Characterization of the variable region in the 3' non-translated region of dengue type 1 virus.
The first 84 nt in the 3' non-translated region (3' NTR) of dengue type 1 virus (DENV-1) exhibit lower levels of conservation than the other regions; this region is named the variable region (VR). The VR is further divided into two subregions: a 5'-terminal hypervariable region (HVR) and a 3'-terminal semi-variable region (SVR). Recent reports suggested that the VR of DENV-2 is required for efficient virus growth in mammalian cells. To investigate whether this is also true for the VR of DENV-1, deletion or replacement mutations were introduced into the VR by using recombinant DENV-1 cDNA clones. Recombinant viruses with deletion of either or both subregions exhibited reduced growth properties compared with the original virus. Mutants with incompletely reversed or unrelated sequences in the HVR demonstrated growth properties similar to those of the original virus. However, a replacement mutation in the SVR did not cause recovery of growth properties. Furthermore, the amount of viral RNA was decreased in Vero cells infected with the growth-attenuated mutant viruses. Results of reporter translation assays suggest that VR mutations may not affect the translation process of DENV-1. These data indicate that the VR is important for DENV-1 replication and is associated with the accumulation of DENV-1 RNA in mammalian cells, and that the HVR and SVR in the VR may have different roles in DENV-1 replication.
Tajima
Shigeru
S
Laboratory of Vector Borne Viruses, Department of Virology 1, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan.
Nukui
Yoko
Y
Department of Infectious Diseases, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan.|Laboratory of Vector Borne Viruses, Department of Virology 1, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan.
Takasaki
Tomohiko
T
Laboratory of Vector Borne Viruses, Department of Virology 1, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan.
Kurane
Ichiro
I
Laboratory of Vector Borne Viruses, Department of Virology 1, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan.
D020413:3' Untranslated Regions / Q000235:genetics*; D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D009033:Culicidae; D003715:Dengue / Q000821:virology*; D003716:Dengue Virus / Q000502:physiology*; D017353:Gene Deletion; D016679:Genome, Viral / Q000235:genetics*; D008969:Molecular Sequence Data; D014779:Virus Replication
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions