Molecular Diagnosis of Coronavirus Disease 2019

An AIEgen/graphene oxide nanocomposite (AIEgen@GO)-based two-stage "turn-on" nucleic acid biosensor for rapid detection of SARS-CoV-2 viral sequence

The ongoing outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic has posed significant challenges in early viral diagnosis. Hence, it is urgently desirable to develop a rapid, inexpensive, and sensitive method to aid point-of-care SARS-CoV-2 detection. In this work, we report a highly sequence-specific biosensor based on nanocomposites with aggregation-induced emission luminogens (AIEgen)-labeled oligonucleotide probes on graphene oxide nanosheets (AIEgen@GO) for one step-detection of SARS-CoV-2-specific nucleic acid sequences (Orf1ab or N genes). A dual "turn-on" mechanism based on AIEgen@GO was established for viral nucleic acids detection. Here, the first-stage fluorescence recovery was due to dissociation of the AIEgen from GO surface in the presence of target viral nucleic acid, and the second-stage enhancement of AIE-based fluorescent signal was due to the formation of a nucleic acid duplex to restrict the intramolecular rotation of the AIEgen. Furthermore, the feasibility of our platform for diagnostic application was demonstrated by detecting SARS-CoV-2 virus plasmids containing both Orf1ab and N genes with rapid detection around 1 h and good sensitivity at pM level without amplification. Our platform shows great promise in assisting the initial rapid detection of the SARS-CoV-2 nucleic acid sequence before utilizing quantitative reverse transcription-polymerase chain reaction for second confirmation.

Cold traps as reliable devices for quantitative determination of SARS-CoV-2 load in aerosols

Spread of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a demanding challenge. This is of particular importance in schools and public areas of unavoidable access. New viral mutations may increase infectivity and require even better methods to identify areas of potential hazards. High-throughput SARS-CoV-2 testing and legal restrictions are not effective in order to get the current outbreak under control. The occurrence of new SARS-CoV-2 variants with a higher transmissibility requires efficient strategies for early detection and surveillance. Until today, testing focuses on nasal or pharyngeal mucosa swabs, neglecting the origin of aerosolic transmission, thus failing to detect the spread by carriers of the virus. Therefore, in this study, SARS-CoV-2 RNA levels were determined by quantitative real time PCR in aerosols collected by non-powered cold traps. SARS-CoV-2 spreading kinetics were recorded in indoor hotspots within a high-endemic area. These hotspots included a SARS-CoV-2 isolation unit, an outpatient endoscopy facility, a concert hall, and a shopping mall. For determination of viral presence aerosols were collected by cold traps positioned at different locations in the area of interest over a period of 4-6 h. Indoor SARS-CoV-2 hotspots were found in non-ventilated areas and in zones that are predisposed to a buoyancy (chimney) effect. SARS-CoV-2 RNA in those aerosols reached concentrations of 10⁵ copies/mL, while extensive outdoor air ventilation reliably eliminated SARS-CoV-2 aerosol contamination. The method presented herein is effective for the identification of SARS-CoV-2 indoor hotspots and may help to characterize the spreading kinetics of SARS-CoV-2. Moreover, it can be used for the surveillance of emerging SARS-CoV-2 variants. Due to low costs and easy handling, the procedure might enable efficient algorithms for COVID-19 screening and prevention.

Testing for COVID-19 in dental offices: Mechanism of action, application, and interpretation of laboratory and point-of-care screening tests

BACKGROUND

The dental office potentially possesses all transmission risk factors for severe acute respiratory syndrome coronavirus 2. Anticipating the future widespread use of COVID-19 testing in dental offices, the authors wrote this article as a proactive effort to provide dental health care providers with current and necessary information surrounding the topic.

METHODS

The authors consulted all relevant and current guidelines from the Centers for Disease Control and Prevention and the US Food and Drug Administration, as well as online resources and review articles.

RESULTS

Routine COVID-19 screening and triage protocols are unable to detect all infected people. With the advancements in diagnostic tools and techniques, COVID-19 testing at home or in the dental office may provide dentists with the ability to evaluate the disease status of their patients. At-home or point-of-care (POC) tests, providing results within minutes of being administered, would allow for appropriate measures and rapid decisions about dental patients' care process. In this review, the authors provide information about available laboratory and POC COVID-19 screening methods and identify and elaborate on the options available for use by dentists as well as the regulatory requirements of test administration.

CONCLUSIONS

Dentists need to be familiar with COVID-19 POC testing options. In addition to contributing to public health, such tests may deliver rapid, accurate, and actionable results to clinical and infection control teams to enhance the safe patient flow in dental practices.

PRACTICAL IMPLICATIONS

Oral health care must continue to offer safety in this or any future pandemics. Testing for severe acute respiratory syndrome coronavirus 2 at the POC offers a control mechanism contributing to and enhancing the real and perceived safety of care in the dental office setting.

Characteristics and Detection Rate of SARS-CoV-2 in Alternative Sites and Specimens Pertaining to Dental Practice: An Evidence Summary

Knowledge about the detection potential and detection rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in various body fluids and sites is important for dentists since they, directly or indirectly, deal with many of these fluids/sites in their daily practices. In this study, we attempt to review the latest evidence and meta-analysis studies regarding the detection rate of SARS-CoV-2 in different body specimens and sites as well as the characteristics of these sample. The presence/detection of SARS-CoV-2 viral biomolecules (nucleic acid, antigens, antibody) in different clinical specimens depends greatly on the specimen type and timing of collection. These specimens/sites include nasopharynx, oropharynx, nose, saliva, sputum, bronchoalveolar lavage, stool, urine, ocular fluid, serum, plasma and whole blood. The relative detection rate of SARS-CoV-2 viral biomolecules in each of these specimens/sites is reviewed in detail within the text. The infectious potential of these specimens depends mainly on the time of specimen collection and the presence of live replicating viral particles.