When did viruses appear on earth? I. History of discovery and methods for studying viruses. Human papillomavirus in women

Viruses (biology deciphers the meaning of this term as follows) are extracellular agents that can reproduce only with the help of living cells. Moreover, they are capable of infecting not only people, plants and animals, but also bacteria. Bacterial viruses are commonly called bacteriophages. Not so long ago, species were discovered that infect each other. They are called “satellite viruses”.

General characteristics

Viruses are a very numerous biological form, as they exist in every ecosystem on planet Earth. They are studied by a science such as virology - a branch of microbiology.

Each viral particle has several components:

Genetic data (RNA or DNA);

Capsid (protein shell) - performs a protective function;

Viruses have a fairly diverse shape, ranging from the simplest spiral to icosahedral. Standard sizes are about one hundredth the size of a small bacterium. However, most specimens are so small that they are not even visible under a light microscope.

They spread in several ways: viruses living in plants travel with the help of insects feeding on grass juices; Animal viruses are carried by blood-sucking insects. They are transmitted in a large number of ways: through airborne droplets or sexual contact, as well as through blood transfusions.

Origin

Nowadays, there are three hypotheses about the origin of viruses.

You can read briefly about viruses (our knowledge base on the biology of these organisms, unfortunately, is far from perfect) in this article. Each of the theories listed above has its own disadvantages and unproven hypotheses.

Viruses as a form of life

There are two definitions of the life form of viruses. According to the first, extracellular agents are a complex of organic molecules. The second definition states that viruses are a special form of life.

Viruses (biology implies the emergence of many new types of viruses) are characterized as organisms on the border of life. They are similar to living cells in that they have their own unique set of genes and evolve based on the method of natural selection. They can also reproduce, creating copies of themselves. Since viruses are not considered by scientists as living matter.

In order to synthesize their own molecules, extracellular agents need a host cell. The lack of their own metabolism does not allow them to reproduce without outside help.

Baltimore classification of viruses

Biology describes in sufficient detail what viruses are. David Baltimore (Nobel Prize winner) developed his own classification of viruses, which is still successful. This classification is based on how mRNA is produced.

Viruses must make mRNA from their own genomes. This process is necessary for the replication of its own nucleic acid and the formation of proteins.

The classification of viruses (biology takes into account their origin), according to Baltimore, is as follows:

Viruses with double-stranded DNA without RNA stage. These include mimiviruses and herpeviruses.

Single-stranded DNA with positive polarity (parvoviruses).

Double-stranded RNA (rotaviruses).

Single-stranded RNA of positive polarity. Representatives: flaviviruses, picornaviruses.

Single-stranded RNA molecule of double or negative polarity. Examples: filoviruses, orthomyxoviruses.

Single-stranded positive RNA, as well as the presence of DNA synthesis on an RNA template (HIV).

Double-stranded DNA, and the presence of DNA synthesis on an RNA template (hepatitis B).

Life period

Examples of viruses in biology are found almost at every step. But everyone’s life cycle proceeds almost the same. Without a cellular structure, they cannot reproduce by division. Therefore, they use materials located inside the cell of their host. Thus, they reproduce large numbers of copies of themselves.

The virus cycle consists of several stages that are overlapping.

At the first stage, the virus attaches, that is, it forms a specific bond between its proteins and the receptors of the host cell. Next, you need to penetrate the cell itself and transfer your genetic material to it. Some species also carry squirrels. Subsequently, loss of the capsid occurs and the genomic nucleic acid is released.

Human diseases

Each virus has a specific mechanism of action on its host. This process involves cell lysis, which leads to cell death. When a large number of cells die, the entire body begins to function poorly. In many cases, viruses may not cause harm to human health. In medicine this is called latency. An example of such a virus is herpes. Some latent species can be beneficial. Sometimes their presence triggers an immune response against bacterial pathogens.

Some infections can be chronic or lifelong. That is, the virus develops despite the body’s protective functions.

Epidemics

Horizontal transmission is the most common type of virus spread among humanity.

The rate of transmission of the virus depends on several factors: population density, the number of people with poor immunity, as well as the quality of medicine and weather conditions.

Body protection

The types of viruses in biology that can affect human health are innumerable. The very first protective reaction is innate immunity. It consists of special mechanisms that provide nonspecific protection. This type of immunity is not able to provide reliable and long-term protection.

