Little fragments of genetic material called microRNA (miRNA) may offer a clue to how HIV, the AIDS virus, evades detection while hiding in the immune system.
Researchers at Jefferson Medical College in Philadelphia have shown that when a HIV infected person is given a powerful mixture of antiviral agents called HAART (highly active antiretroviral therapy), the virus turns to miRNAs to remain quiet and undetectable, for the moment shutting down the ability to multiply and infect.According to Hui Zhang, M.D., Ph.D., associate professor of Medicine in the Division of Infectious Diseases at Jefferson Medical College of Thomas Jefferson University, who led the work, if scientists find the method to manipulate miRNA’s inhibitory effect on HIV, they can develop strategies to bring out the virus from its latency state. “HIV latency and how to eliminate the replication-competent – and hidden – virus are big problems,” Nature Medicine quoted Dr. Zhang ,as saying.
Dr. Zhang, post-doctoral fellow Jialing Huang, Ph.D., and their colleagues have found that the virus ruses cellular miRNA – noncoding genetic material that are known play a variety of roles in cancer and in biological regulation, in inactive T cells to ‘control the translation of viral RNA into protein’. The team showed that a cluster of miRNAs attach to certain spot in viral RNA that stops the replication of the virus and the production of important proteins.
The team also found that resting CD4 T cells were “enriched” with more than the normal amount of these miRNAs compared to the activated T cells. With the use of antisense technology researchers blocked miRNA-caused viral inhibition that made the HIV again active and continue to replicate, establishing miRNA’s critical role in maintaining latency.
While Dr. Zhang and his team continue to find how cellular miRNA contributes to latency, he notes that miRNA inhibitors ‘might become a kind of therapeutic approach to get the virus out of hiding, making it visible and a target” for the immune system’. “That’s the next step,” he said. The study appears in an early online edition of the journal Nature Medicine.
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