Nucleic acid testing (NAT) in high prevalence–low resource settings

Translating diagnostics and drug delivery technologies to low-resource settings

Diagnostics and drug delivery technologies engineered for low-resource settings aim to meet their technical design specifications using strategies that are compatible with limited equipment, infrastructure, and operator training. Despite many preclinical successes, very few of these devices have been translated to the clinic. Here, we identify factors that contribute to the clinical success of diagnostics and drug delivery systems for low-resource settings, including the need to engage key stakeholders at an early stage, and provide recommendations for the clinical translation of future medical technologies.

Neurosurgical Patients’ Experiences and Surgical Outcomes Among Single Tertiary Hospitals in Ethiopia and the United States

Background

In 2020, we published findings on reported outcomes of anterior cervical decompression and fusion surgery among neurosurgeons in Africa and North America. We found more similarities in outcomes than expected, however, differences still existed. Most notable was the length of stay of patients postoperatively in Africa compared to North America. We sought to examine the neurosurgical practices more closely at a single hospital in Ethiopia and compare it to our own institution, the University of Missouri in Columbia (UMC).

Methods

Two authors spent one week at Aabet Hospital (AH) in Ethiopia. Throughout the week, one author rotated in the clinic and OR gathering the information. Data collection for patients at UMC was collected through retrospective chart review over one week.

Results

A total of eight elective surgeries and four emergency procedures occurred at AH and 18 clinic patients were included in the study. The intraoperative data was collected during the elective procedures at AH. At UMC there were 99 clinic patients, and 29 elective surgeries and one emergency procedure were performed. Procedures at both institutions included cranial, spinal, vascular, and implantable/other cases. Distance travelled by patients to UMC was an average of 57 miles compared to 85 miles at AH. The median pre-op and post-op stays at AH were 2.5 and 6 days compared to 0.2 and 2.1 at UMC, respectively. Blood loss was greater at AH with a median blood loss of 175 mL. Median blood loss at UMC was 50 mL.

Conclusion

We found notable differences among neurosurgical practice and patient demographics at AH compared to UMC. This information will serve as the cornerstone for gathering more information about neurosurgical practice in Ethiopia where electronic medical records are unavailable.

Assessing the global burden of hemorrhage: The global blood supply, deficits, and potential solutions

There is a critical shortage of blood available for transfusion in many low- and middle-income countries. The consequences of this scarcity are dire, resulting in uncounted morbidity and mortality from trauma, obstetric hemorrhage, and pediatric anemias, among numerous other conditions. The process of collecting blood from a donor to administering it to a patient involves many facets from donor availability to blood processing to blood delivery. Each step faces particular challenges in low- and middle-income countries. Optimizing existing strategies and introducing new approaches will be imperative to ensure a safe and sufficient blood supply worldwide.

Characteristic of HBV nucleic acid amplification testing yields from blood donors in China

BACKGROUND

Nucleic acid amplification testing (NAT) for blood screening has been previously performed in some countries to determine NAT yields. The current study sought to explore the non-discriminating reactive NAT yields using individual-NAT (ID-NAT) and characteristics of HBV NAT yields through a 10-year retrospective analysis in Zhejiang, China.

METHODS

Blood donations were analyzed using individual-NAT mode by the transcription-mediated amplification (TMA) method. Supplementary HBV serological tests were performed using chemiluminescent immunoassay, and HBV viral load assay was performed by real-time polymerase chain reaction. Follow-up studies were performed in partial donors with low HBV viral loads.

RESULTS

Non-discriminating reactive NAT yields and HBV NAT yields varied in different years. The yields ranged from 853.73 per million to 2018.68 per million and 624.60 per million to 1669.50 per million, respectively. In the 476 NAT yields, 19 were probable window periods (WP), 33 probable occult hepatitis B virus infections (OBIs), 409 were confirmed OBIs and 15 were chronic HBV infections. ID-NAT results were categorized in four groups, and the findings showed that the levels of HBV DNA viral loads were different in the four different groups (χ² = 275.02, p < 0.01). HBV viral load distribution was significantly different between anti-HBs positive and anti-HBc positive samples (χ² = 49.429, p < 0.01). Notably, only 42.03% donors were NAT repeated positive in the 138 repeat donors' follow up tests.

CONCLUSION

NAT screening of blood donations can reduce the risk of transfusion-transmitted HBV infections. Positive proportions of anti-HBs and anti-HBc are correlated with the HBV viral load level. However, low level of viral load donors pose risks in HBV NAT assays, and show fluctuating state for HBV viral load and leads to non-repeated NAT results during follow up studies.

Challenges and Opportunities for Clustered Regularly Interspaced Short Palindromic Repeats Based Molecular Biosensing

Clustered regularly interspaced short palindromic repeats, CRISPR, has recently emerged as a powerful molecular biosensing tool for nucleic acids and other biomarkers due to its unique properties such as collateral cleavage nature, room temperature reaction conditions, and high target-recognition specificity. Numerous platforms have been developed to leverage the CRISPR assay for ultrasensitive biosensing applications. However, to be considered as a new gold standard, several key challenges for CRISPR molecular biosensing must be addressed. In this paper, we briefly review the history of biosensors, followed by the current status of nucleic acid-based detection methods. We then discuss the current challenges pertaining to CRISPR-based nucleic acid detection, followed by the recent breakthroughs addressing these challenges. We focus upon future advancements required to enable rapid, simple, sensitive, specific, multiplexed, amplification-free, and shelf-stable CRISPR-based molecular biosensors.

