Nucleoprotein-based indirect enzyme-linked immunosorbent assay (indirect ELISA) for detecting antibodies specific to Ebola virus and Marbug virus

Simultaneous Detection of Ebola Virus and Pathogens Associated With Hemorrhagic Fever by an Oligonucleotide Microarray

Ebola virus infection causes severe hemorrhagic fever, and its mortality rates varied from 25 to 90% in the previous outbreaks. The highly infectious and lethal nature of this virus highlights the need for reliable and sensitive diagnostic methods to distinguish it from other diseases present with similar clinical symptoms. Based on multiplex polymerase chain reaction (PCR) and oligonucleotide microarray technology, a cost-effective, multipathogen and high-throughput method was developed for simultaneous detection of Ebola virus and other pathogens associated with hemorrhagic fever, including Marburg virus, Lassa fever virus, Junin virus, Machupo virus, Rift Valley fever virus, Crimean-Congo hemorrhagic fever virus, malaria parasite, hantavirus, severe fever with thrombocytopenia syndrome virus, dengue virus, yellow fever virus, Chikungunya virus, influenza A virus, and influenza B virus. This assay had an excellent specificity for target pathogens, without overlap signal between the probes. The limit of detection was approximately 10³ pathogen copies/μl. A total of 60 positive nucleic acid samples for different pathogens were detected, a concordance of 100% was observed between microarray assay and real-time PCR analysis. Consequently, the described oligonucleotide microarray may be specific and sensitive assay for diagnosis and surveillance of infections caused by Ebola virus and other species of hemorrhagic fever pathogens.

Molecular and Immunological Diagnostic Techniques of Medical Viruses

Viral infections are causing serious problems in human population worldwide. The recent outbreak of coronavirus disease 2019 caused by SARS-CoV-2 is a perfect example how viral infection could pose a great threat to global public health and economic sectors. Therefore, the first step in combating viral pathogens is to get a timely and accurate diagnosis. Early and accurate detection of the viral presence in patient sample is crucial for appropriate treatment, control, and prevention of epidemics. Here, we summarize some of the molecular and immunological diagnostic approaches available for the detection of viral infections of humans. Molecular diagnostic techniques provide rapid viral detection in patient sample. They are also relatively inexpensive and highly sensitive and specific diagnostic methods. Immunological-based techniques have been extensively utilized for the detection and epidemiological studies of human viral infections. They can detect antiviral antibodies or viral antigens in clinical samples. There are several commercially available molecular and immunological diagnostic kits that facilitate the use of these methods in the majority of clinical laboratories worldwide. In developing countries including Ethiopia where most of viral infections are endemic, exposure to improved or new methods is highly limited as these methods are very costly to use and also require technical skills. Since researchers and clinicians in all corners of the globe are working hard, it is hoped that in the near future, they will develop good quality tests that can be accessible in low-income countries.

Evaluation of Diagnostic Performance of Three Indirect Enzyme-Linked Immunosorbent Assays for the Detection of IgG Antibodies to Ebola Virus in Human Sera

Filovirus serological diagnosis and epidemiological investigations are hampered due to the unavailability of validated immunoassays. Diagnostic performance of three indirect enzyme-linked immunosorbent assays (I-ELISA) was evaluated for the detection of IgG antibody to Ebola virus (EBOV) in human sera. One I-ELISA was based on a whole EBOV antigen (WAg) and two utilized recombinant nucleocapsid (NP) and glycoproteins (GP), respectively. Validation data sets derived from individual sera collected in South Africa (SA), representing an EBOV non-endemic country, and from sera collected during an Ebola disease (EBOD) outbreak in Sierra Leone (SL), were categorized according to the compounded results of the three I-ELISAs and real time reverse-transcription polymerase chain reaction (RT-PCR). At the cut-off values selected at 95% accuracy level by the two-graph receiver operating characteristic analysis, specificity in the SA EBOV negative serum panel (n = 273) ranged from 98.17% (GP ELISA) to 99.27% (WAg ELISA). Diagnostic specificity in the SL EBOV negative panel (n = 676) was 100% by the three ELISAs. The diagnostic sensitivity in 423 RT-PCR confirmed EBOD patients was dependent on the time when the serum was collected after onset of disease. It significantly increased 2 weeks post-onset, reaching 100% sensitivity by WAg and NP and 98.1% by GP I-ELISA.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.

