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Mellors J, Carroll M. Direct enhancement of viral neutralising antibody potency by the complement system: a largely forgotten phenomenon. Cell Mol Life Sci 2024; 81:22. [PMID: 38200235 PMCID: PMC10781860 DOI: 10.1007/s00018-023-05074-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/24/2023] [Accepted: 11/29/2023] [Indexed: 01/12/2024]
Abstract
Neutralisation assays are commonly used to assess vaccine-induced and naturally acquired immune responses; identify correlates of protection; and inform important decisions on the screening, development, and use of therapeutic antibodies. Neutralisation assays are useful tools that provide the gold standard for measuring the potency of neutralising antibodies, but they are not without limitations. Common methods such as the heat-inactivation of plasma samples prior to neutralisation assays, or the use of anticoagulants such as EDTA for blood collection, can inactivate the complement system. Even in non-heat-inactivated samples, the levels of complement activity can vary between samples. This can significantly impact the conclusions regarding neutralising antibody potency. Restoration of the complement system in these samples can be achieved using an exogenous source of plasma with preserved complement activity or with purified complement proteins. This can significantly enhance the neutralisation titres for some antibodies depending on characteristics such as antibody isotype and the epitope they bind, enable neutralisation with otherwise non-neutralising antibodies, and demonstrate a better relationship between in vitro and in vivo findings. In this review, we discuss the evidence for complement-mediated enhancement of antibody neutralisation against a range of viruses, explore the potential mechanisms which underpin this enhancement, highlight current gaps in the literature, and provide a brief summary of considerations for adopting this approach in future research applications.
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Affiliation(s)
- Jack Mellors
- Centre for Human Genetics and the Pandemic Sciences Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - Miles Carroll
- Centre for Human Genetics and the Pandemic Sciences Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Guetiya Wadoum RE, Sevalie S, Baimba Kargbo M, Clarke A, Bangura S, Kargbo M, Sesay HM, Kamara AH, Bangura J, Kamara AF, Allieu S, Rogers H, Mattei M, Colizzi V, Montesano C, Momoh EJJ. Identification of Laboratory Biomarkers for Early Detection and Clinical Management of Post-Acute Syndrome Among Survivors of the 2013-2016 West Africa Ebola Outbreak in Sierra Leone. J Blood Med 2023; 14:119-132. [PMID: 36817368 PMCID: PMC9930681 DOI: 10.2147/jbm.s371239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 02/07/2023] [Indexed: 02/13/2023] Open
Abstract
Background The clinical management of persistent medical conditions affecting Ebola survivors, generally described as a post-Ebola syndrome, remains a public health concern. We aimed to analyze Ebola survivors' laboratory biomarkers as compared to their non-infected household relatives to identify biomarkers that could guide the identification of survivors at increased risk of developing severe at odds with the non-severe post-Ebola syndrome. Materials and Methods Data were extracted from medical records of the Ebola survivors clinic, and we included only Ebola survivor's parameters recorded during the first baseline follow-up visit 2 weeks interval after their second negative PCR result. Moreover, household non-infected family contacts of survivors visiting the clinic during the same period were recruited as community control. Results The mean age of survivors was 32.65 (IQR: 15.5, 38.25) years, and Ebola IgG immunoglobulin was detected in all, thus confirming their status. The statistical significance (all p < 0.05) observed in monocyte percentage (MONO%), cluster of differentiation 4 percentage (CD4%), alanine aminotransferase (ALT), creatinine (CREA), and creatinine kinase (C-kinase) proved to be clinically significant as compared to the household relatives' group. Interestingly, the linear regression analysis indicated that the duration at ETU was negatively associated with lymphocyte percentage with a 5% lymphocyte decrease per day spent at ETU. Finally, there was a significant (p < 0.05) association between hematological (Hb, PCV, MCV, MCH), biochemical (ALT, CREA, C-kinase, T-cholesterol, triglycerides) parameters and the risk of developing severe complications. Conclusion We recommend clinicians closely monitor Hb, PCV, MCV, MCH, ALT, CREA, C-kinase, T-cholesterol, triglycerides and lymphocytes as clinically relevant laboratory biomarkers to identify survivors at higher risk of developing severe post-acute syndrome upon discharge from Ebola treatment unit including headache, abdominal pain, chest pain, ocular complication, arthralgia, hearing difficulty and erectile dysfunction which can impact health-related quality of life among Ebola survivors.