When vertebrates develop acquired immunity, they produce special antibodies that attach to the virus and make it safe.

However, acquired immunity is not formed against all existing viruses. For example, HIV constantly changes its amino acid sequence, so it evades the immune system.

Treatment and prevention

Viruses are a very common phenomenon in biology, so scientists have developed special vaccines containing “killer substances” for the viruses themselves. The most common and effective method of control is vaccination, which creates immunity to infections, as well as antiviral drugs that can selectively inhibit viral replication.

Biology describes viruses and bacteria mainly as harmful inhabitants of the human body. Currently, with the help of vaccination, it is possible to overcome more than thirty viruses that have settled in the human body, and even more in the body of animals.

Preventive measures against viral diseases should be carried out in a timely and efficient manner. To do this, humanity must lead a healthy lifestyle and try in every possible way to increase immunity. The state must arrange quarantines in a timely manner and provide good medical care.

Plant viruses

Artificial viruses

The ability to create viruses in artificial conditions could have many consequences. The virus cannot completely die out as long as there are bodies sensitive to it.

Viruses are weapons

Viruses and the biosphere

At the moment, extracellular agents can “boast” of the largest number of individuals and species living on planet Earth. They perform an important function by regulating the populations of living organisms. Very often they form a symbiosis with animals. For example, the venom of some wasps contains components of viral origin. However, their main role in the existence of the biosphere is life in the sea and ocean.

One teaspoon of sea salt contains approximately a million viruses. Their main goal is to regulate life in aquatic ecosystems. Most of them are absolutely harmless to flora and fauna

But these are not all positive qualities. Viruses regulate the process of photosynthesis, therefore increasing the percentage of oxygen in the atmosphere.

Biologists are still arguing about what viruses are, whether they are living creatures or dead matter. Encyclopedic dictionaries frankly admit: at present, science does not understand the nature of these creatures, does not know how and where they came from.

Human immunodeficiency virus (HIV)

To date, about two thousand types of viruses have been discovered. Supposed. that this is only a very small part of them. Viruses constantly mutate, and new varieties arise from somewhere. sometimes causing deadly diseases such as mad cow disease, bird flu, Ebola, AIDS and others.

These ruthless cell killers seem so alien to everything terrestrial that many researchers who study them quite seriously claim that viruses came to Earth from deep space. Their actions really look like episodes from horror films about an attack by representatives of an extraterrestrial civilization. A monstrous-looking dwarf bites into a gigantic, nothing-

goes to an unsuspecting cell, dissolves its shell and screws a “spring” of its DNA into it. This “spring” gives the cell its own program, thereby changing its entire work. The unfortunate, affected cell forgets about its original responsibilities and begins to stamp from the resulting matrix more and more new viruses that bring death to neighboring cells.

Representatives of one of the varieties of viruses - bacteriophages (bacteria eaters) - even look like a space module created for landing on an alien planet for the purpose of taking soil samples. The bacteriophage releases peculiar “support posts” with which it is firmly attached to the victim, and then plunges its drill into it.
Viruses don't need food. They do not consume or assimilate it. As scientists admit, in their structure, viruses are more similar to primitive mechanisms that pursue one single goal: to search for living cells and integrate into them. But by whom, when and why was such a task assigned to them? Experts do not even dare to think about this issue.

Viruses originated in space

In 2008, Doctor of Geological and Mineralogical Sciences S. Zhmur proposed his own hypothesis of the origin of life on Earth. In his opinion, the main ancestor of all living things was not cells, or even bacteria, but viruses, which originated in the circumsolar space about five billion years ago.

After the explosion of a certain supernova, huge masses of stellar matter were thrown into space, from which a gas and dust cloud was subsequently formed, and from it then the planets of the Solar System. The high temperature of this substance contributed to the formation of cyanides in it - chemical elements that represent the basis for the creation of the simplest hydrocarbons. The next stage consisted of the appearance of hydrocarbon-based enzyme proteins and peptide proteins, which then led to the synthesis of nucleic acid molecules. And this, in turn, allowed the formation of RNA and DNA, which “created” a peptide shell to protect themselves from harmful external influences. This is how a structure arose that is nothing more than the virus we are familiar with.

Influenza A/H1N1 virus

The further evolution of viruses on Earth took place thanks to water, which penetrated into them through the peptide shell. Some types of viruses swelled, their protoplasm formed, and their genetic apparatus became more complex. All this led to the division and. ultimately, the emergence of a full-fledged bacterial cell, which marked the beginning of life on the planet.

