Understand how a patient treated in the US was cured of HIV

The fourth case of a person cured of HIV infection was announced this Wednesday (27), during press announcements ahead of the International AIDS Conference in Canada.

Prolonged remission of the infection occurred in a 66-year-old man who declined to reveal his identity. He was nicknamed the “City of Hope patient”, citing the City of Hope health facility in Duarte, Calif., where the man was treated.

The patient is now 17 months without signs of the virus in the body, even without treatment with antiretrovirals.

What led to the cure

Remission of the disease occurred after a bone marrow transplant, the site of production of blood cells. The process was necessary to treat leukemia, a cancer that affects blood cells.

Doctors treating the patient began looking for a bone marrow donor who was naturally immune to the HIV virus. For this, a genetic search for a donor with a mutation in the CCR5 gene was initiated.

This gene produces a protein that, in general, allows HIV to enter human CD4+ defense cells. People who have received a particular CCR5 mutation (a deleted stretch of genetic letters) from both their father and mother — that is, they are homozygous for that mutation — are resistant to infection with some of the HIV variants.

The bone marrow received, about three and a half years ago, from an immune donor enabled the City of Hope patient to block the way in which HIV enters his defense cells and, in this way, led to the remission of the infection.

It was not the first time that such a procedure was used. This is the same process that, in 2007, led to the first case of HIV infection cured by the Berlin patient, Timothy Ray Brown. The other three cases of cure already reported are also related to the CCR5 gene.

Now, however, he is the longest-lived HIV patient (31 years of infection) to achieve remission after a bone marrow transplant.

The City of Hope health center also points out that the patient treated there is the oldest person to be cured, due to the transplant, both from HIV infection and from cancer. At the time of the procedure, the man was 63 years old.