Optimization of freeze-drying process for anti-Chlamydia hyperimmune serum

Introduction . The distribution are a of Chlamydia infection in livestock and wild animals currently extends across almost all continents. At present, initial diagnosis, screening tests and certain stages of epizootiological investigations aimed at Chlamydia carrier detection are conducted in the Russian Federation using the “Antigen and Serum Kit for Serological Diagnosis of Chlamydiosis in Livestock”. It is important in theproduction of diagnostics to ensure stability of different test kit components during their storage and transportation. One way of addressing this issue is to stabilize diagnosticum components by freeze-drying. Objective . The study was aimed at optimization of freeze-drying process for specific anti- Chlamydia serum, the serum assessment for compliance with characteristics laid down in the technical specifications for the test kit control and testing of the serum for its stability. Materials and methods . The serum was prepared using blood from sheep immunized with emulsion vaccine based on Chlamydia psittaci AMK-16 strain. Prior tofreeze-drying, the hyperimmune sera were subjected to freezing to a temperature of minus 60 °С. The sera were freeze-dried using a Scientz 30F freeze-dryer (China). Two freeze-drying procedures with different temperature conditions and chamber pressures were applied. The resulting sera were tested for compliance with the technical specifications for thediagnostic test kit. The freeze-driedsera wereput intostorage for 24 months andtested with complement fixation test during this period. Results . Based on the test results, the freeze-drying procedure employing a lower pressure and the highest heating temperature was found to be the most effective for the specific sera. The serum tests for compliance with characteristics laid down in the technical specifications for the test kit showed that the serum quality met all relevant requirements. The stability test results demonstrated that the hyperimmune serum freeze-dried using the improved procedure remains specific during 24 months. Conclusion . The work performed allowed for optimization of freeze-drying process for specific anti- Chlamydia serum intended for the diagnostic test kit. The resulting serum is fully compliant with characteristics laid down in thetechnical specifications for the diagnosticum. It was established that the freeze-dried serum shelf life is at least two years, during this period the serum retains its activity and physico-chemical properties.