Monoclonal antibody-based blocking ELISA for FMD: A Highly Sensitive Assay for Detection of FMD Non-Structural Protein (NSP) Antibodies in All Species

Background:
In India, non-structural protein (NSP) based serological tests (indirect ELISA) have been developed in India 3AB antigen-based indirect ELISA is currently being used across the country. Indirect uses species-specific conjugates and needs optimization with the secondary antibody conjugate of each species and also with each lot of conjugate supplied by the vendors. The multi-species 3ABC indirect ELISA developed earlier by IVRI employs protein G-HRPO conjugate, as Protein G has an affinity for IgG from different species. This test is applicable in many susceptible species but not in some species such as pigs and wild animals. In view of these shortfalls with indirect ELISA formats, there has been a need to develop an improved NSP assay system that can be used across all the susceptible species including wild animals. Use of the new blocking ELISA developed here could serve as a single platform system to screen the serum samples from all animals including wild animals that are susceptible to FMD. The assay is inexpensive to produce as it does not require the purchase of commercially available conjugated antibody supplies for individual species.:

Technology Details:
Unique features of the Assay::

• Application: Detection of Foot-and-mouth disease virus antibodies in sera/plasma of animals. It differentiates infection from vaccination (DIVA).:
• Format: Blocking ELISA that uses recombinant antigen [3AB] and monoclonal antibody to 3AB of FMDV.:
• Total assay time: 135 minutes [2h 15min as compared to the ~20hrs of assay time for one of the widely used and well-validated assays available worldwide.:
• Steps: All room temperature based.:
• Validation stage: Completed at the national and international laboratories. Validated with a panel of sera from Pirbright for NSP test validation.:
• Species compatibility: All species including wild animals susceptible to FMD.:
• Performance: Highly sensitive and specific with Dsn and Dsp values of 93.7% and 99.8%, respectively.:
• Cost-effective: The assay is highly cost-effective as it uses conjugated antibodies and does not need the use of commercial conjugates needed in the indirect ELISAs for different species. It costs ~6 times less than similar imported commercial kit.