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Affiliation(s)
- Raoul Emeric Guetiya Wadoum
- Department of Public Health, Microbiology and Immunology, Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone,Correspondence: Raoul Emeric Guetiya Wadoum; Edwin JJ Momoh, Email ; ;
| | - Stephen Sevalie
- 34th Military Hospital, The Republic of Sierra Leone Armed Forces, Freetown, Sierra Leone
| | - Maurice Baimba Kargbo
- Department of Agriculture and Food Security; Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone
| | - Andrew Clarke
- Global Programs Division, Save the Children UK, London, UK,Department/Division of Health Research, Lancaster University, Lancaster, UK
| | - Sherry Bangura
- Sierra Leone Association of Ebola Survivors, Freetown, Sierra Leone
| | - Mariatu Kargbo
- Sierra Leone Association of Ebola Survivors, Freetown, Sierra Leone
| | | | - Abdul H Kamara
- Sierra Leone Association of Ebola Survivors, Freetown, Sierra Leone
| | - Jamil Bangura
- Sierra Leone Association of Ebola Survivors, Freetown, Sierra Leone
| | - Alie F Kamara
- Sierra Leone Association of Ebola Survivors, Freetown, Sierra Leone
| | - Sophie Allieu
- Department of Public Health, Microbiology and Immunology, Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone
| | - Hassan Rogers
- Department of Public Health, Microbiology and Immunology, Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone
| | - Maurizio Mattei
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Vittorio Colizzi
- Department of Sciences and Technology, Evangelical University of Cameroon, Bandjoun, Cameroon
| | - Carla Montesano
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Edwin J J Momoh
- Department of Public Health, Microbiology and Immunology, Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone,Department of Agriculture and Food Security; Ernest Bai Koroma University of Science and Technology, Makeni, Sierra Leone
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Elias SC, Muthumbi E, Mwanzu A, Wanjiku P, Mutiso A, Simon R, MacLennan CA. Complementary measurement of nontyphoidal Salmonella-specific IgG and IgA antibodies in oral fluid and serum. Heliyon 2023; 9:e12071. [PMID: 36704288 PMCID: PMC9871079 DOI: 10.1016/j.heliyon.2022.e12071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/07/2022] [Accepted: 11/25/2022] [Indexed: 12/23/2022] Open
Abstract
Objectives Immuno-epidemiological studies of orally acquired, enteric pathogens such as nontyphoidal Salmonella (NTS) often focus on serological measures of immunity, ignoring potentially relevant oral mucosal responses. In this study we sought to assess the levels and detectability of both oral fluid and serum IgG and IgA to NTS antigens, in endemic and non-endemic populations. Methods IgG and IgA antibodies specific for Salmonella Typhimurium and Salmonella Enteritidis O antigen and phase 1 flagellin were assessed using Enzyme Linked Immunosorbent Assay (ELISA). Paired oral fluid and serum samples were collected from groups of 50 UK adults, Kenyan adults and Kenyan infants. Additionally, oral fluid alone was collected from 304 Kenyan individuals across a range of ages. Results Antigen-specific IgG and IgA was detectable in the oral fluid of both adults and infants. Oral fluid antibody increased with age, peaking in adulthood for both IgG and IgA but a separate peak was also observed for IgA in infants. Oral fluid and serum responses correlated for IgG but not IgA. Despite standardised collection the relationship between oral fluid volume and antibody levels varied with age and country of origin. Conclusions Measurement of NTS-specific oral fluid antibody can be used to complement measurement of serum antibody. For IgA in particular, oral fluid may offer insights into how protective immunity to NTS changes as individuals transition with age, from maternal to acquired systemic and mucosal immunity. This may prove useful in helping to guide future vaccine design.
