Prof. Lee Sang-kyung |
By Kim Tong-hyung
Staff Reporter
A multinational team of scientists announced a gene treatment strategy that helps prevent HIV from growing in cells, which could prove a major breakthrough in the fight against AIDS.
The researchers, led by Hanyang University's Lee Sang-kyung and Harvard Medical School's Premlata Shankar, said they have developed a therapeutic system that delivers small interfering RNA (siRNA) specifically to T cells, or white blood cells that orchestrate the immune system's response to infections, and as such become primary HIV targets.
This dramatically suppressed HIV infection in ``humanized'' mice with human T cells, the scientists said.
The study will be published in the Aug. 8 edition of the international science journal Cell.
``We believe that the targeted delivery system could work in therapies and also as a vaccine,'' Lee told the Korea Times.
``The system successfully suppressed the spread of HIV in mice that were later injected with the virus, while restoring the cell counts for CD4 T cells (the primary targets of HIV) and nearly eliminated HIV in the infected mice,'' he said.
SiRNA, also known as silencing RNA, are a class of double-stranded RNA molecules that are involved in the RNA interference (RNAi) mechanism, which interferes with the expression of a specific gene.
RNAi, considered among the most important breakthroughs in the past decade, works by switching off individual genes and has been found to be effective in slowing the spread of HIV in mice.
Although the newly discovered immune system has raised new hopes for developing drugs to treat HIV infections and other diseases, clinical application has been considered a distant possibility as HIV attacks only humans and RNAi has never been tested on a person.
The success of the siRNA therapy developed by Lee's team is significant because it was based upon the closest simulation of a human HIV infection to date.
``We think it is a feasible pre-clinical model," said Lee, who added that it is the first time that siRNA therapy for HIV infections has been proven in vivo.
The scientists first eliminated the immune system of the mice and injected them with human white blood cells, a method which replaces the animals' blood with ``virtual human blood'' for about two months.
Then the researchers injected the mice with CD7-specific antibodies, argrine peptide (9R) and siRNA, which conjugated into nano particles and were delivered specifically into the CD7 genes on T cells.
This smart-bomb like function of the therapy will also improve the efficiency of current antiretroviral drugs, whose major side effects have been a problem. The siRNA conjugates could possibly be used in combination with the drugs, maximizing their effectiveness and allowing patients to be given lower doses, Lee said.
thkim@koreatimes.co.kr
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