title: Anti-prion activity of protein-bound polysaccharide K in prion-infected cells and animals.
abstract: Protein-bound polysaccharide K (PSK) is a clinical immunotherapeutic agent that exhibits various biological activities, including anti-tumor and anti-microbial effects. In the present study, we report on the anti-prion activity of PSK. It inhibited the formation of protease-resistant abnormal prion protein in prion-infected cells without any apparent alterations in either the normal prion protein turnover or the autophagic function in the cells. Its anti-prion activity was predominantly composed of the high molecular weight component(s) of the protein portion of PSK. A single subcutaneous dose of PSK slightly but significantly prolonged the survival time of peritoneally prion-infected mice, but PSK-treated mice produced neutralizing antibodies against the anti-prion activity of PSK. These findings suggest that PSK is a new anti-prion substance that may be useful in elucidating the mechanism of prion replication, although the structure of the anti-prion component(s) of PSK requires further evaluation.
authors.affiliation: Department of Neurochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Hamanaka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sakasegawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohmoto
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Takao
authors.initials: T
authors.lastname: Ando
authors.forename: Katsumi
authors.initials: K
authors.lastname: Doh-ura
mesh_terms: D000818:Animals; D001343:Autophagy; D045744:Cell Line, Tumor; D005656:Fungal Proteins / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D007167:Immunotherapy; D051379:Mice; D008815:Mice, Inbred Strains; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D018621:PrPC Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017096:Prion Diseases / Q000188:drug therapy*
chemical_list: D005656:Fungal Proteins; D011134:Polysaccharides; D018621:PrPC Proteins; C494124:protein-bound polysaccharide K, Basidiomycetes