Improvement of Enzyme-Linked Immunoelectrotransfer Blot Assay by Quantitative Approach for Foot-and-Mouth Disease diagnosis

Abstract

Foot-and-mouth disease (FMD) is a highly contagious animal disease that causes devastating economic losses. The trade of live animals and derived products is only possible if the exporting country is free from disease, according to the World Organization for Animal Health (WOAH) code for FMD. One of the most important ways to prove disease-free is to measure the levels of non-structural protein antibodies (NPS) of FMD virus in the target population sampled. For detection of the disease status of a herd, mass screening and assays such as Enzyme-linked immunosorbent assay (ELISA) and Enzyme-linked immunoelectrotransfer blot assay (EITB) were developed and described in the WOAH diagnostic manual. In this study, recombinant FMDV NS proteins were produced and tested with sera panels collected from uninfected and naturally infected animals using a quantitative Western blot assay as an improved EITB, which enables numerical documentation and statistical analysis. NSP band intensities were used to determine the cut-off values, differentiating infected from non-infected animals and revealing variable sensitivity among the different NSPs. The quantitative EITB results also showed a correlation with the NSP-ELISA results.