Challenges in transfusion-transmitted infection screening in Sub-Saharan Africa

In Sub-Saharan Africa, high clinical demand for transfusion faces endemic bloodborne infections and limited resources. Blood screening for transfusion-transmitted bloodborne pathogens is the cornerstone of blood safety. Although there have been substantial improvements over the years, challenges in transfusion-transmitted infection screening that have been identified repeatedly long ago still need to be addressed. Affordability and sustainability of state-of-the-art quality assessed serological and molecular assays, and associated confirmation strategies remain of real concern. In addition, limited resources and infrastructures hamper the development of adequate facilities, quality management, and staff qualification, and exacerbate shortage of reagents and equipment maintenance. It is also important to maintain effort in constituting pools of repeat voluntary non-remunerated donors. Alternative strategies for blood screening that take into account local circumstances might be desirable but they should rely on appropriate field evaluation and careful economic assessment rather than dogma established from high-resource settings.

Nucleic acid sample preparation from whole blood in a paper microfluidic device using isotachophoresis

Nucleic acid amplification tests (NAATs) are a crucial diagnostic and monitoring tool for infectious diseases. A key procedural step for NAATs is sample preparation: separating and purifying target nucleic acids from crude biological samples prior to nucleic acid amplification and detection. Traditionally, sample preparation has been performed with liquid- or solid-phase extraction, both of which require multiple trained user steps and significant laboratory equipment. The challenges associated with sample preparation have limited the dissemination of NAAT point-of-care diagnostics in low resource environments, including low- and middle-income countries. We report on a paper-based device for purification of nucleic acids from whole blood using isotachophoresis (ITP) for point-of-care NAATs. We show successful extraction and purification of target nucleic acids from large volumes (33 µL) of whole human blood samples with no moving parts and few user steps. Our device utilizes paper-based buffer reservoirs to fully contain the liquid ITP buffers and does not require complex filling procedures, instead relying on the natural wicking of integrated paper membranes. We perform on-device blood fractionation via filtration to remove leukocytes and erythrocytes from our sample, followed by integrated on-paper proteolytic digestion of endogenous plasma proteins to allow for successful isotachophoretic extraction. Paper-based isotachophoresis purifies and concentrates target nucleic acids that are added directly to recombinase polymerase amplification (RPA) reactions. We show consistent amplification of input copy concentrations of as low as 3 × 10³ copies nucleic acid per mL input blood with extraction and purification taking only 30 min. By employing a paper architecture, we are able to incorporate these processes in a single, robust, low-cost design, enabling the direct processing of large volumes of blood, with the only intermediate user steps being the removal and addition of tape. Our device represents a step towards a simple, fully integrated sample preparation system for nucleic acid amplification tests at the point-of-care.

Inactivation of a broad spectrum of viruses and parasites by photochemical treatment of plasma and platelets using amotosalen and ultraviolet A light

BACKGROUND

The INTERCEPT Blood System pathogen reduction technology (PRT), which uses amotosalen and ultraviolet A light treatment (amotosalen/UV-PRT), inactivates pathogens in plasma and platelet components (PCs). This review summarizes data describing the inactivation efficacy of amotosalen/UVA-PRT for a broad spectrum of viruses and parasites.

METHODS

Twenty-five enveloped viruses, six nonenveloped viruses (NEVs), and four parasites species were evaluated for sensitivity to amotosalen/UVA-PRT. Pathogens were spiked into plasma and PC at high titers. Samples were collected before and after PRT and assessed for infectivity with cell cultures or animal models. Log reduction factors (LRFs) were defined as the difference in infectious titers before and after amotosalen/UV-PRT.

RESULTS

LRFs of ≥4.0 log were reported for 19 pathogens in plasma (range, ≥4.0 to ≥7.6), 28 pathogens in PC in platelet additive solution (PC-PAS; ≥4.1-≥7.8), and 14 pathogens in PC in 100% plasma (PC-100%; (≥4.3->8.4). Twenty-five enveloped viruses and two NEVs were sensitive to amotosalen/UV-PRT; LRF ranged from >2.9 to ≥7.6 in plasma, 2.4 or greater to greater than 6.9 in PC-PAS and >3.5 to >6.5 in PC-100%. Infectious titers for four parasites were reduced by >4.0 log in all PC and plasma (≥4.9 to >8.4).

CONCLUSION

Amotosalen/UVA-PRT demonstrated effective infectious titer reduction for a broad spectrum of viruses and parasites. This confirms the capacity of this system to reduce the risk of viral and parasitic transfusion-transmitted infections by plasma and PCs in various geographies.

Quality and safety measures in transfusion practice: The experience of eight southern/eastern Mediterranean countries

BACKGROUND AND OBJECTIVES

Blood transfusion is inherently associated with risks, and little is known regarding the available quality and safety measures in developing countries. No studies or census has been carried out, and therefore, no data on this compelling issue are available.

MATERIALS AND METHODS

Data emanating from eight Arabic eastern/southern Mediterranean countries who responded to five surveys were collected and tabulated.

RESULTS

Asepsis during phlebotomy, screening for serological and immuno-haematological parameters and appropriate storage conditions are maintained across all countries. Variations in blood component processing exist. Universal leucoreduction is systematically applied in Lebanon. Nucleic acid testing is only performed in Egypt. Aphaeresis procedure, leucoreduction and quality control for blood components are virtually inexistent in Mauritania. Written donor questionnaire is absent in Algeria and Tunisia. Most donor deferral periods for infectious agents are inconsistent with international standards.

CONCLUSION

Gaps in the processing and in the quality/safety measures applied to the manufacture of blood components are quite evident in most eastern/southern Mediterranean countries. The decision of establishing an effective collaboration network and an independent body - aside from WHO - composed of specialists that oversees all transfusion activities in these countries is certainly a crucial step towards ensuring an optimum level of blood safety.

