Sobemovirus genome appears to encode a serine protease related to cysteine proteases of picornaviruses

A putative serine protease was identified among non‐structural proteins of southern bean mosaic virus (SBMV) by sequence comparison with cellular and viral proteases. The predicted SBMV proteased is played a significant similarity to cysteine proteases of picornaviruses, providing a possible evolutionary link between the two enzyme classes. It is suggested that SBMV follows the general expression strategy characteristic of other positive‐strand RNA viruses containing 5′‐terminal covalently linked proteins (VPg), i.e. generation of functional proteins by polyprotein processing.