Neutralization of DENV RVPs using WHO human reference sera.

DENV RVPs representing each of the four serotypes were pre-incubated for 1 hour with a WHO reference panel of human primary sera reactive to each RVP serotype (monovalent, squares: anti-DENV-1 serum in A; anti-DENV-2 in B; anti-DENV-3 in C; anti-DENV-4 in D) or reactive to all serotypes (tetravalent, triangles in all four panels). Naïve serum was used as a negative control. After incubation, DENV RVPs were used to infect Raji DC-SIGN-R cells. Forty-eight hours after infection, cells were quantified for GFP expression by flow cytometry (n = 3, error bars represent the standard deviation).