Viruses are tiny - what exactly? Scientists say they aren't living creatures, but they come close to life. They aren't real parasites either, but they are need a hostto multiply. Some make you seriously ill, others are easily dealt with by the immune system, and still others are harmless to humans. Some types can even be used. Let's call them particles, which are an integral part of the earth's ecosystem.
Every virus urgently needs its host
Flu viruses, herpes viruses, noroviruses, SARS, the list of viruses is endless. It is said that for every organism there is at least one virus. Regardless of whether you have a cold or are perfectly healthy, the statement “I caught a virus” is always true. Because the electron-microscopically small germs are constantly around us and in us. Outside of cells these are called particle viruses and can't do anything. Just lying in wait until they can get into a cell and multiply there. The fact that the host cell is damaged in the process is not a bad intention, just a bad one Collateral damage.
When it comes to pathogens and microorganisms, the terms bacteria and virus often appear together. In fact, it's two entirely different game types the nature. Because bacteria are cells and therefore independent organisms, viruses are just organic particles with genetic information. They are simply structured particles of nucleic acid, namely ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), surrounded by a protein coat. A typical example of the structure of viruses is shown in the following graphic.
The genetic information (RNA or DNA) is hidden in the nucleic acid, the protein identifies the suitable host cell and attaches itself to its surface. Depending on the type of virus, only the genetic material penetrates the cell interior or the particle fuses with the cell membrane. Now the virus can be multiplied by the host cell, new viruses are released and can infect other cells. Another graphic illustrates the process of virus propagation.
Antivirus measures: Strong immune system, antivirals and vaccinations
We are all virus hosts, including you. Luckily you are not at the mercy of uninvited guests, there is such a thing Immune system with an army of white blood cells (leukocytes). These include B and T lymphocytes and macrophages, which are supposed to destroy the invisible attackers outside of the desired host cell or render them harmless in cells that have already been infected. Sometimes the defense wins and sometimes the virus wins. At best, people don't notice anything about this struggle, at worst a deadly disease takes its course.
antivirals and vaccines
An intact strong immune system can therefore ward off virus attacks. For a long time it was on its own because there was no medicine against viral infections, only the symptoms could be treated. Virus-inhibiting substances are now available for at least some pathogens, which are summarized as antivirals. In addition, vaccines (vaccines) are now available preventive protection form before certain viruses. Think, for example, of the "flu vaccination" against influenza viruses, the tick vaccination against TBE and vaccinations against smallpox, measles and polio.
If the virus infection is over, stay antibodies in the organism back, who can fight this virus immediately in the event of another attack. Therefore, those affected are immune to the pathogen for a certain time or even for life. This effect also occurs through vaccination.
However, many viruses can change minimally so that they are no longer recognized by the immune system and antibodies. In this respect, the influenza virus proves to be a true quick-change artist, “attacking” in a new guise every year. Accordingly, a new flu vaccine must be produced every year.
Spanish flu - a virus pandemic
Such incredibly tiny, simply built viruses can wreak havoc. One of the worst examples is the influenza virus that triggered a pandemic in 1918/19 with the so-called Spanish flu. It claimed more lives worldwide than World War I; depending on Which At that time, between 20 and 100 million people died from the virus infection. There was no influenza vaccine yet.
There are already vaccines against many pathogens that are intended to prevent the outbreak of the disease or weaken the course of the disease. By vaccinating large groups of people, so-called herd protection sets in, which also protects weakened members who cannot be vaccinated. Nevertheless, the topic Vaccination is always a controversial topic. The Robert Koch Institute recommends Vaccination against viral infections and deals with arguments by opponents of vaccination.
How dangerous are viruses for mankind?
In the exciting film series "The Empire of Viruses" from the ARD educational program, you get fascinating insights into the world of viruses and the spread of the SARS virus in 2003.
