EuFMD OS20

1. 1
Post-vaccination serological monitoring of protective antibody levels in buffaloes involves the use of liquid phase
blocking ELISA (LPBE) that measures antibodies against structural proteins. Here we developed an alternative
single dilution avidity (AE) ELISA and compared its proficiency to other standard techniques.
▪ Buffaloes (n=91) from two farms from Corrientes, Argentina were immunized once with
a commercial vaccine (n=58 re-vaccinated; n=33 primo vaccinated).
▪ Samples were taken at 0, 14, 21,30, 60 and 120 dpv
▪ Kinetics of specific antibodies induced by vaccination against O1/Campos and
A24/cruzeiro strains was determined by virus-neutralization test (VNT), avidity ELISA
(AE) and liquid phase blocking ELISA (LPBE
▪ The concordance between the different techniques was assessed using Kappa value
Materials and methods
Juan Sala1 ,Florencia Mansilla2, Cecilia Turco2 and Alejandra Capozzo2 . INTA and CONICET. 1 Experimental Station INTA-
Mercedes, Corrientes.. 2 Institute of Virology and Technical Innovations. Buenos Aires. ARGENTINA
Anti-IgG
CURRENTLY USED
ADVANTAGES
✓ Single dilution
✓ High specificity: low
binders are detached by
washing the urea washing
step.
✓ Only antibodies against
epitopes exposed in the
whole viral capsid are
detected
NEW ASSAY: AVIDITY ELISA
SEROLOGICAL TESTS TO ASSESS VACCINE-INDUCED ANTIBODIES
VNT and AE detected a decrease in the antibody response of
calves with maternal antibodies that was significantly different
on day 0 and at 90 and 120 dpv (panel A)
0 14 28 42 56 70 84 98 112 126
1
2
3
4
A24 Cruz/ Farm B
A24 Cruz/ Farm A
Days post-vaccination
VNTtiter
*
0 14 28 42 56 70 84 98 112 126
0.00
0.25
0.50
0.75
1.00
*
Days post-vaccination
AE-OD
0 14 28 42 56 70 84 98 112 126
1
2
3
4
5
6
Days post-vaccination
LPBEtiter
A
Kinetics of the antibody response using
VNT
Avidity
LPBE
A substantial concordance was found between AE and VNT (C)
C
O1/CAMPOS A24/Cruzeiro
AIDITY ELISA 0.66 0.76 Substancial concordance
Liquid-Phase Blocking ELISA 0.55 0.56 Moderate concordance
KAPPA VALUE
Concoordance with VNT results
LPBE overestimated the antibody levels (panel B)
How do the different assays predict protective antibodies?
B
Farm A Farm B
Conclusions: Avidity of antibodies can be measured using a simple single-dilution ELISA, yielding similar results than the VNT.
Avidity ELISA might replace VNT for vaccine-immunity monitoring.