We all have had a viral disease at least once in our lives. It could have been the usual seasonal flu or something more serious. But rarely does any of us think, writing out another sick leave from a therapist, that the mechanism of action of many of these diseases and their origin remain as much a mystery behind seven seals as hundreds of years ago …
Microscopic killers
In structure, the virus resembles a disposable syringe. As soon as he touches a living cell, he introduces a “spring” of his DNA into it. After that, the cells begin to work as a pest, producing more and more microscopic "syringes" filled with death.
Viruses were discovered at the end of the 19th century, and since then over five thousand species have been identified and described. It is believed that there are many more - millions, but we pay attention only to those that threaten health. For example, today they write a lot about the Ebola virus, which was discovered in 1976 and against which there is still no reliable cure (depending on the strain, from 60 to 90% of those infected die in terrible agony). There are others, no less dangerous.
The origin of viruses remains a mystery. Evolutionary biologists consider three equivalent hypotheses. First hypothesis: viruses were once small cells that parasitize larger ones; over time, they lost genes that were "superfluous" in the parasitic lifestyle. Second, viruses could have emerged from DNA fragments that were “released” from the genome of a larger organism. And third: viruses arose from complex complexes of proteins and nucleic acids at the same time as the first living cells, remaining dependent on the last billions of years.
None of the hypotheses can be supported by facts, since viruses do not leave any fossil remains, and their relationship can only be studied by molecular phylogenetic methods. She, for her part, reports that the viruses are unlikely to have a common ancestor, since there are very significant differences in the organization of the genetic material between their groups.
A popular joke among microbiologists is that viruses are real aliens. Although viruses are built on the same genetic code as other living things, there is too much alien and deadly in them. And as you know, in every joke there is only a fraction of a joke.
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The Spaniard Mystery
One of the most mysterious viruses is the causative agent of the notorious "Spanish flu". It appeared in May 1918 and quickly covered the whole of Europe, overtaking the number of victims killed in the First World War. In eighteen months, a pandemic of this flu has claimed the lives of over forty million people out of five hundred million who become ill. The most remarkable thing is that the “risk group” was not children and the elderly, as is the case with other viral diseases, but young and relatively healthy people aged 20 to 40 years. The development of the disease looked terrible: the faces of people turned blue, the patients burst into a violent cough, then intrapulmonary bleeding began, as a result of which the patient literally choked with his blood. Despite strict quarantine measures, it was not possible to stop the pandemic - it itself faded away by the end of 1919.
When scientists learned to decipher the genome, the idea arose to study the "Spanish flu", because for a long time it was believed that it was some kind of special unique strain of influenza. The sample was obtained from the corpse of an Alaskan native, buried in permafrost. The study was conducted in February 2001, but the result puzzled scientists: "Spanish flu" was no different from the less dangerous pandemic influenza viruses known today. Moreover, it turned out that the virus entered Europe several years before the first deadly outbreak and spread in isolated groups. Then a minor mutation occurred, and the virus became deadly.
Where did he come from? It was then that the assumption arose that the "Spaniard" could fly to us from space - inside the Tunguska meteorite, which fell to Earth in June 1908.
Guided panspermia
The alien hypothesis of the origin of viruses, although considered marginal, is being discussed at a very authoritative scientific level. It was first formulated by the American biophysicists Francis Crick and Leslie Orgel. In 1973, they published an article in which they argued that life on Earth arose as a result of controlled panspermia, that is, someone deliberately brought protoorganisms to our planet, which subsequently developed into higher biological forms. Perhaps, biophysicists noted, this was done after some kind of global catastrophe that befell the “parental” civilization, or, conversely, the aliens were going to transform our world to their standards for future colonization. Two main arguments are given in favor of this unusual idea - the universality of the genetic code and the significant role of molybdenum in some enzymes. Molybdenum is a very rare element in the solar system. According to the authors of the idea, the "parent" civilization lived near a star enriched with molybdenum.
Within the framework of the hypothesis of controlled panspermia, the answer to the question of the origin of viruses finds its place. They could serve as a kind of biological robots, which with the help of their DNA corrected evolution in the right direction. However, over millions of years, the original program began to malfunction, and the microscopic assistant turned into an insidious killer.
At the same time, the hypothesis of random panspermia remains popular. What if no one specially contaminated the Earth with life, but it itself is born in space "incubators" such as cometary nuclei, and then "seeded" on planets? Then viruses can fly to us from space today.
This version of the hypothesis of panspermia and the origin of viruses is adhered to, for example, by the famous British astrobiologist Chandra Wickramasingh. He became famous for having discovered in a meteorite called Polonnaruwa, which is considered part of a comet, a petrified diatom. In support of his calculations, the astrobiologist also refers to a study by colleagues from India who launched a special balloon in April 2005, which took various samples for research at altitudes of 20 to 40 kilometers. As a result of a comprehensive study of the samples, it was found that bacterial colonies exist at such altitudes, with nine of the discovered species existing on Earth, and three are completely new and previously unknown species. What if they really came from space?
Space "Biorisk"
Acceptance of the hypothesis of panspermia is hindered primarily by the opinion that no organism is able to survive in extraterrestrial space under the influence of burning sunlight, penetrating radiation, cold and weightlessness.
To test the panspermia hypothesis, experiments of the Biorisk-MSN series were carried out on the International Space Station. The astronauts placed open containers on the outer surface of the station, into which they placed some types of bacilli, dry eggs, larvae of chironomid mosquitoes, eggs of crustaceans, seeds of higher plants, spores of bacteria and mold fungi. Imagine the surprise of the scientists when they managed to bring almost all samples back to life (only tomato seeds and fish roe died). Most of all, the survival rate of the chironomid mosquitoes was struck - more than 80% of the larvae restored viability (the result was even better than for spores and unicellular organisms!). This means that even multicellular organisms in a state of biological dormancy are able to exist in outer space for a long time. Why can't viruses survive?
Moreover, the recent experiment "Test", during which samples were collected from the outer surface of the windows of the International Space Station, showed that it contains traces of marine plankton (!!!), but plankton could not have been brought to Baikonur, from where the blocks of this station went into orbit. It turns out that the search for aliens should not be limited to space distances. It is possible that they are already here - inside you and me.
Anton Pervushin