What are coronaviruses?
Coronaviruses are a big group of viruses. They include of a core of genetic material and an envelope with protein spikes surround it. These crown-like spikes on the surface make the viruses appear like a crown which is called Corona in Latin and that is where their name comes from. Coronaviruses have four main sub-groupings: alpha, beta, gamma and delta. Different kinds of Coronaviruses cause gastrointestinal symptoms and respiratory. The symptoms of respiratory disease tend to be mild in most people; they can range from common cold to pneumonia.
According to Centers for Disease Control and Prevention (CDC), there are seven types of coronaviruses that can infect people and they were first identified in the mid-1960s. Four of the human coronaviruses are mild and people commonly get infected with them, include:
229E – alpha coronavirus
NL63 – alpha coronavirus
OC43 – beta coronavirus
HKU1 – beta coronavirus
However, some animal coronaviruses circulating among animals can pass to people, become new human coronavirus and bring more serious outcomes. They include:
SARS-CoV (Severe Acute Respiratory Syndrome beta coronavirus) which is first identified in China in November 2002
MERS-CoV (Middle East Respiratory Syndrome beta coronavirus) which first identified in Saudi Arabia in 2012
The “novel” Coronavirus (2019-nCoV) which is first identified in Wuhan, China.
Where do coronaviruses come from?
Several know types of coronaviruses are circulating in a range of animals including cats, bats, camels and pigs and some of these coronaviruses are zoonotic which means they have the capability of jumping from animals to people. This is called a spillover event.
This could be due to a range of factors such as the increase in contact between animals and humans or the evolvement of viruses in which they combine or mutate with other viruses and create new strains that can infect people. For example, SARS-CoV is known to be transmitted from civet cats and MERS-CoV from camels.
1.2 2019 Novel Coronavirus (2019-nCoV)
What is 2019 Novel Coronavirus?
2019 Novel Coronavirus (2019-nCoV) is a new strain of coronavirus that has not been previously detected in human. It is first identified in an outbreak of respiratory illness reported in December 2019 in Wuhan, China. Out of the first 41 people with pneumonia who were identified as having 2019-nCoV infection by 2 January 2020, two-thirds had been associated with Huanan Seafood Market, the largest wholesale market of live animal and seafood in Jiangshan District, Wuhan, Hubei province, China. According to The Wall Street Journal, among 585 animal specimens taken from the market, 33 showed evidence of 2019- nCoV.
Where does the 2019-nCoV come from?
Coronaviruses are known to circulate in animals and some of them have the capability of transmitting to people. However, the animal reservoir of the 2019-nCoV is still unknown.
When the 2019-nCoV sequence is first available, some researchers found that it has a close relationship to relatives that were found in bats. A report on 23 January of a team led by a coronavirus specialist of the Wuhan Institute of Virology – Shi Zheng-Li – showed that the sequence of 2019-nCoV was 79.5% similar to SARS-CoV and had 96.2% similarity to a bat virus. That is why many scientists suspect there is one or more intermediary host pieces between 2019-nCoV and bats.
Early on, a research team led by Wei Ji, a microbiologist at Peking University Health Science Center School of Basic Medical Sciences in Beijing published a sequence analysis online on the Journal of Medical Virology on 22 January and pointed to snakes as “the most likely wildlife animal reservoir for the 2019-nCoV”. The researchers reported that codons of the 2019-nCoV had the most similarity to those used by two snakes which are the Chinese cobra and the many-banded krait and they noted that snakes were sold at the marketplace of live animals in Wuhan where the first cases were documented. Other scientists, however, pilloried it. According to some specialists, the evidence of the study is pretty weak and that coronavirus infections have been detected only in birds and mammals before, there is no proof that these viruses can infect other species so snakes would be a very unusual host. David Robertson, a virologist at the University of Glasgow, UK said that “Nothing supports snakes being involved”.