Frankfurt am Main. An international team of researchers has identified a new vulnerability in the corona virus. The scientists investigated the enzyme papain-like protease – PLpro for short – in cell culture experiments. This can inhibit the multiplication of the virus and at the same time strengthen the immune system’s immune response, according to the study, which appeared in the journal “Nature”.

Enzyme prevents fighting by killer cells

Researchers from Goethe University Frankfurt and the University Clinic Frankfurt were also involved in the investigations. “We concluded that inhibiting PLpro is a promising therapeutic ‘double strike’ strategy for the treatment of COVID-19,” said Ivan Đikić, director of the Institute of Biochemistry II at the University Hospital Frankfurt, quoted in a statement from the hospital.

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The enzyme PLpro is essential for the multiplication and spread of the coronavirus. It has two functions: First, it ensures the maturation and release of new virus particles, and secondly, it prevents the fight against the body’s own killer cells. It inhibits the formation of type I interferons.

Sars-CoV-2 can suppress immune defense

Type I interferons are messenger substances that are released by body cells infected with viruses. These substances activate natural killer cells, which kill the infected cells. The corona virus can suppress this immune defense using the enzyme PLpro. The Sars CoV-2 pathogen has human cells produce the virus protein for this.

As soon as the researchers blocked PLpro in their cell culture experiments, virus production was inhibited and the innate immune response of human cells was strengthened. “The further development of PLpro-inhibiting substance classes for use in clinical studies is now a central challenge for this therapeutic approach,” said Đikić.