Genetic and Antigenic Evaluation of Foot-and-mouth Disease Virus Type A in the Endemic Area of Iran within 2014-2015

The foot-and-mouth disease virus (FMDV) with a wide variety of genomes and complicated biology is one of the infectious agents that put the lives of animals at risk. Therefore, to introduce suitable strains for vaccine production, it is essential to constantly evaluate genetic changes of circulating viruses in field. Within 2014-2015, a total of 126 clinical specimens consisting of epithelial tissue and vesicular fluid from tongue, dental pad, and hoofs suspected of FMD virus were submitted to the Reference Laboratory for FMD in Razi Vaccine and Serum Research Institute, and 86 of them were identified as FMD virus type A using sandwich Enzyme-Linked Immunosorbent Assay (ELISA). This virus was isolated from 42 samples from 16 provinces using cell culture. Firstly, the coding region that produces the main part of viral capsid was amplified by Polymerase chain reaction (PCR). This part of the genome by 800 bp length was related to the 1D gene that synthesizes the VP1 protein. The phylogenetic analysis of VP1 coding region determined two distinct genotypes with more than 15% nucleotide differences. The first cluster consisted of closely related viruses registered in the GeneBank of neighboring countries, including Afghanistan, Pakistan, and Turkey. All samples in Cluster1 were determined as relative viruses with genotype Iran-05. In-vitro serological examination indicated an antigenic relationship between Cluster 1 viruses and routine vaccine strain (A-IRN-2013). The second cluster with only two members was genetically far from earlier ones and could be considered a separate genotype. Furthermore, it was revealed that cluster 2 has not been previously reported in Iran. Genetic tracing indicated that these viruses might have been originated from circulating viruses from India.  Antigenic evaluation exhibited that this group could not be cross-protected by the routine vaccinal strain (A-IRN-2013) used during the research period.