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Background: Dengue virus (DENV) causes febrile illness that may be misdiagnosed with other infectious diseases. This may contribute to the possibility of missing out DENV infections. Recent reports show seroepidemiologic evidence of DENV infections in Ghana, but the frequency of infection and the geographic dissemination are unknown. Objectives: To examine the seroprevalence, the geographical pattern and the age distribution of DENV infections in Ghana. Design: A cross sectional epidemiological study with sera (N = 417) from all 10 regions in Ghana. The sera were obtained during the national surveillance of suspected outbreak of yellow fever (YF) in 2014. The Panbio Dengue IgG Indirect ELISA kit was used for the detection of IgG antibodies. Results: The seroprevalence of dengue IgG was 29.7% among the suspected YF patients in Ghana. Seroprevalence of DENV IgG increased with age. It was 10.4% in the 0-9 year olds, 26.1% in children and adolescents from 10-19 years, 43.1% in the group of 20-29 year old young adults and 57.0% in the age group ≥ 30 years. The seroprevalence ranged from 18.2% in the Western region to 57.9% in the Upper East. The Upper East and the Volta region had a significantly higher seroprevalence than the overall seroprevalence in Ghana (p = 0.0094). Conclusion: The study shows low to moderate levels of dengue virus infection in Ghana and demonstrates that infections occur in all age group and differ between regions. Awareness of DENV infection should be created in the country in cases of undifferentiated fever. [ABSTRACT FROM AUTHOR]

Background/objectives: The body's immune response to infections and vaccination leads to the formation of memory B cells (MBCs), which protect against future infections. MBCs circulate in the blood, and the strength of the MBC response is measured with different tests. In this study, tests to measure the MBC response were compared., Methods: An MBC enzyme-linked immunospot assay (MBC-ELISpot), which counts the antibody-releasing cells (MASCs) that arise from memory B cells in vitro, and two versions of an MBC enzyme-linked immunosorbent assay (MBC-ELISA), which measures the concentration of antibodies released by the MASCs, were compared. The lower measurement limit of MBC-ELISpot and ELISA was determined, and it was investigated how the measurement results of individual samples and in a sample of test persons correlate., Results: Both methods had similar lower limits of detection, and the antibody concentration correlated strongly with the number of MASCs in individual samples. The antibody concentrations measured on a sample correlated with Pearson correlation coefficients of R = 0.83-0.87 with the number of MASCs, and the proportion of antigen-specific antibodies in total IgG correlated with R = 0.74-0.82 with the proportion of antigen-specific MASCs in all antibody-secreting cells., Conclusions: Since the measurement sensitivity of MBC-ELISA and MBC-ELISpot is similar and the measurement results correlate strongly in a random sample, the tests are interchangeable. The MBC-ELISA has an advantage over the ELISpot in that the antibody measurements can be divided up over time, repeated, and extended. This creates new possibilities for measuring the MBC response.

Little is known about the frequency of Zika virus (ZIKV) infections in Sudan. The aim of this study was to obtain data on the prevalence of ZIKV infections and the immunity of the population in the country. To this end, 198 sera obtained between December 2012 and January 2013 in different regions in Sudan were examined for neutralizing antibodies against ZIKV, dengue virus (DENV), and yellow fever virus (YFV). The sera were non-randomly selected. The neutralization titers were compared with each other and with the WHO 1st International Standard for anti-Asian lineage Zika virus antibody. Twenty-six sera neutralized ZIKV. One-third of these sera had higher neutralization titers against ZIKV than against DENV-2 and -3. Two sera showed higher neutralization titers than the WHO standard for ZIKV antibodies. These data suggest occasional ZIKV infections in Sudan. The low percentage of sera in this cohort that neutralized ZIKV indicates that, in the study period, the population was susceptible to ZIKV infection.

