Coronavirus Research Tools

Coronaviruses are enveloped, positive-sense single-stranded RNA viruses in the family Coronaviridae. Human coronaviruses include the endemic viruses HCoV-229E, HCoV-NL63, HCoV-OC43, and HCoV-HKU1, as well as the highly pathogenic SARS-CoV, MERS-CoV, and SARS-CoV-2. These viruses primarily infect the respiratory tract, although some coronaviruses can also affect the gastrointestinal tract and other organ systems.

Coronavirus genomes are approximately 26–32 kb, among the largest known RNA virus genomes. The 5′ two-thirds of the genome contains ORF1a and ORF1b, which are translated into the polyproteins pp1a and pp1ab. Viral proteases process these polyproteins into 16 nonstructural proteins that form the replication-transcription complex and carry out RNA synthesis, proofreading, RNA modification, and regulation of host-cell responses.

The 3′ region encodes the four major structural proteins: spike (S), envelope (E), membrane (M), and nucleocapsid (N), together with virus-specific accessory proteins. The S protein mediates receptor binding and membrane fusion; M and E participate in virion assembly and budding; and N binds the viral RNA genome and contributes to replication, transcription, and particle formation.