- Princeton University experts analyze SARS virus bond to receptors
- They found that some rodent species had been repeatedly exposed to the coronavirus
- This allows them to develop a certain level of tolerance to the infection.
- As such, they may represent a potential viral reservoir that can infect humans.
- Team finds that most primates have little adaptation against coronavirus
Rodents can be asymptomatic carriers of viruses such as SARS, a study has warned – meaning the ‘next COVID-19’ may well come from mice.
Researchers at Princeton University conducted genomic analysis of various mammal species, specifically looking at the receptors to which the SARS virus binds.
They found evidence that some rodent species had been repeatedly exposed to coronaviruses such as SARS in the past, making them likely to develop a certain level of resistance.
SARS-CoV-2 – the virus that causes COVID-19 infection – is ‘zoonotic’, meaning it jumped from a non-human animal to humans.
And previous research has shown that Chinese horseshoe bats can play host to themselves without showing extreme symptoms, like many SARS.
Identifying animals that may have similar protection against such infections – and thus serve as viral reservoirs – is critical to preventing future pandemics.
Rodents may be asymptomatic carriers of viruses such as SARS, a study has warned – meaning the ‘next COVID-19’ may well come from mice, as in the one pictured (stock image)
The study was carried out by molecular biologist Sean King and computer scientist Mona Singh of Princeton University in New Jersey.
The two wrote in their paper, ‘Our study suggests that ancestral rodents may have been exposed to recurrent infections with coronaviruses such as SARS.
This, he said, may have allowed them to acquire ‘some form of tolerance or resistance to coronaviruses such as SARS’ as a result of these infections.
‘This raises the tentative possibility that some modern rodent species may be asymptomatic carriers of coronaviruses such as SARS – including those that have yet to be discovered.,
In their investigation, Dr. King and Professor Singh studied the so-called ACE2 receptors that SARS viruses use to gain entry into mammalian cells – a characteristic of the evolution of receptors in different mammal species.
The team found that primates and other mammals not previously known to be SARS hosts have little evidence of past adaptation in ACE2 receptors, which leaves us vulnerable to symptomatic cases of the disease today.
Among rodents, however, genomic analysis of both uncovered a pattern of rapid evolution at the ACE2 binding interface – evidenced by greater diversity in the amino acid sequences that code for the receptor.
This suggests that some rodent species were likely to have been repeatedly exposed to coronaviruses such as SARS during their evolution and, as a result, may have acquired a form of tolerance to these types of infections.
In their investigation, Dr. King and Professor Singh studied the so-called ACE2 receptors that SARS viruses use to gain entry into mammalian cells – a characteristic of the evolution of receptors in different mammal species. Image: a SARS-CoV-2 spike protein (red) bound to an ACE2 receptor (blue), allowing it to enter the cell (as seen in background)
‘It will be important to continue to explore adaptations in coronavirus animal hosts’ […] To understand which animals may have adapted tolerance mechanisms through ancient exposure and may have been carriers of viruses such as SARS,’ the duo began.
Such studies, he continued, would help us ‘find those who are vulnerable symptomatic hosts, as humans have unfortunately proven.’
The full findings of the study were published in the journal PLOS Computational Biology,
Zoonotic diseases: These are viruses that usually start in wild animals that can pass on to other species and survive
Zoonotic diseases are capable of passing from one species to another.
The infectious agent – called a pathogen – is able to cross the species boundary in these diseases and still survive.
They range in vigor, and are often less dangerous in one species than another.
They rely on long and direct contact with a variety of animals in order to be successful.
Common examples are strains of influenza that have adapted to survive in humans from various different host animals.
H5N1, H7N9 and H5N6 are all strains of avian influenza that originated in birds and infected humans.
These cases are rare but outbreaks occur when a person is in direct contact with infected animals for a long time.
The flu strain is also unable to pass from human to human once a person is infected.
The 2009 swine flu outbreak – H1N1 – was considered a pandemic and governments spent millions developing ‘Tamiflu’ to stop the spread of the disease.
Influenza is zoonotic because, as a virus, it can grow rapidly and change its shape and structure.
Examples of other zoonotic diseases such as chlamydia.
Chlamydia is a bacteria with many different strains in the common family.
It is known to occur with certain strains, for example Chlamydia abortus.
This specific bacteria can cause miscarriage in small ruminants, and if it spreads to a human it can cause miscarriage, premature birth and life-threatening diseases in pregnant women.