Serological assays for SARS-CoV-2 play a pivotal role in the definition of whether patients are infected, the understanding of viral epidemiology, the screening of convalescent sera for therapeutic and prophylactic purposes, and in obtaining a better understanding of the immune response towards the virus. The aim of this study was to investigate the performance of a bead-based multiplex assay. This assay allowed for the simultaneous testing of IgG antibodies against SARS-CoV-2 spike, S1, S2, RBD, and nucleocapsid moieties and S1 of seasonal coronaviruses hCoV-22E, hCoV-HKU1, hCoV-NL63, and hCoV-OC43, as well as MERS and SARS-CoV. We compared the bead-based multiplex assay with commercial ELISA tests. We tested the sera of 27 SARS-CoV-2 PCR-positive individuals who were previously tested with different ELISA assays. Additionally, we investigated the reproducibility of the results by means of multiple testing of the same sera. Finally, the results were correlated with neutralising assays. In summary, the concordance of the qualitative results ranged between 78% and 96% depending on the ELISA assay and the specific antigen. Repeated freezing-thawing cycles resulted in reduced mean fluorescence intensity, while the storage period had no influence in this respect. In our test cohort, we detected up to 36% of sera positive for the development of neutralising antibodies, which is in concordance with the bead-based multiplex and IgG ELISA.

Background: Vaccination against SARS-CoV-2 is recommended for cancer patients. However, long-term data on the effectiveness in the pediatric setting are lacking., Methods: Pediatric patients < 18 years on active treatment for cancer and without prior SARS-CoV-2 infection received three doses of an mRNA vaccine. The clinical course and humoral and cellular immunity were evaluated at the end of the follow-up period of ≥ 1 year after the third dose of vaccine., Results: SARS-CoV-2 infection occurred in 17 of 19 analyzed patients (median age 16.5 years) during the follow-up period (median 17 months), but no severe symptoms were seen. At ≥ 1 year after the last SARS-CoV-2 antigen exposure, 4 of 17 patients had received the recommended booster vaccine. At the end of the follow-up period, all evaluable 15 patients had anti-SARS-CoV-2 receptor-binding domain IgG antibodies. Twelve of the 15 patients had neutralizing antibody titers ≥ 1:10 against the Delta variant and 12/15 and 13/15 against the BA.1 and BA.5 variants, respectively. Specific T cells against SARS-CoV-2 antigens were seen in 9/13 patients., Conclusions: Most SARS-CoV-2-vaccinated pediatric cancer patients had SARS-CoV-2 infections and limited interest in booster vaccination. At 1 year after the last antigen exposure, which was mostly an infection, humoral immune responses remained strong., Trial Registration: German Clinical Trials Register DRKS00025254, May 26, 2021., (© 2024. The Author(s).)

