MOSCOW, August 31. /TASS/. Specialists of the Institute of Bioorganic Chemistry of the Russian Academy of Sciences have grown a mouse cell culture capable of producing large amounts of antibodies to one of the key proteins of the coronavirus, potentially suitable for COVID-19 treatment and use in diagnostic systems. The description of this cell culture was published in an article at the bioRxiv electronic library.

"We created a new monoclonal antibody which can be used both to study SARS-CoV-2 and to create diagnostic systems and therapies capable of helping patients with COVID-19. The main advantage of our antibodies is the fact that they can be produced in almost unlimited numbers for a very small amount of money," the researchers wrote.

Over the past six months biologists worldwide discovered dozens of various antibodies capable of attaching themselves to the key part of the coronavirus, the so-called S-protein, which directly participated in the cell infection. Such molecules may be used both to treat COVID-19 and to detect traces of the virus in humans or animals.

Despite a large number of such preparations, almost all of them are produced abroad. A group of scientists headed by Marat Pavlyukov, senior research associate at the Institute of Bioorganic Chemistry of the Russian Academy of Sciences in Moscow, developed one of the first Russian cell cultures capable of mass production of such antibodies.

They are represented by the so-called hybridoma, a cell line obtained as a result of merging of certain types of neoplastic cells and B-lymphocytes, immune system corpuscles, which can produce antibodies. Such a procedure allows "hybrid" cells to divide unlimited number of times and mass-produce antibodies, which is widely used to obtain monoclonal antibodies.

Cheap and selective antibodies

In order to obtain such cells the researchers first prepared a large number of copies of the RBD protein, a key fragment of the S-protein, which directly joins the ACE2 receptor on the surface of human cells and lets the coronavirus inside. Having obtained these molecules, biologists administered them to several mice and waited for the formation of the immune reaction.

These experiments demonstrated that the RBD protein molecules by themselves caused a massive immune reaction which allowed the scientists to trap a large number of antibody-producing cells and select the most effective and convenient ones. Having fused them with myeloma cells, the researchers obtained over a hundred variations of antibody-producing hybrids.

Having selected 14 most interesting versions, the scientists attempted to use the antibodies produced to create prototypes of test systems, aimed to detect the coronavirus S-protein traces in a solution or a biological sample. During these experiments the scientists singled out one cell culture whose antibodies could recognize the full version of the coronavirus membrane and were highly selective at that.

Using this cell variation, the scientists traced the appearance of mutations in the genome of its descendants which led to small changes in the antibody structure and sometimes improved its properties. One of such variants, dubbed 11/9, was interacting much more actively with the coronavirus particles than its "predecessor."

For instance, subsequent experiments showed that the antibodies decreased the number of coronavirus models inside the human cell culture at least twice. Additionally they recognized the S-protein both in its pure form and in the format, in which it exists inside the infected cells.

The researchers hope that a simple technology of the production of the antibodies and their high effectiveness will allow making the diagnostic systems necessary to trace the spread of the coronavirus much cheaper. Additionally, the team of scientists presumes that the RBD protein may be used as one of the vaccine components, but its safety for humans is yet to be established.