Ebola virus - epidemiology, diagnosis, and control: threat to humans, lessons learnt, and preparedness plans - an update on its 40 year's journey

Ebola virus (EBOV) is an extremely contagious pathogen and causes lethal hemorrhagic fever disease in man and animals. The recently occurred Ebola virus disease (EVD) outbreaks in the West African countries have categorized it as an international health concern. For the virus maintenance and transmission, the non-human primates and reservoir hosts like fruit bats have played a vital role. For curbing the disease timely, we need effective therapeutics/prophylactics, however, in the absence of any approved vaccine, timely diagnosis and monitoring of EBOV remains of utmost importance. The technologically advanced vaccines like a viral-vectored vaccine, DNA vaccine and virus-like particles are underway for testing against EBOV. In the absence of any effective control measure, the adaptation of high standards of biosecurity measures, strict sanitary and hygienic practices, strengthening of surveillance and monitoring systems, imposing appropriate quarantine checks and vigilance on trade, transport, and movement of visitors from EVD endemic countries remains the answer of choice for tackling the EBOV spread. Herein, we converse with the current scenario of EBOV giving due emphasis on animal and veterinary perspectives along with advances in diagnosis and control strategies to be adopted, lessons learned from the recent outbreaks and the global preparedness plans. To retrieve the evolutionary information, we have analyzed a total of 56 genome sequences of various EBOV species submitted between 1976 and 2016 in public databases.

Development of a Sensitive and Specific Serological Assay Based on Luminex Technology for Detection of Antibodies to Zaire Ebola Virus

The recent Zaire Ebola virus (EBOV) outbreak in West Africa illustrates clearly the need for additional studies with humans and animals to elucidate the ecology of Ebola viruses (EBVs). In this study, we developed a serological assay based on the Luminex technology. Nine recombinant proteins representing different viral regions (nucleoprotein [NP], 40-kDa viral protein [VP40], and glycoprotein [GP]) from four of the five EBV lineages were used. Samples from 94 survivors of the EBOV outbreak in Guinea and negative samples from 108 patients in France were used to calculate test performance for EBOV detection and cross-reaction with other Ebola virus lineages. For EBOV antibody detection, sensitivities of 95.7%, 96.8%, and 92.5% and specificities of 94.4%, 95.4%, and 96.3% for NP, GP, and VP40, respectively, were observed. All EBOV-negative samples that presented a reaction, except for one, interacted with a single antigen, whereas almost all samples from EBOV survivors were simultaneously reactive with NP and GP (90/94) or with NP, GP, and VP40 (87/94). Considering as positive for past EBOV infection only samples that reacted with EBOV NP and GP, sensitivity was 95.7% and specificity increased to 99.1%. Comparing results with commercial EBOV NP and GP enzyme-linked immunosorbent assays (ELISAs; Alpha Diagnostic, San Antonio, TX), lower sensitivity (92.5%) and high specificity (100%) were observed with the same positivity criteria. Samples from EBOV survivors cross-reacted with GP from Sudan Ebola virus (GP-SUDV) (81.9%), GP from Bundibugyo Ebola virus (GP-BDBV) (51.1%), GP from Reston Ebola virus (GP-RESTV) (9.6%), VP40-SUDV (76.6%), and VP40-BDBV (38.3%). Overall, we developed a sensitive and specific high-throughput serological assay, and defined an algorithm, for epidemiological surveys with humans.

Laboratory diagnosis of Ebola virus disease and corresponding biosafety considerations in the China Ebola Treatment Center

Ebola virus disease (EVD), caused by Ebola virus (EBOV), is a potent acute infectious disease with a high case-fatality rate. Etiological and serological EBOV detection methods, including techniques that involve the detection of the viral genome, virus-specific antigens and anti-virus antibodies, are standard laboratory diagnostic tests that facilitate confirmation or exclusion of EBOV infection. In addition, routine blood tests, liver and kidney function tests, electrolytes and coagulation tests and other diagnostic examinations are important for the clinical diagnosis and treatment of EVD. Because of the viral load in body fluids and secretions from EVD patients, all body fluids are highly contagious. As a result, biosafety control measures during the collection, transport and testing of clinical specimens obtained from individuals scheduled to undergo EBOV infection testing (including suspected, probable and confirmed cases) are crucial. This report has been generated following extensive work experience in the China Ebola Treatment Center (ETC) in Liberia and incorporates important information pertaining to relevant diagnostic standards, clinical significance, operational procedures, safety controls and other issues related to laboratory testing of EVD. Relevant opinions and suggestions are presented in this report to provide contextual awareness associated with the development of standards and/or guidelines related to EVD laboratory testing.