Studies on newly synthesized peptides having parasitocidal activity, and their mechanisms on host immune repsponses.

(1)新合成肽的研究从细胞因子中分离出具有免疫调节作用的活性单位，研究其对弓形虫慢性感染动物的作用。用环磷酰胺(Cyp)、Obio-1(Obio-1)和/或抗CD4单抗治疗慢性感染弓形虫的小鼠，以确定这些免疫抑制剂对脑囊肿的影响。在未治疗和感染Cyp-OBI-1的小鼠脑内，用苏木精-伊红染色或抗弓形虫ABC标记染色，大多可见大的典型圆形组织囊肿，在本实验研究中还观察到某些区域有分隔的微囊。相比之下，仅用Cyp或抗cd4治疗的感染小鼠的脑组织在某些脑区有多个大小不一的退行性囊泡，以及成簇的微囊团，然而，这种变化在an…中更为显著。更多的ti-CD4处理的小鼠。用Cyp和Obio-I联合治疗的感染小鼠的存活率显著高于仅用Cyp治疗的小鼠，存活率为80%和20%。这些结果表明，弓形虫慢性感染Cyp后小鼠组织囊破裂的再激活可能主要是由CD4+细胞介导的，而不是其他CD8和CD5+细胞。(2)携带弓形虫主要表面蛋白原虫基因SAG-1(P30)的转基因小鼠的产生被认为是弓形虫宿主细胞入侵过程中的重要配体。如果这种蛋白质是由宿主细胞产生并干扰寄生虫的蛋白质，那么宿主就会对寄生虫的入侵产生抵抗力。或者，由于缺乏对P30抗原的免疫反应，它可能变得更容易感染。为了获得携带P30基因的转基因小鼠，将一段3.3kb的DNA片段显微注射到C57BL/6J、BA Lb/c或F1(C57BL/6J x C3H/He)小鼠的单细胞胚胎的原核中。将胚胎移植到假孕ICR小鼠的输卵管中。在第一系列近交系实验中，从159只注射卵子发育的小鼠中获得了两个P30阳性的创始人(雄性C57BL/61和雌性BALB/c)。此外，我们还利用F1(C57BL/6J x C3H/He)胚胎获得了几只表达该基因产物并将其传递给下一代的P30小鼠。据我们所知，这是第一只携带弓形虫原生动物基因的转基因小鼠。较少

(1) Studies on newly synthesized peptidesNewly synthesized peptide (Obioactin to Obiopeptides) of the activity units which were isolated from cytokines as an immunoregulator were examined in the effect of Toxoplasma chronically infected animals. Mice chronically infected with Toxoplasma gondii were treated with cyclophosphamide (Cyp), Obiopeptide- 1 (Obio- 1) and/or anti-CD4 monoclonal antibody to determine the effect of these immunosuppressive agents on the cysts in the brain. In the brain of non-treate, and infected Cyp-Obi-1 treated mice, with hematoxyline-eosine staining or anti-Toxoplasma ABC labelling staining, large typically rounded tissue cysts were mostly detected, and in some regions dividing microcysts were also observed in this experimental studies. In contrast, brain tissue from Cyp only or anti-CD4 treated infected mice had multiple degenerated cysts of varied sizes in some brain regions, as well as clusters of microcysts, however, such change was more striking in the an … More ti-CD4 treated mice. Infected mice treated with a combination of Cyp and Obio- I showed a significantly higher survival of 80% compared to 20% survival in mice treated with Cyp only. These results indicate that reactivation of rupture of tissue cysts in mice treated with Cyp, chronically infected with Toxoplasma, might be mainly mediated by CD4 positive cells rather than other CD8 and CD5 positive cells.(2) Production of transgenic mice carrying protozoan geneSAG-1 (p30), the major surface protein of Toxoplasma gondii, is considered as an important ligand in the process of host cell invasion. If this protein is produced by host cells and interfere with that of parasites, then the host will become resistant to parasite invasion. Or, it may become more susceptible to infection due to the lack of immune response against p30 antigen. To generate transgenic mice carrying p30 gene, a 3.3kb DNA fragments, containing p30 cDNA fused with CAG promoter, that has been shown to direct a ubiquitous expression of a reporter gene in transgenic mice, were microinjected into one of the pronuclei of one-cell embryos of C57BL/6J, BA LB/c or Fl (C57BL/6J x C3H/He) mice. The embryos were transferred to the oviducts of pseudopregnant ICR mice. In the first series of experiment using inbred strains, two p30-positive founders (male C57BL/61 and female BALB/c) were obtained among 159 mice that developed from the injected eggs. Furthermore, we have obtained several P30-founder mice expressing the gene product and transmitting the gene to the next generation, by using Fl (C57BL/6J x C3H/He) embryos. As far as we are aware, this is the first transgenic mice bearing a protozoan gene derived from T.gondii. Less