Background: The Abbott SARS-CoV-2 IgG Quant II assay and the Roche Elecsys double antigen sandwich (DAgS) immunoassay measure SARS-CoV-2 receptor binding domain (RBD)-specific antibodies in serum samples in different ways. The IgG Quant II assay uses an antigen in combination with a secondary antibody and the DAgS assay uses two antigens. The aim of the study was to investigate whether the assays give comparable results with monoclonal antibodies., Material and Methods: The immunoassays were tested with the RBD-specific human monoclonal antibodies (mAbs) casirivimab. imdevimab, CR3022, etesevimab and sotrovimab. The mAbs were tested at various concentrations in µg/ml, alone or in combination and the relative light units (RLU) and binding antibody units (BAU)/ml were determined., Results: With 1 µg/ml of casirivimab, imdevimab, CR3022 and etesevimab the Abbott IgG II Quant assay yielded between 65 and 158 BAU/ml and the Elecsys assay < 0.4 - 7.1 BAU/ml. In the DAgS assay, the addition of a second and a third mAb increased the BAU/ml values synergistically. With increasing concentrations of the mAb combinations in µg/ml the Abbott IgG Quant II assay showed proportionate and the Elecsys DAgS assay disproportionate increases in BAU/ml. With 1 µg/ml sotrovimab the Abbott assay gave 39 and the Elecsys assay 136 BAU/ml. The DAgS assay showed a high dose hook effect in the µg/ml range., Conclusions: The secondary antibody-based and the DAgS-based SARS CoV-2 antibody assays gave very different results with 4 of 5 mAbs. This suggests that the two assays measure different binding characteristics. The ability of antibodies to cross-link multiple antigen-antibody complexes may contribute to the measurement signal in the DAgS assay., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Our study in 21 pediatric cancer patients demonstrates that 3 doses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA vaccine (BioNTech/Pfizer) elicited both humoral and cellular immunity in most patients during chemotherapy. Immunity was stronger in children with solid tumors and during maintenance therapy compared to those with hematological malignancies or during intensive chemotherapy. Clinical Trials Registration.ȃGerman Registry for Clinical Trials (DRKS00025254)., Competing Interests: Potential conflicts of interest. T. L. received consulting fees and honoraria from Pfizer. S. C. received consulting fees and honorarium from BioNTech for serving on an advisory board. C. J. reports payment for expert testimony from Landschaftsverband Rheinland, Department for Social Decompensation and Institut für Medizinische und Pharmazeutische Prüfungsfragen. J. H. K. reports grants or contracts unrelated to this work from Deutsche Forschungsgemeinschaft (KL2374/3-1, KL2374/5-1), European Research Council for the European Union’s Horizon 2020 research and innovation program (grant agreement number 714226), St Baldrick’s Robert Arceci Innovations Award (551589), and the German Federal Ministry of Education and Research (01GM1911D myPred); consulting fees from Bluebird Bio, Novartis, Roche, and Jazz Pharmaceuticals; and participation on a data safety and monitoring board or advisory board for Bluebird Bio, Novartis, Roche, and Jazz Pharmaceuticals. S. Ho. reports speaker’s fees from Streamedup GmbH and Sanofi Genzyme and receipt of materials and reagents for other study from Roche Diagnostics. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Dengue virus (DENV) antibody assays frequently cross-react with sera from individuals who have been infected with or vaccinated against related flaviviruses. The goal of this study was to determine the specificity of two DENV ELISAs with sera from individuals vaccinated against yellow fever virus (YFV) and Japanese encephalitis virus (JEV). The Panbio and the Novatec Dengue IgG ELISAs were tested with sera obtained 3-4 weeks or 0.5-6 years after YFV or JEV vaccination and the diagnostic specificity of the assays was determined. As controls, the sera were tested using DENV, YFV, JEV, Zika and West Nile virus neutralization assays. The diagnostic specificity of the Panbio and the Novatec ELISA with sera from YFV-vaccinated subjects was 98.2% and 88.2%, respectively. Cross-reactions were rare in the first 4 weeks despite high YFV-neutralizing antibody titers and were mostly found later. The specificity of the Panbio and Novatec assays with sera from JEV-vaccinated individuals was 100% and 92.9%. Cross-reactions occurred in the early time period after vaccination. The measurement values of the two ELISAs correlated strongly. Thus, the Panbio ELISA showed higher diagnostic specificity and may be suitable for seroprevalence studies in areas with high disease prevalence.

