THE DEVELOPMENT OF NEW DAIAGNOSTICS AND CHEMOTHERAPEUTICS AGAINST ECHINOCOCCAL INFECTION

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13670258
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 寄生虫学(含医用動物学)
• Research Institution: National Institute of Infectious Diseases
• Principal Investigator: FUJITA Osamu NATIONAL INSTITUTE OF INFECTIOUS DISEASES, DEPARTMENT OF VETRINARY SCIENCE, RESEARCHER, 獣医科学部, 研究員 (20260276)
• Co-Investigator(Kenkyū-buntansha): NOZAKI Tomoyoshi NATIONAL INSTITUTE OF INFECTIOUS DISEASES, DEPARTMENT OF PARASITOLOGY, LABORATORY CHIEF, 寄生動物部, 室長 (60198588)
• Project Period (FY): 2001 – 2003
• Keywords: ECHINOCOCCUS / MULTILOCULARIS / ANTIOXIDANT / ACTIN BINDING PROTEIN / 2-CYS PEROXIREDOXIN / LOCALIZATION / ANTIGENIC

Research Abstract

Alveolar echinococcosis (AE) is a potentially-fatal zoonotic disease if not diagnosed early enough to provide curative treatment. Therefore, identification and characterization of unique molecules and pathways should help in the development of effective chemotherapeutic measures. We screened an Echinococcus multilocularis (Em) cDNA expression library with a patient serum, and identified 6 novel antigen encoding genes previously not reported. Among them, actin-modulator protein (EmAMP) and peroxiredoxin (EmPrx) was characterized at molecular level in this study. 1)AMP revealed common structural motifs shared by other actin-binding proteins previously reported. An Escherichia coli-expressed recombinant EmAMP showed severing activity toward the polymerized F-actin, verifying its biochemical function. We also evaluated its antigenicity in an enzyme-linked immunosorbent assay (ELISA) using 39 AB patients and 97 patients with other parasitic infections. Results of ELISA showed that EmAMP is one of major immuno-dominant antigens recognized by the AE patient sera. Altogether, we propose that EmAMP from E. multilocularis could be a good target to develop new diagnostics as well as chemotherapeutics against echinococcal infection. 2)Prx possesses two active cysteine residues at amino acids 48 and 169 that are totally conserved among all eukaryotic Prx. Recombinant EmPrx protein protected supercoiled plasmid DNA from nicking by Fenton reaction. Furthermore, EmPrx catalysed degradation of endoperoxides when coupled with an E. coli thioredoxin/ thioredoxin reductase system. We examined the immunolocalization of EmPrx during its development. Polyclonal antibody raised EmPrx bound to the oncosphera and oncoshperal membrane, the surface of protoscolex, and the excretory canal in adults. We propose that EmPrx plays a role in the protection of the parasite from reactive oxygen species generated in host defense responses as an important antioxidant enzyme, and EmPrx also could be a good target to develop new chemotherapeutics.