Amazing Virus Facts
Virus (lat. Virus - poison) is a non-cellular infectious agent that can only be reproduced inside living cells. Viruses infect all types of organisms, from plants and animals to bacteria and archaea (bacteria viruses are usually called bacteriophages). Also found viruses that can replicate only in the presence of other viruses (satellite viruses).
Since Dmitry Ivanovsky’s article describing a non-bacterial pathogen of tobacco plants and the discovery of tobacco mosaic virus in 1898 by Martin Beyerin in 1892, more than 6,000 virus types have been described in detail, although they suggest that there are more than one hundred million. Viruses are found in almost every ecosystem on Earth, they are the most numerous biological form. The study of viruses is engaged in the science of virology, a section of microbiology.
While the virus is in the extracellular environment or in the process of infecting a cell, it exists as an independent particle. Viral particles (virions) consist of two or three components: genetic material in the form of DNA or RNA (some, for example mimiviruses, have both types of molecules); protein shell (capsid), protecting these molecules, and, in some cases, additional lipid membranes. The presence of a capsid distinguishes viruses from virus-like infectious nucleic acids, viroids. Depending on the type of nucleic acid present in the genetic material, DNA-containing viruses and RNA-containing viruses are isolated; Baltimore virus classification is based on this principle. Previously, viruses were also mistakenly attributed to prions, but later it turned out that these pathogens are special infectious proteins and do not contain nucleic acids. The shape of viruses ranges from simple spiral and icosahedral to more complex structures. The size of an average virus is about one hundredth the size of an average bacterium. Most viruses are too small to be clearly visible under a light microscope.
Viruses are obligate parasites, as they are not able to multiply outside the cell. Outside the cell, viral particles do not show signs of life and behave like particles of biopolymers. Viruses differ from living parasitic organisms by the complete absence of basic and energy metabolism and the absence of the most complex element of living systems - the translation apparatus (protein synthesis), the degree of complexity of which exceeds that of the viruses themselves.
The appearance of viruses on the evolutionary tree of life is unclear: some of them could have been formed from plasmids, small DNA molecules capable of being transferred from one cell to another, while others could have come from bacteria. In evolution, viruses are an important means of horizontal gene transfer, causing genetic diversity. Some consider viruses to be a special form of life, as they have genetic material, are able to create similar viruses of their own, and evolve by natural selection. However, viruses lack important characteristics (such as cell structure), without which they cannot be classified as living. Since they possess some, but not all properties, viruses are described as “organisms on the edge of life”.
Viruses spread in many ways: plant viruses are often transmitted from plant to plant by insects that feed on plant sap, such as aphids; animal viruses can spread by blood-sucking insects, such organisms are known as vectors. Influenza virus spreads through coughing and sneezing. Norovirus and rotavirus, which usually cause viral gastroenteritis, are transmitted through the fecal-oral route through contact with contaminated food or water. HIV is one of several sexually transmitted viruses and transfused infected blood. Each virus has a specific host specificity, determined by the types of cells it can infect. The host circle may be narrow or, if the virus infects many species, wide.
In animals, viral infections cause an immune response, which most often leads to the destruction of the pathogenic virus. An immune response can also be triggered by vaccines that give active acquired immunity against a specific viral infection. However, some viruses, including the human immunodeficiency virus and the causative agents of viral hepatitis, manage to escape the immune response, causing a chronic disease. Antibiotics do not act on viruses, but several antiviral drugs have been developed.
Are there really giant viruses that are larger than the size of bacteria? Is it true that 2/5 of human DNA consists of remnants of ancient viruses that infected cells of our ancestors at different stages? It will be really interesting ...
Plant viruses are harmless to animals, and most animal viruses are safe for humans.
Viruses are not living beings. They have no cells, they do not know how to convert food into energy, and without a “host,” these are just small bunches of chemicals. Viruses are also not something dead - they have genes, they multiply, natural selection processes work for them.
It is believed that approximately 2/5 of human DNA consists of the remnants of ancient viruses that infected cells of our ancestors at various stages.
To date, there are more than 2,000 variants of the influenza virus, which differ in the antigenic spectrum.
In 1859, an Australian farmer imported rabbits from England to create a small population and hunt them.
The lack of natural enemies and ideal conditions for life and breeding all year round caused uncontrolled growth of the rabbit population, which led to the extinction of many species of native plants.
They tried to fight with rabbits by shooting, bursting holes, poisons, building mesh barriers, but all is useless. Finally, in the middle of the 20th century, the virus myxomatosis was spread among them, which reduced the population from 600 million to 100 million. However, the surviving individuals acquired genetic resistance to the virus and again began to actively proliferate.
Viruses are undoubtedly the most numerous biological objects on Earth, and by this indicator they surpass all organisms combined.
Large-sized viruses are called mamaviruses.
Their dimensions often exceed the size of even some bacteria.
Such viruses have satellite viruses.
The so-called mimic is so named because it mimics the behavior and structure of the bacteria.
Some experts believe that it is an intermediate link between bacteria and viruses, others believe that this is a separate form of life.
This virus is characterized by the most voluminous and complex set of DNA among all viruses.
In 1992, scientists traced the source of pneumonia that broke out in England - it turned out that it was a virus hiding inside an amoeba that lives in the towers of a cooling tower (cooling tower). He was so large that at first scientists took him for a bacterium.
Amoebas for viruses are a kind of sandboxes and free dining rooms - they absorb large objects within their reach and are a source of nutrients for bacteria, which inside the amoeba exchange genes with other bacteria and viruses.
The poachers, instead of poison, introduce to their victims a virus that suppresses the victim’s immune system.
Suppressed immunity allows the larva of the parasitic larva to grow inside the victim.
Biologists have found that this virus is more than a hundred million years old, and most likely it has merged with the DNA of the wasp.
When an embryo forms inside a woman, the immune system recognizes a new generation as something foreign.
Thanks to the DNA of the virus that encodes proteins, the fetus is not threatened by immunity.
Via Internet & wiki