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Affiliation(s)
- Sean C. Elias
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, UK
- Corresponding author.
| | - Esther Muthumbi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene & Tropical Medicine, UK
| | - Alfred Mwanzu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Agnes Mutiso
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
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Akpogheneta O, Dicks S, Grant D, Kanneh Z, Jusu B, Edem-Hotah J, Kanneh L, Alhasan F, Gbakie M, Schieffelin J, Ijaz S, Tedder R, Bower H. Boosting understanding of Lassa Fever virus epidemiology: Field testing a novel assay to identify past Lassa Fever virus infection in blood and oral fluids of survivors and unexposed controls in Sierra Leone. PLoS Negl Trop Dis 2021; 15:e0009255. [PMID: 33788861 PMCID: PMC8041174 DOI: 10.1371/journal.pntd.0009255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 04/12/2021] [Accepted: 02/18/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Despite identification 50 years ago, the true burden of Lassa Fever (LF) across Africa remains undefined for reasons including research focus on hospitalised patients, lack of validated field-feasible tools which reliably identify past infection, and the fact that all assays require blood samples making large-scale surveys difficult. Designated a priority pathogen of epidemic potential requiring urgent research by the World Health Organisation, a better understanding of LF sero-epidemiology is essential to developing and evaluating new interventions including vaccines. We describe the first field testing of a novel species-neutral Double Antigen Binding Assay (DABA) designed to detect antibodies to LF in plasma and oral fluid. METHODOLOGY/PRINCIPAL FINDINGS Paired plasma and oral fluid were collected in Sierra Leone from survivors discharged from Kenema Government Hospital Lassa Fever Unit between 1980 and 2018, and from controls recruited in Freetown in 2019. Epidemiological sensitivity and specificity of the DABA measured against historical diagnosis in survivors and self-declared non-exposed controls was 81.7% (95% CI 70.7%- 89.9%) and 83.3% (72.7%- 91.1%) respectively in plasma, and 71.8% (60.0%- 81.9%) and 83.3% (72.7%- 91.1%) respectively in oral fluid. Antibodies were identified in people infected up to 15 years and, in one case, 40 years previously. Participants found oral fluid collection easy and painless with 80% happy to give an oral fluid sample regularly. CONCLUSIONS/SIGNIFICANCE Given the difficulties of assay validation in a resource-limited setting, including unexpected exposures and diagnostics of varying accuracy, the new assay performed well in both plasma and oral fluid. Sensitivity and specificity are expected to be higher when case/control ascertainment is more definitive and further work is planned to investigate this. Even at the performance levels achieved, the species-neutral DABA has the potential to facilitate the large-scale seroprevalence surveys needed to underpin essential developments in LF control, as well as support zoonotic investigations.
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Affiliation(s)
- Onome Akpogheneta
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Steve Dicks
- Blood Borne Virus Unit, Public Health England, Colindale, United Kingdom
- Microbiology Services, NHS Blood and Transplant, London, United Kingdom
| | - Donald Grant
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - Zainab Kanneh
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - Brima Jusu
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - Joseph Edem-Hotah
- Faculty of Nursing, University of Sierra Leone, Freetown, Sierra Leone
| | - Lansana Kanneh
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - Foday Alhasan
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - Michael Gbakie
- Kenema Government Hospital Lassa Fever Unit, Kenema, Sierra Leone
| | - John Schieffelin
- Sections of Infectious Disease, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Samreen Ijaz
- Blood Borne Virus Unit, Public Health England, Colindale, United Kingdom
| | - Richard Tedder
- Department of Infectious Disease, Imperial College, London, United Kingdom
| | - Hilary Bower
- UK Public Health Rapid Support Team, London School of Hygiene & Tropical Medicine/Public Health England, London, United Kingdom
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Matz KM, Marzi A, Feldmann H. Ebola vaccine trials: progress in vaccine safety and immunogenicity. Expert Rev Vaccines 2020; 18:1229-1242. [PMID: 31779496 DOI: 10.1080/14760584.2019.1698952] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Introduction: Ebolaviruses are non-segmented negative-strand RNA viruses in the Filoviridae family that cause a neglected infectious disease designated as Ebola virus disease (EVD). The most prominent member is the Ebola virus (EBOV), representing the Zaire ebolavirus species that has been responsible for the largest reported EVD outbreaks including the West African epidemic and the current outbreak in the Democratic Republic of the Congo. Today, the most advanced EVD vaccine approaches target EBOV and multiple phase 1-4 human trials have been performed over the past few years. The most advanced platforms include vectored vaccines based on vesicular stomatitis virus (VSV-EBOV), distinct human (Ad5 and Ad26) and chimpanzee (ChAd3) adenoviruses and modified vaccinia Ankara (MVA) as well as DNA-based vaccines administered as a prime-only or homologous or combined prime-boost immunization.Areas covered: Here, we review and discuss human trials with a focus on vaccine safety and immunogenicity.Expert opinion: Despite obvious progress and promising success in EBOV vaccine development, many shortcomings and challenges remain to be tackled in the future.
