The effect of beta-tubulin-specific antisense oligonucleotide encapsulated in different cationic liposomes on the suppression [correction of supression] of intracellular L. donovani parasites in vitro.

An antisense oligonucleotide (20 mer) targeted to the parasite beta-tubulin gene and encapsulated in cationic liposomes, was used to test its antileishmanial activity in vitro. Cationic liposomes containing dioleyl trimethyl ammonium propane (DOTAP) were found to have higher antileishmanial activity (88% at 4 microM oligonucleotide) compared to two other liposomes with stearyl amine (SA) and cetyl trimethyl ammonium bromide (CTAB) as cations. Dot-blot experiments were performed to analyse the expression of beta-tubulin mRNA using beta-tubulin-specific radiolabelled DNA as a probe. When compared with their respective controls, beta-tubulin-specific gene expression was found to be diminished by treatment with a specific antisense oligonucleotide encapsulated in cationic liposomes (CTAB:DOPE) in a concentration-dependent manner. These experiments show that antisense oligonucleotides targeted to the beta-tubulin gene of Leishmania donovani inhibit beta-tubulin synthesis leading to the arrest of multiplication of intracellular parasites.