Cell-free translation ofDrosophila C virus RNA: Identification of a virus protease activity involved in capsid protein synthesis and further studies onin vitro processing of Cricket paralysis virus specified proteins

Abstract

Drosophila C virus RNA acted as mRNA in rabbit reticulocyte lysates and directed the synthesis of at least one capsid protein and a number of higher molecular weight proteins. Kinetic analysis by pulse-chase experiments showed that a number of high molecular weight products acted as precursors to the capsid protein(s). Various dilution experiments were performed which showed that the virus specified a protease activity essential for the correct processing of precursors to give the capsid protein(s). A similar result was obtained with Cricket paralysis virus, and mixing experiments showed that the protease activity specified by one virus could perform some of the cleavages resulting in the production of the capsid proteins of the other virus. Some of the cleavages involving the highest molecular weight precursors could not be performed by the protease activity of the other virus. We could find no evidence for intramolecular cleavage of the capsid precursors of either of the viruses.

General Characteristics, Gene Organization and Expression of Small RNA Viruses of Insects

“…However, lysate preincubated with DCV RNA and unlabelled methionine was able to process labelled CrPV-specified capsid protein precursors. Similar experiments performed by dilution of labelled DCV translation products with lysate preincubated with CrPV RNA resulted in an increase in the amount of DCV capsid proteins (Reavy & Moore, 1983c). This was the first demonstration that two distinctly different picornaviruses could catalyse the processing events of each other.…”

Genome-wide RNAi screen reveals a specific sensitivity of IRES-containing RNA viruses to host translation inhibition

“…Despite this difference, these insect viruses share many physical and morphological properties with mammalian picornaviruses (King and Moore 1988;Johnson and Christian 1998;Tate et al 1999). Moreover, where studied, the infectious cycle of DCV resembles that of pathogenic IRES-containing mammalian viruses (Scotti et al 1981;Reavy and Moore 1983;Moore et al 1985;King and Moore 1988). The recent use of DCV to identify a set of host factors required for viral entry found conserved proteins involved in clathrin-mediated endocytosis (Cherry and Perrimon 2004).…”

Antiviral Immunity in the Fruit Fly, Drosophila melanogaster

“…ORF2 encodes the structural proteins VP0, VP1, VP2, VP3, and VP4. VP0 is a precursor for VP3 and VP4, which combine to form the capsid [24]. The capsid proteins are encoded in a different reading frame and initiated independently from ORF1 [15].…”