BETA-CYCLODEXTRIN DERIVATIVES AS CARRIERS TO ENHANCE THE ANTIVIRAL ACTIVITY OF AN ANTISENSE OLIGONUCLEOTIDE-DIRECTED TOWARD A CORONAVIRUS INTERGENIC CONSENSUS SEQUENCE

The ability of cyclodextrins to enhance the antiviral activity of a ph osphodiester oligodeoxynucleotide has been investigated. A 18-mer olig odeoxynucleotide complementary to the initiation region of the mRNA co ding for the spike protein and containing the intergenic consensus seq uence of an enteric coronavirus has been tested for antiviral action a gainst virus growth in human adenocarcinoma cells. The phosphodiester oligodeoxynucleotide only showed a limited effect on virus growth rate (from 12 to 34% viral inhibition in cells treated with 7.5 to 25 mu M oligodeoxynucleotide, respectively, at a multiplicity of infection of 0.1 infectious particle per cell). In the same conditions, the phosph orothioate analogue exhibited stronger antiviral activity, the inhibit ion increased from 56 to 90%. The inhibitory effect of this analogue w as antisense and sequence-specific. Northern blot analysis showed that the sequence-dependent mechanism of action appears to be the inhibiti on of mRNA transcription. We conclude that the coronavirus intergenic consensus sequence is a good target for an antisense oligonucleotide a ntiviral action. The properties of the phosphodiester oligonucleotide was improved after its complexation with cyclodextrins. The most impor tant increase of the antiviral activity (90% inhibition) was obtained with only 7.5 mu M oligonucleotide complexed to a cyclodextrin derivat ive, -beta-D-galactopyranosyl-6-thio-cyclomaltoheptaose in a molar rat io of 1:100. These studies suggest that the use of cyclodextrin deriva tives as carrier for phosphodiester oligonucleotides delivery may be a n effective method for increasing the therapeutic potential of these c ompounds in viral infections.