Slide Diagnostics
HIV testing is performed in a two-step scheme – first a screening test is performed, which is confirmed by a confirmatory test. The screening test is an immunological procedure – a so-called ELISA test. Specific antibodies can bind the antigen of the virus envelope.
This binding can be measured enzymatically or by fluorescence. If the ELISA test is positive, a Western Blot test is performed for confirmation. The performance of this test is somewhat more complex.
Some HIV proteins are transferred to a special membrane. Then the blood of the patient is added – if antibodies against HIV are present, they bind to the proteins of the membrane. In addition, a Western blot also allows the differentiation between HIV 1 and HIV 2.
A positive ELISA and Western blot test allow the diagnosis of an HIV infection. If the ELISA test should turn out positive, but this cannot be confirmed by a Western blot procedure, a PCR is performed. A PCR (polymerase chain reaction) amplifies the RNA of the viruses and can detect very precisely whether an HIV infection is present and what the concentration of the viruses is.
However, since this procedure is very expensive, it is only used for inaccurate questions. In order to make a diagnosis of HIV infection, more than one HIV test should always be carried out. Usually an ELISA and a Western blot procedure are used for this purpose.
They can detect an HIV infection with a very high probability. However, there is a diagnostic gap – in the first weeks of infection the body has not yet produced antibodies against the HIV virus. Without these antibodies, however, the test is negative.
For this reason, if there is a strong suspicion of HIV infection, the test should be repeated after a few weeks. After 12 weeks at the latest, an infection turns out positive, so that a repetition within this period should be aimed for. If the results are unclear, a PCR can be performed in addition to the ELISA and Western blot procedure.
This is a very precise detection method that can provide a reliable result.The rapid test can also be performed by laypersons independently at home. Like the other methods, the test detects antibodies against HIV. However, it should be noted that an HIV infection can only be ruled out 12 weeks after exposure, as the body needs time to produce the antibodies.
To perform the test, blood must first be drawn. This can be taken from the fingertip or earlobe. Then the blood is put into the rapid test and waited for about 15 – 30 minutes.
If this test is positive, you should consult a doctor who should perform another HIV test to confirm the result. If the result is negative, it is recommended to repeat the test after a few weeks to be sure. If there is any doubt, it is also advisable to see a doctor.
An HIV infection is still not curable. However, it is not an immediate death sentence. The ever-improving drugs maintain and improve the quality of life significantly.
These are summarized under the term antiretroviral therapy, i.e. a treatment that is specifically directed against the specific behavior of this type of virus. There are now a whole range of different agents that attack at different points in the life cycle of a virus. For example, the penetration of the viruses into the T-cell can be suppressed.
Usually at least three different agents are combined. This is called highly active antiretroviral therapy (HAART). With the help of this form of therapy, a normal life expectancy is now possible if treatment is started early enough.
However, the highly effective drugs cause many side effects. Depending on the active substance, for example, there may be disturbances in metabolism, nerves or blood formation. Since the drugs have to be taken permanently, it is important to weigh up the side effects against their effectiveness in order to find the best individual therapy.
The effectiveness is regularly checked. Again, the number of T cells, but also the amount of viruses in the blood plays a role. An HIV infection should always be treated, otherwise the immune system is destroyed.
There are numerous different drugs available that inhibit viral replication and have a positive influence on the course of the disease. There are five important substance classes in HIV therapy: Nucleoside reverse transcriptase inhibitors (e.g. lamivudine, abacavir, emtricitabine) Nucleotidic reverse transcriptase inhibitors (e.g.
Tenefovir) Non-nucleoside reverse transcriptase inhibitors (e.g. Protease inhibitors (e.g. darunavir, atazanir, lopinavir) Integrase inhibitors (e.g. Raltegravir, Elvitegravir, Dolutegravir) In order to achieve optimal therapeutic success, the different substance classes are combined.
Common combinations are the intake of 2 nucleoside or nucleotide reverse transcriptase inhibitors and 1 integrase inhibitor. Another alternative is the combination of 2 nucleosidic or nucleotidic reverse transcriptase inhibitors and a non-nucleosidic reverse transcriptase inhibitor. Furthermore, the intake of 2 nucleosidic or nucleotidic reverse transcriptase inhibitors and 1 protease inhibitor is possible.
Some of these preparations are available in fixed combinations, so that a patient does not have to take many different tablets and does not lose track of what is happening. The therapy can be varied individually and can also be changed in the course of the treatment. It is important for the patient to take it regularly, as inconsistent use can lead to the development of resistance.
This means that the viruses develop a mechanism and the drugs can no longer be effective. This can have a very unfavorable effect on the course of a patient’s disease. In addition, HIV therapy must be continued throughout the patient’s life.
Fortunately, HIV patients have a normal life expectancy with a well adjusted treatment.
- Nucleoside reverse transcriptase inhibitors (e.g. lamivudine, abacavir, emtricitabine)
- Nucleotidic reverse transcriptase inhibitors (e.g.
Tenefovir)
- Non-nucleoside reverse transcriptase inhibitors (e.g. efavirenz, nevirapin, etravirin)
- Protease inhibitors (e.g. darunavir, atazanir, lopinavir)
- Integrase inhibitors (e.g. Raltegravir, Elvitegravir, Dolutegravir)
