Infection of adult Syrian hamsters with flagellar variants of Campylobacter jejuni.

Two variants of Campylobacter jejuni IN1 differing in the expression of flagella, IN1 (Fla+ Mot+, wild type) and IN1-NM (Fla- Mot-), were tested for their ability to establish infection in adult hamsters. Animals were challenged intracecally with 2 X 10(9) to 5 X 10(10) CFU and monitored for evidence of infection. None of the challenged animals developed illness. There was a significant difference, however, in the ability of IN1 to infect hamsters (35 of 43) compared with that of IN1-NM (1 of 42) (P less than 0.01). Additionally, eight animals challenged with IN1-NM excreted only the campylobacters of Fla+ phenotype, which were shown to be identical with the parental Fla+ Mot+ type. Both groups of animals developed serum immunoglobulin G antibodies to outer membrane proteins of IN1 as measured by an enzyme-linked immunosorbent assay; however, only animals that excreted Fla+ organisms developed antiflagellin antibodies. In vitro reversibility from Fla+ to Fla- occurred with a frequency of 9.2 X 10(-6) per cell per generation; however, reversion from Fla- to Fla+ could not be detected in vitro. Further characterization of IN1-NM showed that it produced a cytoplasmic 62K flagellin subunit protein, but this protein lacked six epitopes detected in IN1 and also differed in its two-dimensional gel electrophoresis pattern. The results of these studies support the concept that an intact flagellum is necessary for intestinal infection with C. jejuni and that this model may be useful for studying the immune response to C. jejuni.