ANNALS OF IBADAN POSTGRADUATE MEDICINE
EDITORIAL ON 2019 NOVEL CORONAVIRUS
The outbreak of 2019 Novel Coronavirus (2019- nCoV) is still recent, and new knowledge is being discovered daily about the novel virus as well as the disease it causes. The objective of this editorial is to update us on what is known to date about 2019-nCoV.
In December 2019, the outbreak of a new disease began in Wuhan, Hubei Province, China. The causative agent of the new disease outbreak was identified as 2019 novel Coronavirus 2019 (2019-nCoV) and it was named Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). On February 11, 2020, the WHO officially named the new disease - Coronavirus disease 2019 (COVID-19) 1,2 . Coronaviruses are predominant among different species of animals, such as cats, camels, cattle and bats. However, on rare occasions, some types can be transferred to humans and subsequently spread among people 3 . Some of the common human coronaviruses are HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, which cause milder diseases, as well as other types, including Middle East Respiratory Syndrome Coronavirus (MERS-CoV), SARS-CoV and the new SARS-CoV-2, which causes more fatal diseases 4 .
Coronaviruses (CoVs) (order Nidovirales, family Coronaviridae, and subfamily Coronavirinae) are large, enveloped, positive-sense, single-stranded RNA viruses. Based on genetic and antigenic criteria, CoVs have been organized into three groups: -CoVs, -CoVs, and - CoVs. SARS-CoV-2 is a beta coronavirus, similar to MERS-CoV and SARS-CoV5 . The coronaviral genome encodes four major structural proteins: the spike (S) protein, nucleocapsid (N) protein, membrane (M) protein, and envelope (E) protein, all of which are required to produce a structurally complete viral particle 5 .
When viewed under an electron microscope, the ultrastructural morphology of the virus shows spiky projections on its surface, giving it an appearance of a corona around the virion. Hence, the appearance gave it the name “coronavirus”.
Source and spread
Coronaviruses primarily infect birds and mammals, but some of them have crossed the animal-human species barrier and progressed to establish zoonotic diseases in humans 5 . The initial victims of the outbreak of SARS-CoV-2 in Wuhan, China, had some links with seafood and live animal markets; thus, indicating a likely animal-to-human mode of transmission. However, the subsequent transmission of the virus was through human to human spread 3,7 .