Transfusion Transmissible Infections: Maximizing Donor Surveillance

Introduction

The World Health Organization (WHO) recommends that all blood transfusion services must screen donated blood for human immunodeficiency virus (HIV) one and two, hepatitis B, hepatitis C and syphilis. A mandatory screening for malaria is also warranted in malaria endemic areas. Our study aimed at analyzing the prevalence and different diagnostic methods of screening transfusion transmitted infections (TTIs) in replacement and voluntary, non-remunerated donors in the blood bank of a tertiary care hospital in Islamabad, Pakistan.

Methods

The cross-sectional, descriptive study was conducted on 30,470 blood donors from July 2015 to October 2017, in the blood bank of a 500-bed teaching hospital in Islamabad. Initially all blood donors were screened for HIV one, HIV two, hepatitis B and hepatitis C by serological testing. The seronegative samples were further tested by nucleic acid amplification test (NAT). Malaria was screened using immuno-chromatographic antigen-detection tests, while treponema pallidum was screened by electrochemiluminescence immunoassay to detect treponema pallidum (TP) antibodies. All infected blood and blood products were discarded and donors were contacted. The donors were deferred from blood donation according to WHO guidelines. They were also counselled and referred to the infectious diseases clinic. The collected data was analyzed on IBM's statistical package for the social sciences (SPSS) version 21.

Results

The results revealed that amongst the 30,470 donors, 997 (3.27%) donors were found infected with one or more TTI while 29,473 (96.73%) donors were found safe. Individuals who tested positive on serology for hepatitis B were 322 (1.06%), hepatitis C were 392 (1.29%) and HIV were 49 (0.16%). The seronegative donors were tested by NAT. NAT on seronegative samples showed that 10 (0.03%) donors tested positive for hepatitis B virus deoxyribonucleic acid, while only three (0.01%) were positive for hepatitis C ribonucleic acid. No donor was found positive for HIV by NAT testing. Syphilis testing revealed a frequency of 228 (0.75%) positive results while only five (0.02%) donors were found infected with malaria.

Conclusion

The results testify that standardized blood component screening can save transmission of infections through blood transfusion. They also establish the superiority of NAT screening over serological tests in decreasing the residual risk of transfusion transmitted infections.

Addressing gaps in international blood availability and transfusion safety in low- and middle-income countries: a NHLBI workshop

In April 2017, a workshop sponsored by the National Heart, Lung, and Blood Institute, Division of Blood Diseases and Resources, and the Center for Translation Research and Implementation Science was held to discuss blood availability and transfusion safety in low- and middle-income countries (LMICs). The purpose of the workshop was to identify research opportunities for implementation science (IS) to improve the availability of safe blood and blood components and transfusion practices in LMICs. IS describes the late stages of the translational research spectrum and studies optimal and sustainable strategies to deliver proven-effective interventions. Regional working groups were formed to focus on opportunities and challenges in East Africa, Central/West Africa, Middle East and North Africa, Latin America and the Caribbean, Southeast Asia, Western Pacific Asia, Eastern Europe, and Central Asia. The need for an "adequate supply of safe blood" emerged as the major overriding theme. Among the regional working groups, common cross-cutting themes were evident. The majority of research questions, priorities, and strategies fell into the categories of blood availability, blood transfusion safety, appropriate use of blood, quality systems, health economics and budgeting, and training and education in IS. The workshop also brought into focus inadequate country-level data that can be used as the basis for IS initiatives. A mixed approach of needs assessment and targeted interventions with sufficient evidence base to move toward sustainment is an appropriate next step for blood availability and transfusion safety research in LMICs.

Three-Year Experience in NAT Screening of Blood Donors for Transfusion Transmitted Viruses in Croatia

Background

Croatia implemented individual donation (ID)-NAT testing of blood donors in 2013 for three viruses HBV, HCV, and HIV-1 as a mandatory test for all blood donors. This study assessed the impact of NAT screening 3 years after its implementation.

Methods

A total of 545,463 donations were collected and screened for HBV, HCV, and HIV-1 using the Procleix Ultrio Plus Assay. All initially reactive (IR) NAT samples were retested in triplicate and, if repeatedly reactive (RR), NAT discriminatory assay (dNAT) was performed. ID-NAT positive donations were confirmed by RT-PCR on the COBAS AmpliPrep/TaqMan platform.

Results

Out of 545,463 samples tested, 108 (0.02%) were RR in NAT. There were 82 (75,9%) HBV reactive, 16 (14.8%) HCV reactive, and 10 (9.3%) HIV-1 reactive samples. 51 (47.2%) samples were ID-NAT positive only. Out of these 51 NAT yield cases, 1 window period HIV-1 and 50 occult HBV infections (OBI) were determined. There were only two potential HBV DNA transmissions from OBI donors.

Conclusion

The implementation of NAT screening for three viruses has improved blood safety in Croatia. During the 3-year period, 1 window period HIV-1 and a number of occult HBV donations were identified.

Simultaneous detection of multiple viruses based on chemiluminescence and magnetic separation

In this report, a DNA hybridization based chemiluminescent detection method has been proposed for reliable detection of multiple pathogens. The use of surface modified magnetic nanoparticles can help to integrate this system into an automated platform for high throughput applications.

Assessment of semi-automated nucleic acid testing programme in a Regional Blood Transfusion Centre

BACKGROUND

Detection of human immunodeficiency virus type-1 (HIV-1), hepatitis-C (HCV) and hepatitis-B virus (HBV) in the blood donors is crucial. An efficient form of detection is nucleic acid testing (NAT) in blood screening. We assessed the suitability of commercial NAT testing in a developing country, focusing on the Altona RealStar assay and the method of Sacace Biotechnologies.