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Affiliation(s)
- Keesha M Matz
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT, USA
| | - Andrea Marzi
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT, USA
| | - Heinz Feldmann
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT, USA
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Timothy JWS, Hall Y, Akoi-Boré J, Diallo B, Tipton TRW, Bower H, Strecker T, Glynn JR, Carroll MW. Early transmission and case fatality of Ebola virus at the index site of the 2013-16 west African Ebola outbreak: a cross-sectional seroprevalence survey. THE LANCET. INFECTIOUS DISEASES 2019; 19:429-438. [PMID: 30799252 PMCID: PMC6437313 DOI: 10.1016/s1473-3099(18)30791-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 11/15/2018] [Accepted: 12/06/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND To date, epidemiological studies at the index site of the 2013-16 west African Ebola outbreak in Meliandou, Guinea, have been restricted in their scope. We aimed to determine the occurrence of previously undocumented Ebola virus disease (EVD) cases and infections, and to reconstruct transmission events. METHODS This cross-sectional seroprevalence survey of the adult population of Meliandou used a highly specific oral fluid test and detailed interviews of all households in the village and key informants. Each household was interviewed, with all members prompted to describe the events of the outbreak, any illness within the household, and possible contact with suspected cases. Information for deceased individuals was provided by relatives living in the same household. Symptoms were based on Ebola virus Makona variant EVD case definitions (focusing on fever, vomiting, and diarrhoea). For antibody testing, we used an Ebola virus glycoprotein IgG capture enzyme immunoassay developed from a previously validated assay. A maximum exposure level was assigned to every participant using a predetermined scale. We used a generalised linear model (logit function) to estimate odds ratios for the association of sociodemographic variables and exposure level with Ebola virus infection. We adjusted estimates for age and maximum exposure, as appropriate. FINDINGS Between June 22, and July 9, 2017, we enrolled 237 participants from 27 households in Meliandou. Two households refused to participate and one was absent. All adults in participating households who were present for the interview provided an oral fluid swab for testing, of which 224 were suitable for analysis. In addition to the 11 EVD deaths described previously, on the basis of clinical description and oral fluid testing, we found two probable EVD deaths and eight previously unrecognised anti-Ebola virus IgG-positive survivors, including one who had mild symptoms and one who was asymptomatic, resulting in a case fatality of 55·6% (95% CI 30·8-78·5) for adults. Health-care work (adjusted odds ratio 6·64, 1·54-28·56; p=0·001) and level of exposure (odds ratio adjusted for linear trend across five levels 2·79, 1·59-4·883; p<0·0001) were independent risk factors for infection. INTERPRETATION Ebola virus infection was more widespread in this spillover population than previously recognised (21 vs 11 cases). We show the first serological evidence of survivors in this population (eight anti-Ebola virus IgG seropositive) and report a case fatality lower than previously reported (55·6% vs 100% in adults). These data show the high community coverage achievable by using a non-invasive test and, by accurately documenting the beginnings of the west African Ebola virus outbreak, reveal important insight into transmission dynamics and risk factors that underpin Ebola virus spillover events. FUNDING US Food and Drug Administration, Wellcome Trust, and German Research Council.
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Affiliation(s)
| | - Yper Hall
- Research and Development Institute, National Infection Service, Public Health England, Porton Down, Salisbury, UK
| | - Joseph Akoi-Boré
- Public Health England/Tropical Medicine Institute Berlin Reference Laboratory, Guéckédou, Guinea
| | - Boubacar Diallo
- World Health Organization, Regional Office for Africa, Brazzaville, Republic of Congo
| | - Thomas R W Tipton
- Research and Development Institute, National Infection Service, Public Health England, Porton Down, Salisbury, UK
| | - Hilary Bower
- London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas Strecker
- Institute of Virology, Philipps University, Marburg, Germany
| | - Judith R Glynn
- London School of Hygiene & Tropical Medicine, London, UK
| | - Miles W Carroll
- Research and Development Institute, National Infection Service, Public Health England, Porton Down, Salisbury, UK
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Abstract
The West African Ebola virus (EBOV) epidemic has fast-tracked countermeasures for this rare, emerging zoonotic pathogen. Until 2013-2014, most EBOV vaccine candidates were stalled between the preclinical and clinical milestones on the path to licensure, because of funding problems, lack of interest from pharmaceutical companies, and competing priorities in public health. The unprecedented and devastating epidemic propelled vaccine candidates toward clinical trials that were initiated near the end of the active response to the outbreak. Those trials did not have a major impact on the epidemic but provided invaluable data on vaccine safety, immunogenicity, and, to a limited degree, even efficacy in humans. There are plenty of lessons to learn from these trials, some of which are addressed in this review. Better preparation is essential to executing an effective response to EBOV in the future; yet, the first indications of waning interest are already noticeable.
