RESUMO
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.
RESUMO
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 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 EBOV 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.