The isolation and serotyping of foot-and-mouth disease virus in Iran during 2019-2022

Foot-and-mouth disease (FMD) is a significant transboundary animal disease that has a considerable economic impact on livestock systems worldwide. In order to determine the presence and type of FMD virus in Iran, a total of 90 samples of vesicular fluid and epithelial tissue were collected from the tongues, tooth pads, and hooves of clinically suspect cattle on 40 vaccinated farms in 9 provinces of Iran. These samples were collected during four years, from January 2019 to December 2022, and the vaccine was a locally produced polyvalent inactivated vaccine. The collected samples were analyzed using ELISA and isolation methods to identify and characterize the FMD virus. The results of the ELISA tests revealed that 66.66% of the samples were positive for FMD, and the serotypes of the virus were determined. Considering ELISA reslut, 62% of the samples were assigned to serotype O, 33% to serotype A, and 5% to serotype Asia-1. Furthermore, 90% of the positive samples were inoculated onto monolayer cultures of pig kidneys (IB-RS2) for isolation and antigen detection by serotype-specific ELISA kit. The great majority of detected serotype O viruses were from Esfahan province, while the most detected serotype A and serotype Asia-1 viruses were from Qom and Tehran provinces, respectively. These findings indicate that the ELISA and isolation methods are suitable for identifying and typing FMD viruses. The vaccination program in Iran, which includes three serotypes (O, A, and Asia-1), appears to be effective in controlling the spread of the disease. However, the continued circulation of these serotypes in most provinces suggests that ongoing surveillance and vaccination efforts are necessary.