These short films illustrate the danger posed by certain viruses. The Nobel laureate Joshua Lederberg is said to have said: "Viruses are our only rivals for dominance on this planet". Apparently, this rivalry has existed for a long time, as around 98.000 endogenous retroviruses have left their mark in the human genome. These sequences can even be used to trace family relationships back through generations.
What are retroviruses?
To put it very simply: Endogenous retroviruses are viruses that insert their RNA genetic material into the DNA genome of the host cell. If they do this in an egg cell, the viral DNA is passed on from generation to generation of hosts. Further information on this exciting topic can be found in Publications of the Helmholtz Zentrum München.
By the way: About ten percent of the human genome is said to consist of endogenous retroviral sequences.
The virus as a bacteria eater
Types of viruses related to bacteria as host have specialized are summarized under the generic term bacteriophage, which can be loosely translated as bacteria eater. These phages are divided into different groups according to the host bacteria. These include coliphages, which are found in the human Microbiome find and salmonella phages, which are, so to speak, natural enemies of the pathogen salmonella.
With this example we have arrived at the useful side of viruses. Because the bacteriophages in particular are used specifically against their potential host bacteria. This is done, among other things, in the medicine, agricultural science, biology and the food industry. Another area of application is the Gene technology.
phage therapy
From a medical point of view, phage therapy is interesting, although no procedure has yet been approved in human medicine in this country. In this therapy, appropriate bacteriophages are targeted at their potential hosts in order to render them harmless. Maybe that's her Solution against antibiotic-resistant germs. Several renowned research institutes are working on it Project Phage4Cure together to develop drugs from bacteriophages against bacterial information. If you want to know more about phage therapy, we recommend the Information page of the Leibnitz institutes.
Other areas of application for bacteriophages
- Biological pest control in agriculture
- Control of listeria and salmonella in food
- Genetic engineering: introducing DNA fragments into cells
- E-waste recycling: recovery of rare earths, gold, copper
- As "phage display" in biochemistry
- Various purposes in veterinary medicine
As you can see, viruses can be very useful. While some scientists are looking for other beneficial uses, others are tinkering with biological weapons with viruses. In this context, his smallpox pathogen variola virus, the Ebola virus and the hantavirus are named as examples.
Diseases caused by viral infections
Let's get back to the virusesthat we encounter in everyday life and that our cells desire as hosts. As a rule, the particles seek the path of least resistance to penetrate the body. Mucous membranes, airways and wounds are potential entry points. They often get through from person to person Droplet infections or direct skin contact transfer. Some types of viruses are transmitted by exchanging body fluids or contact via blood and mucous membranes.
In addition are animals are often the vectors, just think of ticks, mosquitoes, mice or foxes infected with rabies. Depending on the particle and the type of transmission, you can reduce or even eliminate the risk of infection through hygiene measures. Yes, sometimes nothing helps, people get infected. Especially when a cold wave is sweeping the country or an intestinal virus is on the way.
viruses and cold
By the way, one cold does not come from cold, but by flu viruses such as rhinoviruses or parainfluenza viruses. About 200 types of viruses are currently known to cause a flu-like infection. If you are currently immune to one pathogen, the next one or a mutated variant will infect you. No wonder children and adults catch a cold several times a year.
Presumably, these infections accumulate in the cold, dark season, because mucous membranes and Weakened immune system e.g. due to dry heating air or long periods of freezing. Before the body's defenses defeated the infection, the cold virus could multiply thousands of times. Sneezing, sniffling and coughing, those affected spread the new viruses in the air, on doorknobs, keyboards and…
More examples of viral diseases
The flu infection is one of the most common diseases caused by viruses. Certainly several other viral diseases immediately come to mind. Perhaps you are carrying herpes viruses that lie dormant for a long time and cause unpleasant blisters to grow on your skin when you are stressed. Many adults, but also children, have suffered from severe gastrointestinal complaints caused by noroviruses or rotaviruses. Infectious particles are also for Teething problems such as measles, chickenpox and mumps. This list could be continued for a long time. As already written: Virons are everywhere! Be defensive and get as immune as possible.
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