Jt. Patton et al., Open reading frame in rotavirus mRNA specifically promotes synthesis of double-stranded RNA: Template size also affects replication efficiency, VIROLOGY, 264(1), 1999, pp. 167-180
The 11 rotavirus mRNAs are capped, but not polyadenylated, have a high AU c
ontent, and serve as templates for the synthesis of double-stranded (ds)RNA
. Earlier studies using a cell-free replication system showed that the 5'-
and 3'-untranslated regions (UTRs) of the mRNAs have cis-acting signals tha
t promote minus-strand synthesis. To identify additional factors that affec
t RNA replication, chimeric RNAs were made that consisted of portions of th
e gene 8 mRNA of SA11 rotavirus and of the gene for green fluorescent prote
in (gfp) or for the N protein of respiratory syncytial virus. Analysis of t
he chimeras in the cell-free replication system under noncompetitive condit
ions showed that the open reading frame (ORF) of viral mRNAs contains infor
mation that specifically promotes minus-strand synthesis. Results were also
obtained indicating that a high AU content may increase the replication ef
ficiency of RNAs and that, in general, an inverse correlation exists betwee
n replication efficiency and the length of the RNA template. Replication as
says performed under competitive conditions showed that nonviral RNAs can i
nterfere significantly with the replication of viral mRNAs, mostly likely b
y sequestering nonspecific RNA-binding proteins that are of limited concent
ration in the replication system and that are essential for dsRNA synthesis
. In summary, rotavirus dsRNA synthesis is affected by many factors includi
ng cis-acting replication signals located in the 5'-UTR, 3'-UTR, and ORF of
the mRNA as well as the size and possibly the AU content of the mRNA. (C)
1999 Academic Press.