coronaviridae

• What is the family name of viruses with a solar corona-like appearance?

  Coronaviridae
• Why are coronaviruses named after a solar corona-like appearance?

  Due to surface projections seen in EM
• What are the main characteristics of the Coronaviridae family?

  • Enveloped viruses
  • Baltimore group IV: (+) RNA genome
  • 15 species infecting humans, birds, mammals
  • Genus Coronavirus has 4 antigen groups
• How many antigen groups are in the Coronavirus genus?

  Four antigen groups
• What are the four antigen groups in the Coronavirus genus?

  • Group I: 229E, ZP, 840
  • Group II: OC43, OC38, OC44
  • Group III: B814
  • Group IV: Unclassified viruses, SARS-CoV
• Which group do all highly pathogenic coronaviruses belong to?

  Betacoronavirus genus, group 2
• What is the size range of coronaviruses?

  • Size ranges from 60 to 220 nm
• What is the genome type of coronaviruses?

  (+) ssRNA genome
• How long is the coronavirus genome?

  27,000 - 30,000 bases
• What does the coronavirus genome function like?

  It functions like mRNA
• How does the SARS-CoV-2 genome compare to SARS-CoV and MERS-CoV?

  Shares ~80% with SARS-CoV, ~50% with MERS-CoV
• How many open reading frames (ORFs) does the coronavirus genome comprise?

  14 open reading frames
• What are the four structural proteins of coronaviruses?

  • Spike (S)
  • Envelope (E)
  • Membrane (M)
  • Nucleocapsid (N)
• What is the function of the Spike protein in coronaviruses?

  It mediates entry into host cells
• How are coronaviruses primarily spread?

  • By aerosols
  • By large droplets
• What type of infections do most human coronaviruses cause?

  Upper Respiratory Tract infections
• Are reinfections common with human coronaviruses?

  Yes, despite pre-existing antibodies
• What percentage of URT and LRT infections are due to human coronaviruses?

  10-15%
• What is SARS and its mortality rate?

  Atypical pneumonia with 10% mortality rate
• What outbreak occurred in 2012 related to coronaviruses?

  MERS-CoV outbreak
• When did SARS-CoV-2 (COVID-19) emerge?

  In 2019
• What is the life cycle of SARS-CoV-2?

  1. Spike protein binds to ACE2 receptor
  2. S1/S2 cleavage by cathepsin L and TMPRSS2
  3. Viral entry facilitated by TMPRSS2
  4. Cathepsin L activates Spike in endosomes
  5. Genome released into cytosol
  6. ORFs 1a and 1b translated into replicase proteins
  7. RNA-dependent RNA polymerase formed
  8. ER rearranged into double-membrane vesicles for replication
  9. SgRNAs translated into accessory and structural proteins
• What is the receptor that the Spike protein of SARS-CoV-2 binds to?

  Angiotensin-converting enzyme 2 (ACE2)
• What role does TMPRSS2 play in SARS-CoV-2 entry?

  Facilitates viral entry at the plasma membrane
• What does cathepsin L do in the context of SARS-CoV-2?

  Activates the Spike protein in endosomes
• What is the function of the RNA-dependent RNA polymerase in SARS-CoV-2?

  It replicates the viral genome
• What are the laboratory diagnosis methods for coronaviruses?

  • Not routinely performed for general infections
  • Detection of viral RNA by RT-PCR
  • Virus isolation requires biosafety level 3
  • ELISA for acute and convalescent sera
• What is the treatment mentioned for coronaviruses?

  Molnupiravir