Human coronavirus HKU1

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Human coronavirus HKU1
Formation of HcoV-HKU1.
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Pisuviricota
Class: Pisoniviricetes
Order: Nidovirales
Family: Coronaviridae
Genus: Betacoronavirus
Subgenus: Embecovirus
Species:
Human coronavirus HKU1

Human coronavirus HKU1 (HCoV-HKU1) is a species of coronavirus in humans and animals. It causes an upper respiratory disease with symptoms of the common cold, but can advance to pneumonia and bronchiolitis.[1] It was first discovered in January 2004 from one man in Hong Kong.[2] Subsequent research revealed it has global distribution and earlier genesis.

The virus is an enveloped, positive-sense, single-stranded RNA virus which enters its host cell by binding to the N-acetyl-9-O-acetylneuraminic acid receptor.[3] It has the Hemagglutinin esterase (HE) gene, which distinguishes it as a member of the genus Betacoronavirus and subgenus Embecovirus.[4]

History

HCoV-HKU1 was first detected in January 2004, in a 71-year-old man who was hospitalized due to

bilateral pneumonia. The man had recently returned to Hong Kong from Shenzhen, China.[2][5]

Virology

Woo and coworkers were unsuccessful in their attempts to grow a HCoV-HKU1 isolate but were able to obtain the complete genomic sequence.

HCoV-OC43.[2] The virus has been successfully cultured by Pyrc and coworkers in the ex vivo model of human respiratory epithelium.[6] Additional research has revealed that the virus attaches itself to O-acetylated sialic acids on the cell surface,[7] which instigates a conformational shift in the S protein, facilitating interaction with the entry receptor.[8] Intriguingly, the enzyme kallikrein 13 has been identified as an activating factor responsible for the spike protein processing by the Pyrc's team. This could potentially specify the virus's tissue and cellular preference, and might also govern the regulation of interspecies transmission.[9]

When the RNA-dependent RNA polymerase (RdRp), spike (S), and nucleocapsid (N) genes were analyzed, incompatible phylogenetic relationships were discovered. Complete genome sequencing of 22 strains of HCoV-HKU1 confirmed this was due to natural recombination.[2] HCoV-HKU1 likely originated from rodents.[10]

HCoV-HKU1 is one of seven known coronaviruses to infect humans. The other six are:[11]

The structures of HCoV-HKU1 spike (S) and hemagglutinin esterase (HE) proteins have been resolved by Cryo-EM in 2016 and 2020, respectively. The S protein (PDB: 5I08​) has been noted for its large size.[12] The HE protein (PDB: 6Y3Y​) differs from conventional ones (such as the one in OC43) by having a much smaller vestigial lectin domain. This domain is shielded from recognition by the immune system via size changes and glycosylation.[13]

Epidemiology

A trace-back analysis of SARS negative nasopharyngeal aspirates from patients with respiratory illness during the SARS period in 2003, identified the presence of CoV-HKU1 RNA in the sample from a 35-year-old woman with pneumonia.[5]

Following the initial reports of the discovery of HCoV-HKU1, the virus was identified that same year in 10 patients in northern Australia. Respiratory samples were collected between May and August (winter in Australia). Investigators found that most of the HCoV-HKU1–positive samples originated from children in the later winter months.[14]

The first known cases in the Western hemisphere were discovered in 2005 after analysing older specimens by clinical virologists at

direct immunofluorescence assay as well as human metapneumovirus and HCoV-NH by reverse transcription polymerase chain reaction
(RT-PCR). The researchers reported that the strains identified in New Haven were similar to the strain found in Hong Kong and suggested a worldwide distribution.[15] These strains found in New Haven is not to be confused with HCoV-NH (New Haven coronavirus), which is a strain of Human coronavirus NL63.

In July 2005, six cases were reported in France. In these cases, French investigators utilized improved techniques for recovering the virus from nasopharyngeal aspirates and from stool samples.[16]

See also

References

  1. PMID 28933406
    . See Table 1.
  2. ^
    PMID 15613317
    .
  3. PMID 28933406
    . See Table 1.
  4. PMID 21994708
    . In all members of Betacoronavirus subgroup A, a haemagglutinin esterase (HE) gene, which encodes a glycoprotein with neuraminate O-acetyl-esterase activity and the active site FGDS, is present downstream to ORF1ab and upstream to S gene (Figure 1).
  5. ^
    PMID 16757599
    .
  6. PMID 20719951
    .
  7. PMID 25926653
    .
  8. bioRxiv 10.1101/2023.04.20.536837
    .
  9. PMID 33234691
    .
  10. PMID 31226023
    .
  11. ^ Leung, Daniel (20 January 2019). "Coronaviruses (including SARS)". Infectious Disease Advisor. Decision Support in Medicine, LLC. Retrieved 1 August 2020.
  12. PMID 26935699
    .
  13. PMID 32938911
    .
  14. PMID 16257260
    .
  15. PMID 16704837
    .
  16. PMID 16447108
    .

External links
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