Attenuation of Venezuelan equine encephalitis virus strain TC-83 is encoded by the 5'-noncoding region and the E2 envelope glycoprotein.
The virulent Trinidad donkey (TRD) strain of Venezuelan equine encephalitis (VEE) virus and its live attenuated vaccine derivative, TC-83 virus, have different neurovirulence characteristics. A full-length cDNA clone of the TC-83 virus genome was constructed behind the bacteriophage T7 promoter in the polylinker of plasmid pUC18. To identify the genomic determinants of TC-83 virus attenuation, TRD virus-specific sequences were inserted into the TC-83 virus clone by in vitro mutagenesis or recombination. Antigenic analysis of recombinant viruses with VEE E2- and E1-specific monoclonal antibodies gave predicted antigenic reactivities. Mouse challenge experiments indicated that genetic markers responsible for the attenuated phenotype of TC-83 virus are composed of genome nucleotide position 3 in the 5'-noncoding region and the E2 envelope glycoprotein. TC-83 virus amino acid position E2-120 appeared to be the major structural determinant of attenuation. Insertion of the TRD virus-specific 5'-noncoding region, by itself, into the TC-83 virus full-length clone did not alter the attenuated phenotype of the virus. However, the TRD virus-specific 5'-noncoding region enhanced the virulence potential of downstream TRD virus amino acid sequences.
Kinney
R M
RM
Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522-2087.
Chang
G J
GJ
Tsuchiya
K R
KR
Sneider
J M
JM
Roehrig
J T
JT
Woodward
T M
TM
Trent
D W
DW
D000818:Animals; D000917:Antibody Formation; D000956:Antigens, Viral / Q000276:immunology*; D017123:Bacteriophage T7 / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004666:Encephalitis Virus, Venezuelan Equine / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D004685:Encephalomyelitis, Venezuelan Equine / Q000276:immunology / Q000517:prevention & control*; D000939:Epitopes; D016679:Genome, Viral; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D017354:Point Mutation; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D016019:Survival Analysis; D014613:Vaccines, Attenuated; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*; D010948:Viral Plaque Assay; D014774:Virulence
D000956:Antigens, Viral; D000939:Epitopes; D014613:Vaccines, Attenuated; D014759:Viral Envelope Proteins; C064956:glycoprotein E2, equine encephalitis virus