Enzyme-linked immunosorbent assays for virulence properties of Campylobacter jejuni clinical isolates.

To evaluate the capacity of enzyme-linked immunosorbent assays (ELISAs) to identify pathogenic strains among clinical fecal isolates of Campylobacter jejuni, 40 consecutively obtained strains from 39 sick patients and 1 asymptomatic person were tested by respective ELISAs for enterotoxin production in culture filtrates and for the invasive virulence antigen of bacterial cells. Of the 40 strains, 14 produced the enterotoxin; 15 strains, two of which were also enterotoxigenic, were invasive; and 11 strains had no detectable virulence property. The presence or absence of these virulence properties was confirmed by the demonstration that viable cells of all 12 randomly selected enterotoxigenic or invasive strains tested, but none of 9 nonpathogenic strains tested, caused fluid secretion in rat ligated ileal loops.

Immunisation of volunteers with a synthetic peptide vaccine for enterotoxigenic Escherichia coli.

A completely synthetically produced peptide vaccine, consisting of the 18-aminoacid Escherichia coli heat-stable toxin and the 26-aminoacid epitope of the heat-labile toxin B subunit, was given orally to thirteen volunteers. It raised antitoxin titres to both toxin components four-fold in serum samples and seven-fold in jejunal aspirates over preimmunisation control titres. Jejunal aspirates taken after immunisation from vaccinees, but not controls, neutralised the secretory activity of both toxins in appropriate biological assays.

Pathogenic properties of Campylobacter jejuni: assay and correlation with clinical manifestations.

The pathogenic properties of 20 strains of Campylobacter jejuni isolated from persons with clearly defined clinical manifestations were determined. Cell-free broth filtrates were examined for (i) enterotoxin production by Chinese hamster tissue culture assay and an enzyme-linked immunosorbent assay (ELISA) employing GM1 ganglioside and affinity-purified antiserum to Escherichia coli heat-labile toxin, (ii) cytotoxin production by Vero and HeLa cell tissue culture lines, and (iii) their ability to cause fluid secretion in rat ligated ileal loops. Viable bacteria were examined for invasive properties by an ELISA with the immunoglobulin fraction of antiserum to Formalin-killed bacteria of an invasive strain, and by their effect on fluid secretion and morphology in rat ligated ileal loops.

Mucosal antitoxin response in volunteers to immunization with a synthetic peptide of Escherichia coli heat-stable enterotoxin.

Peroral immunization of volunteers on four weekly occasions with 750 micrograms of a conjugate containing 3,000 antigen units of a synthetically produced peptide of hyperantigenic Escherichia coli heat-stable (ST) toxin, conjugated with the heat-labile toxin B subunit as a carrier, raised serum immunoglobulin G antitoxin titers to ST by fourfold and intestinal immunoglobulin A antitoxin titers to ST by sevenfold over control values at five weeks postimmunization. The ability of jejunal aspirates from the immunized volunteers to neutralize ST in the suckling mouse assay correlated with the intestinal immunoglobulin A ST antitoxin response determined by enzyme-linked immunosorbent assay.