Molecular detection, genetic diversity, and phylogenetic analysis of foot-and-mouth disease virus (FMDV) type O in Iran during 2015-2016.

Background: The major challenge of foot-and-mouth disease (FMD) control is attributed to the rapid mutations in the FMDV RNA genome, resulting in continuous antigenic changes of circulating strains. Despite widespread vaccination of livestock populations, the incidence of the FMDV serotype O outbreaks in Iran during 2015-2016 raised concerns about the emergence of new strains. Aims: The aim of this study is the genetic and antigenic evaluation of FMDV type O isolates from different outbreak areas including Alborz, Tehran, Isfahan, Markazi, Zahedan, and Qom provinces. Methods: For this purpose, 71 FMD-infected samples were collected from six provinces of Iran, of which 12 serotype O positive were selected for genetic analysis. Results: All samples were in ME-SA topotypes/OPanAsia2 lineage, and the overall mean of genetic diversities at the 1D gene level was about 5% between the sequences. Blasting 1D gene sequences of isolated viruses showed more than 90% genetic identity with sequences registered from neighboring countries; therefore, it could be concluded that they had a common origin. Six isolates showed the highest genetic diversity (6% to 11%) with the OPanAsia2 vaccine strain (JN676146), which three of them (Qom, Alborz, and Zahedan isolates), had less than 30% antigenic homology with the OPanAsia2 virus (JN676146). Conclusion: Results of this study suggested OPanAsia2 vaccine had no enough coverage with some circulating strains in outbreak areas in Qom, Alborz, and Zahedan provinces, and the necessity of OPanAsia2 replacement with a new vaccine strain in Iran.