Molecular mechanisms of pathogenicity of rinderpestvirus and its molecular epidemio1ogy

1.重组牛瘟疫苗免疫效果的研究(1)表达牛瘟病毒H基因的牛痘病毒免疫持续期已达一年之久。这项挑战测试是在接种疫苗两年后进行的。结果表明，接种牛痘疫苗后，除极少数牛外，其余牛均能在攻毒后存活2年。(2)表达牛瘟病毒N基因的牛痘病毒的免疫效果前一年兔未表现出保护性免疫，因此对牛进行了免疫试验。通过中等毒力水平的牛瘟挑战，牛存活了下来。然而，在高毒力牛瘟病毒的攻击下，动物出现了牛瘟的临床症状。这些结果表明该病毒的免疫效果低于表达H基因的痘苗病毒。细胞免疫在牛瘟病毒感染中的作用针对表达H基因的痘苗病毒可能参与细胞免疫的问题，建立了一种利用表达H基因的自体靶细胞进行细胞毒试验的方法。用这种方法在接种后1周证实出现了细胞毒性T细胞。表达NP蛋白的痘苗病毒也表明特异性表位参与了细胞免疫的形成。

1. Studies on the efficacy of recombinant rinderpest vaccine(1) Duration of immunity by vaccinia virus expressing the H gene of rinderpest virusThe immunity induced by the virus had already shown to last for one year. The challenge test was conducted two years after the vaccination. As a result, most of the cattle vaccinated survived the challenge except few animals, indicating the duration of immunity for two years(2) Immune effect of vaccinia virus expressing the N gene of rinderpest virusAs the protective immunity by the virus was not shown in rabbits in the previous year, test was conducted on cattle. By the challenge with rinderpest of moderate level of virulence the cattle survived the challenge. However, the animals developed c1inical signs of rinderpest by the challenge with highly virulent rinderpest virus. These results indicate that the immunizing effect of the virus is lower than that by the vaccinia virus expressing the H gene.2. Cell-mediated immunity in rinderpest virus infectionAs the involvement of cell-mediated immunity was suggested for the vaccinia virus expressing the H gene, a method for cytotoxic test was developed by using the autologous target cells expressing the H gene. By this method appearance of cytotoxic T cells was confirmed at 1 week after the vaccination.An involvement of specific epitope in the development of cell-mediated immunity was also indicated for the vaccinia virus expressing the NP protein.