resource-limited settings. Barriers to accessing treatment, high rates of loss to initiation and poor retention in care are prompting the need to find alternatives to conventional centralized laboratory testing in certain countries. Strong advocacy has led to a rapidly expanding repertoire of point-of-care tests for HIV. point-of-care testing is not without its challenges: poor regulatory control, lack of guidelines, absence of quality monitoring and lack of industry standards for connectivity, to name a few. The management of HIV increasingly requires a multidisciplinary testing approach involving hematology, chemistry, and tests associated with the management of non-communicable diseases, thus added expertise is needed. This is further complicated by additional human resource requirements and the need for continuous training, a sustainable supply chain, and reimbursement strategies. It is clear that to ensure appropriate national implementation either in a tiered laboratory model or a total decentralized model, clear country-specific assessments need to be conducted.

Use of a prequalification panel for rapid scale-up of high-throughput HIV viral load testing.

Increased access to antiretroviral drugs expands needs for viral load (VL) testing. South Africa's National Health Laboratory Service responded to demands by implementing two testing platforms in 17 laboratories within 8 months. An industry partner's collaboration, training programs, and method verification with a VL prequalification panel ensured testing quality and rapid implementation.

Comparison of Xpert MTB/RIF with other nucleic acid technologies for diagnosing pulmonary tuberculosis in a high HIV prevalence setting: a prospective study.

BACKGROUND: The Xpert MTB/RIF (Cepheid) non-laboratory-based molecular assay has potential to improve the diagnosis of tuberculosis (TB), especially in HIV-infected populations, through increased sensitivity, reduced turnaround time (2 h), and immediate identification of rifampicin (RIF) resistance. In a prospective clinical validation study we compared the performance of Xpert MTB/RIF, MTBDRplus (Hain Lifescience), LightCycler Mycobacterium Detection (LCTB) (Roche), with acid fast bacilli (AFB) smear microscopy and liquid culture on a single sputum specimen. METHODS AND FINDINGS: Consecutive adults with suspected TB attending a primary health care clinic in Johannesburg, South Africa, were prospectively enrolled and evaluated for TB according to the guidelines of the National TB Control Programme, including assessment for smear-negative TB by chest X-ray, clinical evaluation, and HIV testing. A single sputum sample underwent routine decontamination, AFB smear microscopy, liquid culture, and phenotypic drug susceptibility testing. Residual sample was batched for molecular testing. For the 311 participants, the HIV prevalence was 70% (n = 215), with 120 (38.5%) culture-positive TB cases. Compared to liquid culture, the sensitivities of all the test methodologies, determined with a limited and potentially underpowered sample size (n = 177), were 59% (47%-71%) for smear microscopy, 76% (64%-85%) for MTBDRplus, 76% (64%-85%) for LCTB, and 86% (76%-93%) for Xpert MTB/RIF, with specificities all >97%. Among HIV+ individuals, the sensitivity of the Xpert MTB/RIF test was 84% (69%-93%), while the other molecular tests had sensitivities reduced by 6%. TB detection among smear-negative, culture-positive samples was 28% (5/18) for MTBDRplus, 22% (4/18) for LCTB, and 61% (11/18) for Xpert MTB/RIF. A few (n = 5) RIF-resistant cases were detected using the phenotypic drug susceptibility testing methodology. Xpert MTB/RIF detected four of these five cases (fifth case not tested) and two additional phenotypically sensitive cases. CONCLUSIONS: The Xpert MTB/RIF test has superior performance for rapid diagnosis of Mycobacterium tuberculosis over existing AFB smear microscopy and other molecular methodologies in an HIV- and TB-endemic region. Its place in the clinical diagnostic algorithm in national health programs needs exploration. Please see later in the article for the Editors' Summary.

Should South Africa be performing nucleic acid testing on HIV enzyme-linked immunosorbent assay-negative samples?

The frequency of acute HIV infection (AHI) among HIV-1 enzyme-linked immunosorbent assay (ELISA)-negative samples received from general hospital patient admissions was assessed. Of 3,005 samples pooled for nucleic acid testing, a prevalence of 0.13% was found. Pooled nucleic acid testing may be feasible for low-cost identification of AHI in high-prevalence settings.

