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Background: The glycoprotein (G) gene sequences of bovine ephemeral fever virus (BEFV) strains derived from mainland China have not been compared with those of the isolates from other countries or areas. Therefore, the G genes of four BEFV isolates obtained from mainland China were amplified and sequenced. A phylogenetic tree was constructed in order to compare and analyze the genetic relationships of the BEFV isolates derived from mainland China and different countries and areas. Results: The complete BEFV G gene was successfully amplified and sequenced from four isolates that originated from mainland China. A total of fifty-one BEFV strains were analyzed based on the G gene sequence and were found to be highly conserved. A phylogenetic tree showed that the isolates were grouped into three distinct lineages depending on their source of origin. The antigenic sites of G1, G2 and G3 are conserved among the isolates, except for several substitutions in a few strains. Conclusions: The phylogenetic relationships of the BEFV isolates that originated from mainland China, Taiwan, Japan, Turkey, Israel and Australia were closely related to their source of origin, while the antigenic sites G1, G2 and G3 are conserved among the BEFV isolates used in this work. [ABSTRACT FROM AUTHOR]

Abstract: The G gene encoding the neutralization antigen of bovine ephemeral fever virus (BEFV) was characterized in order to define the virus''s molecular epidemiology in Japan and the genetic relationships among the Japanese, Taiwanese and Australian isolates. The nucleotide and amino acid sequences of the gene were highly conserved among the Japanese strains, regardless of the year of isolation, and were closely related to the Taiwanese strains. By phylogenetic analysis, the Japanese and Taiwanese strains were classified clearly into three chronological clusters: 1966, 1984–1989 and 1996–2004, indicating that the epidemics of bovine ephemeral fever may occur almost simultaneously in both countries by the same genotype. On the other hand, the Australian strains were distantly related to these East Asian strains and placed in the independent fourth cluster of the phylogenetic tree. It is suggested that three amino acid substitutions at residues 224, 271 and 499 in the neutralizing epitopes, of which two generate new glycosylation sequences, are responsible for antigenic variations of bovine ephemeral fever virus. The cross-neutralization test using the bovine ephemeral fever virus isolated in Japan demonstrated that the vaccine developed based on the oldest Japanese strain, YHL, appears to still be effective for controlling bovine ephemeral fever in Japan. [Copyright &y& Elsevier]