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Cryptosporidium merozoite isolation and purification using differential centrifugation techniques
S Regan1, V Cama, C R Sterling
1Department of Veterinary Science, University of Arizona, Tucson 85721.
Abstract:
Simple modifications to a recently published merozoite purification procedure (Bjorneby et al., J. Immunol. 145:298, 1990) increased yields 3- to 5-fold. Calves were infected with 2.5 x 10(8) Cryptosporidium parvum oocysts and sacrificed 65 h post-infection. The ilium and caecum were removed. The tissue was sieved through a large strainer (2 mm2) to produce a homogeneous suspension. Red blood cells were removed by differential centrifugation (600 g); merozoites remained in the supernatant. The merozoites were pelleted (2,100 g) and washed in modified Hank's balanced salt solution deficient in Mg+2 and Ca+2. Percoll purification (density 1.070 g/ml and centrifugation speed of 22,000 g for 30 min) yielded 8 x 10(8) merozoites. Nineteen monoclonal antibodies (MAb) detected by either an enzyme-linked immunosorbent assay or an immunofluorescence assay, have been generated against the merozoite stage. Gels of proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver-stained showed that sporozoites and merozoites have many common lower molecular weight proteins. Western blots of sporozoite and merozoite antigens reacted with anti-sporozoite MAb showed several cross-reacting antigens shared by these life-cycle stages.
Insights
Researchers enhanced Cryptosporidium parvum merozoite purification, increasing yields 3- to 5-fold. They also generated monoclonal antibodies and identified shared antigens between merozoites and sporozoites.
Area of Science:
- Veterinary Parasitology
- Immunology
- Molecular Biology
Background:
- Cryptosporidium parvum is a significant cause of diarrheal disease in mammals.
- The merozoite stage is crucial for parasite propagation within the host.
- Efficient purification of merozoites is essential for immunological and molecular studies.
Purpose of the Study:
- To improve the yield and purity of Cryptosporidium parvum merozoites.
- To generate monoclonal antibodies against the merozoite stage.
- To investigate shared antigens between different life stages of the parasite.
Main Methods:
- Modified a published merozoite purification protocol using differential centrifugation and Percoll density gradient.
- Infected calves with C. parvum oocysts and collected intestinal tissues.
- Generated monoclonal antibodies using enzyme-linked immunosorbent assay and immunofluorescence assay; analyzed proteins via SDS-PAGE and Western blotting.
Main Results:
- Achieved a 3- to 5-fold increase in merozoite yields, obtaining 8 x 10^8 merozoites.
- Successfully generated 19 monoclonal antibodies targeting the merozoite stage.
- Identified common low-molecular-weight proteins and cross-reacting antigens between sporozoites and merozoites.
Conclusions:
- The optimized procedure significantly enhances merozoite purification for research.
- The generated monoclonal antibodies provide valuable tools for studying C. parvum.
- Shared antigens suggest potential targets for cross-stage protective immunity.