We previously described a single-cycle dengue vaccine (RepliVAX D2) engineered from a capsid (C) gene-deleted West Nile virus (WNV) expressing dengue virus serotype 2 (DENV2) prM/E genes in place of the corresponding WNV genes. That work demonstrated that adaptation of RepliVAX D2 to grow in WNV C-expressing cells resulted in acquisition of non-synonymous mutations in the DENV2 prM/E and WNV NS2A/NS3 genes. Here we demonstrate that the prM/E mutations increase the specific infectivity of chimeric virions and the NS2A/NS3 mutations independently enhance packaging. Studies with the NS2A mutant demonstrated that it was unable to produce a larger form of NS1 (NS1'), suggesting that the mutation had been selected to eliminate a ribosomal frame-shift "slippage site" in NS2A. Evaluation of a synonymous mutation at this slippage site confirmed that genomes that failed to make NS1' were packaged more efficiently than WT genomes supporting a role for NS1/NS1' in orchestrating virion assembly. © 2011 Elsevier Inc.
Winkelmann, E. R., Widman, D. G., Suzuki, R., & Mason, P. W. (2011). Analyses of mutations selected by passaging a chimeric flavivirus identify mutations that alter infectivity and reveal an interaction between the structural proteins and the nonstructural glycoprotein NS1. Virology, 421(2), 96–104. https://doi.org/10.1016/j.virol.2011.09.007