Viral Messenger RNA Synthesis Authored: Bortz, E, Garcia-Sastre, A, 2007-02-12 19:39:05 GENE ONTOLOGYGO:0019083 Like the mRNAs of the host cell, influenza virus mRNAs are capped and polyadenylated (reviewed in Neumann, 2004). The methylated caps, however, are scavenged from host cell mRNAs and serve as primers for viral RNA synthesis, a process termed 'cap-snatching' (Krug, 1981; Hagen, 1994). The PB2 polymerase protein binds the cap, activating endonucleolytic cleavage of the host mRNA by PB1. The 3' poly-A tracts on viral messages are generated by polymerase stuttering on poly-U tracts near the 5' end of the template vRNA (Robertson, 1981; Zheng, 1999). The second process allows polyadenylation of viral mRNAs when the host cell polyadenylation process has been inhibited (Engelhardt, 2006; Amorim, 2006). Notably, early transcripts (including NP and NS1) accumulate in the cytoplasm before late transcripts (M1, HA, and NS2), and in varying abundances, suggesting additional control mechanisms regulating viral gene expression (Shapiro, 1987; Hatada, 1989; Amorim, 2006). Pubmed10233995 Pubmed15298169 Pubmed16806605 Pubmed16933365 Pubmed2760014 Pubmed3806797 Pubmed6269803 Pubmed7241649 Pubmed8107213 Reactome Database ID Release 43168325 Reactome, http://www.reactome.org ReactomeREACT_6354 Reviewed: Squires, B, 2007-02-12 19:39:22 PathwayStep3696 PathwayStep3695 PathwayStep3701 PathwayStep3700 PathwayStep3699 PathwayStep3698 PathwayStep3697 Viral mRNA Splicing (M, NS segments) Export of Spliced Viral mRNA Viral mRNA Export Elongation of viral mRNA Priming and Initiation of Transcription Assembly of an Active Transcription Complex Polyadenylation and Termination