Prokaryotic test system for evaluation of oligonucleotide-affected antisense inhibition.

A new test system is introduced for the estimation of the antisense effect of various types of oligodeoxy-nucleotides. This system is based upon the inhibition of translation of P2 phage repressor protein. Evidence for a direct correlation between phage yield and antisense inhibition was obtained by comparing the concentration-dependent effectiveness of an antisense phosphorothioate 18-mer, its mutated version, and the unmodified oligonucleotide. Oligonucleotides of complementary sequences were synthesized against the ribosome binding site and different sites of the coding region. In our test system only small differences were found based on the location of the target sequence. Rather, the degree of inhibition was related to the calculated ability to hybridize based on Tm values. In this way the sensitivity of the test system could also be demonstrated.