Prolongation of scrapie incubation period by an injection of dextran sulphate 500 within the month before or after infection.
A single intraperitoneal injection of 250 micrograms dextran sulphate 500 (DS500) reduced the susceptibility of mice to scrapie given by the same route. A lower dose (25 micrograms) was less effective but still produced significant incubation period lengthening, while a high dose (2.5 mg) further increased the degree of prolongation. This reduced susceptibility occurred with DS500 administered up to at least 4 weeks prior to intraperitoneal scrapie inoculation and up to at least 2 weeks after scrapie inoculation. A reduced average effect, but more variable between mice, was obtained with DS500 given 1 month or 2 months after scrapie. The effective scrapie titre was reduced by 90% when DS500 was injected either 72 h before or 7 h after ME7 scrapie. Using a relatively lower but normally still fatal dose of the 22A strain of scrapie approximately 50% of the treated mice survived. The effective 90% loss of titre was consistent with either of these strains of scrapie in 11 different inbred strains of mice (BALB/c, BSC, BRVR, C3H, C57BL, IM, LM, MM, RIII, VL and VM). No significant increase in the prolongation effect was obtained using multiple DS500 doses in two different time combinations. DS500 causes long-term interference in both the early processing and the replication of scrapie agent, unlike those immunomodulators which increase susceptibility.
C F
CF
Farquhar
A G
AG
Dickinson
D000818:Animals; D016264:Dextran Sulfate; D003911:Dextrans / Q000008:administration & dosage* / Q000276:immunology; D051379:Mice; D010529:Peritoneal Cavity / Q000166:cytology; D010835:Phytohemagglutinins / Q000494:pharmacology; D011328:Prions / Q000276:immunology / Q000472:pathogenicity*; D012608:Scrapie / Q000209:etiology*; D013997:Time Factors
D003911:Dextrans; D010835:Phytohemagglutinins; D011328:Prions; D016264:Dextran Sulfate