coronaviridae / corona viruses (CoV)

see also:

• viruses
• COVID-19 coronavirus (2019-nCoV / SARS-CoV-2)

• single stranded enveloped RNA viruses with a very long RNA genome, coding up to 30 viral proteins.
  • four or five genes make infectious virus particles, but many others support diseases by modifying immune responses
  • mutate at a steady low rate, selecting changes in the outer spike to allow virus entry into new host cells
• coronaviruses primarily infect the upper respiratory and gastrointestinal tract of mammals and birds.
• four coronaviruses continually circulate in the human population and produce the generally mild symptoms of the common cold in adults and children worldwide of which they cause around 15% (most other common colds are caused by rhinovirus), and the mean age of primary infection is around 4yrs of age¹⁾: sOC43, sHKU1, s229E, sNL63
• they generally enter animal cells via binding to either:
  • the zinc peptidase, aminopeptidase N (APN)
  • ACE2 zinc metallopeptidase - SARS virus and COVID-19 coronavirus (2019-nCoV / SARS-CoV-2)
• The most recent common ancestor (MRCA) of all coronaviruses is estimated to have existed as recently as 8000 BCE, although some models place the common ancestor as far back as 55 million years or more, implying long term coevolution with bat and avian species

• first human Coronaviruses (229E and OC43) were found in 1965 and 1967 respectively (caused mild URTI and gastro symptoms)
• HKU-1 strain in 1995 again was mild symptoms
• they were not considered a major concern until severe acquired respiratory syndrome (SARS-1) first appeared in 2002 in China
• Middle East respiratory syndrome (MERS)
• 2017: Chinese researchers find that GX_P2V, a SARS-CoV-2-related pangolin coronavirus and a mutated version of GX/2017 which was reportedly discovered in Malaysian pangolins in 2017, caused 100% mortality within 8 days of infection in genetically “humanised” mice which also caused their eyes to go completely white! ²⁾
• COVID-19 coronavirus (2019-nCoV / SARS-CoV-2) emerged in late 2019
• 2025: HKU5-Cov-2: new Covid-19 like coronavirus detected in bats in China with ability to infect humans by also binding to ACE2 receptor but transmission risk to humans is much lower

• human-infecting CoV are found in only the alpha and beta subgroups thus far

• a novel group 1 CoV called swine acute diarrhea syndrome CoV (SADS-CoV) emerged from bats causing the loss of over 20,000 pigs in Guangdong Province, China in 2018
• Alphacoronavirus 1
  • canine coronavirus (CCoV) causes intestinal disease in dogs but is thought to be a potential for evolving to resp disease in humans given there have been reported cases since 2017 of the CCoV-HuPn-2018 strain infecting humans (mainly children) causing pneumonia
• Human coronavirus 229E
  • shared a common ancestor with bat coronavirus (GhanaGrp1 Bt CoV) between 1686–1800 CE
  • alpaca coronavirus and human coronavirus 229E diverged sometime before 1960
• Human coronavirus NL63
  • shared a common ancestor with a bat coronavirus (ARCoV.2) between 1190–1449 CE
• Miniopterus bat coronavirus 1
• Miniopterus bat coronavirus HKU8
• Porcine epidemic diarrhea virus
• Rhinolophus bat coronavirus HKU2
• Scotophilus bat coronavirus 512

• many group 2 SARS-like and MERS-like coronaviruses are circulating in bat reservoir species that can use human receptors and replicate efficiently in primary human lung cells without adaptation
• group 2b SARS-like CoV represent an existential and future threat to global health as evidenced by the emergence of SARS-CoV and SARS-CoV-2
• subgenus Embecovirus
  • Betacoronavirus gravedinis, Human coronavirus OC43, Bovine coronavirus
    • Bovine Coronavirus
      • thought to have originated in rodents and not in bats
      • in the 1790s, equine coronavirus diverged from the bovine coronavirus after a cross-species jump.
    • human coronavirus OC43
      • in the 1890s, human coronavirus OC43 diverged from bovine coronavirus after another cross-species jump which may have caused the 1890 “flu” pandemic
      • besides causing respiratory infections, it is also suspected of playing a role in neurological diseases
      • in the 1950s, it began to diverge into its present genotypes
      • this strain is similar to canine respiratory coronavirus (CRCoV)
  • Betacoronavirus hongkongense, Human coronavirus HKU1
    • originated in rodents
  • Betacoronavirus muris, Murine hepatitis virus
  • Betacoronavirus myodae, Myodes rufocanus vole coronavirus 2/JL2014
  • Betacoronavirus ratti, Betacoronavirus HKU24
• subgenus Merbecovirus
  • Betacoronavirus pipistrelli aka Pipistrellus bat coronavirus HKU5 virus
    • some strains are only one mutation away from being able to infect humans
    • found across Asia, Europe, Africa and the Middle East – use a host receptor known as ACE2, the same used by SARS-CoV-2 virus that causes COVID-19. One small difference: HKU5 viruses, for now, can only use the ACE2 gene in bats, but do not use the human version nearly as well.
    • Japanese pipistrelle bat coronavirus HKU5-Cov-2 discovered in 2025 in Hong Kong
  • MERS
    • Betacoronavirus cameli or MERS-CoV emerged in humans from bats through the intermediate host of camels having diverged from bat coronavirus several centuries ago
  • Betacoronavirus erinacei, Hedgehog coronavirus 1
  • Betacoronavirus tylonycteridis, Tylonycteris bat coronavirus HKU4
• subgenus Nobecovirus
  • Betacoronavirus rousetti, Rousettus bat coronavirus HKU9
  • Betacoronavirus cororeum, Rousettus bat coronavirus GCCDC1
  • Betacoronavirus eidoli, Eidolon helvum bat coronavirus CMR704-P12
• subgenus Sarbecovirus
  • Betacoronavirus pandemicum (SARS-related coronavirus)
    • Severe acute respiratory syndrome-related coronavirus
    • SARS related coronaviruses appeared to have coevolved in bats for a long time
    • SARS-CoV
      • most closely related bat coronavirus and SARS-CoV diverged in 1986
    • SARS-CoV-2 / Covid-19
• subgenus Hibecovirus
  • Betacoronavirus hipposideri, Bat Hp-betacoronavirus/Zhejiang2013

• Avian coronavirus
• Beluga whale coronavirus SW1

• Bulbul coronavirus HKU11
• Porcine coronavirus HKU15