Abstract
The 5' terminal cap structure of the mRNAs of human respiratory syncytial virus synthesized in vitro in the presence of S-adenosyl-L- methionine consists of a 7-methyl guanosine linked to an unmethylated guanosine through a 5'-5' pyrophosphate linkage formed by using the alpha and beta phosphates of GTP. The complete cap structure is m7G (5')ppp(5')Gp ... which is devoid of ribose 2'-O-methylation. Capping, including methylation, is coupled to transcription. These results constitute the first report of a pneumoviral mRNA cap structure.