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4. Jan. 2021
Karel Skubnik and his colleagues, led by structural virologist Pavel Plevka from CEITEC Masaryk University (MU), described the mechanism of genome release of honeybee viruses. The research team disproved the previous hypothesis regarding the infection process that takes place during the invasion of the host cells. These remarkable results were achieved thanks to the combination of cryo-electron microscopy and protein simulations performed by the research group of Robert Vacha. The study was published in January 2021 in scientific journal Science Advances.
Over the last seventy years, there has been a significant decline in the Western honeybee population in North America as well as in Europe. Honeybee viruses, which are the main cause of the bee colony collapse, are cellular parasites consisting of a genome carrying genetic information and a protein envelope.
We can think of the virus as a message in a bottle. The life cycle of the virus is very similar to sending messages in a bottle. The message, in this case the genetic information of the virus, is first placed in a bottle, in this case a protein capsid that protects it from external influences. As soon as the genetic information gets to its final destination, which is here the host cell, it is necessary that the message gets out of the protective package as quickly as possible to deliver the message to the host cell. The release of the genome from the protein capsid is one of the most critical steps for successful invasion of the host cells.
The main subject of this research study was the mechanism of bee virus genome release. "Until now, it has been assumed that when the genome is released, a small hole forms in the protein envelope of the virus and through this opening the genome gradually passes out. But our results show that bee viruses use a much faster way of releasing the genome, which causes the protein capsid to rupture suddenly and to launch the genome into the host cell quickly,” describes Karel Skubnik his discovery.
The researchers found out that the mechanism of honeybee virus genome release does not resemble sending message in the bottle, as previously thought, but rather mimics opening of a Kinder Surprise egg. This fast and sudden release of the virus genome reduces the likelihood of its damage by the enzymes found in extracellular environment. The research team used modern technology of cry-electron microscopy that allowed 130,000 magnification of the virus structure and allowed for calculation of its three-dimensional structure with atomic resolution. Subsequently, protein simulations were performed by the research group of Robert Vacha. Understanding the mechanism of how honeybee viruses are infecting host cells can help with the design of new substances that could prevent viral infection in Western honeybees.