Just spit!
When it comes to choosing a screening method for such a serious and widespread infection as HIV, preference is given primarily to a blood test, since it is considered the most reliable.
Researchers from Stanford University (USA) have developed a new reliable analysis of saliva for HIV.
To date, the most common way to detect HIV is to search for antibodies in a blood sample – proteins that are produced by the immune system to fight the virus. This method is much more convenient than a direct search in the blood sample of the virus itself, because antibodies appear in large quantities in the blood already at the early stages of infection.
However, there is a big drawback of such screening – these are needles. The fear of pain and the very process of blood collection frightens some people, so they avoid screening. The researchers suggested that the HIV test, which requires only a saliva sample, will increase the population of those examined and the percentage of early detection of the disease, and this will eventually lead to increased survival.
Another advantage of saliva analysis is its safety for medical personnel. There is no virus in the saliva, which means there is no risk of infection in the event of a biological accident.
The saliva of an HIV-infected person contains antibodies, but, unlike blood, they do not accumulate in such an amount that it can be easily detected. There are especially few antibodies in saliva in the early period of HIV infection.
The task of the research team was to create a tool with sufficient sensitivity to detect the smallest amounts of antibodies in saliva. They decided to do this indirectly: to look not for the antibodies themselves, but for the changes they produce.
Antibodies have a feature: they have two "hands" that close when they come into contact with HIV. The researchers attached fragments of the virus to a single strand of DNA. Then such modified HIV fragments were added to saliva samples. If the saliva belonged to an HIV-infected person, the "hands" of the antibodies captured fragments of the virus with DNA halves attached to them and closed. The DNA halves connected to form a double-stranded helix. And already these full-fledged DNA can be easily detected using the standard laboratory method of polymerase chain reaction (PCR).
The new saliva analysis technique is quite sensitive. In addition, the researchers deliberately made it "low-tech" in order to reduce the cost of screening as much as possible.
If the test result is positive, it is necessary to conduct standard blood tests for HIV antibodies to confirm it.
The first experiments are encouraging: in 22 HIV-positive and 22 healthy study participants, the PCR analysis of saliva was never mistaken, without showing a single false positive or false negative result.
When compared with existing saliva assays based on enzyme immunoassay (ELISA) methods, the new method also showed good results. In a set of 8 samples, the analysis of which by existing methods showed a mixed result, the new method revealed 6 HIV-positive samples. In addition, it is estimated that the PCR method is up to 10,000 times more sensitive than ELISA.
The experimental results are preliminary, but there is already no doubt that the new method for determining HIV antibodies in saliva exceeds the existing ones in sensitivity, that is, it can detect infection at an earlier stage.
The developed antibody detection principle can be used not only for HIV detection, but also for allergy diagnosis, screening for typhoid and tuberculosis infections, as well as for monitoring the effectiveness of measles vaccination.
Article by Cheng-ting Tsai et al. Antibody detection by agglutination–PCR (ADAP) enables early diagnosis of HIV infection by oral fluid analysis published in the journal PNAS.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on Stanford News Service: Stanford researchers develop a hassle-free HIV test that works better, sooner.