HYPERMUTATION OF THE PHOSPHOPROTEIN AND ALTERED MESSENGER-RNA EDITINGIN THE HAMSTER NEUROTROPIC STRAIN OF MEASLES-VIRUS

Sequence analysis of the nucleoprotein and phosphoprotein (P) genes of viruses in the hamster neurotropic lineage of measles virus revealed that the neurotropic variants are quite different from the Philadelphi a 26 progenitor strain. In Vero cells persistently infected with the h amster neurotropic strain, predicted changes occur in 5.0% of the nucl eoprotein and 8.1% of the P amino acids and some of these changes appe ar to affect the relative electrophoretic mobility of each protein. To evaluate one aspect of the viral polymerase complex containing these mutations, the distribution of P mRNA editing in each of the three str ains was determined by both cloning and sequencing of polymerase chain reaction-amplified DNA fragments which included the editing site and by primer extension analysis of viral mRNA. Editing of P mRNA in the n eurotropic strains shows a shift away from the single G insertion prod uct to those with greater than 2 Gs inserted. The altered editing dist ribution has implications for the role of transcriptional regulation i n measles virus persistence.