METHODS

We have standardised and validated commercially available NAT kits with a semi-automated system for detection of HBV, HCV and HIV-1 in blood donations. The MP-NAT (mini-pool) assay consists of pooling of sample, virus extraction, amplification and detection with commercially available NAT kits. An internal control (IC) is incorporated in the assay to monitor the extraction, target amplification and detection process.

RESULTS

The sensitivity of the Altona RealStar assay at 10-MP for each viral target was evaluated, HBV showed amplification in all diluted positive samples of 100, 50, 25, 10 and 5 IU/ml. HIV and HCV infected samples showed amplification in all diluted positive samples of 500, 100, 50 and 30 IU/ml. For HIV, out of six diluted samples of 30 IU/ml, five were amplified. A total of 14,170 seronegative blood samples were tested by RealStar PCR kit in 10-MP and 6 (0.042%) samples/pools were positive. A total of 65,362 seronegative blood donations were also tested by kits of Sacace Biotechnologies, in 10-MP and 45 (0.075%) pools were positive. The prevalence of combined NAT yield cases among routine donors was 1 in 1559 donations tested for all the 3 viruses.

CONCLUSION

The semi-automated combined system for NAT screening assays is robust, sensitive, reproducible, and this gives an additional layer of safety with affordable cost.

Serological Patterns and Molecular Characterization of Occult Hepatitis B Virus Infection among Blood Donors

BACKGROUND

Hepatitis B infections, characterized by the presence of a viral genome without detectable hepatitis B surface antigen (HBsAg; Occult hepatitis B infection [OBI]), have been reported recently.

OBJECTIVES

We performed serological and molecular characterization of OBI among blood donors at Jiangsu province blood center during years 2013 and 2014.

METHODS

All donor samples were routinely screened by double enzyme-linked immunosorbent assay (ELISA) for hepatitis C virus (HCV), hepatitis B virus (HBV), human immunodeficiency virus (HIV), Treponema pallidum (TP), and alanine aminotransferase (ALT). Single-reactive, nonreactive, and ALT-elevated samples were pooled or resolved by nucleic acid testing (NAT). Seromarkers were examined in HBsAg-/DNA+ samples. After 1 to 12 months of follow up, seromarkers were screened again to verify OBI samples.

RESULTS

We studied 157119 samples from blood donors. A total of 154397 ELISA nonreactive donor samples were identified, and HBV DNA was detected in 81 samples; no samples were positive for HIV or HCV RNA. Hepatitis B virus viral loads in most donors were less than 20 - 200 IU/mL. There was only one HBsAg-positive sample. Eighty HBsAg-/DNA+ samples were evaluated further. Of these samples, 85% (68/80) were reactive for anti-HBc and 36.2% (29/800) were reactive for anti-HBc and anti-HBs; 11.3% (9/80) did not have any detectable serological markers. Twenty-nine donors were followed up. One was HBsAg ELISA positive, and of six seronegative donors, all had anti-HBc and anti-HBs, but were negative for DNA. Samples were HBV genotypes B, C and D. Mutations in the S region of HBV DNA included S114T, G119R, P120S, T125M, C139Y, T140I, C147W, T148A, A159V/G, E164D, V168A, and R169C.

CONCLUSIONS

Overall, we found that OBI was rare, but that the prevalence of OBI was slightly higher in Jiangsu than in other areas of China.

All-in-one dry-reagent time-resolved immunofluorometric assay for the rapid detection of HIV-1 and -2 infections

An all-in-one (AIO) dry-reagent time-resolved fluorometric immunoassay that requires minimal liquid handling was developed for the detection of anti-HIV-1 and -2 antibodies. To prepare the AIO wells, in vivo biotinylated capture antigens (r-Bio-HIV-1env and r-Bio-HIV-2env) were immobilized on streptavidin-coated microtitration wells and Eu(III) chelate labelled non-biotinylated tracer antigens [r-HIV-1env-Eu(III) and r-HIV-2env-Eu(III)] were dried in stable form in the same wells. The HIV AIO assay was evaluated with serum/plasma samples (n=148) from in-house and commercial panels at two different incubation times of 15 min and 1h. The overall sensitivity of the AIO assay was 98.6% and specificity was 100% for both the incubation times. The AIO assay can accept whole blood matrix. This assay is envisioned to fill the gap between the rapid point-of-care assays and traditional enzyme immunoassays (EIA) in terms of complexity and turnaround time, without compromising the performance.

Rapid, Fully Automated Digital Immunoassay for p24 Protein with the Sensitivity of Nucleic Acid Amplification for Detecting Acute HIV Infection

BACKGROUND

Nucleic acid testing (NAT) has become the standard for high sensitivity in detecting low levels of virus. However, adoption of NAT can be cost prohibitive in low-resource settings where access to extreme sensitivity could be clinically advantageous for early detection of infection. We report development and preliminary validation of a simple, low-cost, fully automated digital p24 antigen immunoassay with the sensitivity of quantitative NAT viral load (NAT-VL) methods for detection of acute HIV infection.

METHODS

We developed an investigational 69-min immunoassay for p24 capsid protein for use on a novel digital analyzer on the basis of single-molecule-array technology. We evaluated the assay for sensitivity by dilution of standardized preparations of p24, cultured HIV, and preseroconversion samples. We characterized analytical performance and concordance with 2 NAT-VL methods and 2 contemporary p24 Ag/Ab combination immunoassays with dilutions of viral isolates and samples from the earliest stages of HIV infection.

RESULTS

Analytical sensitivity was 0.0025 ng/L p24, equivalent to 60 HIV RNA copies/mL. The limit of quantification was 0.0076 ng/L, and imprecision across 10 runs was <10% for samples as low as 0.09 ng/L. Clinical specificity was 95.1%. Sensitivity concordance vs NAT-VL on dilutions of preseroconversion samples and Group M viral isolates was 100%.