S. Zhmur does not exclude the possibility of a more ancient origin of viruses. They were able to arise in the matter formed immediately after the Big Bang. This means that the age of these microscopic creatures is almost equal to the age of the Universe. That is, it turns out that a single living substance is spread everywhere in space, capable of giving rise to life on any celestial body suitable for it.

Some researchers go even further, believing that viruses are artificially created biorobots that came to Earth billions of years ago along with organic embryos. The purpose of the biorobot viruses was to serve these embryos. Russian scientist M. Daryanenko believes that biorobot viruses were called upon to

ensure the necessary course of evolution by connecting in a certain sequence with the cells of living organisms and introducing the necessary DNA programs into them. But over millions of years of their activity, something went wrong, and viruses turned from servants of cells into their killers. It is possible that the biorobot viruses decided: life on Earth did not follow the scenario prescribed for it by the program. And the experiment must be curtailed, clearing the planet for new experiments.

Mimi virus - the missing link in evolution?

From the point of view of most scientists, the question of the origin of viruses is still not paramount. The main thing is to understand what viruses are, how to coexist with them, how to fight them. We learned about viruses relatively recently - only 100 years ago, but we learned to actually work with them only in the middle of the last century.

Not so long ago, biologists believed that they had finally found patterns in the structure of viruses and the mechanism of their action. But the epiphany came in 1992, when an amazing, unlike anything else object was discovered in an amoeba caught in the water of an industrial reservoir in England. It is 40 times larger in diameter than known viruses, but is not a bacterium. Biologists recognized it as a virus, calling it mimi because of its mimicry, or disguise as a bacterium.

Man is approximately two million years old. The age of viruses, by all estimates, is estimated at billions of years. Moreover, they can exist in a “preserved” state indefinitely. In fact, viruses are immortal. Deciphering our genome has shown that it is full of remnants of ancient viruses. They occupy almost 10% of the human genome. Why these remnants are there is still unknown. Similar questions science began to be discussed only in very recent years.

“Human civilization has seen viral diseases throughout history that have claimed millions of lives,” says Robert Shope, director of the Yale Virus Laboratory. - Sometimes it seemed that humanity was on the verge of complete destruction. But every time everything worked out more or less well. The viruses were receding. Is this a coincidence? Or was it programmed this way from the very beginning, from the moment life appeared on Earth?”

Mysteries of the 20th century No. 34 2011

The human body is susceptible to all kinds of diseases and infections, and animals and plants also get sick quite often. Scientists of the last century tried to identify the cause of many diseases, but even after determining the symptoms and course of the disease, they could not confidently say about its cause. It was only at the end of the nineteenth century that the term “viruses” appeared. Biology, or rather one of its sections - microbiology, began to study new microorganisms, which, as it turned out, have been neighbors for a long time and contribute to the deterioration of his health. In order to more effectively fight viruses, a new science has emerged - virology. It is she who can tell a lot of interesting things about ancient microorganisms.

Viruses (biology): what are they?

Only in the nineteenth century did scientists discover that the causative agents of measles, influenza, foot-and-mouth disease and other infectious diseases not only in humans, but also in animals and plants are microorganisms invisible to the human eye.

After viruses were discovered, biology was not immediately able to provide answers to the questions posed about their structure, occurrence and classification. Humanity has a need for a new science - virology. Currently, virologists are working to study familiar viruses, monitor their mutations and invent vaccines that can protect living organisms from infection. Quite often, for the purpose of experiment, a new strain of the virus is created, which is stored in a “dormant” state. On its basis, drugs are developed and observations are made of their effects on organisms.

In modern society, virology is one of the most important sciences, and the most sought-after researcher is a virologist. The profession of a virologist, according to sociologists, is becoming more and more popular every year, which well reflects the trends of our time. After all, according to many scientists, wars will soon be fought and ruling regimes established with the help of microorganisms. In such conditions, a state with highly qualified virologists may turn out to be the most resilient, and its population the most viable.

The emergence of viruses on Earth

Scientists attribute the emergence of viruses to the most ancient times on the planet. Although it is impossible to say with certainty how they appeared and what form they had at that time. After all, viruses have the ability to penetrate absolutely any living organisms; they have access to the simplest forms of life, plants, fungi, animals and, of course, humans. But viruses do not leave behind any visible remains in the form of fossils, for example. All these features of the life of microorganisms significantly complicate their study.

