The 2014 Ebola outbreak, the largest recorded, took us largely unprepared, with no available vaccine or specific treatment. In this context, the World Health Organization (WHO) declared that the humanitarian use of experimental therapies against Ebola Virus (EBOV) is ethical. In particular, an experimental treatment consisting of a cocktail of three monoclonal antibodies (mAbs) produced in tobacco plants and specifically directed to the Ebola virus glycoprotein (GP) was tested in humans, apparently with good results. Several mAbs with high affinity to the GP have been described. This review discusses our current knowledge on this topic. Particular emphasis is devoted to those mAbs that have been assayed in animal models or humans as possible therapies against Ebola. Engineering aspects and challenges for the production of anti-Ebola mAbs are also briefly discussed; current platforms for the design and production of full-length mAbs are cumbersome and costly.

The development of point-of-care (POC) diagnostic systems has received well-deserved attention in recent years in the scientific literature, and many experimental systems show great promise in real settings. However, in the case of an epidemic emergency (or a natural disaster), the first line of response should be based on commercially available and validated resources. Here, we compare the performance and ease of use of the miniPCR, a recently commercially available compact and portable PCR device, and a conventional thermocycler for the diagnostics of viral nucleic acids. We used both thermocyclers to detect and amplify Ebola and Zika DNA sequences of different lengths (in the range of 91 to 300 nucleotides) at different concentrations (in the range of ~50 to 4.0 x 10 8 DNA copies). Our results suggest that the performance of both thermocyclers is quite similar. Moreover, the portability, ease of use, and reproducibility of the miniPCR makes it a reliable alternative for point-of-care nucleic acid detection and amplification.

Massive worldwide serological testing for SARS-CoV-2 is needed to determine the extent of virus exposure in a particular region, the ratio of symptomatic to asymptomatic infected persons, and the duration and extent of immunity after infection. To achieve this, the development and production of reliable and cost-effective SARS-CoV-2 antigens is critical. We report the bacterial production of the peptide S-RBDN318-V510, which contains the receptor-binding domain of the SARS-CoV-2 spike protein (region of 193 amino acid residues from asparagine-318 to valine-510) of the SARS-CoV-2 spike protein. We purified this peptide using a straightforward approach involving bacterial lysis, his-tag-mediated affinity chromatography, and imidazole-assisted refolding. The antigen performances of S-RBDN318-V510 and a commercial full-length spike protein were compared in ELISAs. In direct ELISAs, where the antigen was directly bound to the ELISA surface, both antigens discriminated sera from non-exposed and exposed individuals. However, the discriminating resolution was better in ELISAs that used the full-spike antigen than the S-RBDN318-V510. Attachment of the antigens to the ELISA surface using a layer of anti-histidine antibodies gave equivalent resolution for both S-RBDN318-V510 and the full-length spike protein. Results demonstrate that ELISA-functional SARS-CoV-2 antigens can be produced in bacterial cultures, and that S-RBDN318-V510 may represent a cost-effective alternative to the use of structurally more complex antigens in serological COVID-19 testing.

BackgroundCurrent Ebola virus (EBOV) detection methods are costly and impractical for epidemic scenarios. Different immune-based assays have been reported for the detection and quantification of Ebola virus (EBOV) proteins. In particular, several monoclonal antibodies (mAbs) have been described that bind the capsid glycoprotein (GP) of EBOV GP. However, the currently available platforms for the design and production of full-length mAbs are cumbersome and costly. The use of antibody fragments, rather than full-length antibodies, might represent a cost-effective alternative for the development of diagnostic and possibly even therapeutic alternatives for EBOV.Methods/Principal FindingsWe report the design and expression of three recombinant anti-GP mAb fragments in Escherichia coli cultures. These fragments contained the heavy and light variable portions of the three well-studied anti-GP full-length mAbs 13C6, 13F6, and KZ52, and are consequently named scFv-13C6, scFv-13F6, and Fab-KZ52, respectively. All three fragments exhibited specific anti-GP binding activity in ELISA experiments comparable to that of full-length anti-GP antibodies (i.e., the same order of magnitude) and they are easily and economically produced in bacterial cultures.Conclusion/SignificanceAntibody fragments might represent a useful, effective, and low cost alternative to full-length antibodies in Ebola related capture and diagnostics applications.

Massive worldwide serological testing for SARS-CoV-2 is needed to determine the extent of virus exposure in a particular region, the ratio of symptomatic to asymptomatic infected persons, and the duration and extent of immunity after infection. To achieve this aim, the development and production of reliable and cost-effective SARS-CoV-2 antigens is critical. Here, we report the bacterial production of the peptide S-RBDN318-V510, which contains the receptor binding domain of the SARS-CoV-2 spike protein. We purified this peptide using a straightforward approach involving bacterial lysis, his-tag mediated affinity chromatography, and imidazole-assisted refolding. The antigen performances of S RBDN318 V510 and a commercial full-length spike protein were compared in two distinct ELISAs. In direct ELISAs, where the antigen was directly bound to the ELISA surface, both antigens discriminated sera from non-exposed and exposed individuals. However, the discriminating resolution was better in ELISAs that used the full-spike antigen than the S-RBDN318-V510. Attachment of the antigens to the ELISA surface using a layer of anti-histidine antibodies gave equivalent resolution for both S-RBDN318-V510 and the full length spike protein. Our results demonstrate that ELISA-functional SARS-CoV-2 antigens can be produced in bacterial cultures. S-RBDN318-V510 is amenable to massive production and may represent a cost-effective alternative to the use of structurally more complex antigens in serological COVID-19 testing.

The Ebola virus (EBOV) disease has caused serious and recurrent epidemics in recent years, resulting in a fatality rate of nearly 50%. The most effective experimental therapy against the EBOV is the use of monoclonal antibodies (mAbs). In this work, we describe the development of HEK293T cells engineered for the transient and stable expression of mAb13C6, a neutralizing anti-EBOV monoclonal antibody. We transfected the HEK293T cells with a tricistronic vector to produce the heavy and the light chain of the antibody 13C6 and intracellular Green Fluorescent Protein (GFP) using Lipofectamine 3000. We then selected the transfected cells using puromycin pressure, dilution cloning, and cloning disks. This integrated strategy generated mAb-producing cells in 7 days with a transient expression of ~1 mg/L. Stable pools were produced after 4 weeks, with expression levels of ~0.8 mg/L. Stable clones with expression levels of ~1.8 mg/L were obtained within 10 weeks. The produced antibodies exhibited the expected functionality; they recognized the GP glycoprotein of the Ebola virus in both ELISA assays and cell binding experiments using HEK293T cells engineered to express the EBOV GP at their membrane surface. By the combined use of GFP and the set of selection techniques here described, we drastically reduced the time from transfection to stable clone generation without resorting to costly equipment. In outbreaks or emergencies, this platform can significantly shorten the development of new biopharmaceuticals and vaccines.