Public Health officials have a difficult decision to make in regards to screening individuals for HIV: administer a dependable blood test that could detect infections early on, but few people would volunteer for, or give people a suitable analysis using HIV saliva test which is less reliable during the initial stages of the disease.
Stanford has been researching an easy and accurate way for the public to be able to get tested for HIV. There is a new improved HIV saliva test could transform that. Produced by Stanford chemists in collaboration with the Alameda County Public Health Laboratory, the evaluation blends the comfort of spitting in a cup with the accuracy of blood tests, this was released in the January 22, 2018 issue of Proceedings of the National Academy of Sciences.
“The earlier you can detect, the better, because people can infect other people,” said Carolyn Bertozzi, the Anne T. & Robert M. Bass Professor in the School of Humanities and Sciences and a professor of chemistry. “Every day that goes by that a person’s behavior is not modified based on their HIV status is a day that they could be infecting other people, especially for young people,” said Bertozzi, who’s also a faculty member of Stanford ChEM-H and a part of Stanford Bio-X.
A Brief History Of HIV Testing
The most popular way to test for HIV disease is to look at a blood sample for proteins, antibodies that the immune system custom-builds to combat the virus and fight back against the disease. That test is a lot more suitable than a direct search for the infection, in part because antibodies are about plentiful in the blood after the first phases of infection.
There is a significant drawback, especially for public health officials and researchers who desire — sometimes need — to get a lot of people tested fast to help contain the spread of this disease: the need to draw blood using a syringe.
“There’s a lot of populations you just can’t reach out to by blood tests,” stated Cheng-ting” Jason” Tsai, the lead author on the new paper and a graduate student in Bertozzi’s laboratory. “But if you were to perform oral fluid, then all of sudden you open up a completely new population that wasn’t otherwise available to you.”
But saliva samples have their issues. When there are HIV antibodies in saliva, they don’t collect at the levels they do in blood, or precisely the same rate — meaning that there are not that many presents, particularly early on.
With the time saliva tests can easily diagnose HIV, Bertozzi said, “you’ve waited a long time” – and at that time, the disease could develop.
credit: Stanford Medicine X
The job of the team, then, was to figure out how to make it easier to detect the small number of antibodies present in the saliva of a person with HIV. To accomplish this, they took an indirect approach. Rather than searching for the HIV antibodies themselves, they looked for what HIV antibodies can do.
They took benefit of a critical feature — they have two arms, each of which readily latches on a virus such as HIV. They took pieces of HIV and attached them to the other half of a part of DNA. Then they combined the altered HIV bits with the saliva sample.
If the sample comprised HIV antibodies, both arms could catch hold of the tagged HIV, bringing the two halves of the DNA together, to a continuous strand. When the DNA piece is made whole, it’s not hard to detect using standard lab methods.
That can all be done without needing a blood sample or even technology to process the examples which are taken. “It is blatantly low tech,” Bertozzi said.
Although the researchers say it takes more research to confirm the results, the initial experiments show that it works nicely: the test perfectly diagnosed 22 individuals who participate in an Alameda County test effort, each of whom had examined positive for HIV with different procedures. Importantly the evaluation did not falsely detect HIV in the 22 additional HIV-negative participants.
It may also work earlier in contrast to saliva tests, although not quicker than blood existing tests. In a set of eight samples which had produced mixed results with the present standard saliva test, six comes out positive with the new HIV test, and one of these was confirmed with a blood test.
However, those results are preliminary; they indicate that the new test is more sensitive and might pick up HIV disease sooner than others. “Our hope is that we can get an earlier read than the present oral test because the sensitivity is better,” Bertozzi said.
Past HIV, Tsai, and she stated the same principles might be useful for allergy screening and testing for tuberculosis typhoid and infection. The team is also exploring the process as a means to test the effectiveness of measles vaccination works, Bertozzi said.