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Affiliation(s)
- Heinz Feldmann
- Laboratory of Virology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA;
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba 93E 0J9, Canada
| | - Friederike Feldmann
- Rocky Mountain Veterinary Branch, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA
| | - Andrea Marzi
- Laboratory of Virology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA;
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Tedder RS, Samuel D, Dicks S, Scott JT, Ijaz S, Smith CC, Adaken C, Cole C, Baker S, Edwards T, Kamara P, Kargbo O, Niazi S, Nwakanma D, d'Alessandro U, Burch G, Doughty H, Brown CS, Andrews N, Glynn JR, van Griensven J, Pollakis G, Paxton WA, Semple MG. Detection, characterization, and enrollment of donors of Ebola convalescent plasma in Sierra Leone. Transfusion 2018; 58:1289-1298. [PMID: 29572862 PMCID: PMC5947131 DOI: 10.1111/trf.14580] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/05/2018] [Accepted: 01/15/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Passive therapy with convalescent plasma provides an early opportunity to intervene in Ebola virus disease (EVD). Methods for field screening and selection of potential donors and quantifying plasma antibody are needed. STUDY DESIGN AND METHODS Recombinant Ebola virus glycoprotein (EBOV GP) was formatted into immunoglobulin G‐capture, competitive, and double‐antigen bridging enzyme immunoassays (EIAs). EVD survivors in Freetown, Sierra Leone, were recruited as potential plasma donors and assessed locally using sera alone and/or paired sera and oral fluids (ORFs). Uninfected controls comprised unexposed Gambians and communities in Western Area, Sierra Leone. Antibody neutralization in selected sera was measured retrospectively in a pseudotype virus assay. RESULTS A total of 115 potential donors were considered for enrollment: 110 plasma samples were concordantly reactive in the three EIAs; three were concordantly unreactive and two were reactive in two of three EIAs (98.2% agreement; 95% confidence interval [CI], 93.9%‐99.8%). In 88 donors with paired ORF and plasma, G‐capture EIA reactivity correlated well in the two analytes (R2 = 0.795). Plasma and ORF from 44 Gambians were unreactive. ORF samples from 338 of 339 unexposed Western Area community controls were unreactive (specificity, 99.7%; 95% CI, 98.4%‐99.7%); ORF samples from 113 of 116 Kerry Town EVD survivors were reactive (sensitivity, 97.4%; 95% CI, 92.5%‐99.5%). Strong reactivity in G‐capture and/or competitive EIAs identified donors with high plasma EBOV GP antibody levels in the double‐antigen bridging assay, correlating with high levels of neutralizing antibody. CONCLUSIONS In‐field testing can qualify convalescent donors for providing high‐titer antibody.
