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Coronavirus: The Origin Story

In recent years, animal-to-human crossovers have been observed with Nipha virus in Malaysia, Ebola and Marburg viruses in Africa. SARS-CoV-2 is just one among three 21st century animal-to-human Coronavirus spillover events. Considering the high rate of mutation among RNA viruses, the number of animal coronaviruses, and the mixing of animals into densely populated areas spillover is not unexpected.

Coronavirus was first identified in the 1960s by Tyrrel and Byone1. Its pathogenicity, for the most part, is considered low, occasionally leading to acute upper respiratory infection in infants, young adults, elderly and immunocompromised patients. The family is taxonomically subdivided into alpha-, beta-, gamma- and deltacoronavirus known to cause disease in human and non-human animals. Prior to SARS-CoV-2, seven Coronavirus strains were known to cause mild to moderate respiratory infections similar to the common cold in humans (see table) 3.

 

Alphacoronavirus

 

Human Coronavirus species

 

229E, NL6 (alpha coronavirus) and OC43, HKU1 (non-SARS human betacoronavirus) common causes of human infections worldwide

 

 

 

Betacoronavirus

 

Non-SARS human species

MERS-CoV

 

Other human coronaviruses from animal spillover

SARS-CoV

SARS-CoV-2

Novel coronavirus that causes COVID-19


Gammacoronavirus

Primarily
avian coronavirus
(IBV)

Avian virus primarily affecting chickens; causative agent for infectious bronchitis virus (IBV)


Deltacoronavirus

Primarily avian;
also detected in marine mammals

 Recently discovered
avian (songbird)
coronavirus

Human Coronavirus (HCoV) is a common cause of respiratory infection worldwide. CoV 229E and OC43 have a prevalence rate of 3-11% among hospitalized elderly patients4 . They cause approximately 25% of colds similar to those caused by the rhinoviruses5. Severe Acute Respiratory Syndrome (SARS) first reported in 2002 and Middle East Respiratory Syndrome (MERS) first reported in 2012 cause severe respiratory infections in humans. Both are zoonotic pathogens suspected to have originated in bats. Coronaviruses that are highly pathogenic in humans are a 21st century phenomenon beginning with the emergence of SARS and MERS6. However, antibodies detected in camel serum samples dating as far back as 1983 suggest MERS may have emerged decades before the 2012 outbreak7. Phylogenetic analysis indicate the virus responsible for coronavirus-associated acute respiratory disease (COVID-19), is closely related to the 2002 virus8.

The limited numbers of BSL-3 and BSL-4 facilities available is a big barrier against the timely development of effective treatments for emerging public health threats such as COVID-19. Recombinant technologies offer tools to accelerate the development of rapid quantitative tests for viral infectivity outside of strict BSL-3 biocontainment9 requirements. For example, neutralization assays using pseudotyped viruses instead of live pathogens, are cost-effective BSL-2 tools for preclinical research and development. Vesicular stomatitis virus (VSV) pseudotyped to express the Coronavirus Spike (s) protein is an effective platform for evaluating the efficacy of antiviral candidates that target Spike-mediated infectivity. Using Luciferase fluorescent signals, the rVSV platforms can be used to screen the neutralization potency of drugs and therapeutics.

At IBT Bioservices our mission is to deliver high quality discovery tools and testing services to advance the fight against infectious diseases. Answering the urgent and immediate need for access to effective and affordable research and development tools, we now offer pseudotyped assay to test neutralization efficacy against several SARS-CoV-2 variants. We also offer proof-of-concept in vitro and in vivo research services for a range of viral and bacterial pathogens. Contact us for a consultation and a no obligation quote.

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Fig. 1 Survival after challenge with INFV H1N1 A/Pert/261/2009 (Tamiflu-resistant strain). Inoculum 1xLD90=1.0E+05 PFU/mouse
Survival after challenge with INFV H1N1 A/Pert/261/2009 (Tamiflu-resistant strain) 1.0E+05 PFU/mouse
Survival and weight change in BALB/c mice challenged with INFV A/ Texas/36/91 (H1N1) and treated with antiviral Osletamivir Phosphate (Tamiflu)
Lung viral load and Survival (30 % weight loss cut-off) in BALB/c mice challenged with INFV H3N2 A/HK/1/68.

Alpha (UK) – B. 1.1.7 / 501Y.V1

amino acid mutations: del69–70 HV, del144 Y, N501Y, A570D, D614G, P681H, T761I, S982A, D1118H

Beta (South Africa) – B.1.351

amino acid mutations: K417N, E484K, N501Y, D614G, A701V

Gamma (Brazil) – P.1

amino acid mutations: L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I

Epsilon (Ca, USA) B.1.427

amino acid mutations: L452R, D614G

SARS-CoV-2 Parental Strain Wild Type (Wuhan)
SARS-CoV-2 D614G Variant

amino acid mutations: D614G

Epsilon (Ca, USA) B.1.429

amino acid mutations: S13I, W152C, L452R, D614G

SARS-CoV-2 Delta Variant

amino acid mutations: L452R, E484Q