The human immunodeficiency virus, or Human immunodeficiency virus (HIV), belongs to the family of retroviruses and the genus Lentivirus. This genus includes members that cause various infectious blood diseases and immunodeficiencies in mammals.
Origin and revelation
This type is represented by two non-cellular agents - HIV-1 and HIV-2, capable of causing acquired immunodeficiency syndrome - AIDS (eng. Acquired immunodeficiency syndrome, AIDS). However, these subspecies differ in the rate of development of the disease. It is believed that the second type of HIV-2 is less aggressive to the human immune system. It has been widely adopted in Asia, Europe, America and Africa.
A sensational discovery was published in the journal Science when the presence of this infectious agent was found in the lymph nodes of a homosexual who suffered from the above syndrome. DNA analysis has shown that these two subtypes of human immunodeficiency viruses have different origins. The closest relative of HIV 1 turned out to be a virus that causes the development of immunodeficiency in monkeys, subsequently they becameconsidered as subspecies of the same species. It is believed that a person was infected by it as a result of contact with an infected animal. The second type was associated with lymphadenopathy.
In this article, we will consider how AIDS proceeds, the consequences of the spread of its carrier throughout the human body.
Infection process
The process of infection is typical for all viruses. Inside the cell, the infectious agent inserts its DNA into the host's chromosomal helix, thereby changing the expression pattern of its genes, resulting in an increase in the percentage of malignant tumors.
AIDS develops when the infectious agent HIV enters the body. It infects any cell that has a specific immunoglobulin receptor on its surface. During sexual contact with an infected partner, the first to receive the virus are dendritic cells and macrophages patrolling the genital epithelium, these receptors and T-lymphocytes (T-cells that detect and destroy foreign antigens), which are present in many mucous membranes. If the virus enters the body with breast milk, then the M-cells of Peyer's patches serve as the entrance gate for it.
Finally, if a virus enters the bloodstream, it inevitably enters the lymph nodes, where potential host cells expressing T-lymphocytes are always present. The lymph nodes also receive antigen-presenting cells (destroying antigens) that can transmit the AIDS virus. The consequences are always very serious.
Stages of disease
In the first days after infection, an acute phase of the disease develops, when almost all immunoglobulin receptors of the cell become carriers of the rapidly multiplying virus, most of which die. Then the infectious agent goes into a latent state and persists mainly as a provirus (embedded in the host cells), localizing mainly in T-lymphocytes. They are formed after a meeting with a specific antigen and are activated if it appears again. They do not reproduce and circulate in the bloodstream in small numbers.
Then comes the asymptomatic stage of the disease, during which the virus population becomes genetically heterogeneous as a result of the accumulation of mutations. T-cells subtly decrease as they die as the virus replicates.
This is why AIDS is dangerous. The consequences of the disease are that at the late stage of the development of the syndrome, the number of T-cells decreases critically, the multiplication of the virus in the tissues of the lymph nodes leads to the degeneration of the latter, and a wide range of host cells becomes available for infection by the virus itself. Cytotoxicity to participants in the cellular immune response, resistance to antiviral antibodies, and in some cases tropism to different tissues is activated.
During the development of the disease, any possible infection can be fatal for the body. Against the background of AIDS, people with a compromised immune system often develop other diseases of viral etiology. For example, HIV has long been considered the cause of cancer,however, later it turned out that against the background of a weakened immune status of the body, completely different pathogens cause cancer, and this is not a consequence of HIV and AIDS.
Why is the human immune system unable to cope with HIV infection?
The fact is that the HIV virus turned out to be the most skillful "manipulator", violating the foundations of immunity and turning it to its own advantage. The "advantage" of HIV is the ability to persist in a latent form for a long time. If immediately after the initial infection, the pathogenic process is suppressed, then gradually (over several years) the immune system is destroyed. The main target of the virus are T-lymphocytes. Normally, they trigger a series of immune response reactions; when they become ill, they lose their ability to reproduce, and their total number drops. The remaining cells of the immune system (B-lymphocytes, monocytes and NK cells) cease to recognize the mediator signals of T-cells, and autoimmune reactions often begin. All antigen-presenting cells also cease to function normally, as they also become infected with the virus.