Driving the usage of tuberculosis diagnostic data through capacity building in low- and middle-income countries.

BACKGROUND: Connectivity platforms collect a wealth of data from connected GeneXpert instruments, with the potential to provide valuable insights into the burden of disease and effectiveness of tuberculosis programmes. The challenge faced by many countries is a lack of training, analytical skills, and resources required to understand and translate this data into patient management and programme improvement. OBJECTIVE: We describe a novel training programme, the tuberculosis Data Fellowship, designed to build capacity in low- and middle- income countries for tuberculosis data analytics. METHODS: The programme consisted of classroom and remote training plus mentorship over a 12-month period. The focus was on skills development in Tableau software, followed by training in exploration, analysis, and interpretation of GeneXpert tuberculosis data across five key programme areas: patient services, programme monitoring, quality of testing, inventory management, and disease burden. RESULTS: The programme was piloted in six countries (Bangladesh, Ethiopia, Ghana, Malawi, Mozambique) in July 2018 and Nigeria in September 2018; 20 participants completed the training. A number of key outputs have been achieved, such as improved instrument utilisation rates, decreased error rates, and improved instrument management. CONCLUSION: The training programme empowers local tuberculosis programme staff to discover and fix critical inefficiencies, provides high-level technical and operational support to the tuberculosis programme, and provides a platform for continued sharing of insights and best practices between countries. It supports the notion that connectivity can increase efficiencies and clinical benefits with better data for decision making, if coupled with commensurate capacity building in data analysis and interpretation.

Evaluation of a mobile application to support HIV self-testing in Johannesburg, South Africa.

BACKGROUND: Human immunodeficiency virus self-testing (HIVST) reduces barriers associated with facility-based testing; however, no formal mechanism exists for users to self-report results or link to care. The AspectTM HIVST mobile application (app) was developed for use in South Africa. OBJECTIVES: This study evaluated the acceptability and feasibility of the AspectTM HIVST app for individuals from the inner city of Johannesburg. METHOD: This cross-sectional pilot, with a convenience sample of 300 adults, was conducted in July 2018. Participants were provided an OraQuick HIVST kit and a smartphone preloaded with the app, then asked to follow the in-app instructions for use (IFU) to complete the HIVST and upload results. Trained healthcare workers (HCWs) observed and recorded any deviations from the IFU, and conducted a post-test survey to assess acceptability. Feasibility was evaluated by the number of participants who agreed to participate, completed the self-test, and uploaded all information onto the app correctly. RESULTS: Most participants (98.7%) found the app easy to use. To reduce difficulties related to the IFU (26; 8.7%), participants suggested multimedia supplements (4; 1.3%), additional languages (4; 1.3%) and simplified instructions (5; 1.7%). All individuals approached, agreed to participate, 267 (89.0%) correctly completed all steps and 210 (78.7%) successfully captured all information on the app. Most errors (26; 8.7%) were testing errors and 1 (0.3%) was from the app sequence. Twelve (4.5%) errors were with test strip imaging and 72 (27.0%) discordances were with demographic information. CONCLUSION: Despite some challenges with IFU interpretation and data capture via the app, this pilot showed that the AspectTM HIVST app is an acceptable way to upload mobile HIVST results and demographic information to a central database.

Racing for results: lessons learnt in improving the efficiency of HIV viral load and early infant diagnosis result delivery from laboratory to clinic.

INTRODUCTION: In pursuit of the 90-90-90 goals, emphasis has been placed on accelerating centralized-laboratory HIV viral load testing of a population that is largely rural and decentralized. Successful outcome requires effective specimen transport, laboratory testing, and results delivery. This paper focuses on the methods currently employed for results delivery. New innovations in this area are yielding mixed results; we analyze different approaches and estimate the impact of each on achieving the third '90.' Areas covered: Strategies employing electronic or mobile health platforms, such as online portals, SMS, and SMS printers are showing potential to deliver results in significantly improved turnaround times but are not without challenges. Also, merely delivering a result to the clinic is not sufficient; results need to be actioned to ensure improved patient linkage and retention. Innovative solutions that not only support real-time reporting but monitor receipt of results and address infrastructure constraints faced by limited-resource settings are discussed. Expert commentary: There is tremendous opportunity to inform better patient care and directly contribute to '90-90-90' progress by developing digital systems for result delivery. Besides infrastructure and technical challenges, systems should address the entire cascade of care from initial diagnosis to monitoring treatment response.

