Structural variants and modifications of hammerhead ribozymes targeting influenza A virus conserved structural motifs

Tomasz Czapik; Julita Piasecka; Ryszard Kierzek; Elzbieta Kierzek

doi:10.1016/j.omtn.2022.05.035

Structural variants and modifications of hammerhead ribozymes targeting influenza A virus conserved structural motifs

Mol Ther Nucleic Acids. 2022 May 31:29:64-74. doi: 10.1016/j.omtn.2022.05.035. eCollection 2022 Sep 13.

Authors

Tomasz Czapik¹, Julita Piasecka¹, Ryszard Kierzek¹, Elzbieta Kierzek¹

Affiliation

¹ Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.

Abstract

The naturally occurring structure and biological functions of RNA are correlated, which includes hammerhead ribozymes. We proposed new variants of hammerhead ribozymes targeting conserved structural motifs of segment 5 of influenza A virus (IAV) (+)RNA. The variants carry structural and chemical modifications aiming to improve the RNA cleavage activity of ribozymes. We introduced an additional hairpin motif and attempted to select ribozyme-target pairs with sequence features that enable the potential formation of the trans-Hoogsteen interactions that are present in full-length, highly active hammerhead ribozymes. We placed structurally defined guanosine analogs into the ribozyme catalytic core. Herein, the significantly improved synthesis of 2'-deoxy-2'-fluoroarabinoguanosine derivatives is described. The most potent hammerhead ribozymes were applied to chimeric short hairpin RNA (shRNA)-ribozyme plasmid constructs to improve the antiviral activity of the two components. The modified hammerhead ribozymes showed moderate cleavage activity. Treatment of IAV-infected Madin-Darby canine kidney (MDCK) cells with the plasmid constructs resulted in significant inhibition of virus replication. Real-time PCR analysis revealed a significant (80%-88%) reduction in viral RNA when plasmids carriers were used. A focus formation assay (FFA) for chimeric plasmids showed inhibition of virus replication by 1.6-1.7 log₁₀ units, whereas the use of plasmids carrying ribozymes or shRNAs alone resulted in lower inhibition.

Keywords: MT: oligonucleotides: therapies and applications; RNA conserved structural motifs; RNA secondary structure; fluoroarabinonucleosides; hammerhead ribozyme; influenza virus; modified nucleosides; shRNA.