A new antiviral compound can interfere with the key feature used by many viruses to invade cells, thereby rendering them unable to infect humans.

The chemical compound MM3122, developed by researchers at the Washington School of Medicine in St. Louis, United States could help prevent Covid-19 infections or even reduce the severity of the disease, if administered early after the infection.

In a new paper published in the journal Proceedings of the National Academy of Sciences, the researchers have revealed that the compound successfully prevented viruses from invading the host’s cells, when tested on mice.

Intriguingly, the compound acts on the same protein found in humans called the transmembrane serine protease 2 (TMPRSS2), harnessed by the SARS-CoV-2 virus to invade and infect human cells.

“Great vaccines are now available for SARS-CoV-2, but we still need effective antiviral medications to help curb the severity of this pandemic,” said James W. Janetka, senior author of the paper and a professor of biochemistry & molecular biophysics at St. Louis’s Washington University.

MM3122 compound (yellow) blocking the protein TMPRSS2 from being harnessed by viruses. Credit: James Janetka/St. Louis Washington School of Medicine .

According to the researchers, they are currently evaluating the therapeutic window within which the compound can be administered to a host to effectively protect it against viral infections.

Ultimately, they are aiming to develop an inhibitor containing the compound that can be administered orally and that can be part of our already existing inhibitors against Covid-19.

The drug derived from MM3122 works by blocking the TMPRSS2 protein and another related protein called matriptase, which is found on the cell surfaces in the lung. Many viruses such as influenza and SARS-CoV-2 are dependent on these proteins to infect host cells and spread throughout the lung. MM3122 blocks the TMPRSS2 protein from releasing certain enzymes crucial for viruses to spread.

Most inhibitors stop viral infections by blocking infected cells from replicating. This means the inhibitors do not stop the virus from infecting cells. The new drug takes a novel approach and stops the virus from invading cells in the first place.

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