Protection of vaccinated IFNAR^(−/−) mice against a lethal BTV-4 challenge.

<p>Mice (8 weeks old, 8 per group) were immunized twice by subcutaneous administration of an inactivated BTV-4 vaccine and inoculated with 10³ PFUs of BTV-4,. (A) ELISA detection of antibodies to BTV-4 VP2 in serum of immunized and nonimmunized IFNAR^(−/−) mice. Serum was collected two days before the challenge with BTV-4, and dilutions (1∶50 to 1∶1350) were analyzed by ELISA as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005171#s4" target="_blank">Materials and Methods</a>. (B) Survival rates of immunized and nonimmunized IFNAR^(−/−) mice after inoculation with BTV-4. The mice were observed every 24 h for 14 days. (C) Titers of BTV-4 recovered in blood of immunized and nonimmunized IFNAR^(−/−) mice after challenge with BTV-4. Virus was extracted from blood and determined as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005171#s4" target="_blank">Materials and Methods</a>. Each point represents the mean values of the viral titer of eight animals, and standard deviations are shown as error bars.