Epitope mapping of Campylobacter jejuni flagellar capping protein (FliD) by chicken (Gallus gallus domesticus) sera

Abstract

Campylobacter jejuni, a Gram-negative rod, is a zoonotic pathogen associated with human acute bacterial gastroenteritis worldwide. The flagellum, composed of more than 35 proteins, is responsible for colonization of C. jejuni in the host gastrointestinal tract as well as inducing protective antibodies against the homologous serotype. In our previous study, we demonstrated that the flagellar capping protein (FliD) is an immunodominant protein that reacted strongly to sera from field chickens. In this communication, we mapped linear immunoreactive epitopes on FliD using a set of 158 synthetic peptides of 15-mer overlapping with 11 amino acid residues on peptide microarrays with sera from field chickens. The results from peptide microarrays showed (1) no cross-reactivity of the immobilized peptides with the secondary anti-chicken antibody in the control incubation, and (2) heterogeneous patterns of sera reacting to the immobilized peptides. The peptides that reacted to more than three chicken sera and had higher averages of fluorescence units were selected for further validation by the peptide ELISA. The results showed peptides 24, 91 and 92 had relatively high reactivity and less variation among 64 individual serum samples, indicating these peptides represented the shared immunodominant epitopes on the C. jejuni FliD protein. These peptides were also recognized by sera from chickens immunized with the purified recombinant FliD protein. The findings of the specific shared linear immunodominant epitopes on FliD in this study provide a rationale for further evaluation to determine their utility as epitope vaccines covering multiple serotypes for chicken immunization, and subsequently, for providing safer poultry products for human consumption.

Development of an enzyme-linked immunosorbent assay for detecting Campylobacter hepaticus specific antibodies in chicken sera – a key tool in Spotty Liver Disease screening and vaccine development

“…Many of the antigenic targets that have been used in serological detection of campylobacters are membrane surface proteins or flagellar proteins, because of their obvious immunogenic nature (Yeh et al, 2013;Yeh et al, 2016). The use of C. jejuni outer membrane proteins and formalin-inactivated whole cells as antigens for ELISA and immuno-blotting tests, demonstrated by Islam et al (2014), was successful in detecting C. jejuni or C. coli infections in humans.…”