Experimental infection with bovine ephemeral fever virus and analysis of its antibody response cattle.

Bovine ephemeral fever (BEF) is an arthropod-borne viral disease that occurs throughout mainland China. LS11 obtained in the 2011 BEF epidemic was a wild strain, and its virulence and antibody response have never been studied in China. Therefore, the issues were investigated in this work. Experimental cattle were intravenously infected with different doses of BEF virus, and some non-infected cattle were simultaneously monitored. Blood and serum samples were collected from all animals over the course of our study. Infected cattle were challenged for a second time with BEF virus to determine protective period of the antibodies. BEF virus was detected in blood samples from infected cattle, but not in monitored cattle. The neutralizing antibodies (nAbs) against BEFV were easier to be detected and persisted for longer periods in cattle infected with higher doses of BEFV than in those infected with lower doses. When the titer of nAbs was equal to 5 or 6, re-infected cattle still could mount a challenge against BEFV. However, after 3 or 6months, when nAbs were no longer apparent, re-infected cattle displayed typical symptoms of BEF. Our findings indicated that vaccination should be performed once the titer of nAb decreased to 5 or 6.