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Avidity as a parameter for diphtheria vaccine efficacy
1Department of microbial biotechnology, National Research Center, Cairo, Egypt.
The Egyptian Journal of Immunology
|February 24, 2005
Summary
Antibody avidity to diphtheria toxin (DT) and its binding site (DTBS) was studied. Vaccine efficacy correlated with DTBS affinity, not general avidity, highlighting the importance of measuring antibody response to specific protective epitopes.
Area of Science:
- Immunology
- Vaccinology
- Biochemistry
Background:
- Antibody avidity is crucial for effective immune responses.
- Assessing antibody avidity to diphtheria toxoids (DTo) and toxin (DT) is important for vaccine development.
Purpose of the Study:
- To investigate the avidity of antibodies (Abs) to diphtheria Toxin (DT), toxoids (DTo), and the DT binding site (DTBS).
- To correlate antibody avidity measurements with vaccine efficacy in guinea pigs.
Main Methods:
- Avidity measurement using the thiocyanate procedure for DTo and DT.
- Affinity determination to the DTBS using a tissue culture procedure (equilibrium constant, K).
Main Results:
- Antibody maturation patterns to DTo and DT differed.
- A 20-fold difference in affinity to the DTBS was observed.
- Vaccine efficacy correlated with DTBS affinity, but not with avidity to DTo or DT.
Conclusions:
- The thiocyanate procedure measures average avidity to complex antigens.
- The tissue culture procedure specifically measures affinity to the DTBS.
- Vaccine assessment should prioritize measuring antibody avidity to protective epitopes over complex antigens.