Characterization of coronavirus DI RNA packaging

Genetic Engineering Systems to Study Human Viral Pathogens from the Coronaviridae Family

The COVID-19 pandemic caused by the previously unknown SARS-CoV-2 Betacoronavirus made it extremely important to develop simple and safe cellular systems which allow manipulation of the viral genome and high-throughput screening of its potential inhibitors. In this review, we made an attempt at summarizing the currently existing data on genetic engineering systems used to study not only SARS-CoV-2, but also other viruses from the Coronaviridae family. In addition, the review covers the basic knowledge about the structure and the life cycle of coronaviruses.

A defective viral genome strategy elicits broad protective immunity against respiratory viruses

RNA viruses generate defective viral genomes (DVGs) that can interfere with replication of the parental wild-type virus. To examine their therapeutic potential, we created a DVG by deleting the capsid-coding region of poliovirus. Strikingly, intraperitoneal or intranasal administration of this genome, which we termed eTIP1, elicits an antiviral response, inhibits replication, and protects mice from several RNA viruses, including enteroviruses, influenza, and SARS-CoV-2. While eTIP1 replication following intranasal administration is limited to the nasal cavity, its antiviral action extends non-cell-autonomously to the lungs. eTIP1 broad-spectrum antiviral effects are mediated by both local and distal type I interferon responses. Importantly, while a single eTIP1 dose protects animals from SARS-CoV-2 infection, it also stimulates production of SARS-CoV-2 neutralizing antibodies that afford long-lasting protection from SARS-CoV-2 reinfection. Thus, eTIP1 is a safe and effective broad-spectrum antiviral generating short- and long-term protection against SARS-CoV-2 and other respiratory infections in animal models.

Assembly of human severe acute respiratory syndrome coronavirus-like particles

Viral particles of human severe acute respiratory syndrome coronavirus (SARS CoV) consist of three virion structural proteins, including spike protein, membrane protein, and envelope protein. In this report, virus-like particles were assembled in insect cells by the co-infection with recombinant baculoviruses, which separately express one of these three virion proteins. We found that the membrane and envelope proteins are sufficient for the efficient formation of virus-like particles and could be visualized by electron microscopy. Sucrose gradient purification followed by Western blot analysis and immunogold labeling showed that the spike protein could be incorporated into the virus like particle also. The construction of engineered virus-like particles bearing resemblance to the authentic one is an important step towards the development of an effective vaccine against infection of SARS CoV.