Domain I of the 5′ non-translated genomic region in coxsackievirus B3 RNA is not required for productive replication

•A coxsackievirus B3 5′ terminal deletion which includes all RNA structures of domain I is viable.•Coxsackievirus B3 5′ terminal deletion of 77 nt (CVB3-TD78) replicates at a level 100,000 fold less than wildtype virus.•As with other coxsackievirus B3 5′ terminal deletions, CVB3-TD78 electroporation produces infectious virions.

Domain I is a cloverleaf-like secondary structure at the 5′ termini of all enterovirus genomes, comprising part of a cis-acting replication element essential for efficient enteroviral replication. 5′ genomic terminal deletions up to as much as 55% of domain I can occur without lethality following coxsackie B virus infections. We report here that the entire CVB structural domain I can be deleted without lethality.