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