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Affiliation(s)
- Richard S Tedder
- Blood Borne Virus Unit.,Transfusion Microbiology, National Health Service Blood and Transplant.,Division of Infection and Immunity, University College London, London, UK
| | - Dhan Samuel
- Serology Development Unit, Virus Reference Department, National Infection Service, Public Health England
| | - Steve Dicks
- Blood Borne Virus Unit.,Transfusion Microbiology, National Health Service Blood and Transplant
| | | | | | - Catherine C Smith
- Travel Medicine and International Health Team, Health Protection Scotland, Glasgow, UK
| | - Charlene Adaken
- Institute of Infection and Global Health, National Institute for Health Research (NIHR) Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK
| | | | - Samuel Baker
- National Safe Blood Service, Connaught Hospital, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Tansy Edwards
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine
| | - Philip Kamara
- National Safe Blood Service, Connaught Hospital, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Osman Kargbo
- National Safe Blood Service, Connaught Hospital, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | | | - Umberto d'Alessandro
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.,Medical Research Council, Fajara, Banjul, The Gambia
| | - Graham Burch
- DiaSorin S.p.A, Biotechnology Manufacturing, Dartford, UK
| | - Heidi Doughty
- National Health Service Blood and Transplant.,College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Colin S Brown
- King's Sierra Leone Partnership, King's Centre for Global Health, King's Health Partners and King's College London.,Reference Microbiology, National Infection Service
| | - Nick Andrews
- Statistics, Modelling and Economics Department, Public Health England, London, UK
| | - Judith R Glynn
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine
| | - Johan van Griensven
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | | | - Georgios Pollakis
- Institute of Infection and Global Health, National Institute for Health Research (NIHR) Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK
| | - William A Paxton
- Institute of Infection and Global Health, National Institute for Health Research (NIHR) Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK
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Asymptomatic infection and unrecognised Ebola virus disease in Ebola-affected households in Sierra Leone: a cross-sectional study using a new non-invasive assay for antibodies to Ebola virus. THE LANCET. INFECTIOUS DISEASES 2017; 17:645-653. [PMID: 28256310 PMCID: PMC6520246 DOI: 10.1016/s1473-3099(17)30111-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/08/2016] [Accepted: 01/16/2017] [Indexed: 01/19/2023]
Abstract
BACKGROUND The frequency of asymptomatic infection with Ebola virus is unclear: previous estimates vary and there is no standard test. Asymptomatic infection with Ebola virus could contribute to population immunity, reducing spread. If people with asymptomatic infection are infectious it could explain re-emergences of Ebola virus disease (EVD) without known contact. METHODS We validated a new oral fluid anti-glycoprotein IgG capture assay among survivors from Kerry Town Ebola Treatment Centre and controls from communities unaffected by EVD in Sierra Leone. We then assessed the seroprevalence of antibodies to Ebola virus in a cross-sectional study of household contacts of the survivors. All household members were interviewed. Two reactive tests were required for a positive result, with a third test to resolve any discrepancies. FINDINGS The assay had a specificity of 100% (95% CI 98·9-100; 339 of 339 controls tested negative) and sensitivity of 95·9% (89·8-98·9; 93 of 97 PCR-confirmed survivors tested positive). Of household contacts not diagnosed with EVD, 47·6% (229 of 481) had high level exposure (direct contact with a corpse, body fluids, or a case with diarrhoea, vomiting, or bleeding). Among the contacts, 12·0% (95% CI 6·1-20·4; 11 of 92) with symptoms at the time other household members had EVD, and 2·6% (1·2-4·7; 10 of 388) with no symptoms tested positive. Among asymptomatic contacts, seropositivity was weakly correlated with exposure level. INTERPRETATION This new highly specific and sensitive assay showed asymptomatic infection with Ebola virus was uncommon despite high exposure. The low prevalence suggests asymptomatic infection contributes little to herd immunity in Ebola, and even if infectious, would account for few transmissions. FUNDING Wellcome Trust ERAES Programme, Save the Children.
