Characterization of messenger RNAs of measles virus.

Ten different RNA species associated with measles virus were detected in virus-infected cells. The largest RNA (no. 1) was considered to be genomic RNA and the other nine RNAs were found to have a methylated cap as well as a poly(A) tail. Northern blot hybridization indicated that RNAs no. 2 and 7 to 10 correspond to mRNAs encoding structural proteins, and that RNAs no. 3 to 6 are intermediate-sized (IS)RNAs. The possibility that the ISRNAs represent defective interfering RNA or a precursor form of the mRNA seems to be unlikely since the amounts of IS RNAs did not increase after undiluted passages or decrease in a pulse-chase experiment. These results indicate that IS RNAs are readthrough transcripts of neighbouring cistrons.