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November 2020 − Exploring Life
Image correction: if you say virus, people think of disease, transmission, pandemic; but microbes can do so much more, and they can certainly do good.
Drivers of Evolution
As parasites, they multiply inside the host cell which then either dies or undergoes change. Therefore, viruses apply high selective pressure and thus ensure genetic variation. Virologists suspect that viruses brought about the different sexes, as well as sexuality. Viruses are not limited to inserting themselves into a genome; they also serve as transport vehicles for sections of genetic material from other living organisms which they subsequently smuggle into the human genome. This much is certain: 145 human genes originate from organisms like bacteria, plants, fungi and animals. The human genome revealed: more than eight percent of human DNA originates from viruses. Bremen-based marine biologist Antje Boetius concludes: “Viruses are the accelerators of evolution”
An Alternative to Antibiotics
What if antibiotics (due to multi-drug resistant pathogens) will no longer work? Viruses may be an alternative – particularly phages. Natural enemies of bacteria, they occur in every environment where bacteria reside, even inside the human body. Félix d’Hérelle discovered their significance as early as 1917: phages exclusively infect bacteria and propagate inside their host cell until it bursts and disappears. At the same time, phages are specialists that only react with specific bacteria. At the present time, they are not approved for therapeutic purposes in Germany. The country of Georgia is considered the global center of phage research; however, pilot studies have now started in Germany, with the Fraunhofer Institute and the Charité participating in “Phage4cure”.
Coast Guard on Patrol
Viruses are ubiquitous – they even exist in the vast depths of the oceans. One teaspoon of sea water teems with up to one hundred million viruses. Canadian marine biologists calculated that every second, 1023 viral infections take place in the oceans. This number alone illustrates the influence that viruses have on the marine ecosystem. In the US state of Maine, researchers observed how the excessive growth of the algae species Emiliana huxleyi is slowed by a virus. Their conclusion: viruses act like the Coast Guard. Since they are host-specific, they control species that threaten to dominate a habitat. Bremen-based microbiologist Rudolf Amann knows: “Viruses kill the victors” and thus ensure the continued diversity of species.
Active Against Cancer Cells
Some cancer patients are cured after an infection with a cold (Adeno) virus. The background behind this chance phenomenon is the tendency of certain viruses to feel at home inside cancer cells and propagate in such a way that tumor cells are destroyed. The German Cancer Research Centre in Heidelberg studies the potential of “oncolytic virotherapy”, which, at this time, is still in its infancy. To date, successful non-clinical studies, as well as initial clinical studies, have been completed. The first oncolytic virus therapy was approved in 2015 – against skin cancer. The University Clinic Ulm plans to combine biotechnology and genetics in order to transport the cancer killers directly via the bloodstream to metastasizing cells.
Save the Chestnut!
Along the East Coast of the United States, almost the entire population of chestnuts (Castanea dentata) has been destroyed by the Asian chestnut blight fungus Cryphonectria parasitica. A more moderate form of this illness, commonly known as chestnut blight, is now moving across the European Alps. A specific therapy has recently been developed in Switzerland. The therapy harnesses hypoviruses in such a way that sick trees are inoculated with a virus-bearing fungus. The sores of the tree trunks must be painted individually. While this type of biological pest control is cumbersome, it is in fact successful. Researchers were delighted to observe that the virus subsequently spread to other trees naturally (perhaps via insects?).