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BackgroundThe current pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the etiology of Coronavirus-induced disease 19 (COVID-19) and poses a critical public health threat worldwide. Effective therapeutics and vaccines against multiple coronaviruses remain unavailable. Single chain variable fragment (scFv), a recombinant antibody exhibits broad-spectrum antiviral activity against DNA and RNA viruses owing to its nucleic acid-hydrolyzing property. ObjectiveThis study is aimed to investigate an antiviral activity of 3D8 scFv against SARS-CoV-2 and other coronaviruses. Methods3D8, a recombinant scFv antibody was evaluated for antiviral activity against SARS-CoV-2, HCoV-OC43 and PEDV in Vero E6 cell cultures. Viral growth was quantified with quantitative RT-qPCR and plaque assay. Nucleic acid hydrolyzing activity of 3D8 was assessed through abzyme assays of in vitro viral transcripts and cell viability was determined by MTT assay. Results3D8 inhibited the replication of SARS-CoV-2, human coronavirus OC43 (HCoV-OC43), and porcine epidemic diarrhea virus (PEDV). Our results revealed the prophylactic and therapeutic effects of 3D8 scFv against SARS-CoV-2 in Vero E6 cells. Immunoblot and plaque assays showed the reduction of coronavirus nucleoproteins and infectious particles respectively in 3D8 scFv-treated cells. ConclusionsThis data demonstrates the broad-spectrum antiviral activity of 3D8 against SARS-CoV-2 and other coronaviruses. Thus, it could be considered a potential antiviral countermeasure against SARS-CoV-2 and zoonotic coronaviruses.
RESUMO
Background: Recently, microplate almar blue assay has been used commonly in detecting gen related to tuberculosis drug resistance, which provides results after 5-7 days with lower cost compared to traditional methods. Objective: To evaluate the application of microplate almar blue assay for rapid detection of drug resistance of M. tuberculosis strains. Subject and Method: A microplate-based assay which uses Alamar blue reagent - an oxidation reduction dye (MABA), was used for the determination of the anti-tuberculosis drug (isoniazid-INH, rifampicine-RIF, streptomycine-STR and ethabuton=EMB) resistance of 96 M. tuberculosis strains isolated from Vietnamese patients in comparison to those obtained by conversional method. Result: MABA showed to have high sensitivity and specificity in testing the sensitivity to individual anti-tuberculosis drugs (from 82.4% for STR to 93.3% for - INH and from 82.5% for EMB to 98.4% for STR; respectively), as well as for the multi-drug resistant M.tuberculosis (86.4% of sensitivity), highly correlated with the result determined by proportion method. Conclusion: MABA reveals the advantage in shortening test time, in simple performance and lower cost compared with the conversional culture based methods.
