A single Amino Acid Deletion in Capsid Protein VP1 G-H Loop Region of a Serotype O Foot and Mouth Disease Virus Isolate from India

Foot and mouth disease is endemic in India with prevalence of O, A and Asia1 serotypes among which type O accounts for more than 80% of the outbreaks. All the Indian serotype O isolates were genetically belonging to a single group, Middle East-South Asia (ME-SA) topotype further divided into three distinct lineages and an unnamed minor group. Sequencing the VP1 region of a field isolate O/GOA/120/2002 revealed a deletion of one amino acid at 139^th site. Further phenotypic characterization of the isolate by plaque assay showed that the plaques size was very small with a diameter of 1–2 mm. However, the isolate was antigenically homologous to the current Indian vaccine strain. The amino acid deletion did not cause any detectable antigen variation. However, the isolate showed smaller plaque size. Additionally this amino acid may not be essential for the virus multiplication and structural stability of VP1.The significance of the deletion is not clear.