|Irradiation and transplantation effective treatment for HIV.|
The human immunodeficiency virus (HIV) is a virus that attacks the immune system. Your immune system protects you from germs that cause infections and make you sick. If HIV is in your system, over time, it lowers the number of healthy immune cells (CD4 cells) that you have to fight infections.
Now researchers show that an irradiation plus transplantation combination approach in nonhuman primates can be used to treat or even possibly cure HIV/AIDS. This new model is also providing some answers about the "Berlin patient", the only human thought to be cured of AIDS. The study is published in PLOS Pathogens.
Researchers performed the first hematopoietic stem cell transplantation in three rhesus macaques infected with a simian human immunodeficiency virus (SHIV). They harvested hematopoietic stem cells from three macaques prior to SHIV infection of all six animals in the study, treated the animals with anti-retroviral therapy (ART) to reduce viral load and mimic the situation in human HIV-infected patients who are treated with ART. They then exposed the three monkeys from which they had collected hematopoietic stem cells to a high dose of radiation. Following the irradiation, the researchers transplanted each monkey's own virus-free hematopoietic stem cells. The stem cells regenerated blood and immune cells in all three monkeys within six weeks, at which time the scientists stopped ART in all of the monkeys.
Post-mortem analysis of the monkey that experienced no virus rebound after ART interruption showed low levels of viral DNA in a number of tissues. An added benefit of the researchers' work is providing insight into the cure of the Berlin patient, who was HIV-infected before irradiation for leukemia and then a bone marrow transplant. The transplant was from a donor who had a mutation that abolishes the function of the CCR5 gene, which codes for a protein that facilitates HIV entry into human cells. The mutation in homozygous carriers who, like the donor, have two defective copies protects against HIV infection. The researchers say using the CCR5 mutant donation and/or the presence of graft versus host disease, which results in the elimination of HIV-positive reservoir cells that survive irradiation, played a significant role in curing the Berlin patient.