• they were part of the DNA and separated over time;
• they were built into the genome initially and, under certain circumstances, “woke up” and began to reproduce.

Scientists suggest that the genome of modern people contains a huge number of viruses that infected our ancestors, and now they are naturally integrated into the DNA.

Viruses: when were they discovered?

The study of viruses is a fairly new branch of science, because it is believed that it appeared only at the end of the nineteenth century. In fact, it can be said that the viruses themselves and their vaccines were unknowingly discovered by an English doctor at the end of the nineteenth century. He worked on creating a cure for smallpox, which at that time killed hundreds of thousands of people during an epidemic. He managed to create an experimental vaccine directly from the sore of one of the girls who had smallpox. This vaccination turned out to be very effective and saved more than one life.

But D.I. Ivanovsky is considered the official “father” of viruses. This Russian scientist studied diseases of tobacco plants for a long time and made an assumption about small microorganisms that pass through all known filters and cannot exist on their own.

A few years later, the Frenchman Louis Pasteur, in the process of fighting rabies, identified its causative agents and introduced the term “viruses”. An interesting fact is that the microscopes of the late nineteenth century could not show viruses to scientists, so all assumptions were made about invisible microorganisms.

Development of virology

The middle of the last century gave a powerful impetus to the development of virology. For example, the invented electron microscope finally made it possible to see viruses and classify them.

In the fifties of the twentieth century, the polio vaccine was invented, which became a salvation from this terrible disease for millions of children around the world. In addition, scientists have learned to grow human cells in a special environment, which has led to the opportunity to study human viruses in the laboratory. At the moment, about one and a half thousand viruses have already been described, although fifty years ago only two hundred similar microorganisms were known.

Properties of viruses

Viruses have a number of properties that distinguish them from other microorganisms:

• Very small sizes, measured in nanometers. Large human viruses, such as smallpox, are three hundred nanometers in size (that's only 0.3 millimeters).
• Every living organism on the planet contains two types of nucleic acids, but viruses have only one.
• Microorganisms cannot grow.
• Viruses reproduce only in a living host cell.
• Existence occurs only inside the cell; outside it, the microorganism cannot show signs of vital activity.

Virus forms

To date, scientists can confidently declare two forms of this microorganism:

• extracellular - virion;
• intracellular - virus.

Outside the cell, the virion is in a “sleeping” state; it shows no signs of life. Once in the human body, it finds a suitable cell and, only having penetrated it, begins to actively multiply, turning into a virus.

Virus structure

Almost all viruses, despite the fact that they are quite diverse, have the same structure:

• nucleic acids that form the genome;
• protein shell (capsid);
• Some microorganisms also have a membrane coating on top of the shell.

Scientists believe that this simplicity of structure allows viruses to survive and adapt to changing conditions.

Currently, virologists distinguish seven classes of microorganisms:

• 1 - consist of double-stranded DNA;
• 2 - contain single-stranded DNA;
• 3 - viruses that copy their RNA;
• 4 and 5 - contain single-stranded RNA;
• 6 - transform RNA into DNA;
• 7 - transform double-stranded DNA through RNA.

Despite the fact that the classification of viruses and their study have made great progress, scientists admit the possibility of the emergence of new types of microorganisms that differ from all those already listed above.

Types of Viral Infection

The interaction of viruses with a living cell and the method of exit from it determines the type of infection:

• Lytic

During the infection process, all viruses simultaneously exit the cell, and as a result, the cell dies. Subsequently, the viruses “settle” in new cells and continue to destroy them.

• Persistent

Viruses leave the host cell gradually and begin to infect new cells. But the old one continues its life activity and “gives birth” to new viruses.

• Latent

The virus is embedded in the cell itself, during its division it is transmitted to other cells and spreads throughout the body. Viruses can remain in this state for quite a long time. Under the necessary circumstances, they begin to actively multiply and the infection proceeds according to the types already listed above.

Russia: where are viruses studied?

In our country, viruses have been studied for quite a long time, and it is Russian specialists who are leaders in this field. The D.I. Ivanovsky Research Institute of Virology is located in Moscow, whose specialists make a significant contribution to the development of science. On the basis of the research institute, I operate research laboratories, maintain an advisory center and a department of virology.

At the same time, Russian virologists are working with WHO and expanding their collection of virus strains. Research institute specialists work in all areas of virology:

• general:
• private;
• molecular.

