The ancestor of the coronavirus could have been lurking in animals for millions of years before it jumped to humans, a virologist has claimed.
The coronavirus, known scientifically as SARS-CoV-2, became able to infect humans when it mutated while inside an animal and then jumped across species.
This happened for the first time last year in China and the virus – which turned out to be both fast-spreading and deadly to humans – has since infected at least 110million people and killed 2.4million.
Dr Emilia Skirmuntt, an evolutionary virologist at the University of Oxford, is studying viruses that affect bats and said it was likely they carried a version of the virus for a long time.
Scientists believe that bats passed the virus to another species which then gave it to humans, but Dr Skirmuntt suggested it could have skipped over the intermediary.
What ‘species zero’ was, she told MailOnline, was still unclear. And scientists would probably never pinpoint the exact moment the virus spread from animals to people.
Experts had suggested pangolins could have transmitted the virus to humans, but Dr Skirmuntt said this was unlikely because it appeared to make them sick, too, meaning they wouldn’t be efficient ‘reservoirs’ to incubate the virus.
The origin of the pandemic is still hazy and China has been accused of covering up the true extent of the outbreak and of failing to hand over key data to a World Health Organization team last month.
Emilia Skirmuntt, an Oxford University virologist, said it was very hard to say which animal the virus came from because of the very small number of samples
Dr Skirmuntt told MailOnline: ‘The virus needed to mutate to be able to jump to humans.
‘The ancestor of this coronavirus was an animal species which were reservoirs for millions of years and then there was some mutations which made it more efficient with infecting other species and humans. That’s how we got SARS-CoV-2.’
She disputed the theory that pangolins might have been the intermediate species between bats and humans.
Bats are known to incubate viruses that are relatively harmless to them but can be dangerous to people or other animals, such as the Nipah virus.
‘With pangolins we have seen similar coronaviruses,’ she said.
‘The problem is the coronaviruses we have seen in them, made them sick and that shouldn’t happen with reservoir species.
‘The long term co-evolution makes the pathogen show more symptoms upon infection.
‘Only one protein of coronavirus seen in pangolins is more than 90 per cent similar to SARS-CoV-2, and it should be a bigger proportion to really say that is the intermediate species.’
Bats are likely to have been the source of the Covid-19 coronavirus, scientists say, because they are known to carry similar viruses without getting sick from them (stock image)
‘WE MAY NEVER FIND COVID’S PATIENT ZERO’, VIROLOGIST SAYS
Scientists are still trying to identify patient zero – or the first person to be infected with the virus SARS-CoV-2 sparking the pandemic.
Emilia Skirmuntt, an evolutionary virologist, fears they will never be identified, saying the virus would have only impacted small communities at first making it tricky to identify.
‘It will be very hard to find it,’ she told MailOnline.
‘Most of the pandemics have certain stages. There is always a stage where we cannot see the pathogen because it’s spreading in small communities.
‘It might be that we will never know who patient zero was.’
She added the evidence currently pointed to an infection from animals, rather than a lab escape.
‘We know right now that there is more evidence pointing at the natural source of infection that the leak from the lab.
‘These viruses tend to jump from animals to humans.
‘Scientists expected the pandemic caused by coronavirus right now for more than several years. We have research and papers on that so it’s not something unexpected.’
Dr Skirmuntt added: ‘It might have been also just a bat which jumped from bat to human. It’s very hard to say with no samples available from all of these animals.’
She said when other coronaviruses — different to the one that causes Covid — have infected humans previously, they had arrived via an intermediate species.
Scientists suspect the same route was traveled by SARS-CoV-2 but it is hard to be sure because the beginning of the pandemic is poorly documented.
World Health Organization microbiologist Dominic Dwyer, who was part of the investigative team sent to China, said authorities in the country had refused to hand over data from early cases in the pandemic.
The WHO asked for details on the first 174 cases detected in Wuhan in early December 2019, half of which were connected to the seafood market, but were only handed a summary.