Background: The concentration of antibodies against the SARS-CoV-2 spike protein is frequently being measured for clinical and epidemiological purposes. The aim of this study was to examine whether the results of different quantitative SARS-CoV-2 spike antibody assays are comparable., Material and Methods: The Siemens SARS-CoV-2 IgG, Abbott SARS-CoV-2 IgG II Quant, Roche ElecsysT Anti-SARS-CoV-2 S, and Euroimmun Anti-SARS-CoV-2-QuantiVac assay were compared with 110 sera from patients 6-9 months after SARS-CoV-2 infection and the WHO First International SARS-CoV-2 antibody standard 20/136. The antibody values were converted into WHO binding antibody units (BAU)/ml. The diagnostic sensitivity of the assays was determined and the antibody values were compared., Results: The diagnostic sensitivity ranged from 57.3% (Euroimmun) to 100% (Roche). The antibody concentration values of different assays correlated with Pearson coefficients of correlation between 0.729 and 0.953. The geometric mean antibody values of the Abbott, Siemens and Euroimmun assay varied by a factor of 1.1-1.2. The geometric mean antibody values of the Roche assay were 2.4-2.8 times higher than those from the other assays. The assays yielded varying results with the WHO International antibody standard., Conclusions: The quantitative SARS-CoV-2 antibody assays from Abbott, Siemens, Roche and Euroimmun correlate strongly but differ in the antibody concentrations. Therefore, the same assay should be used when testing patients repeatedly. In addition, the name of the assay used and the manufacturer should be indicated along with the test results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Background: The possibility of repeat infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) raises questions regarding quality and longevity of the virus-induced immune response., Methods: The antibody course and memory B-cell (MBC) response against SARS-CoV-2 proteins, influenza virus nucleoprotein (NP), and tetanus toxin were examined in adults with mild to moderate SARS-CoV-2 infection in the first year after infection., Results: The concentration of SARS-CoV-2 receptor binding domain (RBD)-specific antibodies was low compared with the concentration of influenza virus NP-specific antibodies. The SARS-CoV-2 RBD antibody half-life increased from 95 days in the first 6 months to 781 days after 9-12 months. The SARS-CoV-2 NP antibody half-life increased from 88 to 248 days. Two thirds of the subjects had SARS-CoV-2-specific MBC responses 12 months after infection. The SARS-CoV-2 antibody levels correlated with the MBC frequency at 12 months., Conclusions: The low concentration of SARS-CoV-2 spike protein antibodies indicates that re-exposure to the virus or vaccination are required to use the B-cell immunity to full capacity. The existence of a robust SARS-CoV-2 MBC response at 12 months in most subjects and the substantially increasing antibody half-life provide evidence that the immune response is developing into long-term immunity. The early antibody reaction and the ensuing MBC response are interdependent., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Objectives: In regions with co-existing flaviviruses, the diagnosis of previous West Nile virus (WNV) infections is challenging due to cross-reacting antibodies. The aim of the study was to determine the frequency of previous WNV infections in sera from three Sudanese states by excluding potentially dengue virus (DENV) and ZIKV cross-reacting sera and to determine the percentage of WNV cross-neutralizing sera from individuals with previous DENV infection. Methods: Serum samples from Kassala, North Kordofan, and Red Sea state were screened for antibodies against DENV by ELISA. Sera without DENV antibodies ( N  = 106) and a matched set of sera with DENV antibodies ( N  = 108) was selected. In all blood samples the frequency of WNV-neutralizing antibodies and the antibody titers were measured with microplate neutralization assays. DENV and Zika virus (ZIKV) microplate neutralization assays were performed with all WNV neutralizing sera of the DENV negative group. Results: A fraction of 30.2% of the DENV antibody negative sera neutralized WNV. The seroprevalence increased with age from 9.5% to 41.7%. Men and women were equally affected. The percentage of DENV positive sera that neutralized WNV was 83.3%. DENV positive sera had higher WNV neutralization titers than DENV negative sera. Conclusions: A significant fraction of the DENV antibody negative sera from three regions in Sudan showed serologic evidence of previous WNV infection. In comparison, the large majority of DENV antibody positive sera had WNV neutralizing antibodies. Studies are needed to identify clinical cases of WNV infection and to determine whether individuals with cross-neutralizing antibodies are protected from WNV disease.