CONCLUSIONS

The digital immunoassay exhibited >4000-fold greater sensitivity than contemporary immunoassays for p24 and sensitivity equivalent to that of NAT methods for early detection of HIV. The data indicate that NAT-level sensitivity for acute HIV infection is possible with a simple, low-cost digital immunoassay.

Minipool caprylic acid fractionation of plasma using disposable equipment: a practical method to enhance immunoglobulin supply in developing countries

Background

Immunoglobulin G (IgG) is an essential plasma-derived medicine that is lacking in developing countries. IgG shortages leave immunodeficient patients without treatment, exposing them to devastating recurrent infections from local pathogens. A simple and practical method for producing IgG from normal or convalescent plasma collected in developing countries is needed to provide better, faster access to IgG for patients in need.

Methodology/Principal Findings

IgG was purified from 10 consecutive minipools of 20 plasma donations collected in Egypt using single-use equipment. Plasma donations in their collection bags were subjected to 5%-pH5.5 caprylic acid treatment for 90 min at 31°C, and centrifuged to remove the precipitate. Supernatants were pooled, then dialyzed and concentrated using a commercial disposable hemodialyzer. The final preparation was filtered online by gravity, aseptically dispensed into storage transfusion bags, and frozen at <-20°C. The resulting preparation had a mean protein content of 60.5 g/L, 90.2% immunoglobulins, including 83.2% IgG, 12.4% IgA, and 4.4% IgM, and residual albumin. There was fourfold to sixfold enrichment of anti-hepatitis B and anti-rubella antibodies. Analyses of aggregates (<3%), prekallicrein (5-7 IU/mL), plasmin (26.3 mU/mL), thrombin (2.5 mU/mL), thrombin-like activity (0.011 U/g), thrombin generation capacity (< 223 nM), and Factor XI (<0.01 U/mL) activity, Factor XI/XIa antigen (2.4 ng/g) endotoxin (<0.5 EU/mL), and general safety test in rats showed the in vitro safety profile. Viral validation revealed >5 logs reduction of HIV, BVDV, and PRV infectivity in less than 15 min of caprylic acid treatment.

Conclusions/Significance

90% pure, virally-inactivated immunoglobulins can be prepared from plasma minipools using simple disposable equipment and bag systems. This easy-to-implement process could be used to produce immunoglobulins from local plasma in developing countries to treat immunodeficient patients. It is also relevant for preparing hyperimmune IgG from convalescent plasma during infectious outbreaks such as the current Ebola virus episode.

Plasma-derived immunoglobulin G (IgG) is on WHO’s Essential Medicines List, yet developing countries face severe shortages of this critical treatment. Infusion of IgG prepared from locally-collected plasma provides an advantageous mix of antibodies to viral and bacterial pathogens found in the living environment, and this can reduce recurrent infections in immune-deficient patients. We developed a simple manufacturing process using disposable equipment (blood bags, hemodialyzer, and filters) to isolate immunoglobulins from minipools of 20 plasma donations. This process yields a ca. 90% pure virally-inactivated immunoglobulin fraction at 50–60% recovery. Anti-hepatitis B and anti-rubella immunoglobulins were enriched fourfold to sixfold. The product was free of in-vitro thrombogenic and proteolytic activity, confirming its expected clinical safety profile. Virus validations showed caprylic acid treatment robustly inactivated or removed infectivity of lipid-enveloped viruses, including human immunodeficiency virus (HIV) and hepatitis C virus model. This simple and cost-effective process is implemented in Egypt to prepare experimental batches for clinical evaluation. It can enhance immunoglobulin supplies to treat immunodeficient patients through passive transmission of antibodies directed against local pathogens. The method requires minimal training and reasonable infrastructure, and is a practical means to prepare convalescent hyperimmune IgG during infectious outbreaks such as the current Ebola episode.

Half a decade of mini-pool nucleic acid testing: Cost-effective way for improving blood safety in India

BACKGROUND AND OBJECTIVES

It is well established that Nucleic acid testing (NAT) reduces window phase of transfusion transmissible infections (TTI) and helps improve blood safety. NAT testing can be done individually or in pools. The objectives of this study were to determine the utility, feasibility and cost effectiveness of an in-house minipool-NAT(MP-NAT).

MATERIALS AND METHODS

Blood donors were screened by history, tested by ELISA and sero-negative samples were subjected to an in-house NAT by using reverse transcriptase-polymerase chain reaction (RT-PCR). Testing was done in mini-pools of size eight (8). Positive pools were repeated with individual samples.

RESULTS

During the study period of Oct 2005-Sept 2010 (5 years) all blood donors (n=53729) were screened by ELISA. Of which 469 (0.87%) were positive for HIV-1, HBV or HCV. Sero-negative samples (n=53260) were screened by in-house MP-NAT. HIV-NAT yield was 1/53260 (n=1) and HBV NAT yield (n=2) was 1/26630.

CONCLUSION

NAT yield was lower than other India studies possibly due to the lower sero-reactivity amongst our donors. Nevertheless it intercepted 9 lives including the components prepared. The in-house assay met our objective of improving blood safety at nominal cost and showed that it is feasible to set up small molecular biology units in medium-large sized blood banks and deliver blood within 24-48 hours. The utility of NAT (NAT yield) will vary based on the donor population, the type of serological test used, the nature of kit employed and the sensitivity of NAT test used. The limitations of our in-house MP-NAT consisted of stringent sample preparation requirements, with labor and time involved. The benefits of our MP-NAT were that it acted as a second level of check for ELISA tests, was relatively inexpensive compared to ID-NAT and did not need sophisticated equipment.

