Figure 5: Histopathological analysis of lung, liver and kidney from hamsters inoculated with PBS or OMVs at 21 days post L. interrogans serovar Pomona challenge. All tissues were fixed in 10% neutral formalin buffer, sectioned at 5 um and stained with hematoxylin and eosin. Left panel; tissue sections from control group. Right panel: tissue sections from hamsters immunized with Leptospira OMVs (A) Lung. Severe alveolar hemorrhage disseminated throughout the lung was found in animals in the control group. Lungs from OMV vaccinated hamsters were within normal limits. (B) Liver section. Moderate to severe hepatitis with mixed inflammatory cell infiltrates was evident in the control group. Note the unaffected liver from a vaccinated hamster. (C) Kidney section. Severe, acute, tubulointerstitial nephritis with locally extensive hemorrhage in uriniferous spaces and tubules was present in all kidneys collected from PBS-immunized hamsters. The kidney from an OMV vaccinated hamster is unaffected.