It is worth noting that in recent years there has been a tendency to unite the efforts of virologists around the world. Such joint work is more effective and allows serious progress in the study of the issue.

Viruses (biology as a science has confirmed this) are microorganisms that accompany all living things on the planet throughout their entire existence. Therefore, their study is so important for the survival of many species on the planet, including humans, who have more than once in history fallen victim to various epidemics caused by viruses.

Recently, we received a letter from Vladivostok, full of despair, in which an entire family, from grandmother to little Nastya and Kostya, has practically not left the hospital for several months due to an intestinal infection caused by viruses. No nifuroxazides, enterosgels, smects, rehydrons and other drugs, including droppers, solve the problem. Severe vomiting, high fever, muscle and headaches, inflammation of the nasopharynx, lacrimation, photophobia, convulsions, heart pain, rapid pulse, weakness, drowsiness, diarrhea - all this literally haunts and has not let go of this family for a long time. We literally became the last hope for these people, especially after their distant relative from Moscow with similar symptoms was cured by us within one month. People were amazed that “living herbs” managed to cope with the virus!

However, in recent years, trends in the emergence of new diseases have been clearly visible, or “old” diseases are changing so much that it is necessary to carefully improve and modernize their formulation and treatment regimens, for example, as is the case with MRSA - resistant Staphylococcus aureus. The article brought to your attention may provide an answer about the reasons for the emergence of new diseases and viruses.

In mid-April 2009, virus samples from two California children suffering from influenza arrived at the Centers for Disease Control and Prevention in Atlanta (USA) for further study. The doctors saw “something” that did not fit with the normal ideas about those specific strains of influenza that they already knew and had. After careful study and observation, a virus was discovered that had a unique genetic code different from any known human influenza virus. This was a completely new discovery for science.

But at the same time, this event marked the beginning of the 2009 swine flu pandemic. The virus, which may have started infecting people first in Mexico, has spread around the world, infecting millions of people and killing thousands. The pandemic ended by the end of August 2010.

The killer virus was a new strain of H1N1, an influenza virus involved in the 1918 Spanish flu pandemic, which killed 30 to 50 million people worldwide, more than died during World War I, or 2.7 to 5. 3% of the world's population.

Emergency hospitals during the 1918 influenza epidemic.

The emergence of the new H1N1 in 2009 was a reminder to people that despite advances in treating infectious diseases in recent decades, the looming shadow of deadly pandemics remains.

Every appearance of another mysterious virus causes concern and concern among scientists: once in 2002

People on the street wear masks due to the swine flu outbreak.

SARS (atypical pneumonia) in the Chinese province of Guangdong, or in 2009 swine flu that infected many people in Mexico and spread throughout the world, or more recently - 2012 MERS-CoV (Middle East respiratory syndrome - a viral respiratory infection that originated around the Arabian peninsula and killed half of the people who became infected with it; because of this, and also against the background of the growing number of deaths, the Minister of Health of Saudi Arabia was fired).

This 3-D model illustrates a common influenza virus (there are different types). A seasonal respiratory infection, influenza is responsible for three to five million cases of severe illness and an estimated 250,000 to 500,000 deaths, according to the World Health Organization.

Every time another mysterious virus appears, researchers are reminded of the same questions: is this the virus that will cause the next pandemic? Will humanity be able to stop him?

But now, new threatening trends are being added to the existing challenges. These are the latest UN demographic forecasts, according to which the world population will reach 9.6 billion people by mid-century, and 11 billion by 2100.

Eleven billion people. This is the number of people, according to preliminary estimates by the United Nations, that could live on Earth by the end of this century. This is 4 billion more people than are alive today. This is a staggering number compared to just 2.5 billion people who lived in 1950. These 11 billion people will leave a huge imprint on the Earth: they all must eat, they must have enough drinking water; all waste generated from their vital activity can potentially contribute to the spread of diseases; they could affect the planet's already changing climate and many of Earth's animal and plant species.

A huge number of people, their interaction with animals and different ecosystems, an increase in international trade and travel, all these factors will change the life of humanity, which is constantly faced with the problems of preventing and combating epidemics. And this is not a book theory. In fact, the unprecedented growth of the human population in the second half of the last century - growing from 2.5 billion to 6 billion - caused changes, including the emergence of new infections. Researchers have established a link between pandemic risk and population density.

