Disease relevance of UUKVsLgp1

• In the February 20 issue of Cell, report that Rift Valley Fever Virus (RVFV) targets cellular transcriptional apparatus to inhibit RNA polymerase II-mediated transcription [1].
• Uukuniemi virus contains an RNA polymerase [2].
• Reverse genetics system for Uukuniemi virus (Bunyaviridae): RNA polymerase I-catalyzed expression of chimeric viral RNAs [3].
• The role of the variable portion of the noncoding regions (NCRs) of the three Bunyaviridae RNA segments (L, M, S) in transcription, replication, and packaging was studied using the recently developed plasmid-driven RNA polymerase I minigenome system for Uukuniemi (UUK) virus, genus Phlebovirus (11), as a model [4].
• An RNA-dependent RNA polymerase activity has been found associated with Uukuniemi virions [2].

High impact information on UUKVsLgp1

• We established a T7 RNA polymerase-driven reverse genetics system to rescue infectious clones of RVFV MP-12 strain entirely from cDNA, the first for any phlebovirus [5].
• The particles are able to infect new cells, and reporter gene expression can be monitored if the trans-acting viral proteins (RNA polymerase and nucleoprotein) are also expressed in these cells [6].
• We established an RVFV T7 RNA polymerase-driven minigenome system in which T7 RNA polymerase from an expression plasmid drove expression of RNA transcripts for viral proteins and minigenome RNA transcripts carrying a reporter gene between both termini of the M RNA segment in 293T cells [7].
• CAT activity was determined after cotransfection with viral expression plasmids encoding the RNA-dependent RNA polymerase (L) and the nucleoprotein (N) or, alternatively, after superinfection with UUK virus helper virus [8].
• When such cells were either superinfected with Uukuniemi virus or cotransfected with expression plasmids encoding the L (RNA polymerase), N (nucleoprotein), and NSs (nonstructural protein) viral proteins, strong CAT activity or GFP expression was observed [3].

Biological context of UUKVsLgp1

• This was achieved by using a recently developed RNA polymerase I (Pol I)-driven reverse genetics system (R. Flick and R. F. Pettersson, J. Virol. 75:1643-1655, 2001) [8].
• The L segment is 6404 nucleotides long, containing a single open reading frame (ORF) in the viral complementary sense coding for a protein of 2095 amino acids that, as in the case of negative strand RNA viruses, could be part of the RNA polymerase of TOS virus [9].

References