Table 1.
Details of peptides with amino acid sequences corresponding to conserved linear epitopes present in the E2 envelope protein.
Fig 1.
ELISA-based reactivity of three peptides corresponding to conserved linear epitopes, with CP and SR serum samples.
ELISA was performed using peptides corresponding to three conserved linear epitopes, the 412-epitope, the 432-epitope and the 523-epitope, against three different serum dilutions (10-fold, 100-fold, 1000-fold) of (a) 30 serum samples from chronic patients and (b) 49 serum samples from spontaneous resolvers. Dotted line represents the cutoff value using the mean value from five healthy serum controls plus three times the standard deviation.
Fig 2.
Comparison of the CP and the SR sera for their reactivity to a single epitope or multiple epitopes.
Fig 3.
Dose response curves of selected CP serum samples to measure their ED50 values in HCVpp neutralization assay.
Dose response curves showing neutralization of HCVpp by serum samples of chronic patients. Serum samples at varying dilutions were mixed with HCVpp at 37°C and subsequently added to the wells containing Huh7.5 cells. After 72 h, cells were lysed and luciferase activity was measured. Subsequently, percent neutralization of each dilution was calculated by comparing with the control containing no serum.
Table 2.
Details of peptide reactivity (epitope specificity) and HCVpp neutralization activity of different CP and SR serum samples.
Fig 4.
Dose response curves of selected SR serum samples to measure their ED50 values in HCVpp neutralization assay.
Dose response curves showing neutralization of HCVpp by serum samples of spontaneous resolvers. Serum samples at varying dilutions were mixed with HCVpp at 37°C and subsequently added to the wells containing Huh7.5 cells. After 72 h, cells were lysed and luciferase activity was measured. Subsequently, percent neutralization of each dilution was calculated by comparing with the control containing no serum.
Table 3.
Details of peptide reactivity (epitope specificity) and effect of respective peptides on HCVpp neutralization activity of different CP serum samples.
Fig 5.
Effect of peptides corresponding to different conserved linear epitopes on HCVpp neutralization by the SR serum samples.
HCVpp neutralizing serum samples of spontaneous resolvers were incubated at 1:50 dilution with different peptides at 125 μg/ml concentration at 37°C for 2 hr before performing HCVpp neutralization assay. Column bars labeled with HCVpp represent 100% infection; column bars labeled with “Serum” represent HCV neutralization by the respective serum sample in the absence of peptide; and column bars labeled with “Serum+412”, “Serum+432” or “Serum+523” represent neutralization by the serum samples after incubation of that serum with respective peptides. Plus and minus signs at the tops of each graph indicates the presence or absence of ELISA reactivity of that serum sample with individual peptides indicated by colors. HCVpp neutralization by the AP33 monoclonal antibody at 1 μg/ml concentration and the effect of the 412 peptide on this neutralization was also determined and shown in the bottom left panel. significance was defined as *p≤0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001.