A three-nucleotide insertion in the H stem-loop of the 5' untranslated region of Theiler's virus attenuates neurovirulence.
The highly structured 5' untranslated region (5' UTR) of Theiler's murine encephalomyelitis virus is involved in cap-independent translation of the viral RNA. Previously, we reported that the bicistronic mRNA chloramphenicol acetyltransferase-5' UTR-luciferase (Luc) efficiently expressed Luc both in a rabbit reticulocyte lysate and when transfected into BHK-21 cells. Insertion of 3 nucleotides at position 665 in the 5' UTR of this bicistronic mRNA resulted in greatly reduced Luc expression in BHK-21 cells but had little effect on expression of Luc in rabbit reticulocyte lysate. This mutation was also introduced into a virulent Theiler's murine encephalomyelitis virus chimera, Chi-VL. The kinetics of viral RNA and protein synthesis and virus production in BHK-21 cells were slower for the mutant chimera [Chi-VL(IN668)] than for Chi-VL; however, the final virus yields were comparable. Intracerebral inoculation of mice with the chimeras revealed that Chi-VL(IN668) was completely attenuated in neurovirulence. The reduced neurovirulence of Chi-VL(IN668) may be ascribed to its reduced growth in the central nervous system, most likely due to an impaired ability to synthesize viral proteins.
Bandyopadhyay
P K
PK
Department of Neurology, University of Colorado Health Sciences Center, Denver 80262.
Pritchard
A
A
Jensen
K
K
Lipton
H L
HL
D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000382:microbiology*; D002478:Cells, Cultured; D004769:Enterovirus Infections / Q000235:genetics*; D004680:Maus Elberfeld virus / Q000235:genetics* / Q000472:pathogenicity*; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D012313:RNA; D012367:RNA, Viral / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D014774:Virulence
D012367:RNA, Viral; C039919:RNA, recombinant; D012313:RNA