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International collaborative study: evaluation of proposed International Reference Reagent of pertussis antiserum
R Gaines Das1, D Xing, P Rigsby
1Informatics Laboratory, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, UK.
Abstract:
A freeze dried preparation of mouse serum in vials coded 97/642 containing antibodies to five pertussis antigens [pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), fimbriae type 2 and 3 (Fim 2 and 3)] has been assessed for its suitability as an international reference reagent in an international collaborative study by thirteen laboratories in nine countries. This serum has been compared with U.S. Standard Pertussis Antiserum (mouse) Lot No. 1 (US Lot 1), which has been in use since 1995, for antibodies for each antigen. Calibration of the proposed International Reference Reagent of Pertussis Antiserum (pIRR) in terms of US Lot 1 gives results which are broadly consistent between laboratories for antibodies to each antigen, although the between-laboratory differences are larger than those seen for comparison of identical sera. Calibration of two positive control sera in terms of the pIRR gave similar between laboratory variability of estimates to that obtained when the same sera were calibrated in terms of US Lot 1. Overall continuity of estimates is maintained if units are assigned to the pIRR based on its calibration in terms of US Lot 1 in this study. Data presently available indicate that the pIRR is sufficiently stable to serve as a reference reagent. It was therefore recommended, with the agreement of all participants, that the preparation in vials coded 97/642 be established as the First International Reference Reagent for Pertussis Antiserum, mouse, with assigned unitages 16 units of anti-PT per vial, 143 units of anti-FHA per vial and 30 units of anti-PRN per vial based on its calibration in terms of US Lot 1. These unitages are also consistent with calibration of 97/642 in terms of the Japanese preparations JNIH-11 for anti-FHA and of JNIH-12 for anti-PT. Purified antigens for Fim 2 and Fim 3 are not readily available and an arbitrary value of 32 units per vial is suggested for anti-Fim 2 and 3 mixture. These recommendations were agreed by the Expert Committee on Biological Standardization of the World Health Organization.
Insights
A new mouse serum preparation (pIRR) has been established as the First International Reference Reagent for Pertussis Antiserum. This reagent provides continuity for pertussis antibody measurements across laboratories.
Area of Science:
- Immunology
- Microbiology
- Biotechnology
Background:
- Pertussis antiserum is crucial for standardizing diagnostic assays.
- Existing reference reagents require validation for global use.
Purpose of the Study:
- To evaluate a novel mouse serum preparation (97/642) as an International Reference Reagent for pertussis antibodies.
- To establish unitages for key pertussis antigens.
Main Methods:
- International collaborative study involving thirteen laboratories across nine countries.
- Comparative calibration of the proposed International Reference Reagent (pIRR) against the U.S. Standard Pertussis Antiserum (US Lot 1).
- Assay of antibodies against pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and fimbriae types 2 and 3 (Fim 2 and 3).
Main Results:
- Broadly consistent results were obtained between laboratories for antibody calibration.
- The pIRR demonstrated stability suitable for a reference reagent.
- Assigned unitages: 16 units/vial anti-PT, 143 units/vial anti-FHA, 30 units/vial anti-PRN, and 32 units/vial for anti-Fim 2 and 3 mixture.
Conclusions:
- The mouse serum preparation (97/642) is recommended as the First International Reference Reagent for Pertussis Antiserum.
- The established unitages ensure continuity of pertussis antibody estimates.
- The pIRR facilitates standardized global pertussis diagnostics.