Short, but sweet

Gene silencing is a mechanism mediated by short interfering RNAs (siRNAs), which suppress the activity of particular genes at certain places or times. In plants this process has an antiviral defense role but in animal cells its specific function has been unclear. Separate papers in 27 June Nature, show that siRNAs can inhibit HIV-1 replication and confer intracellular antiviral immunity against poliovirus in human cells (Nature 2002, DOI:10.1038/nature008796).

Jean-Marc Jacque and colleagues at University of Massachusetts Medical School, Worcester, Massachusetts, used synthetic or plasmid-derived siRNAs in cell cultures and observed that siRNAs targeted to various regions of the HIV-1 genome can inhibit HIV-1 replication in human cell lines and primary lymphocytes. The siRNAs interrupted early events in the HIV replication cycle by directing the specific degradation of genomic HIV-1 RNA. This prevented subsequent synthesis of viral reverse-transcription intermediates and establishment of the provirus.

In the second paper Leonid Gitlin and ...