, a novel coronavirus (nCoV or SARS-CoV-2) belonging to the betacoronavirus family emerged 1,2. All human betacoronaviruses are unique from one another, however, they do share a certain degree of genetic and structural homology. SARS-CoV-2 genome sequence homology with SARS-CoV and MERS-CoV is 77% and 50%, respectively 3. In contrast to the relatively smaller outbreaks of SARS-CoV in 2002 and MERS-CoV in 2012, SARS-CoV-2 is exhibiting an unprecedented scale of infection, resulting in a global pandemic declaration of Coronavirus Infectious Disease (COVID-19) on 11 March 2020 by the World Health Organization (WHO). On 1 June 2020, the World Health Organization reported >6 million confirmed cases and 371 thousand deaths globally. Of note, during the 1918 influenza pandemic, more death was observed in the second phase of outbreak 4. Similar to influenza, COVID-19 harbours the potential to become a seasonal disease 5. The high infection rate, long incubation period, along with mild-to-moderate symptoms experienced by many, make COVID-19 a troubling disease. A vaccine is crucial, in particular because data indicate asymptomatic transmission of COVID-19 6-8. More than 10 years ago, scientists predicted the pandemic potential of the coronaviruses 9. And for the past 30 years, a once-per-decade novel coronavirus has pushed our public health system to the limit, with SARS-CoV-2 being the most severe. Despite the repeated warnings and discussion, the world was not prepared for this pandemic. The rapid development, distribution and administration of a vaccine to the global population is the most effective approach to quell this pandemic and the only one that will lead to a complete lifting of restrictions. Challenges include the vaccine design itself, but also its manufacture and global distribution; cold chain requirements present logistical and fiscal barriers to the availability of important, life-saving vaccines in resource-poor areas of the world. Innovating vaccine delivery platforms and devices to break cold chain limitations are therefore an efficient solution to safeguard potent vaccination for both wealthy and lower-income countries.

Although researchers have noted high level activation of rodent mononuclear phagocytes for nitric oxide (NO) synthase type 2 (S2) expression and NO production with a variety of agents such as interferon (IFN) γ and endotoxin, it has been difficult to demonstrate activation of human mononuclear phagocytes. The purpose of this study was to determine if IFN-α serves as an activator in vitro and in vivo in humans. Treatment of normal monocytes or mononuclear cells in vitro with IFN-α caused a dose-dependent increase in monocyte NOS2 activity and NO production, and increased expression of NOS2 protein and mRNA expression. To determine if in vivo administration of IFN-α also modulated NOS2, we studied blood cells from patients with hepatitis C before and after IFN-α therapy. Untreated patients with chronic hepatitis C virus infection had levels of NOS activity and NOS2 antigen in freshly isolated mononuclear cells similar to those of healthy subjects, and they expressed minimal or no NOS2 mRNA. However, IFN-α treatment of patients with hepatitis C infection was associated with a significant elevation in mononuclear cell NOS activity, NOS2 antigen content, and NOS2 mRNA content. IFN-α–treated patients had significant decreases in levels of serum alanine aminotransferase and plasma hepatitis C mRNA. The degree of IFN-α–enhanced mononuclear cell NOS2 antigen content correlated significantly with the degree of reduction in serum alanine aminotransferase levels. Thus, IFN-α treatment of cells in vitro or administration of IFN-α to hepatitis C patients in vivo increases expression of mononuclear cell NOS2 mRNA expression, NOS activity, NOS2 antigen expression, and NO production. Since NO has been reported to have antiviral activity for a variety of viruses, we speculate that induced NO production may be related to the antiviral action(s) of IFN-α in hepatitis C infection.

Coronavirus disease 2019 (COVID-19) is a highly transmissible disease that has affected more than 90% of the countries worldwide. At least 17 million individuals have been infected, and some countries are still battling first or second waves of the pandemic. Nucleic acid tests, especially reverse transcription polymerase chain reaction (RT-PCR), have become the workhorse for early detection of COVID-19 infection. Positive controls for the molecular assays have been developed to validate each test and to provide high accuracy. However, most available positive controls require cold-chain distribution and cannot serve as full-process control. To overcome these shortcomings, we report the production of biomimetic virus-like particles (VLPs) as SARS-CoV-2 positive controls. A SARS-CoV-2 detection module for RT-PCR was encapsidated into VLPs from a bacteriophage and a plant virus. The chimeric VLPs were obtained either by in vivo reconstitution and coexpression of the target detection module and coat proteins or by in vitro assembly of purified detection module RNA sequences and coat proteins. These VLP-based positive controls mimic SARS-CoV-2 packaged ribonucleic acid (RNA) while being noninfectious. Most importantly, we demonstrated that the positive controls are scalable, stable, and can serve broadly as controls, from RNA extraction to PCR in clinical settings.

G-quadruplexes are made up of guanine-rich RNA and DNA sequences capable of forming noncanonical nucleic acid secondary structures. The base-specific sterical configuration of G-quadruplexes allows the stacked G-tetrads to bind certain planar molecules like hemin (iron (III)-protoporphyrin IX) to regulate enzymatic-like functions such as peroxidase-mimicking activity, hence the use of the term DNAzyme/RNAzyme. This ability has been widely touted as a suitable substitute to conventional enzymatic reporter systems in diagnostics. This review will provide a brief overview of the G-quadruplex architecture as well as the many forms of reporter systems ranging from absorbance to luminescence readouts in various platforms. Furthermore, some challenges and improvements that have been introduced to improve the application of G-quadruplex in diagnostics will be highlighted. As the field of diagnostics has evolved to apply different detection systems, the need for alternative reporter systems such as G-quadruplexes is also paramount.