Introduction: Many people living with HIV/AIDS (PLHIV) in Uganda widely use herbal medicines. However, their toxicity and safety have not been investigated. The use of these plants can potentially cause harmful effects to the health of patients. The purpose of this study was to determine the cytotoxicity of some commonly used medicinal plant species used by PLHIV. Methods: The cytotoxicity of the plant extracts was determined with the AlamarBlue cell viability assay using the human glioblastoma cell line U87.CD4.CXCR4. The cells were treated with varying concentrations of extracts of Warburgia ugandensis , Erythrina abyssinica , Cryptolepis sanguinolenta , Albizia coriaria , Psorospermum febrifugium , Gymnosporia senegalensis , Zanthoxylum chalybeum , Securidaca longipendunculata , Vachellia hockii , Gardenia ternifolia , and Bridelia micrantha reconstituted with ethanol and dimethyl sulfoxide (DMSO). Using regression analysis, the half maximal cytotoxic concentration (CC 50 ) of the plant extracts were calculated from exponential curve fits, since they provided the highest coefficient of determination, R 2 . Results: The ethanol extracts of W. ugandensis (CC 50 = 7.6 μg/ml) and A. coriaria (CC 50 = 1.5 μg/ml) as well as the DMSO-reconstituted extracts of W. ugandensis (CC 50 = 6.4 μg/ml) and A. coriria (CC 50 = < 4 μg/ml) were highly cytotoxic. The cytotoxicity of W. ugandensis and A. coriaria compared well with the indigenous traditional knowledge of the toxic effects experienced when the plants were not used correctly. However, the cytotoxicity of most of the plant extracts (15/22) was low to moderate (CC 50 = 21-200 μg/ml). Conclusion: Most of the plant species tested in this study had low to moderate cytotoxicity against U87.CD4.CXCR4 cells, except W. ugandensis and A. coriria which were highly cytotoxic., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Anywar, Kakudidi, Oryem-Origa, Schubert and Jassoy.)

SARS CoV-2 antibody assays measure antibodies against the viral nucleoprotein (NP) or spike protein. The study examined if testing of antibodies against both antigens increases the diagnostic sensitivity. Sera (N=98) from infected individuals were tested with ELISAs based on the NP, receptor-binding domain (RBD), or both proteins. The AUROCs were 0.958 (NP), 0.991 (RBD), and 0.992 (NP/RBD). The RBD- and NP/RBD-based ELISAs showed better performance than the NP-based assay. Simultaneous testing for antibodies against NP and RBD increased the number of true and false positives. If maximum diagnostic sensitivity is required, the NP/RBD-based ELISA is preferable. Otherwise, the RBD-based ELISA is sufficient., (© 2021. The Author(s).)

Arbovirus infections are widespread, and their disease burden has increased in the past decade. In Africa, arbovirus infections and fever with unknown etiology are common. Due to the lack of well-established epidemiologic surveillance systems and accurate differential diagnosis in most African countries, little is known about the prevalence of human arbovirus infections in Africa. The aim of this review is to summarize the available epidemiological data and diagnostic laboratory tools of infections with dengue, yellow fever, Zika, and chikungunya viruses, all transmitted by Aedes mosquitoes. Studies indicate that these arboviral infections are endemic in most of Africa. Surveillance of the incidence and prevalence of the infections would enable medical doctors to improve the diagnostic accuracy in patients with typical symptoms. If possible, arboviral diagnostic tests should be added to the routine healthcare systems. Healthcare providers should be informed about the prevalent arboviral diseases to identify possible cases.

SARS-CoV-2-specific IgM antibodies wane during the first three months after infection and IgG antibody levels decline. This may limit the ability of antibody tests to identify previous SARS-CoV-2 infection at later time points. To examine if the diagnostic sensitivity of antibody tests falls off, we compared the sensitivity of two nucleoprotein-based antibody tests, the Roche Elecsis II Anti-SARS-CoV-2 and the Abbott SARS-CoV-2 IgG assay and three glycoprotein-based tests, the Abbott SARS-CoV-2 IgG II Quant, Siemens Atellica IM COV2T and Euroimmun SARS-CoV-2 assay with 53 sera obtained 6 months after SARS-CoV-2 infection. The sensitivity of the Roche, Abbott SARS-CoV-2 IgG II Quant and Siemens antibody assays was 94.3% (95% confidence interval (CI) 84.3-98.8%), 98.1 % (95% CI: 89.9-100%) and 100 % (95% CI: 93.3-100%). The sensitivity of the N-based Abbott SARS-CoV-2 IgG and the glycoprotein-based Euroimmun ELISA was 45.3 % (95% CI: 31.6-59.6%) and 83.3% (95% CI: 70.2-91.9%). The nucleoprotein-based Roche and the glycoprotein-based Abbott receptor binding domain (RBD) and Siemens tests were more sensitive than the N-based Abbott and the Euroimmun antibody tests ( p  = 0.0001 to p  = 0.039). The N-based Abbott antibody test was less sensitive 6 months than 4-10 weeks after SARS-CoV-2 infection ( p  = 0.0001). The findings show that most SARS-CoV-2 antibody assays correctly identified previous infection 6 months after infection. The sensitivity of pan-Ig antibody tests was not reduced at 6 months when IgM antibodies have usually disappeared. However, one of the nucleoprotein-based antibody tests significantly lost diagnostic sensitivity over time., Competing Interests: The authors declare that there are no conflicts of interests., (© 2021 The Author(s).)