Why are there such consequences of AIDS?
An infected body produces neutralizing antibodies against HIV. However, their number is never high, and in a sense they even serve not as a defense, but as a stimulant for the variability of the virus. In parallel, a certain amount of antibodies are synthesized that overlap the epitopes (part of the molecule recognized by the antibody) of the virus envelope, which are already inaccessible due tospecific confirmation of their glycoproteins. For some reason, such antibodies are poorly recognized by the cells of the immune system.
In some cases, macrophages give the virus the ability to interact with additional receptors on the surface of target cells and penetrate into them by endocytosis. Thus, the humoral immune response, the most powerful weapon of the immune system, is completely disrupted by HIV infection.
Symptoms
It is difficult to immediately recognize the disease, because there are no symptoms in the first stages of infection. And the following symptoms can easily be confused with other diseases. For example, swollen lymph nodes, chronic fatigue and weakness, decreased appetite, weight loss, memory impairment, foggy consciousness - all these symptoms can also be caused by nutritional deficiencies. And this, as it sometimes turns out, is the consequences of HIV infection and AIDS.
Therefore, the following symptoms should be especially looked out for: profuse sweating or chills, especially at night, the appearance of various kinds of spots or rashes on the skin, shortness of breath and rapid coughing, fever, abnormal bowel function.
An important signal is the increased frequency of fungal infections. This applies to both genital and herpes viruses, oral infections, etc. Therefore, if several of the above symptoms appear at the same time, it is important to undergo an examination, not to mention the annual medical examination, in order to diagnose AIDS in time. The consequences of the disease canprove yourself at any time.
Disease statistics
Despite the efforts of doctors, scientists, the public, the support of the sick, the problem remains poorly controlled, and it is not yet possible to stabilize the situation. According to the World He alth Organization, more than 25 million people died from the "plague of the twentieth century" from the late 1980s to 2006. For many states, this problem is becoming more acute. According to data announced at the International AIDS Conference, in 2010 more than 40 million people are considered infected carriers of the disease. The causes and consequences of AIDS are discussed above.
Data on infected people
The Russian Scientific and Methodological Center for Combating Immunodeficiency Syndrome provides the following data on infected people since 1994:
- 1994 - 887 people;
- 1999 - 30647 people;
- 2004 - 296045 people,;
- 2009 - 516167 people
By analyzing these data, we can trace the dynamics of the spread of the epidemic. Modern society still needs further research on the body's sensitivity to a viral agent so that the consequences of AIDS are not so terrible. The virus affects the body, definitely, negatively.
Treatment and prevention
The noted abilities of HIV create huge problems in the search for ways to treat AIDS. Many measures of protection against viral infections are associated with the stimulation of the immune system, and this virus completely disrupts its coordinatedaction, which in this case can lead to unpredictable consequences.
It is impossible to fight HIV by destroying all the cells it infects, as this would lead to an irreparable loss of immune memory. This is the consequences of AIDS. Some other influence must be exerted on the human body.
A promising direction in the development of AIDS therapy is the search for drugs that suppress the reproduction of the virus, primarily the process of reverse transcription, which as such is practically absent in eukaryotes. Some progress has been made in this direction. So, if in the last trimester of pregnancy the mother takes Zidovudine or Lamivudine once, the child is born not infected with HIV in 99% of cases. The use of highly active antiretroviral therapy, when the patient is simultaneously treated with a reverse transcriptase inhibitor and a protease inhibitor, can slow down the development of the disease for many years.
Conclusion
Vaccination against AIDS is still unrealistic, because many aspects of the impact of HIV on the immune system have not been clarified. Even the most immunogenic epitopes of viral proteins have not been identified. The rate of mutational variability of this virus that entered the human body is very high, which excludes the possibility of developing long-term vaccines, while unsuccessful vaccination can stimulate the development of infection. These are the terrible consequences of AIDS.
