Promising vaccines promise remission to HIV patients

Julia Korowski, XX2 century

A team of Korean, American and Dutch scientists tested a combination of drugs that causes remission in monkeys with HIV. Researchers have shown that experimental vaccines in combination with an immunostimulator reduce the viral load and delay the reactivation of the virus at the end of antiretroviral therapy. The results of the work are published in the journal Nature (Borducchi et al., Ad26/MVA Therapeutic Vaccination with TLR7 Stimulation in SIV-Infected Rhesus Monkeys).

"The goal of our study is to develop a functional treatment for HIV – not to destroy the virus, but to control it without the need for antiretroviral therapy (ART)," says Dan Barouch, lead author of the study. – Modern antiretroviral drugs prolong life, but do not cure HIV. They just keep it under control. We are trying to develop a strategy to achieve long-term viral suppression without the use of ART" (see the press release of Beth Israel Deaconess Medical Center New Therapeutic Vaccine Approach Holds Promise for HIV Remission).

Usually, vaccines "teach" the body to get rid of viruses on its own, causing an immune response, but HIV infects the cells of the immune system. Most of them are killed by the virus, but some are used as a kind of "shelter". These "reservoirs" of latent HIV cells are the main reason why the disease cannot be completely cured. Scientists are looking for ways to "lure" the virus out of hiding and destroy it.

During the two-year study, scientists tracked the viral load of 36 rhesus monkeys infected with the monkey immunodeficiency virus, a related HIV disease that affects non–human primates. The animals were treated with ART for six months, and then divided into four groups. The first was introduced only experimental vaccines – Modified Vaccinia Ankara (MVA) and a drug based on adenovirus 26th serotype (Ad26). The second is only an immunostimulator, an experimental drug that acts on a protein called "toll–like receptor 7" (TLR7). The third is a combination of these drugs. The control group did not receive any treatment.

To evaluate the effectiveness of the vaccine and the immunostimulator, the researchers interrupted antiretroviral therapy in all animals and monitored their viral load. The viral load decreased in monkeys who were injected with vaccines, but the effect was stronger in those who were treated with a combination of drugs. The scientists managed not only to reduce the amount of viral RNA in the blood plasma of all nine primates, but also to delay the return of the viral load by 2.5 times compared to the control group. In a third of the animals that underwent complex therapy, the virus was not detected in the blood at all.

The researchers speak about their success with restraint and caution. "If the viral load was not determined in all monkeys, it would be a complete success. But the fact that all animals showed a decrease in viral load, and three out of nine could not register it – this is already a good start. It is definitely possible to work with this," says Baruch.

HIV infection is a slowly progressive disease caused by the human immunodeficiency virus. The virus infects cells of the immune system that have CD4 receptors on their surface: T-helpers, monocytes, macrophages, Langerhans cells, dendritic cells, microglia cells. As a result, the work of the immune system is suppressed, acquired immune deficiency syndrome (AIDS) develops, the patient's body loses the ability to protect itself from infections and tumors, secondary diseases arise that are not characteristic of people with normal immune status.
Highly active antiretroviral therapy (HAART) is a method of HIV infection therapy consisting of taking three or four drugs. Thanks to VAART, most HIV-infected people can now lead a normal lifestyle. The main goals of the VAART are to stop the reproduction of the virus in the body, restore the state of the immune system, increase the duration and quality of life. The combination of drugs is assembled from three or four components, therapy requires strict adherence to the schedule of admission.

Portal "Eternal youth" http://vechnayamolodost.ru 11.11.2016