Saliva-Based Test for HIV Is Accurate and Rapid

This could replace taking a blood sample, which is invasive and frequently painful.

The new test is based on oral mucosal transudate (OMT), a fluid that is secreted at the base of the gums before it becomes saliva. The level of antibodies in OMT is comparable to that of blood plasma, making it an excellent sample.

The underlying method, called immunochromatography, is the same as for pregnancy tests. The OMT is simply collected on a stick, which is also similar to the one used in a pregnancy test, and then placed in a small tube containing a special solution. Between 20 and 40 minutes later, a purple line will appear at the top of the stick if the result is positive.

To test the technique under real world conditions, especially in vulnerable pregnant women, Dr. Nitika Pant Pai, a post-doctoral fellow at the division of infectious diseases and immunodeficiency service at the McGill University Health Centre (MUHC; Montreal, QC, Canada) carried out clinical trials in the labor ward of the Mahatma Gandhi Institute of Medical Sciences, (Sevagram, India). "In such cases, it is vital to determine the HIV status of the mother very quickly to prevent transmission to the child during delivery. Many Indian women do not receive prenatal care and therefore do not get tested for HIV during pregnancy. Testing in the labor ward is the last chance to prevent HIV transmission to the newborn baby. Also, Indian patients often refuse blood collection, while saliva collection poses no problem,” explained Dr. Pant Pai.

In the study, 1222 mothers were tested for HIV in the labor ward using both saliva and blood samples. The results from both kinds of tests corresponded in 100% of cases. In addition, use of the saliva test in the labor ward helped to identify several HIV-infected women who were unaware of their HIV status. These women received treatments to reduce the chance of HIV infection in the newborn babies.

"Rapid saliva tests are not in use yet in Canada, as they are met here with a lot of skepticism,” Dr. Pant Pai acknowledged. "However, their efficacy has now been demonstrated for all subtypes of HIV-1 and HIV-2.”

These tests could become highly useful for vulnerable or at-risk people who are not always given adequate medical follow-up. A rapid, low-cost test would therefore reduce the number of patients who are unaware of their HIV status.


Related Links:
McGill University Health Centre
Mahatma Gandhi Institute of Medical Sciences