Analysis of the Tomato spotted wilt virus ambisense S RNA-encoded hairpin structure in translation.

Background: The intergenic region (IR) of ambisense RNA segments from animal- and plant-infecting (-)RNA viruses functions as a bidirectional transcription terminator. The IR sequence of the Tomato spotted wilt virus (TSWV) ambisense S RNA contains stretches that are highly rich in A-residues and U-residues and is predicted to fold into a stable hairpin structure. The presence of this hairpin structure sequence in the 3' untranslated region (UTR) of TSWV mRNAs implies a possible role in translation.

Base-pairing promotes leader selection to prime in vitro influenza genome transcription.

The requirements for alignment of capped leader sequences along the viral genome during influenza transcription initiation (cap-snatching) have long been an enigma. In this study, competition experiments using an in vitro transcription assay revealed that influenza virus transcriptase prefers leader sequences with base complementarity to the 3'-ultimate residues of the viral template, 10 or 11 nt from the 5' cap. Internal priming at the 3'-penultimate residue, as well as prime-and-realign was observed.

Preferential use of RNA leader sequences during influenza A transcription initiation in vivo.

In vitro transcription initiation studies revealed a preference of influenza A virus for capped RNA leader sequences with base complementarity to the viral RNA template. Here, these results were verified during an influenza infection in MDCK cells. Alfalfa mosaic virus RNA3 leader sequences mutated in their base complementarity to the viral template, or the nucleotides 5' of potential base-pairing residues, were tested for their use either singly or in competition.

Multiple virus resistance at a high frequency using a single transgene construct.

RNA silencing is a natural antiviral defence in plants, which can be exploited in transgenic plants for preprogramming virus recognition and ensuring enhanced resistance. By arranging viral transgenes as inverted repeats it is thus possible to obtain strong repression of incoming viruses. Due to the high sequence specificity of RNA silencing, this technology has hitherto been limited to the targeting of single viruses.