Vaccines, cell therapy: what future for HIV treatment? – 03/10/2022

In the 1990s, after being diagnosed with a viral infection HIV (cause of AIDS) was like a “death sentence”. There was no treatment available and it was the natural course of the patient. But as soon as the first drugs against HIV appeared, the scenario began to change and Brazil became a pioneer and a world reference in public policies for the treatment of the disease.

According to David Lewi, infectious disease specialist at the Israelita Albert Einstein Hospital, the treatment of HIV has evolved a lot since the arrival of the first drug, the famous AZT, which is now in disuse.

“AZT has had a great history in fighting disease, but over the years the drugs have improved in terms of safety and toxicity, side effects have diminished, and today most patients don’t take only one tablet. There are already cases of patients taking monthly injections abroad”, explains the doctor, also a retired professor at Unifep (Federal University of São Paulo).

Currently, antiretroviral therapy aims to make the viral load undetectable – which does not leave the person free from HIV, but stops transmission of the virus.

For the treatment to be truly effective, it is necessary to make continuous and uninterrupted use of the drug, otherwise the latent virus will circulate again.

This is because existing drugs only work on viruses that are circulating in the blood – they cannot reach those that are latent in cells.

“When the virus is dormant in the cells, without activation, it does not cause immunity damage and the drug cannot reach them. If the patient stops taking the drug, those viruses that are in ‘hibernation’ will eventually circulate again,” explains the doctor.

Cure in the future?

Since the lack of good medication compliance is one of the greatest difficulties encountered in the fight against HIV, researchers have been looking for a fixed-term treatment for ten years, and no longer for life.

“Instead of taking the drug for an indefinite period, what we are looking for is that this latent virus is expelled from the ‘sanctuary’ and, once released in the blood, is extinguished under the action of the drug. And then one could, in the future, stop the medication and the patient would be effectively cured,” says Lewi.

Another attempted cure that has been sought is the total elimination of the virus – as happened in the case of the so-called “Berlin patient”. Timothy Ray Brown, believed to be one of the few people to be cured of HIV infection, was diagnosed with acute myeloid leukemia and in 2007 received a bone marrow transplant from an HIV-positive donor. a genetic mutation that would guarantee resistance against the virus.

“The doctors chose a compatible bone marrow donor, who had this genetic deletion that prevented the HIV virus from entering the cells. And it worked. as clinical practice because, in addition to being an expensive procedure, bone marrow transplantation itself carries a risk of mortality,” he says.

The use of cell therapy against disease is also being investigated. In a research carried out by Unifep, in collaboration with the Instituto Superiore di Sanità, in Rome (Italy), the scientists carried out the genetic sequencing of the virus circulating in the cells of each patient.

These cells were then processed and reinfused, as in an autologous bone marrow transplant (when the patient’s own cells are collected and used later).

Two of the study participants ended up with undetectable viral RNA in the experimental protocol, showing a possible avenue for personalized HIV cell therapy, taking into account both the patient’s immune system and viral profile. of the individual. You results have been published in the scientific journal AIDS research and therapy.

HIV vaccine

The development of an HIV vaccine is also another attempt by researchers. “HIV is a virus that undergoes several mutations and so far no center has succeeded in creating an antibody thanks to a vaccine which could eliminate it. HIV creates subterfuges against these antibodies. Unfortunately, all the vaccines tried so far have not induced sufficient immunity against HIV,” says Lewi.

According to the infectiologist, several centers around the world are looking for a cure for HIV, but, for him, the most promising is the development of a definitive treatment.

“What I highlight today is the ease with which the patient takes the drug, with increasingly simple treatment regimens and with very low side effects. At this precise moment, it is still essential that the patient has adherence to the treatment. In about five years, we can speak of definitive treatment, for a predetermined time, until the patient can suspend the medication and consider himself cured”, he concluded .

Even though the number of new cases is decreasing in Brazil, it remains very high. The most recent data from the Epidemiological Bulletin of the Ministry of Health indicates that over the past five years the annual average of cases is around 36,800 new diagnoses and has increased among young men. Worldwide, there are approximately 1.5 million new cases per year.

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