Natural and experimental Helicobacter pullorum infection in Brown Norway rats

Helicobacter pullorum is an enterohepatic Helicobacter species (EHS) that was recently reported as a naturally acquired infection in mice. Faecal samples from 18 out of 20 Brown Norway (BN) rats, housed in the same barrier as the H. pullorum-infected mice, were positive for H. pullorum using species-specific PCR. In addition, we determined whether H. pullorum was able to persistently colonize the gastrointestinal tract and/or biliary tree and elicit tissue inflammation as well as a serum IgG response in BN rats. Six (four male, two female) 6-week-old, H. pullorum-negative BN rats were orally dosed with 4×10(8) c.f.u. of H. pullorum every other day for a total of three doses. At 2 weeks post-infection, all rats were H. pullorum-positive by faecal PCR. Five out of the six BN rats remained H. pullorum-positive for the entire 30 week study. PCR analysis of tissue collected at necropsy confirmed that the colon and caecum were the primary sites of H. pullorum colonization. Rats that were persistently colonized by H. pullorum had a sustained H. pullorum-specific IgG response measured by ELISA. Intestinal or hepatic pathology associated with H. pullorum infection was not noted. To our knowledge, this is the first report documenting that rats can be persistently colonized with an EHS that also infects humans.