Comparison between screening and confirmatory serological assays in blood donors in a region of South Italy

BACKGROUND

Screening assays are needed in order to guarantee safety of donated blood, but a significant number of safe donations are removed from blood supply because of reactive screening results. It is important to evaluate the positive predictive value (PPV) of screening assays in order to modulate confirmatory algorithm and implement an adequate counseling.

METHODS

An analysis of 17,912 blood donations has been conducted at Transfusion Medicine at Second University Naples, Italy, in 2009-2012. Serological screening for syphilis, hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) was performed by ARCHITECT (Abbott Diagnostics, Wiesbaden, Germany); repeatedly reactive (RR) samples were checked by respective confirmatory tests. The relationship between sample/cutoff and confirmed seropositivity were analyzed.

RESULTS

RR rates were low as expected in blood donors: 0.47% for syphilis, 0.42% for HBV, 0.50% for HCV, and 0.15% for HIV. The specificity on RR + gray zone (GZ) was 99.67%, 99.79%, 99.77%, and 99.88%, respectively; due to the low prevalence, PPV value was 30.6% for syphilis, 50.7% for HBV, 42.2% for HCV, and 18.5% for HIV. These values increased substantially reaching a plateau of 89.3% for syphilis, 94.6% for HBV, 85.7% for HCV, and 100% for HIV at the threshold established by receiver operating characteristics curve analysis.

CONCLUSIONS

Supplemental testing on samples with high signal by screening assays seems to add little information. GZ settings and confirmatory testing for positive screening results should be designed taking in account several factors, including difference in the natural history among blood-borne infections, the characteristics of first- and second-level tests, and, when available, the results of nucleic acid amplification testing.

Estimating window period blood donations for human immunodeficiency virus Type 1, hepatitis C virus, and hepatitis B virus by nucleic acid amplification testing in Southern Pakistan

BACKGROUND

Recently, strategic planning was initiated by the National Blood Transfusion Services Pakistan to improve its blood bank facilities. Emphasis has been placed on appropriate screening of blood products. Located in the southern region, Aga Khan University Hospital is a 700-bed tertiary care academic institute with comprehensive blood banking. Screening of blood donors has been based on verbal screening and serologic testing to date. Additionally, the need of implementing nucleic acid testing (NAT) was considered in 2011 because of an upsurge in hepatitis epidemiology. The aim of this study was to analyze the efficacy of this additional donor screening program and to evaluate the impact of NAT on the yield and residual risk of transfusion-transmissible viral infections.

STUDY DESIGN AND METHODS

A total of 42,830 blood donations collected between 2011 and 2012 were screened for routine serologic assays. Only serologically negative donors (n=41,304) were tested for NAT. The frequency of viral infections was evaluated through serologic techniques and NAT yield for viral agents was estimated for computing window period donors. Residual risk per million donors was computed for viral infections in seronegative blood donors.

RESULTS

Serologic work-up showed 1571 abnormal screening results in 1526 blood donors with the following results: hepatitis C virus antibodies (anti-HCV; n=708), hepatitis B surface antigen (n=555), human immunodeficiency virus antibodies (anti-HIV; n=29), malaria (n=30), VDRL (n=249), and coinfection (n=45). Thirty-five NAT-reactive samples were identified: HIV-1, one; HCV, 27; and hepatitis B virus (HBV), seven. Incident rates per 10(5) donors were highest for HCV (453.3) followed by HBV (171.5) and HIV (72.2). Calculated residual risk per million donors was highest at 1 in 10,900 for HBV, intermediate at 1 in 13,900 for HCV, and least at 1 in 62,600 for HIV.

CONCLUSION

Incidence rates and estimated residual risk indicate that the current risk of transfusion-transmitted viral infections attributable to blood donation is relatively high in this country. The study recommends the parallel use of both serology and NAT screening of donated blood in countries that have high seroprevalence of these viral infections.

Nucleic acid testing for blood banks: an experience from a tertiary care centre in New Delhi, India

INTRODUCTION

Blood safety is a challenging task in India; with a population of around 1.23 billion and a high prevalence rate of HIV (0.29%), HBV (2-8%) and HCV (≈ 2%) in general population. Nucleic acid testing (NAT) in blood donor screening has been implemented in many developed countries to reduce the risk of transfusion-transmitted viral infections (TTIs). NAT shortens this window period, thereby offering blood centers a much higher sensitivity for detecting viral infections.

MATERIALS AND METHODS

Routine ID-NAT for HIV-1, HCV and HBV was started from June 2010 at AIIMS blood bank by the Procleix® Ultrio® Assay (Novartis Diagnostics, USA) a multiplex NAT, which allows the simultaneous detection of HIV-1, HCV, and HBV in a single tube. During the period of 27 months from June 2010 to August 2012, around 73,898 samples were tested for all the three viruses using both ELISA (by Genscreen Ultra HIV Ag-Ab(BIO-RAD), Hepanostika HCV Ultra & HBsAg Ultra(Biomerieux) and Nucleic acid testing. The comparative results of both the assays are being presented here in this study.

RESULTS

Out of 73,898 samples, 1104 samples (1.49%) were reactive by NAT. out of these 1104 samples, 73 were reactive for HIV-1 (0.09%), 186 were reactive for HCV only (0.25%), 779 (1.05%) were reactive for HBV only, and around 66 (0.08%) were HBV-HCV co-infections. There was one HIV, 37 HCV, 73 HBV and 10 HBV-HCV co-infection cases that were not detected by serology but reactive on NAT testing, with a combined yield of 1 in 610 donations (total 121 NAT yields).

CONCLUSION

NAT could detect HIV, HBV and HCV cases in blood donor samples that were undetected by serological tests. NAT can interdict a large number of infected unit transfusions and thus help in providing safe blood to the patients.

