He received two bone-marrow transplants from a donor with a rare mutation the CCR5 gene, which prevents the virus from entering the cells of the immune system, making people resistant to HIV, and became the first patient to be "cured" of HIV. His blood viral load remains undetectable 18 months later, no HIV DNA can be found in peripheral CD4 cells using a sensitive assay with a 1 copy/ml limit and tests showed no "reactivatable" virus in 24 million resting T cells. The milestone came about three years after the man received bone marrow stem cells from an HIV-resistant donor and about a year and a half after coming off antiretroviral drugs.
However, news that a second person may have been "cured" demonstrates that the Berlin Patient was not an anomaly.
This is why blood stem cells (also called hematopoietic stem cells or bone marrow cells) are so significant.
But the current news "does teach us a great deal about the HIV virus and how we can possibly create other ways to eradicate it", says Dr. Rosenthal. Scientists have wondered, however, whether this good fortune could be shared around by injecting stem cells from people with two Δ32 copies into HIV patients.
"While this type of treatment is clearly not practical to treat the millions of people around the world living with HIV, reports such as these may help in the ultimate development of a cure for HIV".
The male London patient, who has not been named, was diagnosed with HIV in 2003 and advanced Hodgkin's lymphoma in 2012.
Nevertheless, the researchers are clear: "At 18 months post-treatment interruption it is premature to conclude that this patient has been cured".
Researchers are inching closer to a possible cure for HIV as a second patient was declared HIV-free after undergoing a bone marrow transplant.
The new patient, treated by doctors in Europe and nicknamed "the London patient" for anonymity, mirrors a similar case from over a decade ago, which scientists have spent years trying to replicate.
The transplant was relatively uncomplicated, but with some side effects including mild graft-versus-host disease, a complication of transplants wherein the donor immune cells attack the recipient's immune cells. CCR5 is also the gene that Chinese researcher He Jiankui tweaked in embryos to give them a genetically-engineered resistance to HIV infection throughout their lifetimes. "It shows the Berlin patient was not just a one-off, that this is a rational approach in limited circumstances", said Daniel Kuritzkes, chief of infectious diseases at Brigham and Women's Hospital, who was not involved in the study.
Hopes that a cure will be available to all any time soon are misplaced though.
"We've always wondered whether all that conditioning, a massive amount of destruction to his immune system, explained why Timothy was cured but no one else", AIDS expert Dr. Steven Deeks, who has worked with Brown medically, told NYT.