An immunobiosensor using a piezo electric (PZ) crystal was developed and standardized for foot-and-mouth disease (FMD) diagnosis and virus typing [213] . Allosteric biosensors allow detection of antibodies against different viruses by accommodating peptide sequences from surface viral proteins, acting as antibody receptors, into permissive sites of allosterically responsive recombinant β-galactosidases. Among the advantages of such biosensors as diagnostic tools is the homogeneous nature of the assay, the short time required for the enzymatic reaction and antibody detection, and the potential for handling large number of samples and for automatic processing, as shown for human immunodeficiency virus [214, 215] . In the serological diagnosis of infectious diseases, the use of allosteric biosensors, namely, hybrid enzymes that respond enzymatically to antibodies directed to foreign peptides displayed on the enzyme surface [216, 217] , is highly promising [218] . Multiple insertions of a major FMDV Bcell epitope from the VP1 capsid protein near the active site of recombinant β-galactosidases dramatically increased the enzyme responsiveness to specific antipeptide antibodies, including sera from infected animals [219, 220] . It has been reported that recombinant β-galactosidases accommodating one or two different peptides from the FMDV NS protein 3B per enzyme monomer can be reactivated by anti-3B monoclonal antibodies (MAbs) and these recombinant βgalactosidases could be also efficiently reactivated by sera from infected animals that permitted differentiation between sera from infected animals and those from naïve and conventionally vaccinated pigs. These infection-specific FMDV biosensors can provide an effective and versatile alternative for the serological distinction of FMDV-infected animals [221] .