Six-year pilot study on nucleic acid testing for blood donations in China

A six-year pilot study on nucleic acid testing for HBV, HCV and HIV-1 has been undertaken on sero-negative plasmas in mini-pool and individual donation testing at Shenzhen Blood Center. Of 307,740 sero-negative blood samples, 95 of 102 HBV DNA yields were confirmed positive, 80/95 (84.2%) were classified as occult HBV infection (OBI) and 15 (15.8%) as window period cases. Amongst OBIs, 45% carried anti-HBc only, 41.3% anti-HBc and anti-HBs and 13.7% anti-HBs only. HBV DNA yield was 1:3239. One HCV WP and one HIV-1 infected donations were detected. High residual risk was found in current blood donations screening in China.

Simple diffusion-constrained immunoassay for p24 protein with the sensitivity of nucleic acid amplification for detecting acute HIV infection

Nucleic acid amplification techniques have become the mainstay for ultimate sensitivity for detecting low levels of virus, including human immunodeficiency virus (HIV). As a sophisticated technology with relative expensive reagents and instrumentation, adoption of nucleic acid testing (NAT) can be cost inhibited in settings in which access to extreme sensitivity could be clinically advantageous for detection of acute infection. A simple low cost digital immunoassay was developed for the p24 capsid protein of HIV based on trapping enzyme-labeled immunocomplexes in high-density arrays of femtoliter microwells and constraining the diffusion of the enzyme-substrate reaction. The digital immunoassay was evaluated for analytical sensitivity for HIV capsid protein p24, and compared with commercially available NAT methods and immunoassays for p24, including 4th-generation antibody/antigen combo assays, for early detection of HIV in infected individuals. The digital immunoassay was found to exhibit 2000-3000-fold greater analytical sensitivity than conventional immunoassays reactive for p24, and comparable sensitivity to NAT methods. Assaying serial samples from 10 HIV-infected individuals, the digital immunoassay detected acute HIV infection as early as NAT methods, and 7-10 days earlier than conventional immunoassays. Comparison of assay results between the digital immunoassay and a quantitative NAT method from HIV infected serum exhibited a linear correlation R(2)>0.99. The data indicate that by constraining diffusion of the signal generation step of a simple sandwich immunoassay and enabling the digital counting of immunocomplexes, dramatic improvements in sensitivity to virus can be obtained to match the sensitivity of NAT at a fraction of the cost.

Need for nucleic Acid testing in countries with high prevalence of transfusion-transmitted infections

Introduction. In India, family/replacement donors still provide more than 45% of the collected blood. With increasing voluntary blood donation and the still-prevalent infectious diseases in donors, we need to augment transfusion-transmitted infections (TTIs) testing before use. Our study was aimed to know the seroprevalence of TTIs among the donors of Rajasthan and the need for newer technologies like nucleic acid testing (NAT). Materials and Methods. Enhanced chemiluminescence immunoassay (ECi) was used for detection of HBsAg, anti-HIV, and anti-HCV in donor serum. 50% of the blood units which were negative on ECi were randomly selected and subjected to NAT testing for HBV, HCV, and HIV. Results. The total seroprevalence of TTIs is 2.62%. Of the randomly selected donor units negative by ECi, 8 turned out to be reactive on NAT testing: 4 were voluntary and 4 were family/replacement donors. Combined NAT yield (NAT reactive/seronegative) for HIV, HCV, and HBV was 0.034% (1 in 2972 donations). All the 8 reactive samples were positive for HBV DNA. Conclusion. In countries with a high prevalence of TTIs like India there are likely to be a significant number of window period donations that can be identified by NAT which may be implemented in blood centers allover India with serological testing to provide safe blood and cost alone should not be a deterrent to the government and implementing agencies.

Trends in prevalence, incidence, and residual risk of major transfusion-transmissible viral infections in United Arab Emirates blood donors: impact of individual-donation nucleic acid testing, 2004 through 2009

BACKGROUND

United Arab Emirates (UAE) has a heterogeneous population consisting of more than 160 nationalities and 85% of the population being non-UAE. In 2007, Dubai Blood Donation Centre (DBDC), the major local supplier of blood in the UAE, introduced six-minipool nucleic acid test (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV), which in 2008 upgraded to individual-donation (ID)-NAT. The aim of this study was to analyze the efficacy of the donor screening program in the UAE and evaluate the impact of NAT on the yield and residual risk of transfusion-transmissible viral infections (TTVIs).

STUDY DESIGN AND METHODS

A total of 169,781 blood donations collected at DBDC between 2004 and 2009 were screened for TTVIs. During the period 2008 through 2009, a total of 59,283 donations were tested with both ID-NAT and serologic assays. The incidence, prevalence, and residual risk for each viral agent were estimated and analyzed.

RESULTS

The individual prevalences of HBV, HCV, and HIV per 100,000 donation were 234.4, 110, and 4, respectively. Calculated residual risk per million donations for HBV was decreased from 1.41 in pre-NAT period to 0.92 in post-NAT period. These figures were decreased for HCV and HIV from 1.73 and 0.39 to 0 and 0.32, respectively.

CONCLUSION

Incidence rates and estimated residual risk indicate that the current risk of TTVIs attributable to blood donation is relatively low in the UAE. The study recommends the parallel use of both serology and ID-NAT TTVIs screening in blood donations and suggests the exclusion of antibody to hepatitis B core antigen-positive donations as this can eliminate the potential infectivity of these units with marginal effects on the blood stock in UAE.

