Closer to understanding why the Berlin patient was cured of HIV

01 October 2014
An HIV ribbon

A recent study has attempted to further understand why Timothy Ray Brown, also known as the Berlin man, was cured of HIV in 2006 after living with the virus for 11 years. The research has narrowed down critical factors that were involved in eliminating the HIV virus from Brown’s body. Brown remains the only known case of someone who has been cured of HIV and his case has subsequently gained immense interest among researchers striving to find a cure for HIV.

Brown was diagnosed with acute myeloid leukemia after living with HIV and being on antiretroviral treatment (ART) for 11 years. To save his life, he underwent chemotherapy and a bone marrow transplant, meaning he also had to stop taking ART. As a consequence, it was thought that the level of HIV in his body would increase; however over the past seven years, only very small traces of HIV have been found and have not replicated.

Several factors have been identified to try and understand how Brown may have been cured. It has been suggested that the high levels of chemotherapy and irradiation Brown received destroyed his immune system and may have reduced the virus infected cells in his body – a process known as conditioning. Other hypotheses have emphasised the importance Brown’s bone marrow transplant played in the elimination of HIV, with the bone marrow donor having a rare gene mutation that prevented the replication of HIV in Brown’s body. Furthermore, a process known as graft-versus-host disease has also been suggested, where Brown’s new immune system post-bone-marrow transplant, attacked the remaining HIV infected cells of his old immune system.

Researchers at Emroy University in the USA, are exploring these theories further, and have found that conditioning alone cannot result in the elimination of HIV. HIV infected monkeys on treatment were taken off their treatment and given irradiation and chemotherapy to destroy their immune systems. But in contrast to Brown, the virus quickly returned. The failure of conditioning to eradicate HIV highlights the important role that the bone marrow transplant played in Brown’s case, specifically the graft-versus-host process. In the research, the monkeys received their own stem cells, which did not result in a graft-versus-host response.

Future experiments are therefore vital to test the different variables beyond conditioning which might have lead to Brown’s miracle recovery, and may eventually lead to a cure for people living with HIV.

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