The emergence of the severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) has been followed by the rapid development of antibody tests. To assess the utility of the tests for clinical use and seroepidemiologic studies, we examined the sensitivity of commercial antibody tests from Roche, Abbott, Novatec, Virotech Siemens, Euroimmun, and Mediagnost in a prospective diagnostic study. The tests were evaluated with 73 sera from SARS CoV-2 RNA positive individuals with mild to moderate disease or asymptomatic infection. Sera were obtained at 2-3 weeks (N = 25) or > 4 weeks (N = 48) after symptom onset and viral RNA test. The overall sensitivity of the tests ranged from 64.4-93.2%. The most sensitive assays recognized 95.8-100 % of the sera obtained after 4 weeks or later. Sera drawn at 2-3 weeks were recognized with lower sensitivity indicating that the optimal time point for serologic testing is later than 3 weeks after onset of the disease. Nucleoprotein- and glycoproteinbased assays had similar sensitivity indicating that tests with both antigens are suitable for serological diagnostics. Breakdown of the test results showed that nucleoprotein- and glycoprotein-based tests of comparable sensitivity reacted with different sets of sera. The observation indicates that a combination of nucleoprotein- and glycoprotein-based tests would increase the percentage of positive results., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: COVID-19 Ag Respi-Strip, an immunochromatographic (ICT) assay for the rapid detection of SARS-CoV-2 antigen on nasopharyngeal specimen, has been developed to identify positive COVID-19 patients allowing prompt clinical and quarantine decisions. In this original research article, we describe the conception, the analytical and clinical performances as well as the risk management of implementing the COVID-19 Ag Respi-Strip in a diagnostic decision algorithm. Materials and Methods: Development of the COVID-19 Ag Respi-Strip resulted in a ready-to-use ICT assay based on a membrane technology with colloidal gold nanoparticles using monoclonal antibodies directed against the SARS-CoV and SARS-CoV-2 highly conserved nucleoprotein antigen. Four hundred observations were recorded for the analytical performance study and thirty tests were analyzed for the cross-reactivity study. The clinical performance study was performed in a retrospective multi-centric evaluation on aliquots of 328 nasopharyngeal samples. COVID-19 Ag Respi-Strip results were compared with qRT-PCR as golden standard for COVID-19 diagnostics. Results: In the analytical performance study, the reproducibility showed a between-observer disagreement of 1.7%, a robustness of 98%, an overall satisfying user friendliness and no cross-reactivity with other virus-infected nasopharyngeal samples. In the clinical performance study performed in three different clinical laboratories during the ascendant phase of the epidemiological curve, we found an overall sensitivity and specificity of 57.6 and 99.5%, respectively with an accuracy of 82.6%. The cut-off of the ICT was found at CT <22. User-friendliness analysis and risk management assessment through Ishikawa diagram demonstrate that COVID-19 Ag Respi-Strip may be implemented in clinical laboratories according to biosafety recommendations. Conclusion: The COVID-19 Ag Respi-Strip represents a promising rapid SARS-CoV-2 antigen assay for the first-line diagnosis of COVID-19 in 15 min at the peak of the pandemic. Its role in the proposed diagnostic algorithm is complementary to the currently-used molecular techniques., (Copyright © 2020 Mertens, De Vos, Martiny, Jassoy, Mirazimi, Cuypers, Van den Wijngaert, Monteil, Melin, Stoffels, Yin, Mileto, Delaunoy, Magein, Lagrou, Bouzet, Serrano, Wautier, Leclipteux, Van Ranst, Vandenberg and LHUB-ULB SARS-CoV-2 working diagnostic group.)

