HIV-1 induces RNA silencing

HIV-1 elicits RNA silencing in human cells, but also contains a sequence that suppresses the process, researchers report in the May issue of Immunity.

"Nucleic acid-based immunity in mammalian cells has been found before, but to date, there has been no single report of a natural small interfering RNA [siRNA] that is triggered by HIV in human cells," coauthor Kuan-Teh Jeang of the National Institute of Allergy and Infectious Diseases in Maryland told The Scientist. The virus' "counter strategy" described in the paper is also unprecedented, according to Jeang.

Coauthor Yamina Bennasser and her colleagues characterized a sequence in the HIV-1 genome that encodes a rare siRNA precursor, a short hairpin RNA that is processed by the Dicer (or by a Dicer-like) ribonuclease into small siRNAs. In addition, they found that the virus prevents RNA silencing through a suppressor present in its Tat protein, which interferes with Dicer's activity.

"It's ...