‘That’s why we’ve persisted to ask for that,’ Professor Dwyer said. ‘Why that doesn’t happen, I couldn’t comment.
‘Whether it’s political or time or it’s difficult… But whether there are any other reasons why the data isn’t available, I don’t know. One would only speculate.’
And the importance of animals in the spread of disease continues to be investigated, with a study published in the journal Nature Communications this week suggesting that the next pandemic could come from hedgehogs.
UK researchers used machine learning to predict associations between 411 strains of coronavirus and 876 potential mammal host species.
Their model ‘implicated’ the common hedgehog, the European rabbit and the domestic cat as possible hosts for new coronaviruses.
It also highlighted the lesser Asiatic yellow bat as a possible source, which is already known to host coronaviruses that are common in East Asia.
The University of Liverpool team said in their paper: ‘Our results demonstrate the large under-appreciation of the potential scale of novel coronavirus generation in wild and domesticated animal.
‘These hosts represent new targets for surveillance of novel human pathogenic coronaviruses.’
They said the emergence of new strains is an ‘immediate threat to public health’.
There may be more than 30 times more host species for coronaviruses than currently known, they say, which could all potentially harbour new strains of Covid-19.
In addition, they estimate that there are over 40 times more mammal species with four or more coronavirus strains than has previously been observed.
Some mammals identified in the study as potential hosts for new coronavirus strains – like horseshoe bats, palm civets and pangolins – have already been linked to either SARS-CoV-1, which caused the 2003 SARS outbreak, or SARS-CoV-2, which causes Covid-19.
CORONAVIRUS IS MUTATING SLOWER THAN ANTICIPATED AND VARIANTS ARE NOT A CAUSE FOR PANIC
Coronavirus is mutating more slowly than expected and variants are not a cause for panic, an evolutionary virologist has said.
Many different strains of the virus have already been identified, but only a few are triggering concern among scientists.
They include the South African strain and Brazilian strain, which both have the E484K mutation that could make vaccines less effective.
Dr Emilia Skirmuntt told MailOnline the new variants should not be a source of panic.
‘We should observe them. We knew that it would happen.
‘In fact this coronavirus is evolving and mutating slower than we expected from this kind of viruses.
‘We should be cautious but we will see new mutations and new variants. It’s not unexpected.’
She added that the E484K mutation, seen in several new variants, could help to predict the design of future vaccines.
‘What is interesting is that this mutation appears more and more in different variants which helps us because we can predict how the virus will mutate further.
‘Right now we can see the progression and the evolution of this virus.’
T CELL IMMUNITY IS MUCH MORE IMPORTANT THAN ANTIBODIES, BUT IS HARDER TO DETECT
Immunity from T-cells is far more effective than that from antibodies, a scientist has said, but this is much harder to detect.
T-cells help are a part of the immune system that destroys infected cells, curbing the spread of the virus in those suffering from the disease, and help to build antibodies – virus-fighting proteins.
Both are triggered by the coronavirus vaccines, which spark immunity and stop an infection if someone is exposed to the virus.
Scientists have recently raised the alarm over variants of the virus which appear to be better able to dodge antibodies, possibly opening the door to re-infection.
But Dr Emilia Skirmuntt, an evolutionary virologist at the University of Oxford, says these must be considered alongside T-cells to fully understand the impact of variants on immunity from vaccines.
‘We found out that the T-cell immunity is more important than antibody immunity,’ she said.
‘T-cells are more important because they are the immune memory and they can remember the pathogen.
‘Most of our tests after vaccinations and infection is based on antibodies because they are much easier to detect. T-cells are not that easy to detect.
‘We cannot really tell how T-cell memory works in case of infection or vaccination but we know it’s much more important.
‘T-cells are the major defence against Coronaviruses. That probably means that are immune memory will last much longer than we expected in the beginning.’
Although there is concern over new variants, research shows the current crop of vaccines still prevent anyone infected with them from developing a severe infection or dying from the disease.