Researchers at the University of Medicine and Dentistry of New Jersey have identified four new compounds--called polyamide nucleotide analogs--that have been shown effective in preventing HIV from replicating. The compounds interfere with HIV's Tat protein and its transactive responsive element (TAR)--which together form a looplike chain that plays a key role in converting HIV RNA into cellular DNA--at four different points along the genetic structures of the viral particles. This prevents the loops from forming and effectively short-circuits the replication process. Two of the four compounds were shown to be 99% effective in preventing HIV replication in infected cell cultures. Additional tests are planned, but the researchers are hopeful that their discovery will pave the way for a new class of anti-HIV medications aimed at disabling the Tat-TAR interactions.