The human immunodeficiency virus, or Human immunodeficiency virus (HIV), belongs to the family of retroviruses and the genus Lentivirus. This genus includes representatives that cause various infectious blood diseases and immunodeficiency in mammals.
Origin and identification
This type is represented by two non-cellular agents - HIV-1 and HIV-2, capable of causing 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 towards the human immune system. It is widely distributed in Asia, Europe, America and Africa.
A sensational discovery was published in the journal Science when the presence of this infectious agent in the lymph nodes of a homosexual who was suffering from the above syndrome was discovered. DNA analysis showed that these two subspecies of human immunodeficiency viruses are of different origin. The closest relative to HIV 1 turned out to be a virus that causes the development of immunodeficiency in monkeys, later they were considered as subspecies of the same species. It is believed that a person was infected with him 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 and the consequences of the spread of its carrier throughout the human body.
Infection process
The infection process is typical of all viruses. Inside the cell, the infectious agent embeds its DNA into the host's chromosomal helix, thereby changing the expression of its genes, resulting in an increase in the percentage of malignant tumors.
AIDS develops when an HIV infectious agent enters the body. It infects any cells on the surface of which there is a specific immunoglobulin receptor. Upon sexual contact with an infected partner, dendritic cells and macrophages that patrol the genital epithelium, these receptors and T-lymphocytes (T-cells that detect and destroy foreign antigens), many of which are present in the mucous membranes, are the first to receive the virus. If the virus enters the body with breast milk, then M-cells of Peyer's plaques serve as the entrance gate for it.
Finally, if the virus enters the bloodstream, it inevitably enters the lymph nodes, where potential host cells expressing T-lymphocytes are always present. Antigen-presenting cells (destroying antigens) that can transmit the AIDS virus also enter the lymph nodes. The consequences are always very serious.
Stages of the disease
In the first days after infection, the acute phase of the disease develops, when almost all immunoglobulin receptors of the cell become the carriers of the intensively propagating virus, most of which die. Then the infectious agent goes into a latent state and is preserved mainly as a provirus (built into the host cells), localizing mainly in T-lymphocytes. They are formed after a meeting with a specific antigen and are activated if it reappears. They do not multiply and circulate in a small amount in the bloodstream.
Then comes the asymptomatic stage of the disease, during which the virus population becomes genetically heterogeneous as a result of the accumulation of mutations. The number of T cells decreases imperceptibly, as they die as the virus multiplies.
This is dangerous for AIDS. The consequences of the disease are that at a late stage of the development of the syndrome, the number of T cells is critically reduced, the multiplication of the virus in the tissues of the lymph nodes leads to degeneration of the latter, and a wide range of host cells becomes available for infection. Cytotoxicity to participants of the cellular immune response is activated, resistance to antiviral antibodies, in some cases, tropism to different tissues.
During the development of the disease, any possible infection can be fatal for the body. Against the backdrop of AIDS, people with a compromised immune system often develop other diseases of the viral etiology. For example, HIV has long been considered the cause of cancer, but later it turned out that against the background of a weakened immune status of the body, cancer is caused by completely different pathogens, and this is not a consequence of HIV and AIDS.
Why is the human immune system unable to cope with HIV?
The fact is that the HIV virus turned out to be the most skilled “manipulator”, violating the basics of immunity and turning it to its advantage. The “benefit” of HIV is its ability to remain latent for a long time. If the pathogenic process is suppressed immediately after the initial infection, then the immune system is gradually destroyed (over several years). The main target of the virus are T-lymphocytes. Normally, they trigger a series of immune response reactions, with a disease they lose their ability to reproduce, and their total number decreases. The remaining cells of the immune system (B-lymphocytes, monocytes and NK cells) cease to recognize 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 these consequences of AIDS?
In an infected body, neutralizing antibodies against HIV are produced. However, their number is never high, and in a sense, they do not even serve as protection, but as a stimulant for the variability of the virus. At the same time, a certain amount of antibodies is synthesized that overlap the epitopes (part of the molecule recognized by the antibody) of the virus membrane, which are already hardly accessible due to the special 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 when infected with HIV.
Symptoms
It is difficult to immediately recognize the disease, because in the first stages of infection there are no symptoms. And the subsequent signs can easily be confused with other diseases. For example, an increase in lymph nodes, chronic fatigue and weakness, loss of 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 noted: 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, impaired normal bowel function.
An important signal is the increased incidence of fungal infections. This applies to both genital and herpes viruses, infections of the oral cavity, etc. Therefore, if several of the symptoms appear simultaneously, 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 can manifest themselves at any time.
Disease statistics
Despite the efforts of doctors, scientists, the public, and support for the sick, the problem remains poorly controlled, and it is not yet possible to stabilize the situation. According to the World Health Organization, from the late 80s to 2006, more than 25 million people died from the “plague of the twentieth century”. 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.
Infected data
The Russian Scientific and Methodological Center for the Fight against Immunodeficiency Syndrome provides the following data on infected people since 1994:
- 1994 - 887 people;
- 1999 - 30,647 people;
- 2004 - 296,045 people;
- 2009 - 516167 people.
By analyzing these data, we can trace the dynamics of the spread of the epidemic. To this day, modern society needs further studies of the body's sensitivity to a viral agent so that the consequences of AIDS are not so terrible. The virus acts on the body, definitely, negatively.
Treatment and prevention
The reported abilities of HIV pose enormous challenges in finding ways to treat AIDS. Many protective measures against viral infections are associated with stimulation of the immune system, and this virus completely disrupts its coordinated action, which in this case can lead to unpredictable consequences.
It is impossible to fight HIV by destroying all cells infected with it, as this would lead to an irreparable loss of immune memory. This is the effect of AIDS. It is necessary to have some other effect 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. In this direction, certain successes have been achieved. So, if in the last trimester of pregnancy the mother takes Zidovudine or Lamivudine once, in 99% of cases the baby is born uninfected with HIV. The use of highly active antiretroviral therapy, when a patient is simultaneously treated with a reverse transcriptase inhibitor and a protease inhibitor, allows the development of the disease to be slowed down for many years.
Conclusion
Vaccination against AIDS is unrealistic, since many aspects of the effect of HIV on the immune system have not been clarified. Not even the most immunogenic epitopes of viral proteins have been identified. The rate of mutational variability of this virus that has 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.