The impact of digital technologies on point-of-care diagnostics in resource-limited settings.

INTRODUCTION: Simple, rapid tests that can be used at the point-of-care (POC) can improve access to diagnostic services and overall patient management in resource-limited settings where laboratory infrastructure is limited. Implementation of POC tests places tremendous strain on already fragile health systems as the demand for training, supply management and quality assurance are amplified. Digital health has a major role to play in ensuring effective delivery and management of POC testing services. Area covered: The ability to digitise laboratory and POC platforms, including lateral flow rapid diagnostic test results, can standardize the interpretation of results and allows data to be linked to proficiency testing to ensure testing quality, reducing interpretation and transcription errors. Remote monitoring of POC instrument functionality and utilization through connectivity, allows programs to optimize instrument placement, algorithm adoption and supply management. Alerts can be built into the system to raise alarm at unusual trends such as outbreaks. Expert commentary: Digital technology has had a powerful impact on POC testing in resource limited settings. Technology, markets, and medical devices have matured to enable connected diagnostics to become a useful tool for epidemiology, patient care and tracking, research, and antimicrobial resistance and outbreak surveillance. However, to unlock this potential, digital tools must first add value at the point of patient care. The global health community need to propose models for protecting intellectual property to foster innovation and for safeguarding data confidentiality.

Impact of the GeneXpert MTB/RIF Technology on Tuberculosis Control.

Molecular technology revolutionized the diagnosis of tuberculosis (TB) with a paradigm shift to faster, more sensitive, clinically relevant patient care. The most recent molecular leader is the GeneXpert MTB/RIF assay (Xpert) (Cepheid, Sunnyvale, CA), which was endorsed by the World Health Organization with unprecedented speed in December 2010 as the initial diagnostic for detection of HIV-associated TB and for where high rates of drug resistance are suspected. South Africa elected to take an aggressive smear replacement approach to facilitate earlier diagnosis and treatment through the decision to implement the Xpert assay nationally in March 2011, against the backdrop of approximately 6.3 million HIV-infected individuals, one of highest global TB and HIV coinfection rates, no available implementation models, uncertainties around field performance and program costs, and lack of guidance on how to operationalize the assay into existing complex clinical algorithms. South Africa's national implementation was conducted as a phased, forecasted, and managed approach (March 2011 to September 2013), through political will and both treasury-funded and donor-funded support. Today there are 314 GeneXperts across 207 microscopy centers; over 8 million assays have been conducted, and South Africa accounts for over half the global test cartridge usage. As with any implementation of new technology, challenges were encountered, both predicted and unexpected. This chapter discusses the challenges and consequences of such large-scale implementation efforts, the opportunities for new innovations, and the need to strengthen health systems, as well as the impact of the Xpert assay on rifampin-sensitive and multidrug-resistant TB patient care that translated into global TB control as we move toward the sustainable development goals.

Multidisciplinary Point-of-Care Testing in South African Primary Health Care Clinics Accelerates HIV ART Initiation but Does Not Alter Retention in Care.

