Each group was boosted with EG95 protein at 4 weeks post-immunization. Antibody levels were determined in 2-weekly collections of serum, Erlotinib mw by ELISA. The results are presented in Figure 3. All sheep infected with VV399 showed evidence of seroconversion. Animals primed with EG95 showed higher levels of priming with EG95 protein compared with animals immunized with VV399. However, there was no difference in the serological response of both groups of sheep to the booster injection of EG95 protein. Poxviruses are proven delivery vehicles for a wide range of antigens against various diseases (11–13). The secreted EG95 protein, produced during the oncosphere and post-oncospheral life stage

prior to metacestode formation, affords protection against hydatid disease in the intermediate host, and in this study, we explored the use of VACV as a delivery system for this antigen. Mice are a well-established species for testing the immune

response against foreign antigens expressed by recombinant VACV (11,19) and were used in this study to examine the antibody response against EG95 expressed from VACV and to examine the ability of the mouse antiserum produced to kill E. granulosus oncospheres in vitro. Whilst all groups infected with VV399 showed little antibody response to EG95 at 2 weeks post-infection, it was observed that the antibody response continued to increase with time, and by 42 days post-infection, antibody levels were comparable with mice learn more immunized intraperitoneally with EG95 protein at 2 weeks post-immunization. Furthermore, it was clear that all animals were primed with VV399 as significant responses were detected in all animals either boosted with VV399 or EG95 protein. The primary antibody response observed was consistent with the immune response seen in foxes and skunks fed orally a sponge bait containing recombinant VACV expressing the rabies virus glycoprotein (20–22). In their experiments, neutralizing antibody next increased up to day 28–30, but decreased thereafter. In addition, the priming effect of VV399 was also observed by

the antibody levels produced in animals boosted intraperitoneally with EG95 protein (Figure 1). We found that a second immunization with VV399 enhanced the antibody response generated from previous exposure, albeit not to the same level as that seen with EG95 protein combined with alum adjuvant. The priming and boosting effect of EG95/HIS with alum is interesting. Previous work (16) has shown that in sheep, alum is a poor adjuvant compared with QuilA. It was necessary to use alum because QuilA was shown to be lethal in our mice. The level of immunity generated by the double exposure to VV399 intranasally prompts the suggestion that this recombinant virus could be used for immunizing grazing animals in the field.