Recombinant PorA, the Major Outer Membrane Protein ofCampylobacter jejuni, Provides Heterologous Protection in an Adult Mouse Intestinal Colonization Model

Immunity againstCampylobacter jejuni , a major food-borne pathogen causing diarrhea, is largely serotype specific. The major outer membrane protein (MOMP) ofC. jejuni , PorA, is a common antigen with the potential to provide broad protection. Adult BALB/c mice were orally immunized with a recombinant glutathioneS -transferase (GST) fused to PorA prepared fromCampylobacter jejuni C31 (O:6,7) (GST-PorA) combined with a modified heat-labile enterotoxin ofEscherichia coli as an adjuvant and later orally challenged with C31 strain or three heterologous strains: 48 (O:19), 75 (O:3), and 111 (O:1,44). Protection from colonization with the challenge organism was studied by fecal screening daily for 9 days. Serum and intestinal lavage fluid antibodies against the vaccine and Sarkosyl-purified MOMP from C31 were measured by using an enzyme-linked immunosorbent assay. The vaccine produced robust antibody responses against both antigens in serum and secretion. Since strain C31 was a poor colonizer, homologous protection could not be studied. The protective efficacies of heterologous strains were 43% (for strain 48,P < 0.001), 29% (for strain 75,P < 0.005), and 42% (for strain 111,P < 0.001) for the 9-day period compared to control mice given phosphate-buffered saline. Thus, PorA provided appreciable protection against colonization with heterologous serotypes.