Tibbetts R S, Kim I Y, Olson C L, Barthel L M, Sullivan M A, Winquist A G, Miller S D, Engman D M
Department of Microbiology-Immunology, Northwestern University Medical School, Chicago, Illinois.
Infect Immun. 1994 Jun;62(6):2499-507. doi: 10.1128/iai.62.6.2499-2507.1994.
The protozoan Trypanosoma cruzi is the etiologic agent of Chagas' disease, an illness responsible for morbidity and death among millions of Latin Americans. Mice also develop this disease when infected with T. cruzi and are a useful model organism for the study of parasite-specific immune responses. To identify immunogenic T. cruzi antigens, serum from an infected mouse was used to isolate clones from a T. cruzi epimastigote cDNA expression library. One of these clones was found to encode the 78-kDa glucose-regulated protein (grp78), the endoplasmic reticular member of the 70-kDa heat shock protein (hsp70) family. Like the mammalian and yeast grp78s, the T. cruzi protein contains an endoplasmic reticular leader peptide and a carboxyl-terminal endoplasmic reticular retention sequence. T. cruzi grp78 is encoded by a tandemly arranged family of three genes located on a chromosome of 1.6 Mb. The effects on grp78 expression of heat shock and tunicamycin treatment, the latter of which specifically stimulates mammalian grp78, were investigated. While the level of the grp78 protein remained constant under all circumstances, grp78 mRNA was unaffected by heat shock but induced fivefold by tunicamycin. Finally, we found that grp78 is the most immunogenic of the T. cruzi heat shock proteins we have characterized, reacting strongly in immunoblots with sera from infected mice.
原生动物克氏锥虫是恰加斯病的病原体，该病导致数百万拉丁美洲人发病和死亡。小鼠感染克氏锥虫后也会患上这种疾病，是研究寄生虫特异性免疫反应的有用模式生物。为了鉴定具有免疫原性的克氏锥虫抗原，利用感染小鼠的血清从克氏锥虫前鞭毛体cDNA表达文库中分离克隆。其中一个克隆被发现编码78 kDa葡萄糖调节蛋白（grp78），它是70 kDa热休克蛋白（hsp70）家族的内质网成员。与哺乳动物和酵母的grp78一样，克氏锥虫蛋白含有内质网前导肽和羧基末端内质网滞留序列。克氏锥虫grp78由位于1.6 Mb染色体上的三个串联排列的基因家族编码。研究了热休克和衣霉素处理对grp78表达的影响，后者特异性刺激哺乳动物grp78。虽然grp78蛋白水平在所有情况下都保持恒定，但grp78 mRNA不受热休克影响，但被衣霉素诱导增加了五倍。最后，我们发现grp78是我们所鉴定的克氏锥虫热休克蛋白中免疫原性最强的，在免疫印迹中与感染小鼠的血清强烈反应。
