Recent advances in immunoassay technologies for the detection of human coronavirus infections

Abstract

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the seventh coronavirus (CoV) that has spread in humans and has become a global pandemic since late 2019. Efficient and accurate laboratory diagnostic methods are one of the crucial means to control the development of the current pandemic and to prevent potential future outbreaks. Although real-time reverse transcription-polymerase chain reaction (rRT-PCR) is the preferred laboratory method recommended by the World Health Organization (WHO) for diagnosing and screening SARS-CoV-2 infection, the versatile immunoassays still play an important role for pandemic control. They can be used not only as supplemental tools to identify cases missed by rRT-PCR, but also for first-line screening tests in areas with limited medical resources. Moreover, they are also indispensable tools for retrospective epidemiological surveys and the evaluation of the effectiveness of vaccination. In this review, we summarize the mainstream immunoassay methods for human coronaviruses (HCoVs) and address their benefits, limitations, and applications. Then, technical strategies based on bioinformatics and advanced biosensors were proposed to improve the performance of these methods. Finally, future suggestions and possibilities that can lead to higher sensitivity and specificity are provided for further research.

Keywords: SARS-CoV-2; diagnosis; human coronavirus; immunosensor; serological testing methods.

Figure 1

Human Coronavirus: Discovery Timeline, Structure and Origin.

Figure 2

The time windows of viral shedding, and antibody responses against HCoVs infections, and the principles of the mainstream immunoassay methods. (A) A typical course of human coronavirus infection. The infection starts with an asymptomatic incubation period. Viral shedding begins during the incubation period and continues for some time after antibody production. Antibodies are produced a few days after infection. Among the antibodies, IgM appears within a few days after infection and can persist for several months. IgG is produced shortly after the appearance of IgM and persists for a longer time. Antigen-target methods, including ICT and ELISA, can be used to screen infected persons during viral shedding. It can realize the differentiation of latent infection and the early diagnosis of disease. After seroconversion occurs, antibody-target methods, including ICT, ELISA, WB and IFA, can be used for diagnosis. It can be used for acute-phase diagnosis as well as epidemiological investigation. (B) Schematic of ICT and ELISA for the detection of antigens. (C) Schematic of ICT, ELISA, WB and IFA for the detection of antibodies.

Figure 3

Examples of optical immunosensors. (A) Schematic illustration of the microfluidic fluorescence immunoassay for IgG/IgM/antigen detection of SARS-CoV-2 (Lin et al., 2020). (B) Schematic illustration of principle of immunoreaction, optical signal transmission and photometer sensing (Zhang et al., 2021). (C) Schematic illustration of procedure of smartphone-based NLICS (Liang et al., 2021a). (D) Schematic illustration of overview of our SERS-based strategy to identify COVID-positive individuals using their breath volatile organic compounds (BVOCs) (Leong et al., 2022).

Figure 4

Examples of electrochemical biosensors. (A) Schematic illustration of the wireless graphene-based telemedicine platform for rapid and multiplex electrochemical detection of SARS-CoV-2 in blood and saliva (Torrente-Rodrıguez et al., 2020). (B) Schematic illustration of preparing BSA/S-gene/CysOH/Au/GCE for the electrochemical detection of the SARS CoV-2 spike antibody (Liv et al., 2022). (C) Schematic illustration of the electrochemical immunosensor with Cu2O nanocube coating for detection of SARS-CoV-2 spike protein (Rahmati et al., 2021). (D) Schematic illustration of the cotton-tipped electrochemical immunosensor for COVID-19 (Eissa and Zourob, 2021).

Figure 5

Examples of strategies for improving sensitivity. (A) Schematic illustration for ELISA combines MIP with catalase-mediated growth of plasma AuNPs (Jia et al., 2021). (B) Schematic diagram of an ELISA in which SA-HRP is replaced by an SA-bound AuNP and no TMB substrate is used (Zhao et al., 2016). (C) Schematic diagram of the ratiometric fluorescent sensing system integrated of a ratiometric quantum dots (QDs) hybrid and chemical redox reaction for drug residue analysis (Yu et al., 2020). (D) Schematic illustration for photoelectrochemical immunosensor based on AuNPs/g-C3N4 coupling with CdTe quantum dots for detection of target avian viruses (Sun et al., 2019). (E) Scheme of ULISA for counting single molecules of PSA (Farka et al., 2017). (F) Schematic diagram of influenza virus diagnostic process using magnetic beads in a structure-free digital microfluidic platform (Lu et al., 2020).