OS18 - 10.b.3 Potency assessment of FMD Vaccines using standardised serological assays - S. Jamal
1. OS18
Potency assessment of FMD vaccine
using standardized serological assays
Syed M. Jamal
Department of Biotechnology
University of Malakand
Pakistan
2. OS18
Potency test for FMD vaccine
• Limitations of Potency test:
Varying outcome
Disease security hazards
Costly
One valency in any given trial
Animal welfare
• European Pharmacopoeia
Challenge protection studies in cattle
Determination of PD50
3. OS18
Serological based methods
Alternatives to challenge-protection test provided that a
correlation is established between antibody titre and protection
Advantages:
1. No logistic problems
2. No disease security hazards
3. Relatively in-expensive
4. More than one valency at given time
5. Simultaneous testing of several vaccines
4. OS18
• Mackowiak et al., 1962
• van Bekkum, 1970
• Sutmoller and Vieira, 1980
• Pay and Hingley, 1987
• van Maanen and Terpstra, 1989
• Amadori et al., 1991
• Pay and Hingley, 1992a,b
• Dus Santos et al., 2000
• Barnett et al., 2003
Studies on correlation between antibody titre and
protection
5. OS18
• Correlation between antibody titre and level of protection
accepted worldwide
• Test results often vary considerably between laboratories
• difference between route and dose of challenge virus
• the condition of cattle
• the interval between vaccination and challenge
• the type of serological test
• sensitivity of cells used in neutralization test
6. OS18
Objectives
Standardization of antibody titres against O/Manisa
for determination of vaccine potency using:
• A standardized commercial PrioCHECK FMDV type O
ELISA
• Inclusion of a standard 4 week post-vaccination serum
from a cow vaccinated with O/Manisa FMD vaccine in
both the ELISA and VNT
7. OS18
Serum samples from 18 potency tests performed at:
• Belgium (n=10)
• The Netherlands (n=6)
• The United Kingdom (n=2)
Standard control serum (4 week post-vaccination serum from
O/Manisa vaccinated cow)
Serum samples were tested in respective laboratories
using:
• Neutralization test
• ELISA (PrioCHECK)
Unit/standardized antibody titres determined by
subtracting the log titre of a standard control serum from that of
the test serum
Results were analysed using logistic regression
Materials and Methods
8. OS18
RESULTS: Antibody titres v/s protection
---------- Pirbright
---------- Ukkal
Lelystad
• Significant difference in antibody
titres among laboratories
• The slope of the curve steeper in
VNT compared to ELISA
---------- Pirbright
---------- Ukkal
Lelystad
9. OS18
Standardized/Units antibody titres v/s protection
---------- Pirbright
---------- Ukkal
Lelystad
Unit antibody titres reduced variation
among laboratories
BUT
Significant difference still present
---------- Pirbright
---------- Ukkal
Lelystad
10. OS18
Conclusions
Inclusion of the standard serum reduced variation between
the laboratories.
However, significant differences were still present, which could be
due to differences in vaccine composition.
Inclusion of a standard serum is a good way to make results
between laboratories more comparable.
Cattle vaccinated with 1/3rd dose of a standard FMD vaccine
(containing 3 PD50) should have antibody titre at least as high as that
of a standard serum representing 50% protection.
11. OS18
Acknowledgements
• CVI-lelystad, the Netherlands
• CODA-CERVA, Belgium
• Pirbright Institute, United Kingdom
• Thanks to the EuFMD for supporting my participation in the OS18