Prevalence and trend of HIV infection among voluntary blood donors in China since implementation of the Blood Donation Law: a systematic review and meta-analysis

OBJECTIVE

In 1998, the Blood Donation Law was enacted in China in response to the outbreak of HIV endemic in central rural China as a result of unhygienic and commercial blood collection. This study aims to provide a first comprehensive review of available data on the prevalence, trend and other epidemiological characteristics of HIV infection among voluntary blood donors since 1998.

METHODS

Major English and Chinese databases were searched and a systematic review was constructed. Pooled infection rates by province and year were calculated using random-effect or fixed-effect models.

RESULTS

A total of 87 studies met our inclusion criteria. A total of 2573 HIV-positive cases were identified among voluntary blood donors in the past 10 years; the pooled prevalence was 13.22/100,000, with a range of 0.74-125.97 per 100,000. Among the 24 provinces that reported yearly data, the prevalence of HIV increased from 5.62/100,000 to 28.90/100,000. The male-to-female ratio was 2.8; about 60% were below the age of 30 years.

CONCLUSIONS

The prevalence of HIV in voluntary blood donors has risen steadily and fast. Efficient measures need to be taken urgently to prevent HIV test-seeking through blood donor programmes, to promote voluntary blood donation in low-risk groups and to enforce the Blood Donation Law strictly.

Protocol for the use of a rapid real-time PCR method for the detection of HIV-1 proviral DNA using double-stranded primer

This chapter describes a real-time PCR method for the detection of HIV-1 proviral DNA in whole blood samples using a novel double-stranded primer system. The assay utilizes a simple commercially available DNA extraction method and a rapid and easy-to-perform real-time PCR protocol to consistently detect a minimum of four copies of HIV-1 group M proviral DNA in as little as 90 min after sample (whole blood) collection. Co-amplification of the human RNase P gene serves as an internal control to monitor the efficiency of both the DNA extraction and amplification. Once the assay is validated properly, it may be suitable as an alternative confirmation test for HIV-1 infections in a variety of HIV testing venues including the mother-to-child transmission testing sites, clinics, and diagnostic testing centers.

Seroprevalence of transfusion-transmissible infections and evaluation of the pre-donation screening performance at the Provincial Hospital of Tete, Mozambique

Background

The World Health Organization recommends universal and quality-controlled screening of blood donations for the major transfusion-transmissible infections (TTIs): human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis. The study objectives were to determine the seroprevalence of these TTIs among blood donors at the Provincial Hospital of Tete, Mozambique, and to assess the local pre-donation screening performance.

Methods

All consenting voluntary and replacement candidate blood donors were consecutively included from February to May 2009. Sera of all candidates, independent of deferral by questionnaire, were submitted to screening with quality-assured rapid or simple assays for HIV, HBV surface antigen (HBsAg), HCV and syphilis. Assays locally used by the blood bank for HBV and syphilis screening were run in parallel to quality-assured external assays supplied during the study, and all discordant samples were submitted to confirmation testing in reference laboratories in Mozambique and Belgium.

Results

Of 750 consenting candidates (50.5% of voluntary donors), 71 (9.5%) were deferred by the questionnaire, including 38 specifically because of risk behavior for TTI. Of the 679 non-deferred candidates, 127 (18.7%) had serological confirmation of at least one TTI, with a lower prevalence in voluntary than in replacement donors (15.2% versus 22.4%, p = 0.016). Seroprevalence of HIV, HBsAg and syphilis infections was 8.5%, 10.6 % and 1.2%. No confirmed HCV infection was found. Seroprevalence of TTIs was similar in the 38 candidates deferred for TTI risk as in the non-deferred group, except for HBsAg (26.3 % versus 10.6 %; p = 0.005). The local assays used for HBV and syphilis had sensitivities of 98.4% and 100% and specificities of 80.4% and 98.8% respectively. This resulted in the rejection of 110 of the 679 blood donations (16.2%) because of false positive results.

Conclusions

The seroprevalence of TTIs after questionnaire screening is high in Tete, Mozambique, but HCV infection does not appear as a major issue. The questionnaire did not exclude effectively HIV-infected donor candidates, while the locally used assays led to unnecessary rejection of many safe donations. A contextualized questionnaire and consistent use of quality-assured assays would considerably improve the current screening procedure for blood donation.

Hepatitis B virus (HBV) infection and recombination between HBV genotypes D and E in asymptomatic blood donors from Khartoum, Sudan

Sudan is a highly endemic area for hepatitis B virus (HBV), and >5% of blood donors are chronically infected. To examine potential strategies to improve HBV blood safety, 404 replacement donor samples previously screened for HBV surface antigen (HBsAg) were tested for antibody to HBV core (anti-HBc), anti-surface antigen (anti-HBs), and HBV DNA. Of 145 anti-HBc-containing samples (36%) identified, 16 retested were HBsAg positive (11%). Anti-HBs was detected in 43/77 (56%) anti-HBc-reactive samples. Six samples were HBsAg(-)/anti-HBc(+)/anti-HBs(+) and contained HBV DNA, meeting the definition of occult HBV infection (OBI). OBIs had low HBV DNA loads (<10 IU/ml) and were genotype B (n = 1) or genotype D (n = 5). Pre-S/S and/or whole genome sequences were obtained from 47 randomly selected HBsAg-positive donors added to the previous 16. Genotype E was identified in 27 strains (57.5%), genotype D in 19 strains (40.5%), and genotype A2 in 1 strain (2%). Two outlier strains within genotype D ultimately were identified as recombinants of genotypes D and E with identical recombination points, suggesting circulating, infectious, recombinant strains. Anti-HBc screening does not appear to be a sustainable blood safety strategy because of the cost and the negative impact on the Sudanese blood supply, even when reduced by anti-HBs testing. Being at the junction between two main African HBV genotypes, genetic recombination occurred and became part of the molecular epidemiology of HBV in Sudan.