Immunotherapy of cryptosporidiosis in immunodeficient animal models.

The researchers conducted a study on immunotherapy as a treatment method for a persistent infection caused by Cryptosporidium parvum using two immunodeficient animal models: BALB/c Athymic mice and SCID foals. The results indicated a substantial reduction in the number of C. parvum organisms in mice and highlighted the potential of SCID foals as a large animal research model for persistent C. parvum infection.

Animal Models Used

• The immunodeficient animal models used were BALB/c Athymic (nude) mice and young horses with severe combined immunodeficiency (SCID), both susceptible to persistent infection after exposure to C. parvum oocysts.
• The mice were orally infected with two doses of 2 x 10^7 C. parvum oocysts and the foals were exposed orally to 10^8 oocysts, establishing persistent infection in both species.

Immunotherapy Treatment

• To treat the infected mice, they used monoclonal antibody (MAb) 17.41, which neutralizes sporozoites and merozoites of the Cryptosporidium species.
• The MAb 17.41 was administered orally to the mice for 10 consecutive days. This therapy resulted in a significant reduction (p less than 0.005) in the number of C. parvum organisms as observed through microscopic examination of the mice’s intestinal tracts.
• In comparison, SCID foals exhibited symptoms such as diarrhea and oocyst shedding. Two of the foals were treated orally with monoclonal antibody (MAb) 18.44 and immune serum, both capable of neutralizing C. parvum sporozoites and merozoites.

Results and Implications

• Despite the treatment in SCID foals, the oocyst shedding patterns did not show any significant difference compared to five SCID foals treated with nonimmune reagents. This implies that the used therapy didn’t demonstrably affect oocyst shedding in SCID foals.
• The results verify that SCID foals are a worthwhile large animal model for the study of diseases related to persistent C. parvum infections.
• The Athymic nude mice proved to be a suitable animal model for assessing the therapeutic potential of antibodies in persistent cryptosporidial infection and, due to the specific responses observed, imply potential efficacy of monoclonal antibodies in the treatment of such infections.