Abstract
Bovine ephemeral fever virus (BEFV) is an economically important arbovirus of cattle. The disease occurs seasonally in Egypt. Several observations suggest there may be a connection between the outbreaks which have occurred simultaneously in Middle East countries. This study aimed to explore BEFV transmission link between Egypt and other Middle East countries. The viral agent was successfully isolated from preserved leucocytic fractions of feverish cattle obtained during 2000, 2001 and 2004 Egyptian outbreaks through serial passages in brain of suckling mice and cell culture. Isolation of BEFV was confirmed by RT-PCR. Phylogenetic analysis based on the surface glycoprotein (G) gene including this study sequences and 97 BEFV isolates from Middle East, Australia and East Asia revealed that BEFVs detected in Egypt during 2000, 2001 and 2004 were almost identical and genetically close to the Japanese vaccinal strain (YHL isolate). All the Egyptian isolates clustered phylogenetically within the Middle East clade except the 2005 isolates, which clustered, with the China/East Asia clade. The Egyptian BEFV 2000, 2001 and 2004 isolates were genetically distance from Israeli isolates within the same periods. Even the Egyptian 2012 and 2017 isolates are not so close genetically to Israeli and Turkish isolates. These results suggest that the link between BEFV outbreaks that occurred in Middle East countries at approximately the same periods cannot be attributed to winds and animal transport only but also, environmental factors such as hot and humid weather that favored the abundancy of the vectors in the region during the same time.