Scientists have developed two new drugs to both prevent the COVID-19 infection, and also treat people who have been exposed to the novel coronavirus so that they do not develop severe disease. The peptide-based drugs developed by researchers at QIMR Berghofer Medical Research Institute in Australia are being tested in hamsters at France's pre-clinical and clinical research facility, IDMIT.
Early promising results, published in the journal Nature Cell Discovery, show the drugs are not toxic, and have few side effects.
The drugs are also stable and can be stored at room temperature, which would make them easy to distribute, the researchers said. They target how human cells respond to the SARS-CoV-2 virus, instead of the virus itself.
The first peptide-based drug would be given before exposure to the virus and help boost the efficacy of vaccines, while the second drug would stop the spread of the virus in already infected cells. The discovery of the peptide-based drugs was made possible after the researchers uncovered a previously unknown mode of entry that SARS-CoV-2, the virus that causes COVID-19, exploits to invade cells and cause COVID-19 disease.
Laboratory tests show the first peptide-based drug reduces infection by cloaking the ACE2 receptor protein on human cells.
The SARS-CoV-2 spike protein uses the ACE2 receptor to bind to and invade cells. The virus then latches onto the cloaking peptides, which they mistake for human cells, preventing infection.
The lab tests have also shown that if the virus finds its way into cells, the second peptide-drug can block how the virus hijacks the host cell and replicates, according to the researchers. It also boosts the immune system's ability to recognise the virus, they said.
Senior researcher and Professor, Sudha Rao, said the team was able to develop the drugs after discovering that some people have a chemical tag which acts like a padlock on the ACE2 receptor.
"The tag can either keep the receptor locked or open -- controlling infection. This means people who have the 'padlock-like' tag on their ACE2 receptors will be less susceptible to SARS-CoV-2 and those without the tag are more vulnerable to infection," Rao said.
"Our drugs stop the tag from being removed and also protect the untagged ACE2 receptors from being infected," she explained.
The researchers also found that if the virus invaded the cells it would unlock the tag from the inside, allowing more efficient virus replication.
"Our new peptide-based drugs can keep the padlock closed and prevent infection taking hold," Rao said.
The researchers noted that these are the first known drugs that can operate on dual fronts.
If the clinical trials are successful, the first drug could be given as a therapy alongside vaccination to prevent the virus binding to cells and taking hold, they said. The second peptide could be used to stop the virus replicating in already-infected patients, the researchers added.