Guinea Pig as an appropriate model for colonization of helicobacter pylori

ABSTRACT

Animal models have been proven useful in elucidating the details of interaction between pathogenic bacteria and their human hosts, in addition to assessing the efficacy of therapeutic compounds and vaccines. In this study, we investigate the colonization of Helicobacter pylori [H. pylori] in experimentally-infected guinea pigs over a six-month period. A bacterial suspension was prepared by mixing four H. pylori isolates obtained from patients diagnosed with gastric ulcer. Within a one week period, five female guinea pigs were dosed orally with bacterial suspension for a total of three times. One control animal was gavaged with normal saline. Stool samples were collected at two-week intervals for six months. We used PCR, the stool antigen test, and indirect immunofluorescence assay [IFA] to assess samples for the presence of H, pylori. Stomachs obtained from two chloroform-killed animals, at 8 and 24 weeks, were investigated for histopathologic changes. H. pylori 16S rDNA was amplified from the stool samples of five guinea pigs. The stool antigen test was also positive in all five animals. IFA demonstrated the presence of H, pylori antigens in the stools from all five animals. PCR, stool antigen test and IFA results showed no H. pylori in the stool of the control animal. We observed infiltration of mature lymphocytes and plasma cells in the stomachs of animals killed at 8 and 24 weeks. The occurrence of H, pylori 16S rDNA and antigens in stool samples of guinea pigs demonstrated persistent colonization off H, pylori in the stomachs of guinea pigs. Histopathological findings have confirmed mild-severe gastritis induced by the bacterial infection. The stomach of a guinea pig is similar to the human stomach, in that it is sterile, lined by glandular epithelium, lacks a vitamin C synthesizing system and produces the cytokine interleukin-8. Accordingly, the guinea pig can be considered an appropriate animal model for long-term experiments to follow the process of H, pylori pathogenesis or to assess the efficacy of antibiotics or vaccines