SARS-CoV, MERS-CoV and SARS-CoV-2: A Diagnostic Challenge

Abstract

The highly pathogenic MERS-CoV, SARS-CoV and SARS-CoV-2 cause acute respiratory syndrome and are often fatal. These new viruses pose major problems to global health in general and primarily to infection control and public health services. Accurate and selective assessment of MERS-CoV, SARS-CoV and SARS-CoV-2 would assist in the effective diagnosis of infected individual, offer clinical guidance and aid in assessing clinical outcomes. In this mini-review, we review the literature on various aspects, including the history and diversity of SARS-CoV-2, SARS-CoV and MERS-CoV, their detection methods in effective clinical diagnosis, clinical assessment of COVID-19, safety guidelines recommended by World Health Organization and legal regulations. This review article also deals with existing challenges and difficulties in the clinical diagnosis of SARS-CoV-2. Developing alternative diagnostic platforms by spotting the shortcomings of the existing point-of-care diagnostic devices would be useful in preventing future outbreaks.

Keywords: Biosensors; MERS-CoV; Point-of-Care Diagnostics; SARS-CoV; SARS-CoV-2.

Scheme 1

Schematic representation of the use of point-of-care diagnostics in the diagnosis of SARS-CoV, MERS-CoV and SARS-CoV-2.

Fig. 1

Investigation of binding affinity between nucleocapsid protein (N protein) of SARS-CoV and SARS-CoV double-stranded DNA (dsDNA) genome using transistors. (a) Schematics of the N protein sensor, (b) plan-view photography of the sensor and (c) real-time detection of the N protein from 0.003 nM to 3000 nM at constant bias of 350 mV. Figures modified from Ref. and used with permission.

Fig. 2

L-AC2 cells were infected with MHV at MOI 10. At 1 h p.i., cells were infected with 4 µg poly(I:C). At 8 h p.i. total RNA was isolated and reverse transcribed using random hexamers. (A) IFN-α4 mRNA concentration was determined using specific RT-qPCR and (B) endogenous IRF3 localization and MHV nucleocapsid protein were detected in IFA with specific poly- and monoclonal antibodies, respectively. Nuclear IRF3 is indicated with arrows. Subsequently, L-ACE2 cells were seeded on coverslips in 35-mm wells and infected with SeV for 30 min. Next, cells were infected with MHV at MOI 5. At 8.5 h.p.i. cells on coverslips were fixed in 3% paraformaldehyde. From the remainder of the cells, total RNA was isolated and reverse transcribed using random hexamers. (C) IFN-α4 mRNA concentration was determined using specific RT-qPCR and (D) endogenous IRF3 and MHV nucleocapsid protein were detected in IFA with specific poly- and monoclonal antibodies, respectively. Nuclear IRF3 is indicated with arrows. Figures modified from Ref. and used with permission.

Fig. 2

L-AC2 cells were infected with MHV at MOI 10. At 1 h p.i., cells were infected with 4 µg poly(I:C). At 8 h p.i. total RNA was isolated and reverse transcribed using random hexamers. (A) IFN-α4 mRNA concentration was determined using specific RT-qPCR and (B) endogenous IRF3 localization and MHV nucleocapsid protein were detected in IFA with specific poly- and monoclonal antibodies, respectively. Nuclear IRF3 is indicated with arrows. Subsequently, L-ACE2 cells were seeded on coverslips in 35-mm wells and infected with SeV for 30 min. Next, cells were infected with MHV at MOI 5. At 8.5 h.p.i. cells on coverslips were fixed in 3% paraformaldehyde. From the remainder of the cells, total RNA was isolated and reverse transcribed using random hexamers. (C) IFN-α4 mRNA concentration was determined using specific RT-qPCR and (D) endogenous IRF3 and MHV nucleocapsid protein were detected in IFA with specific poly- and monoclonal antibodies, respectively. Nuclear IRF3 is indicated with arrows. Figures modified from Ref. and used with permission.

Fig. 3

Schematic representation of the principle of an isothermal, rapid and label-free one-step RNA amplification/detection (iROAD) assay. First, preparation of the iROAD chip through the primers (forward) grafting on the optical sensor would be needed for a ready-to-use viral RNA detection assay (#1). Then, the mixture containing recombinase polymerase amplification-reverse transcription (RPA-RT) reagents, reverse primers, and extracted RNA is added into the reaction chip (#2). During the isothermal reaction, complementary DNA (cDNA) is synthesized from the RNA template via RNA-RT kit (#3). Thereafter, recombinase/primer complexes bind to double-stranded target cDNA and facilitate strand exchange at a constant temperature. After the displaced strand forms a D-loop by gp32 (sky blue), the immobilized primers are extended by polymerase (light green) on the surface of the silicon microring resonator (#4). The formation of two duplexes is caused by the amplification of the solid and the solution. The exponential RNA amplification after the reverse transcription based on the asymmetric assay is achieved by the repletion of the process (#5). The amplification and detection of the target is simultaneously monitored by measuring the wavelength shift on an optical sensor for 20 min. Figures modified from Ref. and used with permission.

Fig. 4

Clinical assessment of COVID-19.