Studying outbreaks of epidemics since the mid-20th century, scientists have discovered that the rate of occurrence of diseases caused by pathogenic microorganisms new to humans is in no way related to progress in diagnostic and surveillance methods, which merely record the dynamics of the emergence of more and more new diseases.

At the Centers for Disease Control and Prevention (CDC), a scientist takes measurements of the amount of H7N9 virus that was grown and collected in the CDC laboratory.

So, between 1940 and 2004, more than 300 new infectious diseases were “recorded”.

Some of these diseases were caused by a pathogen that was present in different species and then in humans - for example, West Nile Virus, SARS coronavirus and HIV.

Coronavirus, the family of viruses to which the common cold belongs, are a group of viruses that have a corona-like (corona) appearance when viewed under an electron microscope.

Others were caused by new pathogens that evolved to negate the effects of available drugs, making diseases such as multidrug-resistant tuberculosis and malaria worse or virtually impossible to treat.

Some pathogens, such as the bacteria that cause Lyme disease, are not new to humans, but their frequency has increased dramatically, perhaps due to changes that newly arrived humans brought with them from the environment of the animal hosts of these pathogens.

Scientists are confident that more and more diseases will arise every year. One of them even joked, saying that if for most people this is something incomprehensible and abstract, then for specialists and researchers it is also completely new and unknown.

Diseases of the future are already waiting for us in nature.

When scientists analyzed the characteristics of the emerging diseases, they found some similarities between them. All known emerging diseases have been associated with sudden population growth, new human activity in the environment, and high wildlife diversity in the area where the pathogen originated. The researchers found that about two-thirds of the new diseases were transmitted to humans from animals.

More than 70% of these diseases are known as zoonotic infections (that is, infectious diseases that affect not only people, but also some species of animals from which humans become infected. A person becomes infected from sick animals either through close contact with them or by consuming food their meat, milk, as well as products made from this milk. In some cases, an infection, for example, anthrax, can be transmitted to a healthy person through objects made from the skin, bristles and hair of sick animals). For example, the Nipah virus, which causes inflammation of the brain and first appeared in 1999 in Perak, Malaysia, or the SARS coronavirus, when both hosts of the virus that infected farmers were bats.

If humans do not frequently come into contact with wildlife, then such pathogens should theoretically pose little risk to humans. But pathogens can attack humans by first infecting other animals, as humans are in contact with, for example, domestic pigs. Animals serve as the middle link in this disease chain, however, they must have been in areas that growing populations had begun to take away from wildlife, or where people rarely, if ever, ventured into such areas.

Scientists say that every region of the wild harbors a whole host of microbes, most of which we know nothing about. By building a road through a new area of ​​tropical forest, creating pig farms there, people come into contact with these pathogens.

The number of pathogens found in wildlife and capable of infecting people has increased over time and especially over the last decade of the 20th century. Such pathogens were responsible for more than half of the new infectious diseases that emerged unexpectedly during this time period.

Human contact with different species of wild animals, during which transmission of new viruses occurs, may increase in the future as the population grows and people seek places to live and build settlements in areas where they live, including close to wildlife.

Prediction of the future.

When the first case of HIV/AIDS was discovered in the United States in 1981, it essentially began another pandemic that continues to this day. HIV is believed to have originated in chimpanzees, infected 60 million people and killed an estimated 30 million.

Over the years, if there was complacency and thought that infectious diseases had been conquered, that was history.

The complacency that was present in the years before HIV largely no longer exists. Scientists are constantly on the lookout for the next pathogen that could cause an epidemic. One of the viruses that scientists suspected was H5N1, a strain of influenza virus that was circulating among birds and killing them. Resources dedicated to preparing for and managing an avian influenza pandemic in humans were transferred and applied to the swine influenza pandemic in 2009.

Another worrisome flu virus on the watch list is H7N9, the bird flu first detected in China in 2013. It infected a number of people who came into contact with infected birds.

How do viruses constantly change, how do they mutate, allowing them to easily spread among people?

Under an electron microscope, a flu virus is in the process of copying itself. Viral nucleoproteins (blue) encapsulate the influenza genome (green). The influenza virus polymerase (orange) reads and copies the genome.

In fact, these are the most difficult questions for scientists to find answers to, not only how viruses living in animals become capable of infecting humans, but also what makes them able to move from person to person.

