Potential Cure for HIV
According
to the
World Health Organization (WHO),
approximately 0.8% of adults between the ages of 15-49 years old are living
with
human immunodeficiency virus (HIV) worldwide. Despite the global
prevalence of the virus, there has not yet been a
functional
cure. However, recently an HIV-positive patient with leukemia was cured of
the virus. The patient underwent
total
body irradiation (TBI) and a bone-marrow transplant. The bone-marrow donor
had a mutation which prevents the function of the
CCR5 gene. The CCR5 gene codes for a
protein which allows HIV to enter human cells. The mutation the donor
possessed, however, protects cells against HIV infection.
Experts believe three factors may
have contributed to the cure in the Berlin patient. The first factor which may
have contributed to the patient’s cure is that the removal of blood and immune
cells which occurred after irradiation killed many of the viral reservoir cells. The second
contribution may have been that the CCR5 deletion mutation from the
donor cells protected those cells and their progeny from HIV infection.
The third contribution to the patient’s cure may have been a graft versus
host reaction which resulted in the transplanted cells and their progeny
attacking and eliminating the remaining HIV-positive cells.
In order to further research this potential cure for HIV, a study was conducted involving six rhesus macaques
infected with simian immunodeficiency virus (SIV). The researchers harvested
hematopoietic
stem cells from three of the six of the macaques prior to infection with SIV
and treated the macaques with
antiretroviral therapy
(ART). They treated the three macaques from which they collected hematopoietic
stem cells with high doses of radiation. The radiation killed 94%-99% of the
monkeys’
CD4-T
cells. The three monkeys then received their own virus-free hematopoietic
stem cells. The viral load rebounded rapidly in the three control group monkeys
and in two of the monkeys who received the transplant. Due to the failure of
the treatment, the researchers suggest that “the use of the CCR5 mutant donor
and/or the presence of graft versus host disease played a significant role” in
the cure of the Berlin patient.
Overall, this potential treatment
for HIV seems to have promise and should definitely be more extensively
researched. This treatment involving ART, irradiation, and a hematopoietic stem
cell transplant is very complex, and there are many aspects of it which should
be thoroughly examined. I found this article extremely interesting because the
graft versus host disease in the Berlin patient seemed to have been a vital
factor in how the patient was cured of HIV. Due to the complexity of the Berlin patient’s
case, the results will be difficult to replicate; however, replication of the
Berlin patient’s results has profound implications in the search for a cure for
HIV.
