Impact of mutations on the neutralization potency of DENV1 immune serum.

<p>A panel of 54 DENV1 RVP variants containing single, double, or triple amino acid changes was constructed by site-directed mutagenesis. This panel represented all surface-accessible residues identified in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003761#ppat-1003761-g001" target="_blank"><b>Figure 1c</b></a>. (<b>A</b>) The infectious RVP titer for each variant was determined concurrently with WT DENV1 using Raji-DCSIGNR cells. Values are the mean relative titer as compared to WT DENV1 infectivity measured in parallel from at least two independent RVP preparations; error bars represent standard error of the mean. Variants located in domains I, II and III of the E protein are colored in red, yellow, and blue, respectively. The sensitivity of the 54 DENV1 variants to neutralization by DENV1 immune serum was compared to WT DENV1 as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003761#ppat-1003761-g002" target="_blank"><b>Figure 2</b></a>. (<b>B–D</b>) Examples of the three patterns of neutralization by DENV1 immune sera observed are shown. Error bars represent the standard error of duplicate infections. (<b>E</b>) Neutralization sensitivities of all DENV1 variants to DENV1 immune sera are depicted as the mean fold increase in neutralization sensitivity ([NT50 variant]/[NT50 WT]); error bars represent standard error of the mean of 2–5 independent experiments.