PNAS: Developed a new HIV saliva test method
2023-10-10 05:08:27
When it comes to screening people for HIV, public health officials face a difficult choice: to conduct a reliable blood test so that infections can be detected earlier, but few will voluntarily use it. Or use saliva for a convenient test, but in the initial stages of infection, this test is less reliable.
In a new study, a new test method developed by researchers from Stanford University, the Alameda County Public Health Laboratory, and the University of California, San Francisco may change this. This new test method combines the convenience of spitting in the test cup with the reliability of blood testing. The relevant research results were published online in the PNAS journal on January 22, 2018, and the title of the paper was "Antibody detection by agglutination-PCR (ADAP) enabling early diagnosis of HIV infection by oral fluid analysis".
Carolyn Bertozzi, a professor and professor of chemistry at Stanford University's School of Humanities and Sciences, said, "The sooner the better, the better, because HIV-infected people can infect other people. Every day a person's behavior does not change based on their HIV status. They may infect others (especially young people) for a day."
A brief history of HIV testing
By far the most common method of detecting HIV infection is to look for antibodies in blood samples, proteins that are produced by the immune system against the virus and against infection. This test method is much more convenient than looking for the virus directly, in part because the antibodies are relatively abundant in the blood during the early stages of infection.
However, it also has a major drawback, especially for public health officials and researchers who want (and sometimes need) many people to quickly test to curb the spread of HIV: needles.
Cheng-Ting Tsai, the first author of the paper and a graduate student at Bertozzi Lab, said: "There are many people who are not willing to go to the blood test. But if you use the liquid in the mouth to carry out the test, then suddenly there will be new people willing to accept such a Testing, but they are not willing to accept the previous blood test."
But oral fluid testing also has its own problems. Although HIV antibodies are present in saliva, they do not accumulate at levels in the blood, or do not accumulate at the same rate, which means that there are not many antibodies present in saliva, especially in the early stages of infection. Bertozzi said that when the oral fluid test can reliably detect HIV, "you have been waiting too long - at that time, the infection may spread."
Clinical transformation
In this new study, the work of these researchers is how to more easily detect small amounts of antibodies present in the saliva of HIV-infected people. To this end, they take an indirect approach. Instead of looking for the antibodies themselves, they are looking for what the antibodies can do.
These researchers have taken advantage of a key feature of antibodies -- they have two arms, each of which is easily attached to a virus such as HIV. They get some HIV and attach them to one or the other half of a DNA fragment. They then added these modified HIV to the saliva sample. If the sample contains HIV antibodies, then their two arms will seize the modified HIV and join the two halves of the DNA fragment into a continuous chain. Once this complete DNA fragment is produced, it can be easily detected using standard laboratory techniques. All of this can be done without the need to collect blood samples or use too much technology to process the collected samples.
Although the researchers said that more research is needed to validate these results, the first experiments showed that the new test method performed well: it correctly diagnosed 22 HIV screening trials in Alameda County. People, each of these people have been diagnosed HIV positive when tested by other methods. Importantly, this test method did not detect HIV erroneously in another 22 HIV-negative participants.
It may also be tested at an earlier stage than other saliva test methods, but not earlier than existing blood tests. In a group of 8 samples (when the current standard saliva test method was used to test these samples, complex test results were produced), 6 samples were positive using this new HIV test, and one of them was used. Blood tests have been confirmed. Although these results are preliminary, they suggest that this new assay has better sensitivity and may detect HIV infection earlier than other test methods.
Bertozzi said, "Our hope is that we can give results earlier than the current oral fluid test because it has better sensitivity." In addition to HIV, she and Tsai said that the same test principles are possible. Suitable for allergy testing and screening for typhoid and tuberculosis infections. Bertozzi said the researchers are also investigating whether this method can be used as a way to test the efficacy of measles vaccination.
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