Prevalence of an Unidentified <i>Helicobacter</i> Species in Laboratory Mice and its Distribution in the Hepatobiliary System and Gastrointestinal Tract

Abstract

An unidentified Helicobacter species, strain MIT 01-6451, was frequently detected in mice obtained from domestic commercial and academic institutions in Japan. To partially characterize this strain, its distributions in the gastrointestinal tract and hepatobiliary system of mice were investigated. In gastrointestinal tissues, this strain was detected in all cecum, colon, and feces samples tested, whereas fewer mice were positive in the ileum, jejunum, and duodenum. Interestingly, strain MIT 01-6451 was also detected in most stomach samples and in 33% of gallbladder samples. One mouse was found to be infected with multiple Helicobacter species. Fourteen copies of 16S rRNA genes were cloned from the tissues of this mouse. One had the highest level of sequence homology with H. canadensis, while 13 had the highest level of homology with the H. ganmani type strain or strain MIT 01-6451. Twelve of these 13 16S rRNA genes were mosaic sequences, being partially derived from H. ganmani and strain MIT 01-6451. These results suggest that H. ganmani and Helicobacter sp. MIT 01-6451 are prevalent in specific-pathogen-free mouse colonies in Japan and that lateral gene transfer probably occurs among Helicobacter species during coinfection.

NovelHelicobacterspeciesH.japonicumisolated from laboratory mice from Japan induces typhlocolitis and lower bowel carcinoma in C57BL/129 IL10−/−mice

“…At 6 weeks p.i, multifocal hepatitis was noticed in the infected mice which may indicate H.japonicum infection in the liver by translocating the intestinal barrier into hepatic tissues or alternatively, indirect effect of systemic cytokine response due to the primary intestinal infection (40). Even though we did not detect H.japonicum in the liver samples, in another study H.japonicum was identified in 33% gallbladder samples tested; however, they too did not detect the organism in liver samples (12).…”

“…In a previous report, H.japonicum was abundantly detected in the colon and cecum of clinically normal mice, while lower amounts were present in the stomach, gallbladder and other regions of the intestinal tract (12). The lack of clinical signs in these mice is consistent with our analysis of H.japonicum-infected C57BL mice or C57BL mice infected with H.hepaticus, which also did not have clinical signs (8,12). Importantly, however, it has been reported that the severe combined immunodeficient mice infected with H.japonicum had lower birth rates when compared with Helicobacter spp.…”

“…It has also been reported that a novel Helicobacter sp., we have now named H.japonicum, is present at high frequency in laboratory mice in Thailand (35). In a previous report, H.japonicum was abundantly detected in the colon and cecum of clinically normal mice, while lower amounts were present in the stomach, gallbladder and other regions of the intestinal tract (12). The lack of clinical signs in these mice is consistent with our analysis of H.japonicum-infected C57BL mice or C57BL mice infected with H.hepaticus, which also did not have clinical signs (8,12).…”

“…that we now name H.japonicum had the highest prevalence among the Helicobacter spp. detected; however, the bacteria were not isolated from mice imported from Europe and the USA (12,34). It has also been reported that a novel Helicobacter sp., we have now named H.japonicum, is present at high frequency in laboratory mice in Thailand (35).…”

“…(MIT 01-6451) from mice from Japan during a survey of mice from commercial and academic institutions in Asian, Europe and Northern America (10). Subsequently, this species was reported to colonize a high prevalence of mice used in biomedical research in Japan (11,12). In this study, additional strains of this mouse Helicobacter spp.…”