Education of medical students requires teaching students how to navigate in the broad field of medical research. The objective of this article is to provide an overview about medical research and to show how to denote a medical study in a concise fashion. Medical research can be classified into categories according to the object of investigation. Examples for medical research categories are therapeutic, diagnostic and prognostic studies, epidemiological studies, animal and in vitro studies etc. Each research category uses a specific set of study types with names such as cross-sectional study, case-control study etc. The article describes the principles of the study types. Together, research category and study type briefly describe the design of a medical study., Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Dengue IgG testing is being recommended before dengue vaccination. Presently, the diagnostic method of choice is the dengue IgG ELISA., Objective: Determine the test performance and concordance of two commercial dengue IgG ELISA kits., Study Design: A diagnostic study to examine the sensitivity, specificity, accuracy and concordance of the Panbio Dengue Indirect IgG ELISA kit and the NovaLisa Dengue IgG ELISA kit. Sera (483) were from dengue-endemic regions in Sudan. Test performance characteristics were determined when tests were performed as indicated in the test kits and when the Panbio calibrator sample was used for both tests., Results: The sensitivity of the Panbio and the NovaLisa ELISA was 91.1% and 99.0% and the specificity was 79.4% and 50.9%. The Panbio test was slightly more accurate (87.5% compared with 84.0%). Quantitative measurement readings of the tests correlated. The calibrator samples gave different cutoff values. Replacing the NovaLisa cutoff sample with the Panbio calibrator sample raised the accuracy of the NovaLisa assay to 88% and increased the concordance of the tests from 82.8 to 93%., Conclusions: The study shows that the two dengue IgG ELISAs differed clearly in sensitivity and specificity and gave discordant results for 17.2% of the sera. For the most part the discrepancy depended on the calibrator sample. The findings indicate that an optimized dengue IgG calibrator standard can enhance accuracy and concordance of commercial dengue ELISAs. An optimized standard calibrator would make dengue IgG seroprevalence testing more reliable., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease that can evolve into deadly hemorrhagic fever and that is endemic in many parts of Europe, Middle East, Central Asia, and Africa. Because of several reports about CCHF outbreaks in the south of Sudan during the last years, we examined in this study if unrecognized CCHF-V infections also occurred in the eastern and central parts of the country. The study examined the seroprevalence of CCHF virus infection in 464 sera from three regions of Sudan without previous reports of CCHF infection. The total CCHF virus seroprevalence was 2.6% (12 sera). The percentage was significantly elevated (7.5%) in sera from Khashm el Girba in eastern Sudan. The population in this area should be educated about the risk of disease transmission and how to avoid the infection. Health-care providers should be informed about the disease to identify possible cases and to prevent nosocomial transmission.

Background: The flaviviridae family comprises single-stranded RNA viruses that enter cells via clathrin-mediated pH-dependent endocytosis. Although the initial events of the virus entry have been already identified, data regarding intracellular virus trafficking and delivery to the replication site are limited. The purpose of this study was to map the transport route of Zika virus and to identify the fusion site within the endosomal compartment., Methods: Tracking of viral particles in the cell was carried out with confocal microscopy. Immunostaining of two structural proteins of Zika virus enabled precise mapping of the route of the ribonucleocapsid and the envelope and, consequently, mapping the fusion site in the endosomal compartment. The results were verified using RNAi silencing and chemical inhibitors., Results: After endocytic internalization, Zika virus is trafficked through the endosomal compartment to fuse in late endosomes. Inhibition of endosome acidification using bafilomycin A1 hampers the infection, as the fusion is inhibited; instead, the virus is transported to late compartments where it undergoes proteolytic degradation. The degradation products are ejected from the cell via slow recycling vesicles. Surprisingly, NH 4 Cl, which is also believed to block endosome acidification, shows a very different mode of action. In the presence of this basic compound, the endocytic hub is reprogrammed. Zika virus-containing vesicles never reach the late stage, but are rapidly trafficked to the plasma membrane via a fast recycling pathway after the clathrin-mediated endocytosis. Further, we also noted that, similarly as other members of the flaviviridae family, Zika virus undergoes furin- or furin-like-dependent activation during late steps of infection, while serine or cysteine proteases are not required for Zika virus maturation or entry., Conclusions: Zika virus fusion occurs in late endosomes and is pH-dependent. These results broaden our understanding of Zika virus intracellular trafficking and may in future allow for development of novel treatment strategies. Further, we identified a novel mode of action for agents commonly used in studies of virus entry. Schematic representation of differences in ZIKV trafficking in the presence of Baf A1 and NH 4 Cl.

