Experimental Infection of Pigs with ‘Candidatus Helicobacter suis’

‘Candidatus Helicobacter suis’ is a spiral-shaped bacterium that colonizes the stomach of more than 60% of slaughter pigs. The role of ‘Candidatus Helicobacter suis’ in gastric disease of pigs is still unclear. Experimental studies in pigs are lacking because this bacterium is unculturable until now. An inoculation protocol using ‘Candidatus Helicobacter suis’ infected mouse stomach homogenate was used to reproduce the infection in pigs. Control animals were inoculated using negative mouse stomach homogenate. Pigs were inoculated three times with one-week intervals and euthanized 6 weeks post inoculation. Tissue samples were taken from different mucosal stomach regions to detect ‘Candidatus Helicobacter suis’ by PCR and urease test. Mucosal inflammation was evaluated on formalin-fixed tissue samples. Lesions in the pars oesophagea were scored macroscopically. Infection was succesful in all challenged animals, with the antrum and the fundus being predominantly positive. Infection was associated with infiltration of lymphocytes and plasma cells in the antral mucosa, evolving to follicular gastritis. No apparent inflammation of the fundic stomach region was detected in the infected animals. A clear link between ‘Candidatus Helicobacter suis’ and pars oesophageal lesions could not be found.