RNA viruses can exploit self-cleaving ribozymes for translation initiation.

Self-cleaving hammerhead ribozymes in the 5'-UTRs of fungal chrysovirids and fusarivirids are essential for protein translation initiation, enabling cap-independent translation.

• Why it matters: The work addresses how conserved catalytic RNAs, once linked to viroid-like circRNA replication, are repurposed by linear RNA viruses to control translation.
• What they did: The authors surveyed linear genomes of fungal and plant RNA viruses and found conserved small ribozymes (type I hammerhead, plus hepatitis delta and twister) in UTR motifs, then tested 5'-UTRs in vivo and in plants.
• The result: In a fungal chrysovirus, 5'-UTR self-cleaving activity is required for translation initiation, and in plants, self-cleaving activity alone can induce cap-independent translation.

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