A new method of HIV prevention
New implant will protect women from sexual transmission of HIV
Natalia Pelezneva, Naked Science
Canadian researchers have developed a vaginal implant that reduces the risk of sexual transmission of HIV. The technology reduces the number of cells that the virus can infect. An article about the new development was published in the Journal of Controlled Release (Chen et al., Implant delivering hydroxychloroquine attenuates vaginal T lymphocyte activation and inflammation).
The human immunodeficiency virus remains one of the main problems of world medicine. According to the World Health Organization, in 2016 there were about 36.7 million people with HIV infection in the world. The current methods of antiretroviral therapy help to reduce the risk of developing severe forms of the disease, but do not allow you to get rid of it completely. Therefore, researchers are still looking for ways to prevent the spread of infection.
The new development is based on the results of studies on the spread of HIV in Kenya in the 1990s: scientists found that some local sex workers remain resistant to infection, although they do not use barrier methods of contraception. Researchers have suggested that this is caused by the peculiarities of T-lymphocytes in the body of women. The cells, known as T helper cells, usually become the main target for the virus. By binding to the CD4 protein on the surface of these cells, HIV penetrates into the cell and destroys it – independently or with the help of other cells of the body. It is known that HIV multiplies mainly in activated cells. Scientists have concluded that many T-lymphocytes of the vaginal mucosa of these women, when interacting with the virus, remain in a "dormant state" and are not activated.
The authors of the new technique reproduced the process artificially: in order to suppress the mechanisms of cell activation, they proposed using hydroxychloroquine, a malaria drug with a moderate immunosuppressive effect. It is used for some autoimmune diseases. According to the authors of the technique, the drug in tablets is rapidly destroyed in the body and does not have time to get to the vaginal mucosa. Therefore, scientists have developed a biocompatible polyurethane vaginal implant for point delivery of the drug. The drug "seeps" through the porous material and is absorbed.
Device operation diagram / © University of Waterloo
The new device was successfully tested on rabbits. Scientists managed to reduce the activity of RLA-DR markers associated with the "awakening" of T-lymphocytes, and CCR5 and CD69 proteins. It is known that a mutation in the CCR5 gene makes a person resistant to HIV: one of the methods of gene therapy is based on this.
It is unknown whether it will be possible to use such implants as the only means of prevention. Perhaps they will turn out to be just "insurance" for other ways of protection.
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