Abstract
In the course of reovirus replication the double-stranded virion RNA serves as a template for reovirus mRNA (+ strand) formation. The reovirus mRNA in turn serves as a template for the synthesis of the complementary (−) strand. The latter remains associated with the template, thus forming double-stranded virion RNA. The virion associated enzymes can be activated
in
vitro
to synthesize reovirus mRNAs with an m
7G(5′)ppp(5′)GmpCp… 5′ terminal structure (cap 1 structure). We find that about 50% of reovirus mRNAs formed in L cells (between 5 and 11 hours after infection) have m
7G(5′)ppp(5′)GmpCmp… as their 5′ terminal structure (cap 2 structure); the rest have a cap 1 structure. Interestingly, the large majority (over 95%) of the + strands in reovirion double-stranded RNA have cap 1 structures at their 5′ termini. These observations may indicate that reo mRNAs serve as a template in double-stranded RNA formation before their cap 1 termini become converted to cap 2 termini. It is also possible, however, that mRNAs with cap 1 type 5′ termini are preferred templates for double-stranded RNA formation over those with cap 2 type 5′ termini.
