Conserved Structural Motifs of Two Distant IAV Subtypes in Genomic Segment 5 RNA.

The functionality of RNA is fully dependent on its structure. For the influenza A virus (IAV), there are confirmed structural motifs mediating processes which are important for the viral replication cycle, including genome assembly and viral packaging. Although the RNA of strains originating from distant IAV subtypes might fold differently, some structural motifs are conserved, and thus, are functionally important. Nowadays, NGS-based structure modeling is a source of new in vivo data helping to understand RNA biology. However, for accurate modeling of in vivo RNA structures, these high-throughput methods should be supported with other analyses facilitating data interpretation. In vitro RNA structural models complement such approaches and offer RNA structures based on experimental data obtained in a simplified environment, which are needed for proper optimization and analysis. Herein, we present the secondary structure of the influenza A virus segment 5 vRNA of A/California/04/2009 (H1N1) strain, based on experimental data from DMS chemical mapping and SHAPE using NMIA, supported by base-pairing probability calculations and bioinformatic analyses. A comparison of the available vRNA5 structures among distant IAV strains revealed that a number of motifs present in the A/California/04/2009 (H1N1) vRNA5 model are highly conserved despite sequence differences, located within previously identified packaging signals, and the formation of which in in virio conditions has been confirmed. These results support functional roles of the RNA secondary structure motifs, which may serve as candidates for universal RNA-targeting inhibitory methods.