The H5N1 virus, scientists believe, must undergo four mutations before it can be transmitted through the air among mammals.

Despite efforts to thoroughly study the H5N1 and H7N9 viruses, scientists still do not know how people become infected. The mechanism of infection usually begins to be investigated when the virus has already spread among people.

Scientists have found that in some parts of the world, new viruses have a high chance of “proving” themselves. Tropical Africa, Latin America and Asia, with their great biodiversity and the rapid development of human interaction with the environment, contribute to the activation of viruses that immediately penetrate the human body. And only then, they will be able to follow the human chain to reach any point on the globe.

Epidemics can grow faster and be more costly.

Today, travelers are able to travel distances in a few hours from places that in the past would have taken months to reach. But this is a benefit not only for humans, but also for microbes. Sick travelers can be carriers and carry pathogens to their destination before they even realize they are sick. In the future, population growth and the rapid development of tourism, and this is confirmed by elementary mathematical calculations, will invariably be linked: where there are more tourists, there will be the appearance and growth of epidemics.

The emergence of SARS in China in 2002 provided a clear picture of how a virus can travel when its host is a human using modern travel communications: the virus spread rapidly throughout the world within weeks, infecting more than 8,000 people and killing about 800 before what measures were taken were taken under control and restrictions on travel and quarantine of victims were introduced.

The traveler virus can cause economic losses related to disease treatment and epidemic control. The SARS virus cost billions of dollars by reducing international travel by 50 to 70 percent and hurting businesses in several sectors. Chinese GDP growth fell 2% point in one quarter and half a percentage point in annual growth, according to World Bank data and Chinese government estimates.

Is humanity ready to face the future?

The migration of the world's population from sparsely populated rural areas to densely populated cities may also affect the spread of pathogens. By 2050, 85 percent of people in the developed world and 54 percent in so-called developing countries are expected to leave rural areas for cities.

From a global disease control perspective, urbanization may have some positive aspects. However, this will only happen if an effective surveillance and early warning system can be put in place. Concentrating populations in cities requires a stronger public health sector, as people in crowded cities are often more vulnerable to infectious diseases.

Scientists say a robust public health system is needed to respond to population growth, urbanization, an aging population and increased travel and interactions between humans and animals that lead to the emergence of new diseases.

The only source of optimism is the "tremendous progress" that has been made in reducing the amount of time it takes to get a swine flu vaccine. Less than two months after swine flu became a pandemic in 2009, vaccines were developed and mass produced.

Unfortunately, people nowadays have a false sense of security and are quite careless. After all, although it is possible to eliminate some diseases, the truth is that most new diseases are simply waiting for their time, and some letters in which people turn to us with requests for help, because standard treatment regimens no longer work, only confirm this.

Researching the history of viruses is problematic because they leave no fossils and because of their machinations to copy themselves. To complicate matters, viruses can infect not only people, but also bacteria, algae and even fungi.

But it’s not for nothing that scientists are chilling in their laboratories - they have managed to put together theories about the origin of viruses. Scientists assumed that viruses like herpes or tonsillitis exchange their properties with the host cell. It can be assumed that viruses were originally like large pieces of DNA and then became independent, or that viruses arose at the dawn of evolution, and some of them remained for a long time in the genomes of cells. The fact that viruses that infect humans and bacteria share common features suggests that they have a common origin, originating roughly several billion years ago. This highlights another problem with tracking the history of viruses: they are made up of many small particles that come from different sources. I would compare the structure of the virus with a modern New Year tree - they are of different colors and shapes, made of different materials, with New Year's toys of infinitely different shapes and colors.

The fact that deadly viruses like Ebola, as well as their distant relatives that cause measles and rabies, can only be found within a limited number of species suggests that these viruses are relatively new; after all, these organisms arose together in recent times. by the standards of evolution. Many of these "new" viruses likely originated in insects many millions of years ago, and at some point in evolution developed the ability to infect other species.

HIV, which first emerged in humans in 1920, is believed to be another type of virus known as a retrovirus. These simple viruses contain related elements found in normal cells, so they have the ability to copy and paste themselves throughout the genome. There are a number of viruses that have a similar self-copying process that alters the normal flow of information in cells ( lat. retro - reverse). Their signature mode of replication may be a bridge between the origins of life on Earth and the life we ​​know now. In fact, among our genes we recognize many “fossilized” retroviruses left over from the infection of distant ancestors. This can help trace our evolution as a species.