Laboratory diagnosis of emerging human coronavirus infections - the state of the art

Abstract

The three unprecedented outbreaks of emerging human coronavirus (HCoV) infections at the beginning of the twenty-first century have highlighted the necessity for readily available, accurate and fast diagnostic testing methods. The laboratory diagnostic methods for human coronavirus infections have evolved substantially, with the development of novel assays as well as the availability of updated tests for emerging ones. Newer laboratory methods are fast, highly sensitive and specific, and are gradually replacing the conventional gold standards. This presentation reviews the current laboratory methods available for testing coronaviruses by focusing on the coronavirus disease 2019 (COVID-19) outbreak going on in Wuhan. Viral pneumonias typically do not result in the production of purulent sputum. Thus, a nasopharyngeal swab is usually the collection method used to obtain a specimen for testing. Nasopharyngeal specimens may miss some infections; a deeper specimen may need to be obtained by bronchoscopy. Alternatively, repeated testing can be used because over time, the likelihood of the SARS-CoV-2 being present in the nasopharynx increases. Several integrated, random-access, point-of-care molecular devices are currently under development for fast and accurate diagnosis of SARS-CoV-2 infections. These assays are simple, fast and safe and can be used in the local hospitals and clinics bearing the burden of identifying and treating patients.

Keywords: COVID-19; Human coronavirus; POCT; SARS-CoV-2; real-time PCR; serology.

Figure 1.

Evolutions in molecular testing procedures. The point-of-care test (POCT) devices incorporate nucleic acid extraction, amplification and detection together into an integrated and sealed cartridge making it simple, rapid and safe. During end-point PCR, DNA is detected or measured at the completion of PCR amplification, requiring post-PCR processing. Real-time PCR is a closed-tube system in which DNA is detected or measured during the exponential phase of amplification.