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COVID-19 ( Co rona vi rus D isease 2019) is the disease caused by the novel Coronavirus, SARS-CoV-2. Genome sequence of the virus revealed that it’s a new zoonotic virus which might have evolved by jumping from bats to humans with one or more intermediate hosts. The immediate availability of the sequence information in public domain has accelerated development of quantitative-reverse-transcription PCR based diagnostics. Besides, numbers of clinical trials have been prioritized globally for testing new vaccines and treatments against this disease. This review gives a broad insight into different aspects of the COVID-19 disease, introduction to SARS-CoV-2, mitigation strategies, present status of diagnostics and therapeutics.

The Development of reliable and field-compatible detection methods is essential to monitoring and controlling the spread of any global pandemic. We herein report a novel anti-RNA:DNA hybrid (anti-RDH) antibody-based biosensor for visual, colorimetric lateral flow assay, using gold nano-particles, coupled with transcription-mediated-isothermal-RNA-amplification (TMIRA) for specific and sensitive detection of viral RNA. We have demonstrated its utility for SARS-CoV-2 RNA detection. This technique, which we have named RDH-LFA (anti-RNA:DNA hybrid antibody-based lateral flow assay), exploits anti-RDH antibody for immunocapture of viral RNA hybridized with specific DNA probes in lateral flow assay. In this method, biotinylated oligonucleotides (DNAB) specific to SARS-CoV-2 RNA (vRNA) are used to generate vRNA-DNAB hybrid. The biotin-tagged vRNA-DNAB hybrid molecules bind to streptavidin conjugated with gold-nanoparticles. This hybrid complex is trapped by the anti-RDH antibody immobilized on the nitrocellulose membrane resulting in pink color signal leading to visual naked-eye detection in 1 minute. Combining RDH-LFA with isothermal RNA amplification (TMIRA) significantly improves the sensitivity (LOD:10 copies/µl) with a total turnaround time of an hour. More importantly, RDH-LFA coupled with the TMIRA method showed 96.6% sensitivity and 100% specificity for clinical samples when compared to a commercial gold standard reverse transcription-quantitative polymerase-chain-reaction assay. Thus, the present study reports a rapid, sensitive, specific, and simple method for visual detection of viral RNA, which can be used at point-of-care, without the requirement of sophisticated instrumentation.

Cationic liposomes have become an attractive tool to deliver genes and interfering RNA into cells. Herein, we report the application of spontaneously formed cationic vesicles in mixtures of lecithin and cationic amphiphiles for efficient transfection of plasmid DNA and siRNA into cells. The average hydrodynamic diameter of the phospholipid vesicles was modulated by changing the ratio of dihexadecyldimethylammonium bromide (DDAB) to phospholipid in the vesicles. The vesicles were characterized by dynamic light scattering, ζ potential, and small-angle X-ray scattering. Depending on the ratio of DDAB to phospholipid, the average size of the vesicles can be varied in the range of 150−300 nm with a ζ potential of +40 mV. The ability of these cationic vesicles to form lipoplexes upon binding with pDNA is demonstrated by ζ potential, isothermal titration calorimetry, gel retardation, and DNase I digestion assay. The enthalpy of binding between pDNA and cationic liposome was found to be −5.7 (±0.8) kJ/mol. The cellular uptake studies of lipoplexes observed by fluorescence microscopy confirmed good transfection efficiency of DDAB liposomes in MCF-7 and HeLa cells. The fluorescent imaging analysis showed effective gene delivery and expression of green fluorescent protein. In addition, the formulation has demonstrated an ability to deliver small interfering RNA (siBRD4) for efficient gene silencing as seen by a significant decrease in BRD4 protein level in siBRD4-treated cells. Comparison of the transfection efficiency of different formulations suggests that DDABrich mixed phospholipid vesicles with size <200 nm are better than large size vesicles for improved endocytosis and gene expression.