New research conducted by Oregon Health & Science University (OHSU) has shed light on the mechanisms behind the cure of HIV in at least five individuals who underwent stem cell transplants. The findings of the study, published in the journal Immunity, have the potential to advance the development of a widespread cure for HIV, which has affected approximately 38 million people worldwide.
The study, led by Jonah Sacha, a professor at OHSU's Oregon National Primate Research Center and Vaccine and Gene Therapy Institute, involved the transplantation of stem cells into two nonhuman primates infected with the simian form of HIV (called SIV). The researchers discovered that two conditions must be present for a cure to occur and documented the sequence in which the virus is eliminated from the body. This knowledge can inform future efforts to develop a cure applicable to a larger population.
The recent study involved Mauritian cynomolgus macaques, a type of nonhuman primate previously shown to successfully receive stem cell transplants. Among the eight subjects with SIV, four underwent transplants using stem cells from SIV-negative donors, while the remaining four served as controls without transplants. Two of the transplanted subjects were cured of the virus after receiving treatment for graft-versus-host disease, a common complication of stem cell transplantation.
Notably, this study marks the first instance in which HIV-cured research animals have survived long-term.
The study also revealed the two primary ways in which the transplants led to elimination of the virus. First, the transplanted donor stem cells recognized and attacked the recipients' SIV-infected cells as foreign invaders. Second, the virus was prevented from infecting the donor cells through the CCR5 receptor, which is essential for the virus to enter cells. The researchers observed a gradual clearance of the virus from the subjects' bodies, starting with the limbs' lymph nodes and followed by those in the abdomen.
This understanding of the step-by-step clearance of HIV can aid physicians in evaluating potential cures and may explain cases where HIV was initially undetectable but later reappeared. The researchers plan to further investigate the immune responses of the cured primates, identifying the specific immune cells involved and the cells or molecules targeted by the immune system.
The findings of this research offer valuable insights into the cure of HIV through stem cell transplantation and pave the way for future advancements in developing a widespread cure for this global health challenge.