title: Aichi virus leader protein is involved in viral RNA replication and encapsidation.
abstract: Aichi virus, a member of the family Picornaviridae, encodes a leader (L) protein of 170 amino acids (aa). The Aichi virus L protein exhibits no significant sequence homology to those of other picornaviruses. In this study, we investigated the function of the Aichi virus L protein in virus growth. In vitro translation and cleavage assays indicated that the L protein has no autocatalytic activity and is not involved in polyprotein cleavage. The L-VP0 junction was cleaved by 3C proteinase. Immunoblot analysis showed that the L protein is stably present in infected cells. Characterization of various L mutants derived from an infectious cDNA clone revealed that deletion of 93 aa of the center part (aa 43 to 135), 50 aa of the N-terminal part (aa 4 to 53), or 90 aa of the C-terminal part (aa 74 to 163) abolished viral RNA replication. A mutant (Delta114-163) in which 50 aa of the C-terminal part (aa 114 to 163) were deleted exhibited efficient RNA replication and translation abilities, but the virus yield was 4 log orders lower than that of the wild type. Sedimentation analysis of viral particles generated in mutant Delta114-163 RNA-transfected cells showed that the mutant has a severe defect in the formation of mature virions, but not in that of empty capsids. Thus, the data obtained in this study indicate that the Aichi virus L protein is involved in both viral RNA replication and encapsidation.
mesh_terms: D000818:Animals; D002384:Catalysis; D002522:Chlorocebus aethiops; D010849:Picornaviridae / Q000235:genetics / Q000502:physiology*; D021382:Protein Sorting Signals / Q000502:physiology*; D012367:RNA, Viral / Q000096:biosynthesis*; D014709:Vero Cells; D014764:Viral Proteins / Q000502:physiology*; D019065:Virus Assembly; D014779:Virus Replication
chemical_list: D021382:Protein Sorting Signals; D012367:RNA, Viral; D014764:Viral Proteins