For strengthening the specificity of test, a subset of serum samples was analyzed in the absence of peptide (no peptide) or in the presence of two irrelevant peptides (1× and 2×). As shown in Fig. 6C, 10 samples from C group showing OD > 1.500 at 1/250 dilution were negative for both peptide-1× and peptide-2×. Only one anti-E1E2A,B–positive sample (C9) was found positive for the peptide-2× whereas the sample C12 showed a very low reactivity Everolimus price with both peptide-1× and peptide-2× (not shown). In conclusion,

the anti-E1E2A,B reactivity was highly specific (80%-90%). Furthermore, in the absence of peptide (no peptide), all the positive samples for E1E2A,B were negative (specificity = 100%). Under these conditions, the mean OD values at 1/500 dilution for NHS were 0.058 ± 0.022 (7), and the cutoff value = 0.124. The Selleck GSK458 NR patients were indeed negative with OD = 0.105 ± 0.045(5)

and the C patients highly positive with OD = 1.196 ± 0.236(12) (positive/negative ratio ∼ 10). Although the role of CD4 and CD8 T cells in controlling HCV infection is widely accepted, the role that antibodies may play in HCV clearance is still a matter of debate.15 Antibodies directed against the E1 and E2 viral envelope proteins may prevent or control viral infection if they are directed against epitopes implicated in virus entry. Therefore, because of the relevant properties of the unique mAb D32.10,12-14 the seroprevalence of E1E2A,B-specific selleck D32.10 epitope-binding antibodies was investigated here at different phases of HCV infection. In sera from patients who had spontaneously resolved HCV infection, the prevalence of these antibodies was close to 90% with high titers > 1/1000 in 80% of cases. In contrast, their prevalence in sera from never treated chronic carrier patients was significantly much lower (<15%,

P < 0.001). To ensure that high prevalence was well-specific, a subset of samples was tested for reactivity to two irrelevant immunogenic peptides 1× and 2× showing sequence homology from 7%-20% with the D32.10 epitope sequences E1, E2A and E2B. No reactivity was observed in 80%-90% of cases. Ten serum samples from patients who had resolved HCV infection and were highly positive for E1, E2A, and E2B were found unequivocally negative for both irrelevant peptides. Furthermore, in the absence of any peptide, the mean OD values for negative controls were much lower leading to cutoff = 0.124 for positive OD values > 1. The sensitivity of the test was also investigated by evaluating the proficiency of different formats: either not involving the streptavidin-biotin system for the capture of peptide-antibody complexes, or by coating the three biotinylated peptides together on the same solid phase. In both cases, the positivity was lower but remained significant (0.001 < P < 0.01).