Figure 3. In vitro neutralization of JEV by heme-treated human monoclonal IgG1.

Neutralization potential of JEV-reactive heme-exposed IgG1 (Rtx) was accessed on distinct genotypes of JEV selected on the basis of their recent circulation in Southeast Asia. Neutralization titrations by focus-reduction neutralization test (FRNT) using either heme-treated or native Rtx are shown. (A) FRNT on a genotype III strain (JEV-RP-9)²⁹ (B) FRNT on a chimeric virus that express the structural proteins of a genotype I strain (CNS769_Laos_2009)³⁰ and the nonstructural proteins of a genotype III strain (JEV-RP-9). (C) FRNT on a genotype V strain (JEV-XZ0934)²⁹. The Y-axes depict the percent neutralization that was calculated using the formula: 100 × (1-FFU of treatment/FFU of control). Results are depicted as means ± SEM of two independent experiments performed in duplicate for each concentration. Statistical significance of the differences between heme-treated or native IgG1 was assessed at each concentration using two-tailed unpaired Student’s t-test. ns: non-significant.