Inhibition of ehrlichial infection using effective proteins from tick, Ixodes ovatus

1.用从日本卵圆硬蜱分离的埃立克体HF 565接种两只SPF比格犬。他们没有临床症状，使用白色血细胞DNA进行的PCR结果均为阴性。结果表明，家犬未感染Ehrlichia HF 565。接种后4周，无临床症状，均存活。接种HF 565 1周后，大鼠出现肝细胞坏死、淋巴细胞浸润等组织病理学变化。在内皮细胞中也观察到较多的埃立克体桑椹胚。PCR检测肝、脾、肾、肺组织DNA均为阳性。实验过程中杠杆病变变轻。外周血DNA PCR均为阴性。以上结果提示，HF 565能感染大鼠，但在感染后3 ~ 4周内被清除。3.犬埃立克体感染犬后，犬细胞因子mRNA表达的变化。感染后3 ~ 8d检测外周血单个核细胞中IFN-γ和肿瘤坏死因子-αmRNA。感染后表达持续2个月以上。证实了犬埃里希体体外感染犬外周血单个核细胞后产生IFN-γ。还证实了添加来自犬艾美耳球虫感染犬的外周血单核细胞可抑制体外犬艾美耳球虫的生长。提示IFN-γ在埃立克体感染的免疫中起重要作用。

1.Two SPF beagle dogs were inoculated with HF565, Ehrlichia which was isolated from Japanese tick (Ixodes ovatus). They had no clinical signs and results of PCR using DNA from white blood cells were all negative. These results suggested that dogs are not infected with Ehrlichia HF565.2.Ten rats were inoculated with HF565. They had no clinical signs and survived 4 weeks after inoculation. Histopathological changes such as necrosis of liver cells and infiltration of lymphoid cells were observed in the rats 1 week after inoculation of HF565. Many ehrlichial morulae were also observed mainly in endothelial cells. PCR using DNA from liver, spleen, kidney and lung showed positive results. The lesion of lever turned to be light during experiment. PCR using DNA from peripheral blood were all negative. These results suggest that HF565 could infect to rats but they were eliminated during 3 to 4 weeks after infection.3.Expression of dog cytokine mRNA in Ehrlichia canis-infected dogs were investigated. Interferon-γ (IFN-γ) and tumor necrosis factor-αmRNA were detected in peripheral blood mononuclear cells on 3 to 8 days after infection. The expression continued for more than 2 months after infection. Production of IFN-γ after infection of E.canis to dog peripheral blood mononuclear cells in vitro was confirmed. It was also confirmed that addition of peripheral blood mononuclear cells from E.canis-infected dog inhibited the growth of E.canis in vitro. These results suggested that IFN-γ has a very important role in immunity of ehrlichial infection.