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Houlihan CF, McGowan CR, Dicks S, Baguelin M, Moore DAJ, Mabey D, Roberts CH, Kumar A, Samuel D, Tedder R, Glynn JR. Ebola exposure, illness experience, and Ebola antibody prevalence in international responders to the West African Ebola epidemic 2014-2016: A cross-sectional study. PLoS Med 2017; 14:e1002300. [PMID: 28510604 PMCID: PMC5433702 DOI: 10.1371/journal.pmed.1002300] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 04/04/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Healthcare and other front-line workers are at particular risk of infection with Ebola virus (EBOV). Despite the large-scale deployment of international responders, few cases of Ebola virus disease have been diagnosed in this group. Since asymptomatic or pauci-symptomatic infection has been described, it is plausible that infections have occurred in healthcare workers but have escaped being diagnosed. We aimed to assess the prevalence of asymptomatic or pauci-symptomatic infection, and of exposure events, among returned responders to the West African Ebola epidemic 2014-2016. METHODS AND FINDINGS We used snowball sampling to identify responders who had returned to the UK or Ireland, and used an online consent and questionnaire to determine their exposure to EBOV and their experience of illness. Oral fluid collection devices were sent and returned by post, and samples were tested using an EBOV IgG capture assay that detects IgG to Ebola glycoprotein. Blood was collected from returnees with reactive samples for further testing. Unexposed UK controls were also recruited. In all, 300 individuals consented, of whom 268 (89.3%) returned an oral fluid sample (OFS). The majority had worked in Sierra Leone in clinical, laboratory, research, and other roles. Fifty-three UK controls consented and provided samples using the same method. Of the returnees, 47 (17.5%) reported that they had had a possible EBOV exposure. Based on their free-text descriptions, using a published risk assessment method, we classified 43 (16%) as having had incidents with risk of Ebola transmission, including five intermediate-risk and one high-risk exposure. Of the returnees, 57 (21%) reported a febrile or diarrhoeal illness in West Africa or within 1 mo of return, of whom 40 (70%) were not tested at the time for EBOV infection. Of the 268 OFSs, 266 were unreactive. Two returnees, who did not experience an illness in West Africa or on return, had OFSs that were reactive on the EBOV IgG capture assay, with similar results on plasma. One individual had no further positive test results; the other had a positive result on a double-antigen bridging assay but not on a competitive assay or on an indirect EBOV IgG ELISA. All 53 controls had non-reactive OFSs. While the participants were not a random sample of returnees, the number participating was high. CONCLUSIONS This is the first study, to our knowledge, of the prevalence of EBOV infection in international responders. More than 99% had clear negative results. Sera from two individuals had discordant results on the different assays; both were negative on the competitive assay, suggesting that prior infection was unlikely. The finding that a significant proportion experienced "near miss" exposure events, and that most of those who experienced symptoms did not get tested for EBOV at the time, suggests a need to review and standardise protocols for the management of possible exposure to EBOV, and for the management of illness, across organisations that deploy staff to outbreaks.
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Affiliation(s)
- Catherine F. Houlihan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Faculty of Medical Sciences, University College London, London, United Kingdom
| | - Catherine R. McGowan
- Faculty of Public Health and Policy, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Humanitarian Public Health Technical Unit, Save the Children UK, London, United Kingdom
| | - Steve Dicks
- Transfusion Microbiology, National Health Service Blood and Transplant, London, United Kingdom
- NHSBT/PHE Blood Borne Virus Unit, Serology Development Unit, Public Health England, London, United Kingdom
| | - Marc Baguelin
- Centre of Infectious Disease Surveillance and Control, Public Health England, London, United Kingdom
- Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David A. J. Moore
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David Mabey
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chrissy h. Roberts
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Alex Kumar
- Department of Infection and Tropical Medicine, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom
| | - Dhan Samuel
- NHSBT/PHE Blood Borne Virus Unit, Serology Development Unit, Public Health England, London, United Kingdom
| | - Richard Tedder
- Transfusion Microbiology, National Health Service Blood and Transplant, London, United Kingdom
- NHSBT/PHE Blood Borne Virus Unit, Serology Development Unit, Public Health England, London, United Kingdom
| | - Judith R. Glynn
- Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Bower H, Glynn JR. A systematic review and meta-analysis of seroprevalence surveys of ebolavirus infection. Sci Data 2017; 4:160133. [PMID: 28140390 PMCID: PMC5283061 DOI: 10.1038/sdata.2016.133] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 12/15/2016] [Indexed: 01/06/2023] Open
Abstract
Asymptomatic ebolavirus infection could greatly influence transmission dynamics, but there is little consensus on how frequently it occurs or even if it exists. This paper summarises the available evidence on seroprevalence of Ebola, Sudan and Bundibugyo virus IgG in people without known ebolavirus disease. Through systematic review, we identified 51 studies with seroprevalence results in sera collected from 1961 to 2016. We tabulated findings by study population, contact, assay, antigen and positivity threshold used, and present seroprevalence point estimates and 95% confidence intervals. We classified sampled populations in three groups: those with household or known case-contact; those living in outbreak or epidemic areas but without reported case-contact; and those living in areas with no recorded cases of ebolavirus disease. We performed meta-analysis only in the known case-contact group since this is the only group with comparable exposures between studies. Eight contact studies fitted our inclusion criteria, giving an overall estimate of seroprevalence in contacts with no reported symptoms of 3.3% (95% CI 2.4-4.4, P<0.001), but with substantial heterogeneity.
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Affiliation(s)
- Hilary Bower
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Judith R. Glynn
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
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