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Abstract
Bovine ephemeral fever (BEF) is an arthropod-borne viral disease caused by Rhabdovirus. There have been outbreaks every 3-6 years in Taiwan. For the purpose of improving the BEF vaccination schedule, we develop a live vaccine with YHL virus strain that isolated from Japan. Several animal tests have been conducted to confirm the safety and efficacy of this live vaccine. In virulent reversion test, the vaccine was serially passaged thrice in calves. Other calves were challenged by BEF virus/2007 two weeks post vaccination. All of them remained healthy, no high fever or symptoms was observed. In addition, we did not isolate any BEF virus from blood samples of these calves t. To establish the challenge model, the brain tissue of baby hamsters showed neurological signs after first intra-cerebral inoculation of the BEF virus/2009, were collected, homogenized and inoculated intra-cerebrally again to the other baby hamsters. The neurological sings were not obvious this time and the virus titer of the brain tissue was not high enough for the challenge test. In another study, mice were used as alternative animal model to evaluate the safety and efficacy of the YHL live vaccine. These mice were all normal and showed no side effects during the trial. The serum neutralizing antibody titers against BEF virus were 2 to 4 times higher than the pre-immune serum. According to the results mentioned above, the live vaccine based on YHL strain is safe for calves. Though it’s hard to evaluate the efficacy of the live vaccine through challenge, we can still learn from the titer of the neutralizing antibody.
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Abstract
The most important pathogenesis of classical swine fever is the great damage to the immune system because the virus has a special affinity to immune cells, which leads to leukopeniaand lymphocyte depletion in pigs. The specificity in the immune system is essential for disease prevention. After vaccination, various cytokines are produced to enhance the immune response and the ability to resist infection. Previous studies showed that there is synergistic effect among cytokines, such as IL-1, IL-4, IL-6, IFN-γ, IL-12, GM-CSF, TNF-α, etc. Therefore, cytokines may play a pivotal role in vaccination. In this project, the purpose of the study is to compare the immune enhancing mechanisms induced by frozen dried lapinized hog cholera vaccine and the E2 subunit vaccine. The results showed that there is no significant difference in the serum concentration of IL-1, IL-4, GM-CSF and TNF-α among all groups, while IL-6 increased significantly on day 4 and day 7 in lapinized hog cholera vaccination group. Serum concentration of IL-2 increased with significance on the first day after vaccination in all groups. IFN-γ concentration increased on day 2 in E2 subunit vaccination group, and on day 3 in lapinized hog cholera vaccination group. However, the immune activation mechanism mediated by the cytokines triggered by different vaccinations and its antibody opsonization related pathways remain to be explored in the future.
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