BACKGROUND: Lack of accessible laboratory infrastructure limits HIV antiretroviral therapy (ART) initiation, monitoring, and retention in many resource-limited settings. Point-of-care testing (POCT) is advocated as a mechanism to overcome these limitations. We executed a pragmatic, prospective, randomized, controlled trial comparing the impact of POCT vs. standard of care (SOC) on treatment initiation and retention in care. METHODS: Selected POC technologies were embedded at 3 primary health clinics in South Africa. Confirmed HIV-positive participants were randomized to either SOC or POC: SOC participants were venesected and specimens referred to the laboratory with patient follow-up as per algorithm (∼3 visits); POC participants had phlebotomy and POCT immediately on-site using Pima CD4 to assess ART eligibility followed by hematology, chemistry, and tuberculosis screening with the goal of receiving same-day adherence counseling and treatment initiation. Participant outcomes measured at recruitment 6 and 12 months after initiation. RESULTS: Four hundred thirty-two of 717 treatment eligible participants enrolled between May 2012 and September 2013: 198 (56.7%) SOC; 234 (63.6%) POC. Mean age was 37.4 years; 60.5% were female. Significantly more participants were initiated using POC [adjusted prevalence ratio (aPR) 0.83; 95% confidence interval (CI): 0.74 to 0.93; P < 0.0001], the median time to initiation was 1 day for POC and 26.5 days for SOC. The proportion of patients in care and on ART was similar for both arms at 6 months (47 vs. 50%) (aPR 0.96; 95% CI: 0.79 to 1.16) and 12 months (32 vs. 32%) (aPR 1.05; 95% CI: 0.80 to 1.38), with similar mortality rates. Loss to follow-up at 12 months was higher for POC (36% vs. 51%) (aPR 0.82; 95% CI: 0.65 to 1.04). CONCLUSIONS: Adoption of POCT accelerated ART initiation but once on treatment, there was unexpectedly higher loss to follow-up on POC and no improvement in outcomes at 12 months over SOC.

Options to Expand HIV Viral Load Testing in South Africa: Evaluation of the GeneXpert® HIV-1 Viral Load Assay.

BACKGROUND: Expansion of HIV viral load (VL) testing services are required to meet increased targets for monitoring patients on antiretroviral treatment. South Africa currently tests >4million VLs per annum in 16 highly centralised, automated high-throughput laboratories. The Xpert HIV-1 VL assay (Cepheid) was evaluated against in-country predicates, the Roche Cobas Taqmanv2 and Abbott HIV-1RT, to investigate options for expanding VL testing using GeneXpert's random access, polyvalent capabilities and already established footprint in South Africa with the Xpert MTB/RIF assay (207 sites). Additionally, the performance of Xpert HIV-1VL on alternative, off-label specimen types, Dried Blood Spots (DBS) and whole blood, was investigated. METHOD: Precision, accuracy (agreement) and clinical misclassification (1000cp/ml) of Xpert HIV-1VL plasma was compared to Taqmanv2 (n = 155) and Abbott HIV-1 RT (n = 145). Misclassification of Xpert HIV-1VL was further tested on DBS (n = 145) and whole blood (n = 147). RESULTS: Xpert HIV-1VL demonstrated 100% concordance with predicate platforms on a standardised frozen, plasma panel (n = 42) and low overall percentage similarity CV of 1.5% and 0.9% compared to Taqmanv2 and Abbott HIV-1 RT, respectively. On paired plasma clinical specimens, Xpert HIV-1VL had low bias (SD 0.32-0.37logcp/ml) and 3% misclassification at the 1000cp/ml threshold compared to Taqmanv2 (fresh) and Abbott HIV-1 RT (frozen), respectively. Xpert HIV-1VL on whole blood and DBS increased misclassification (upward) by up to 14% with increased invalid rate. All specimen testing was easy to perform and compatible with concurrent Xpert MTB/RIF Tuberculosis testing on the same instrument. CONCLUSION: The Xpert HIV-1VL on plasma can be used interchangeably with existing predicate platforms in South Africa. Whole blood and DBS testing requires further investigation, but polyvalency of the GeneXpert offers a solution to extending VL testing services.

Human Immunodeficiency Virus (HIV)-Infected Patients Accept Finger Stick Blood Collection for Point-Of-Care CD4 Testing.

