Genetically engineered, live attenuated vaccines for Venezuelan equine encephalitis: testing in animal models.

The central objective of this research was to test molecularly defined, live attenuated Venezuelan equine encephalitis virus (VEEV) vaccine candidates that were produced through precise genetic manipulation of rationally selected viral nucleotide sequences. Molecular clones of vaccine candidates were constructed by inserting either three independently attenuating mutations or a PE2 cleavage-signal mutation with a second-site resuscitating mutation into full-length cDNA clones. Vaccine candidate viruses were recovered through DNA transcription and RNA transfection of cultured cells, and assessed in rodent and non-human primate models. Based on results from this assessment, one of the PE2 cleavage-signal mutants, V3526, was determined to be the best vaccine candidate for further evaluation for human use.