Measles virus synthesizes both leaderless and leader-containing polyadenylated RNAs in vivo.
The minus-sense RNA genome of measles virus serves as a template for synthesizing plus-sense RNAs of genomic length (antigenomes) and subgenomic length [poly(A)+ RNAs]. To elucidate how these different species are produced in vivo, RNA synthesized from the 3'-proximal N gene was characterized by Northern RNA blot and RNase protection analyses. The results showed that measles virus produced three size classes of plus-sense N-containing RNA species corresponding to monocistronic N RNA, bicistronic NP RNA, and antigenomes. Unlike vesicular stomatitis virus, measles virus does not produce a detectable free plus-sense leader RNA. Instead, although antigenomes invariably contain a leader sequence, monocistronic and bicistronic poly(A)+ N-containing RNAs are synthesized either without or with a leader sequence. We cloned and characterized a full-length cDNA representing a product of the latter type of synthesis. mRNAs and antigenomes appeared sequentially and in parallel with leaderless and leader-containing RNAs. These various RNA species accumulated concurrently throughout infection. However, cycloheximide preferentially inhibited accumulation of antigenomes and leader-containing RNA but not leaderless and subgenomic RNAs late in infection, suggesting that synthesis of the former RNA species requires a late protein function or a continuous supply of structural proteins or both. These results reveal a previously undescribed mechanism for RNA synthesis in measles virus.
Castaneda
S J
SJ
Department of Microbiology, University of Washington School of Medicine, Seattle 98195.
Wong
T C
TC
D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D005814:Genes, Viral; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008459:Measles virus / Q000235:genetics*; D010957:Plasmids; D011061:Poly A / Q000096:biosynthesis* / Q000235:genetics; D012313:RNA / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D012260:Ribonucleases; D013698:Templates, Genetic
D012333:RNA, Messenger; D012367:RNA, Viral; D011061:Poly A; D012313:RNA; D003513:Cycloheximide; D012260:Ribonucleases