Significance in replication of the terminal nucleotides of the flavivirus genome.
Point mutations that resulted in a substitution of the conserved 3'-penultimate cytidine in genomic RNA or the RNA negative strand of the self-amplifying replicon of the Flavivirus Kunjin virus completely blocked in vivo replication. Similarly, substitutions of the conserved 3'-terminal uridine in the RNA negative or positive strand completely blocked replication or caused much-reduced replication, respectively. The same preference for cytidine in the 3'-terminal dinucleotide was noted in reports of the in vitro activity of the RNA-dependent RNA polymerase (RdRp) for the other genera of Flaviviridae that also employ a double-stranded RNA (dsRNA) template to initiate asymmetric semiconservative RNA positive-strand synthesis. The Kunjin virus replicon results were interpreted in the context of a proposed model for initiation of RNA synthesis based on the solved crystal structure of the RdRp of phi6 bacteriophage, which also replicates efficiently using a dsRNA template with conserved 3'-penultimate cytidines and a 3'-terminal pyrimidine. A previously untested substitution of the conserved pentanucleotide at the top of the 3'-terminal stem-loop of all Flavivirus species also blocked detectable in vivo replication of the Kunjin virus replicon RNA.
Khromykh
Alexander A
AA
Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Clinical Medical Virology Centre, University of Queensland, Brisbane, Queensland, Australia.
Kondratieva
Natasha
N
Sgro
Jean-Yves
JY
Palmenberg
Ann
A
Westaway
Edwin G
EG
D017126:Bacteriophage phi 6 / Q000235:genetics; D016679:Genome, Viral; D009690:Nucleic Acid Conformation; D012367:RNA, Viral / Q000096:biosynthesis* / Q000737:chemistry; D012093:Replicon; D013329:Structure-Activity Relationship; D014902:West Nile virus / Q000235:genetics*
D012367:RNA, Viral