EXPERIMENTAL SPOROTRICHOSIS IN SYRIAN-HAMSTERS

Syrian hamsters were infected with Sporothrix schenckii by s.c. footpad inoculation. Two types of infection could be uniformly induced: a self-limited, lymphatic infection resembling the classical disease in humans, and a generalized non-fatal infection. An infecting dose of approximately 5300 yeast cells produced the localized subcutaneous-lymphatic disease which was limited to a single limb. A 1000-fold increase in the inoculum temporarily overwhelmed the animals'' defense mechanisms, producing a systemic infection involving the liver and spleen. These models were used to demonstrate the development of increased resistance to subsequent infection following infection or active immunization with ribosomal fractions or trypsinized cell wall antigens of S. schenckii incorporated in Freund complete adjuvant. Agglutination titers were detectable in all animals that were infected or immunized. In 1 group of infected animals, the titers persisted for at least 1 yr after 3 booster doses of formalin-killed s. schenckii. The ability to produce an infection in hamsters which closely resembles the disease seen in humans makes this animal a good model with which to study experimental sporotrichosis.