Liver diseases linked to
hepatitis B-hepatitis D virus co- or
superinfections are more severe than those during hepatitis B virus (HBV) monoinfection. The diagnosis of hepatitis D virus (HDV)
infection therefore remains crucial in monitoring patients but is often overlooked. To integrate HDV markers into high-throughput viral
hepatitis diagnostics, we studied the binding of anti-HDV
antibodies (Abs) using surface plasmon resonance imaging (SPRi). We focused on the ubiquitous HDV genotype 1 (HDV1) and the more uncommon African-HDV6 and HDV8 genotypes to define an array with
recombinant proteins or
peptides. Full-length and truncated small
hepatitis D antigen (S-
HDAg)
recombinant proteins of HDV genotype 1 (HDV1) and 11 HDV
peptides of HDV1, 6, and 8, representing various portions of the
delta antigen were grafted onto biochips, allowing SPRi measurements to be made. Sixteen to 17 serum samples from patients infected with different HDV genotypes were injected onto
protein and
peptide chips. In all, Abs against HDV
proteins and/or
peptides were detected in 16 out of 17 infected patients (94.12%), although the amplitude of the SPR signal varied. The amino-terminal part of the
protein was poorly immunogenic, while
epitope 65-80, exposed on the viral
ribonucleoprotein, may be immunodominant, as 9 patient samples led to a specific SPR signal on
peptide 65 type 1 (65#1), independently of the infecting genotype. In this pilot study, we confirmed that HDV
infection screening based on the reactivity of patient Abs against carefully chosen HDV
peptides and/or
proteins can be included in a syndrome-based viral
hepatitis diagnostic assay. The preliminary results indicated that SPRi studying direct physical
HDAg-anti-HDV Ab interactions was more convenient using linear
peptide epitopes than full-length S-
HDAg proteins, due to the regeneration process, and may represent an innovative approach for a
hepatitis syndrome-viral etiology-exploring array.