Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2011
Publication Date: 6/13/2011
Citation: Zuerner, R.L., Alt, D.P., Palmer, M.V. 2011. Development of chronic and acute Golden Syrian Hamster infection models with Leptospira borgpetersenii serovar Hardjo. Veterinary Pathology. 49(2):403-411. Interpretive Summary: Infection with Leptospira borgpetersenii serovar Hardjo causes reproductive losses in cattle and can cause human illness. Lack of a small animal model has hampered the ability to study serovar Hardjo pathogenesis. Although many pathogenic Leptospira can infect golden Syrian hamsters, identification of serovar Hardjo strains that could establish reproducible infections in hamsters has been unsuccessful. In this study we report that two strains of serovar Hardjo can infect hamsters with equal ability, but the results of infection are radically different. One strain establishes a chronic infection, quite similar to that seen in cattle, while the other strain produces an acute, potentially lethal infection. This small animal model should be useful to study serovar Hardjo pathogenesis, and also should be useful in evaluating vaccine potency.
Technical Abstract: The golden Syrian hamster (Mesocricetus auratus) is frequently used as a model to study virulence for several species of Leptospira. Onset of an acute, lethal infection following infection with several pathogenic Leptospira species has been widely adopted for vaccine testing. An important exception is the outcome following inoculation of hamsters with live L. borgpetersenii serovar Hardjo, the primary cause of bovine leptospirosis. Typically, inoculation of hamsters with L. borgpetersenii serovar Hardjo usually fails to induce clinical signs of infection. In this study we defined LD50 and ID50 for two strains of L. borgpetersenii serovar Hardjo, one of which preliminary studies showed was hamster lethal (strain JB197) and one that was not hamster lethal (strain 203). These strains differed in tissue invasion and interaction with leukocytes resulting in widely divergent infectious outcomes. Characterization of the infection process of these two L. borgpetersenii serovar Hardjo strains should provide both chronic and acute infection models for studying serovar Hardjo pathogenesis and for testing vaccines for bovine leptospirosis.