INTRODUCTION: HIV-infected patients require antiretroviral treatment for life. To improve access to care, CD4 enumeration and viral load tests have been redesigned to be used as point-of-care techniques using finger-stick blood. Accurate CD4 counting in capillary blood requires a free flowing blood drop that is achieved by blade incision. The aim of this study was to assess the attitude of the patients toward blade-based finger-stick blood donation. METHODS: Four hundred and ninety-nine patients were included (299 patients from South Africa and 200 from Belgium). They completed a questionnaire to express their preference for finger stick or venipuncture, after undergoing both. The South African patient cohort was divided in two groups, receiving either single or multiple finger stick for CD4 and other HIV-related tests. The Belgian patients received a single finger stick for CD4 testing, and were asked to respond directly and again after two days. RESULTS: The majority of the patients preferred the finger stick to the venipuncture. The perceived pain using the blade was superior to a small needle, but similar to a large needle. They preferred up to three finger sticks over one venipuncture. Up to 30% of the patients changed their mind over two days. The main reason for choosing a finger stick was continued bleeding after venipuncture. The most cited objection to finger stick was pain/soreness. CONCLUSION: Patient perceptions support the implementation of donating capillary blood with blade-based finger stick during CD4 point-of-care testing.

Implementation and Operational Research: Implementation of Multiple Point-of-Care Testing in 2 HIV Antiretroviral Treatment Clinics in South Africa.

BACKGROUND: A plethora of point-of-care (POC) tests exist in the HIV and tuberculosis diagnostic pipeline which require rigorous evaluation to ensure performance in the field. The accuracy and feasibility of nurse-operated multidisciplinary-POC testing for HIV antiretroviral therapy (ART) initiation/monitoring was evaluated. METHODS: Random HIV-positive adult patients presenting at 2 treatment clinics in South Africa for ART initiation/monitoring were consented and enrolled. POCT was performed by a dedicated nurse on a venipuncture specimen; Pima (CD4), HemoCue (hemoglobin), Reflotron (alanine aminotransferase, creatinine), Accutrend (lactate) and compared with laboratory testing. External quality assessment, training, workflow, and errors were assessed. RESULTS: n = 324 enrolled at site1; n = 469 enrolled at site 2. Clinical data on n = 305 participants: 65% (n = 198) female with a mean age of 39.8 (21-61) years; mean age of males 43.2 (26-61) years; 70% of patients required 3 or more POC tests/visit. External quality assessment material was suitable for POCT. CD4, hemoglobin and alanine aminotransferase testing showed good agreement with predicate methodology; creatinine and lactate had increased variability. Pima CD4 misclassified up to 11.6% of patients at 500 cells per microliter and reported 4.3%-6% error rate. A dedicated nurse could perform POCT on 7 patients/day; inclusion of Pima CD4 increased time for testing from 6 to 110 minutes. Transcription error rate was 1%. CONCLUSIONS: Nurses can accurately perform multidisciplinary POCT for HIV ART initiation/monitoring. This will however, require a dedicated nurse as current duties will increase if POC is added to workflow. The use of Pima CD4 will increase patients initiated on ART. Connectivity will be central to ensure quality management of results, but overall impact will need to still be addressed.

Diagnosing childhood pulmonary tuberculosis using a single sputum specimen on Xpert MTB/RIF at point of care.

BACKGROUND: The GeneXpertMTB/RIF (Cepheid, USA) (Xpert) has proved successful for pulmonary tuberculosis (TB) diagnosis on decontaminated/concentrated induced sputum specimens from children. Capacity to perform induction in many settings is limited. OBJECTIVE: To assess: (i) volumes of 'routinely obtained' sputum in a district-level academic hospital; (ii) whether sputum specimens not meeting Xpert-required testing volumes could still be tested; and (iii) performance of Xpert on a single paediatric sputum specimen at point of care (POC). METHODS: Two sputa were collected from paediatric TB suspects (£14 years) at Rahima Moosa Mother and Child Hospital, Johannesburg, South Africa. One specimen was weighed at POC; if the volume was ≥0.1 mL but <0.5 mL, it was increased to 0.5 mL using saline. On-site Xpert testing (G3 cartridge) was performed by a dedicated laboratory technician. The second specimen was referred for TB smear microscopy and culture as per standard of care (SOC). RESULTS: A total of 484 patients presumed to have TB (median age 24 months) were eligible for this study, performed between June 2011 and May 2012. Xpert could not be used on 4.1% of specimens because of volumes<0.1 mL, and 62.8% required addition of saline prior to Xpert testing. Xpert generated a 2.2% error and 3.7% invalid rate, compared with the SOC that rejected 2.3% because of insufficient volume and 2.3% that were contaminated. The diagnostic performance compared with culture was 62.5% (95% confidence interval (CI) 24.7-91) and 99.1% (95% CI 97.4-99.8) sensitivity and specificity, respectively, for Xpert (n=345) and 33.3% (7.9-69.9) and 99.5% (98.1-99.9) sensitivity and specificity, respectively, for smear microscopy (n=374). CONCLUSIONS: Up to 67% of 'routinely obtained' sputum specimens from children (£14 years) are below the required volume for Xpert testing but can be 'topped up' with saline. XpertMTB/RIF performed better than microscopy and generated clinically relevant, timeous results, but sensitivity did not reach the same levels as culture in children.

