Development of an ELISA Test for Detection of Anti FMD Virus Type A87/IRN Antibody Using Irradiated Antigen

Background and Aims: The aim of this study was application of gamma irradiated FMDV antigen for liquid phase blocking sandwich ELISA (B-ELISA) to quantify guinea pig anti FMDV type A87/IRN antibody. Methods: FMDV type A87/IRN was propagated to a titer of 10 7.5 /ml TCID50 and then irradiated by gamma irradiator. The irradiated 146 S antigen was purified by sucrose gradient centrifugation after inactivation, and used for inoculation of rabbits and guinea pigs. The antiFMDV sera were collected from the animals. ELISA test was optimized and the titer of antibodies was compared with that of virus neutralization test (VNT) to determine the correlation between these techniques. Results: The results of VNT and B-ELISA did not show significant differences (P>0.05). The sensitivity and specificity of B-ELISA in comparison to VNT for detection of anti FMDV type A 87/IRN antibody were calculated to be %94.73 and %90.9 respectively. Conclusion: The ELISA titers in sera collected from animals were higher than those recorded by VNT. These results suggested that, in addition to neutralizing antibodies, the ELISA was measuring other classes of antibodies which did not neutralize FMDV in vitro. Also comparison of the VNT and B- ELISA results by t-test showed that the gamma irradiated inactivated FMDV antigen has unaltered antigenicity.