Establishment of Helicobacter pylori infection model in Mongolian gerbils

AIM: To establish a stable and reliable model of Helicobacter pylori infection model in Mongolian gerbils and to observe pathological changes in gastric mucosa in infected animals. METHODS: Mongolian gerbils were randomly divided into 18 groups; 6 groups were infected with H pylori clinical strain Y06 (n=6, groups Y), 6 groups were infected with H pylori strain NCTC11637 (n=6, groups N), and 6 uninfected groups as negative controls (n=4, groups C). H pylori suspensions at the concentrations of 2X10(8) and 2X10(9) CFU/mL of strain NCTC11637 and strain Y06 were prepared. The animals in three groups N and in three groups Y were orally challenged once with 0.5 mL of the low concentration of the bacterial suspension. The animals in another three groups N and in another three groups Y were orally challenged with 0.5 mL of the high concentration of the bacterial suspension for 3 times at the intervals of 24 h, respectively. For the negative controls, the animals in six groups C were orally given with the same volume of Brucella broth at the corresponding inoculating time. The animals were killed after 2nd, 4(th) and 6(th) week after the last challenge and the gastric mucosal specimens were taken for urease test, bacterial isolation, pathological and immunohistochemical examinations. RESULTS: Positive isolation rates of H pylori in the animals of groups Y at the 2nd, 4(th) and 6(th) week after one challenge were 0%, 16.7% and 66.7%, while in the animals of groups N were 0%, 0% and 16.7%, respectively. Positive isolation rates of H pylori in the animals of groups Y at the 2nd, 4(th) and 6(th) week after three challenges were 66.7%, 100% and 100%, while in the animals of groups N were 66.7%, 66.7% and 100%, respectively. In animals with positive isolation of H pylori, the bacterium was found to colonized on the surface of gastric mucosal cells and in the gastric pits, and the gastric mucosal lamina propria was infiltrated with inflammatory cells. CONCLUSION: By using H pylori suspension at high concentration of 2X10(9) CFU/mL for multiple times, the orally challenged Mongolian gerbils can be used as a stable and reliable H pylori infection model. The 2 strains of H pylori can colonize in gastric mucosa of the infected animals and cause mild inflammation reaction.