Molecular Basis for Attenuation of Neurovirulence of a Yellow Fever Virus/Japanese Encephalitis Virus Chimera Vaccine (ChimeriVax-JE)

In vitro and in vivo characterization of chimeric duck Tembusu virus based on Japanese encephalitis live vaccine strain SA14-14-2

“…1b). These findings are consistent with the previous observations that chimeric flaviviruses could express the prM and E genes of heterologous flaviviruses, and exhibited growth-similar characteristics (Arroyo et al, 2001;Bhatt et al, 2000;Chambers et al, 1999;Guirakhoo et al, 2000;Pletnev et al, 2001Pletnev et al, , 2003.…”

“…S2). These residues have been implicated to play an important role in the neurovirulence of JEV (Arroyo et al, 2001;Chen et al, 1996;Liang et al, 2009;Sumiyoshi et al, 1995;Zhang et al, 2006;Zhao et al, 2005). The relevance of these residues for neurovirulence of DTMUV needs to be addressed in future studies.…”

Genetic and Phenotypic Properties of Vero Cell-Adapted Japanese Encephalitis Virus SA14-14-2 Vaccine Strain Variants and a Recombinant Clone, Which Demonstrates Attenuation and Immunogenicity in Mice

“…Only one of these mutations, nucleotide change G3599A that ablates NS1 formation, was shown to be attenuating in mice. 37 Mutations E-T177A and E-Q264H were not critical for the attenuated phenotype of ChimeriVax-JE in weanling mice 31 and arose during subcutaneous passages of over-attenuated precursor vaccine strain SA14-5-3 in suckling mice to improve immunogenicity, which produced the SA14-14-2 strain. 27,63 Consistent with this are studies showing that mutation E-Q264H significantly increased virulence in suckling mice and immunogenicity in weanling mice of a JEV/DEN4 chimeric virus.…”

“…The JEV SA14 underwent 100 passages in primary hamster kidney (PHK) cells, several plaque purifications in primary chick embryo cells, peripheral passages in Syrian hamsters, and suckling mice, followed by additional plaque purifications in PHK cells, which resulted in the accumulation of attenuating mutations found in the JEV SA14-14-2 genome. [27][28][29][30] There appear to be multiple attenuating mutations in the JEV SA14-14-2 E protein, 31 however E-E138K seems to be particularly important. [31][32][33][34][35] Interestingly, a recombinant WT JEV Nakayama virus bearing the 5 UTR, C, prM, and E genes of JEV SA14-14-2 had residual neurovirulence in mice, indicating that mutations located outside the structural protein genes might also contribute to attenuation.…”

“…[27][28][29][30] There appear to be multiple attenuating mutations in the JEV SA14-14-2 E protein, 31 however E-E138K seems to be particularly important. [31][32][33][34][35] Interestingly, a recombinant WT JEV Nakayama virus bearing the 5 UTR, C, prM, and E genes of JEV SA14-14-2 had residual neurovirulence in mice, indicating that mutations located outside the structural protein genes might also contribute to attenuation. 36 More recently it was shown that a single nucleotide change in the JEV SA14-14-2 NS2A coding region that ablates NS1 formation contributes to the attenuation phenotype.…”