Molecular epizootiology of bovine ephemeral fever virus in Iran during 2015 to 2022.

Bovine ephemeral fever (BEF) is a debilitating disease of cattle and water buffaloes. Bovine ephemeral fever viruses (BEFVs) form four phylogenetic lineages including the Middle East, East of Asia, Australia and Africa, while the exotic viral strains have also been detected in different geographic areas. We characterized eight BEFVs from different regions of Iran during a period of seven years from 2015 to 2022. Sequencing the entire length of the <i>G</i> gene, the BEFVs were classified in the Middle Eastern lineage with the maximum of 99.73% and minimum of 97.30% nucleotide identity. The all Iranian and Turkish BEFVs detected during the large epizootic in 2020 were clustered phylogenetically together. However, no amino acid variation was observed between the Iranian viruses detected in 2020 and those identified before 2020 in the Middle Eastern lineage suggesting that host, environmental and other genetic factor (s) might have involved in occurrence of the epizootic in 2020. Two BEFVs detected during 2022 outbreak from Kermanshah and Narmashir in the west and east of Iran, respectively, were clustered in two distinct groups as a novel amino acid substitution H51Y in the epitope G3 was also identified in Kermanshah 2022 sequence. These results imply that the Middle Eastern lineage replaced the previously circulated East Asian BEFVs in Iran during 2012 to 2013 and also signify the emergence of new BEFVs due to the intra-lineage evolution. Continuous monitoring of the circulating viruses and identifying the potential vector (s) and its biology help better understand epizootiology of BEFV in the high-risk region.