HI virus and AIDSThe course of AIDS is characterized by the destruction of the immune system. The body can no longer defend itself against infection. Currently, AIDS is treatable but not curable.
Viruses are not living beings and cannot multiply without the help of the host.
The HI virus (human immunodeficiency virus) belongs to the retroviruses. This type of virus is characterized by an RNA genome. The possession of the enzyme reverse transcriptase from. DNA information is formed from the viral RNA information. The steps you know as transcription in protein biosynthesis run "backwards" here. The enzyme reverse transcriptase converts RNA into DNA.
The enzyme activity of reverse transcriptase is necessary for the host cell (human immune cell) to receive the information "make this protein" can also understand.
Method: Repeat again the processes of protein biosynthesis (DNA – mRNA – protein). The HIV behaves a little bit different concerning its genetic mechanisms. Compare retroviruses with z.B. E.-coli bacteria!
Symptoms of the disease
AIDS occurs in several phases. So the first (infection or) acute phase a time during which the affected person does not feel well. Flu-like symptoms such as fever, headache, aching limbs, etc. occur. But there are also patients who show no symptoms at all.
Afterwards the Latent phase a. The virus multiplies in the body. This can be caused by ca. 10 years (!) take time. The symptoms of the acute phase return, but now remain permanent.
Disease phase: AIDS destroys T-helper cells. The immune system no longer functions. Now the body is defenseless against the smallest infections.
Reproduction cycle HI virus
The host cell of the HI virus is the T helper cell. This cell, which is important in the immune system, carries special receptors (CD4 receptors) on its surface. The surface receptors act as part of the humoral immune defense and force antibody formation.
Fusion with the host cell (HIV + T helper cell)
Surface proteins of the virus bind to the CD4 receptor. The special binding mechanism allows the virus to penetrate the cell.
The enzyme reverse transcriptase transcribes the RNA information of the virus into double-stranded DNA information. This "DNA language" is understood by the host cell. The integrase (also supplied by the HI virus) builds the virus information into the genetic material (genome) of the T-helper cell.
Now the viral information is converted. A large number of proteins are produced, which assemble to form a virion that is still immature. The virions are strangulated from the plasma membrane and mature into viruses that infect further T helper cells.
As long as the virus is stored in dormant T-cells, it cannot be attacked by drugs. If the T-helper cells are activated, they produce viruses instead of fighting the antigen.
The HI virus shows a very fast rate of evolution. It occurs in an infected person already in several subtypes. The dangerously long incubation period promotes infection of many more people!
Due to an immune deficiency (z.B. by the HI virus) the HBV can be reactivated again. This means that hepatitis B that has actually been cured can break out again, but then – due to the weakening of the immune system – much more drastically. This reactivation of the virus is possible because the HBV can go into a dormant state and remains in the cells.
Detection of HIV
The HI virus can be detected by ELISA or quantitative PCR. As in the case of hepatitis, a sandwich ELISA is also used in the case of the HI virus.