The virus has no cellular structure, but is capable to breed and evolve. It can be active only in living cell, eating its energy, and at the same time is able to change it, causing a serious illness.
The mankind got acquainted with viruses at the end of IXX of a century, after Dmitry Ivanovsky and Martin Beyerink's works. Studying not bacterial damages of plants of tobacco, scientists for the first time analyzed and described 5 thousand types of viruses. Today it is supposed that their millions and live they everywhere.
Live or not?
Viruses are defined by science as the organisms existing on the verge of live. The body of a virus does not contain cages and can function only in a cell of the owner as a parasite. But at the same time it is not capable to synthesize protein as other living organisms.
Viruses consist of the molecules DNA and RNA transferring gene information in various combinations, a cover which protects a molecule, and additional lipidic protection. Existence of genes and ability to breed allows to rank viruses as live, and the lack of synthesis of protein and impossibility of independent development carries them to lifeless biological organisms. Viruses are also capable to enter into alliance with bacteria and to mutate. They can transmit information through exchange of RNA and leave from the immune answer, ignoring drugs and vaccines. The question of whether the virus is live, remains open still.
The most dangerous enemy
Today the virus which is not reacting to antibiotics — the most terrible enemy of the person. Discovery of antiviral medicines improved matters a little, but AIDS and hepatitis are still not defeated. Vaccines give protection only against some seasonal strains of viruses, but their ability to mutate quickly does inoculations inefficient the next year. The inability in time to cope with the next virus epidemic can become the most serious threat to the population of Earth. Flu — only a small part of "a virus iceberg". The viral infection walking across Africa "Ebola", led to introduction of quarantine actions worldwide. Unfortunately, the disease extremely difficult responds to treatment, and the percent of lethal outcomes is still big. Their incredibly fast ability to breed became feature of viruses. The virus bacteriophage is capable to surpass in reproduction speed a bacterium in 100 thousand times. Therefore scientists-virologists of all countries of the world try to save mankind from deadly threat. The main measures of prevention of viral infections are: inoculations, observance of rules of personal hygiene and the timely address to the doctor in case of infection. High temperature which cannot be brought down independently became one of symptoms. You should not panic at a viral disease, but the care can save, in literal sense, to you life. Doctors say that they will mutate infections so much how many there will be a human civilization, and scientists should make a lot more important discoveries in origin and behavior of viruses and also in fight against them.