Fig. 3: Oligomeric HCV sE2 coupled to cVLPs elicits cross-reactive neutralizing antibodies against cross-genotypic HCVcc panel.

Mouse IgG from BALB/c mice immunized with cVLPs coupled either to monomeric or oligomeric sE2 was used in three replicates in dose-response neutralization of HCV recombinants (A) TN (genotype 1a) or (B) J6 (genotype 2a) HCVcc in FFU reduction assays on Huh7.5 cells. Following 48 h of infection the cells were fixed and FFUs were visualized using HCV anti-NS5A antibody following by anti-mouse antibody coupled to HRP followed by DAB staining of FFUs. Results were normalized to non-infected control cells and neutralization was assessed by four parameter curve fitting to calculate IC₅₀ values. If 50% neutralization was not reached at the highest tested dose then IC₅₀ values were interpolated if neutralization at highest dose reached a minimum of 30% and increased to at least 50% at 3 mg/ml. Data is represented with median value of inverse IC₅₀ values of purified IgG from individual animals. Statistical significance testing was done using non-parametric Mann–Whitney tests (Graphpad Prism 9.2.0) and the significance threshold was set at 95%. Mouse IgG from BALB/c mice immunized with oligomeric HCV sE2 was used at a single dose of 0.4 mg/ml in three replicates to neutralize Huh7.5 cell infection of HCVcc recombinants C H77 (genotype 1a), D T9 (genotype 2a), E DBN (genotype 3a), F ED43 (genotype 4a), G SA13 (genotype 5a), or H HK6a (genotype 6a). Results were normalized to non-infected control cells and is shown as percent neutralization with standard deviation. BS4131-BS4136, refers to individual BALB/c mouse serum samples taken at week 9 from which the IgG was extracted. *No measurable neutralization.