Modified model for the switch from Sendai virus transcription to replication

Abstract

RNase mapping was used to estimate the levels of unencapsidated Sendai virus plus-strand RNAs which cross the leader-NP junction relative to NP mRNA. Significant amounts of leader readthrough RNAs were found in Z strain-infected cells, similar to that described for the poiR mutant of vesicular stomatitis virus, even though this strain is considered wild type. The levels of the readthrough RNAs detected fell sharply when progressively longer probes were used, unlike that of NP mRNA. These studies suggest that polymerases which read through

Interplay between Innate Immunity and Negative-Strand RNA Viruses: towards a Rational Model

“…Late in the infection, ϳ75% of them are found to be associated with N protein, with a buoyancy similar to that of NC on CsCl gradients (26). More abundant free short leRNA N read-through transcripts (Ͻ300 nt long) can be also detected (290). These are distinct from the encapsidated complete (ϳ2 kb long) leRNA N read-through RNAs corresponding to abortive replication products (40,219,290).…”

“…Indeed, purified protein-free RNAs from viruses, i.e., a mixture of genome and antigenome RNAs that likely anneal to each other, are good inducers of RIG-I-mediated IFN response (94,106). However, they are never found as free RNA but are found exclusively as part of the nucleocapsid (NC) in CsCl gradients (290). Although trace amounts of protein-free genome/antigenome can be found in a CsCl pellet, their actual presence in infected cells remains doubtful.…”

“…leRNA and trRNA transcripts remain 5Јppp (54). In SeV-or VSV-infected cells, only limited amounts of free leRNA and/or trRNA species (31,55, and 65 nt long) can be detected, likely because of lack of stability (151,290). Late in the infection, ϳ75% of them are found to be associated with N protein, with a buoyancy similar to that of NC on CsCl gradients (26).…”

“…More abundant free short leRNA N read-through transcripts (Ͻ300 nt long) can be also detected (290). These are distinct from the encapsidated complete (ϳ2 kb long) leRNA N read-through RNAs corresponding to abortive replication products (40,219,290). As their abundance remains largely unchanged when replication is blocked, they likely represent uncapped transcripts, the elongation of which has prematurely stopped (290).…”

“…These are distinct from the encapsidated complete (ϳ2 kb long) leRNA N read-through RNAs corresponding to abortive replication products (40,219,290). As their abundance remains largely unchanged when replication is blocked, they likely represent uncapped transcripts, the elongation of which has prematurely stopped (290). The elongation checkpoint for RSV polymerase is at ϳ50 nucleotides (162).…”