Rana grylio virus (RGV) 50L is associated with viral matrix and exhibited two distribution patterns.

BACKGROUND

The complete genome of Rana grylio virus (RGV) was sequenced and analyzed recently, which revealed that RGV 50 L had homologues in many iridoviruses with different identities; however, the characteristics and functions of 50 L have not been studied yet.

METHODOLOGY/PRINCIPAL FINDINGS: We cloned and characterized RGV50L, and revealed 50 L functions in virus assembly and gene regulation. 50 L encoded a 499-amino acid structural protein of about 85 kDa in molecular weight and contained a nuclear localization signal (NLS) and a helix- extension-helix motif. Drug inhibition assay demonstrated that 50 L was an immediate-early (IE) gene. Immuno-fluorescence assay revealed that 50 L appeared early and persisted in RGV-infected cells following two distribution patterns. One pattern was that 50 L exhibited a cytoplasm-nucleus- viromatrix distribution pattern, and mutagenesis of the NLS motif revealed that localization of 50 L in the nucleus was NLS-dependent; the other was that 50 L co-localized with viral matrix which plays important roles in virus assembly and the life circle of viruses.

CONCLUSIONS/SIGNIFICANCE: RGV 50L is a novel iridovirus IE gene encoded structural protein which plays important roles in virus assembly.