The structure of cowpea mosaic virus replicative form RNA

The structure of Cowpea mosaic virus (CPMV) replicative form (RF) RNA has been investigated by in vitro labelling at the 5' and 3' termini. The results indicate that the 3' termini of the minus (-) strands of the RFs from both M and B RNA (RF-M and RF-B) are exact complements of the corresponding 5' sequences of the virion RNAs. The 5'-labelling studies revealed that both RF-M and RF-B have VPg linked to poly(U) at the 5' ends of the (-) strands and also show that there is heterogeneity in the lengths of the VPg-linked RNAse T1 products derived from the 5' ends of the plus (+) strands. In addition it appears that not all of the 5' ends in RF molecules are linked to the VPg. The results enable us to draw an overall structure common to both RF-M and RF-B.