Four HCoV-OC43 genotypes (A to D) have been identified, with genotype D most likely arising from genetic recombination. The complete genome sequencing of genotypes C and D and bootscan analysis shows recombination events between genotypes B and C in the generation of genotype D. Of 29 viral variants identified, none belong to the more ancient genotype A. Molecular clock analysis using spike and nucleocapsidgenes dates the most recent common ancestor of all genotypes to the 1950s. Genotype B and C date to the 1980s. Genotype B to the 1990s, and genotype C to the late 1990s to early 2000s. The recombinant genotype D variants were detected as early as 2004.[5]
Comparison of HCoV-OC43 with the most closely related strain of Betacoronavirus 1 species, bovine coronavirus BCoV, indicated that they had a most recent common ancestor in the late 19th century, with several methods yielding most probable dates around 1890, leading authors to speculate that an introduction of the former strain to the human population might have caused the 1889–1890 pandemic, which at the time was attributed to influenza.[9] The COVID-19 pandemic brought further evidence of a link, as the 1889–1890 pandemic produced symptoms closer to those associated with COVID-19 (the infection caused by the SARS-CoV-2 betacoronavirus) than to influenza.[10] Brüssow, in August 2021, referred to the evidence that OC43 caused the 1889–1890 outbreak as "indirect, albeit weak" and was "conjectural", yet the 1889 epidemic was the best historical record to make predictions about the current COVID-19 path due to the similar "clinical and epidemiological characteristics".[11]
The origin of HCoV-OC43 is uncertain, but it is thought that it may have originated in rodents, then passed through cattle as intermediate hosts.[12] A deletion from BCoV to HCoV-OC43 may have taken place for the interspecies transmission event from bovines to humans.[9]
If HCoV-OC43 was indeed the pathogen responsible for the 1889–1890 pandemic, which resembled the COVID-19 pandemic, severe disease was much more common and mortality much higher in populations that had not previously been exposed.[16]
Coronaviruses have a worldwide distribution, causing 10–15% of common cold cases (the virus most commonly implicated in the common cold is a rhinovirus, found in 30–50% of cases).[17] Infections show a seasonal pattern with most cases occurring in the winter months in temperate climates, and summer and spring in warm climates.[18][17][19][20] As OC43 is capable of infecting porcine tissues,[21] it is likely that pigs serve as a zoonotic reservoir for this disease, reinfecting the human population.
^Lee, Paul (2007). Molecular epidemiology of human coronavirus OC43 in Hong Kong (Thesis). The University of Hong Kong Libraries. doi:10.5353/th_b4501128 (inactive 2024-04-12). hdl:10722/131538.{{cite thesis}}: CS1 maint: DOI inactive as of April 2024 (link)
^Li, Fang (2016-09-29). "Structure, Function, and Evolution of Coronavirus Spike Proteins". Annual Review of Virology. 3 (1): 237–261. doi:10.1146/annurev-virology-110615-042301. PMC5457962. PMID27578435. BCoV S1-NTD does not recognize galactose as galectins do. Instead, it recognizes 5-N-acetyl-9-O-acetylneuraminic acid (Neu5,9Ac2) (30, 43). The same sugar receptor is also recognized by human coronavirus OC43 (43, 99). OC43 and BCoV are closely related genetically, and OC43 might have resulted from zoonotic spillover of BCoV (100, 101).
^Woo, Patrick C. Y.; Huang, Yi; Lau, Susanna K. P.; Yuen, Kwok-Yung (2010-08-24). "Coronavirus Genomics and Bioinformatics Analysis". Viruses. 2 (8): 1804–20. doi:10.3390/v2081803. PMC3185738. PMID21994708. 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).
^Knudsen, Jeppe Kyhne (13 August 2020). "Overraskende opdagelse: Coronavirus har tidligere lagt verden ned" [Surprising discovery: Coronavirus has previously brought down the world]. DR (in Danish). Retrieved 13 August 2020. A presumed influenza pandemic in 1889 was actually caused by coronavirus, Danish research shows.
^Mahony, James B. (2007). "Coronaviruses". In Murray, Patrick R.; Baron, Ellen Jo; Jorgensen, James H.; Landry, Marie Louise; Pfaller, Michael A. (eds.). Manual of Clinical Microbiology (9th ed.). Washington D.C.: ASM Press. pp. 1414–23. ISBN978-1-55581-371-0.
^Pyrc, K.; Berkhout, B.; Van Der Hoek, L. (2007). "Antiviral Strategies Against Human Coronaviruses". Infectious Disorders Drug Targets. 7 (1): 59–66. doi:10.2174/187152607780090757. PMID17346212.