Objectives: To determine the seroprevalence of dengue in central and eastern Sudan and the breadth of neutralising antibody responses., Methods: Blood was drawn from 483 patients with fever who visited outpatient clinics in Port Sudan, Red Sea state, in three towns in Kassala state and in El Obeid, North Kordofan, in December 2012 and January 2013. Sera were tested for dengue virus IgG and IgM by ELISA (Panbio) and sera without serologic evidence of acute infection (IgM negative) were used for the analysis of the seroprevalence. DENV neutralisation tests were performed to determine the specificity of the ELISA and to examine the degree of cross-neutralisation of multiple DENV serotypes., Results: Sixty-seven per cent (302 of 448) of the sera were dengue virus IgG-positive. The seroprevalence in Port Sudan was 89% (106 of 119 sera), in Kassala 61% (128 of 209) and in North Kordofan 56.7% (68 of 120). Thirty-one of 32 ELISA-positive sera neutralised dengue viruses indicating that the ELISA was highly specific. The majority of the sera broadly neutralised all four dengue virus serotypes indicating multiple infections., Conclusions: The majority of the population in central and eastern Sudan has been infected with dengue viruses, many people repeatedly. The high seroprevalence underscores the need for extended dengue surveillance in Sudan, broad disease awareness in medical institutions and in the population and diagnostic capacity building for severe dengue infections., (© 2018 John Wiley & Sons Ltd.)

Outbreaks of infections with chikungunya virus (CHIKV) have previously been reported from Sudan but the prevalence in the general population is unknown. We investigated the seroprevalence of CHIKV infection in 379 serum samples from patients with fever in the outpatient clinics of three hospitals in eastern and central Sudan. The seroprevalence was 1.8%, indicating that CHIKV infections are rare in these parts of Sudan. As the vector Aedes aegypti is endemic in this area, the population is at risk for a CHIKV epidemic.

The diversity of virus-specific antibodies and of B cells among different individuals is unknown. Using single-cell cloning of antibody genes, we generated recombinant human monoclonal antibodies from influenza nucleoprotein-specific memory B cells in four adult humans with and without preceding influenza vaccination. We examined the diversity of the antibody repertoires and found that NP-specific B cells used numerous immunoglobulin genes. The heavy chains (HCs) originated from 26 and the kappa light chains (LCs) from 19 different germ line genes. Matching HC and LC chains gave rise to 43 genetically distinct antibodies that bound influenza NP. The median lengths of the CDR3 of the HC, kappa and lambda LC were 14, 9 and 11 amino acids, respectively. We identified changes at 13.6% of the amino acid positions in the V gene of the antibody heavy chain, at 8.4% in the kappa and at 10.6 % in the lambda V gene. We identified somatic insertions or deletions in 8.1% of the variable genes. We also found several small groups of clonal relatives that were highly diversified. Our findings demonstrate broadly diverse memory B cell repertoires for the influenza nucleoprotein. We found extensive variation within individuals with a high number of point mutations, insertions, and deletions, and extensive clonal diversification. Thus, structurally conserved proteins can elicit broadly diverse and highly mutated B-cell responses.