Feasibility of performing multiple point of care testing for HIV anti-retroviral treatment initiation and monitoring from multiple or single fingersticks.

BACKGROUND: Point of Care testing (POCT) provides on-site, rapid, accessible results. With current South African anti-retroviral treatment guidelines, up to 4 fingersticks /patient/clinic visit could be required if utilizing POC. We determined the feasibility and accuracy of a nurse performing multiple POCT on multiple fingersticks followed by simplification of the process by performance of multiple POC on a single fingerstick. METHOD AND FINDINGS: Random HIV positive adult patients presenting at a HIV treatment clinic in South Africa, for ART initiation/ monitoring, were approached to participate in the study between April-June 2012. Phase I: n=150 patients approached for multiple POCT on multiple fingersticks. Phase II: n=150 patients approached for multiple POCT on a single fingerstick. The following POC tests were performed by a dedicated nurse: PIMA (CD4), HemoCue (hemoglobin), Reflotron (alanine aminotransferase, creatinine). A venepuncture specimen was taken for predicate laboratory methodology. Normal laboratory ranges and Royal College of Pathologists Australasia (RCPA) allowable differences were used as guidelines for comparison. In 67% of participants, ≥3 tests were requested per visit. All POCT were accurate but ranged in variability. Phase I: Hemoglobin was accurate (3.2%CV) while CD4, alanine aminotransferase and creatinine showed increased variability (16.3%CV; 9.3%CV; 12.9%CV respectively). PIMA generated a misclassification of 12.4%. Phase II: Hemoglobin, alanine aminotransferase and creatinine showed good accuracy (3.2%CV, 8.7%CV, 6.4%CV respectively) with increased variability on CD4 (12.4%CV) but low clinical misclassification (4.1%). No trends were observed for the sequence in which POC was performed on a single fingerstick. Overall, PIMA CD4 generated the highest error rate (16-19%). CONCLUSIONS: Multiple POCT for ART initiation and/or monitoring can be performed practically by a dedicated nurse on multiple fingersticks. The process is as accurate as predicate methodology and can be simplified using a single fingerstick.

Retrospective characterization of the S open reading frame of HBV isolated from children with membranous nephropathy treated with interferon-alpha2b.

BACKGROUND: A causal relationship exists between HBV infection and membranous nephropathy. The association is especially close in Black children in sub-Saharan Africa. Interferon-alpha2b is commonly used to treat this condition, but is effective in only 30-40% of patients. The reason for the poor response is unknown. The objective of this study was to determine if mutations in the surface gene of HBV isolated from Black children with HBV-associated membranous nephropathy before, during and after interferon treatment, have any effect on treatment response and vice versa. METHODS: HBV DNA was extracted from a responder, a reverter and a non-responder before and after initiation of 16 weeks of interferon-alpha2b treatment. The preS1/preS2/S region was amplified, cloned and sequenced. RESULTS: The preS2 region was the most variable in the reverter and the non-responder, and the S region was the most variable in the non-responder. Phylogenetic analysis showed that the viral population dynamics between the responder and the reverter/non-responder strains differed as a result of mutations in the surface gene. CONCLUSIONS: The presence of mutations in the S region of HBV could be used as predictive markers to differentiate interferon-alpha2b responders from non-responders provided that detailed analysis of further genomes confirms our findings.