Quantitative Assessment of Prion Infectivity in Tissues and Body Fluids by RT-QuIC. J Gen Virol. 2014 Oct 10. pii: vir.0.069906-0. doi: 10.1099/vir.0.069906-0. [Epub ahead of print] ncbi.nlm.nih.gov/pubmed/25304654 Henderson DM1, Davenport KA1, Haley NJ2, Denkers ND1, Mathiason CK1, Hoover EA Jr3. Author information Abstract Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving the templated conversion of the normal cellular prion protein (PrPC) to a pathogenic misfolded conformation. Templated conversion has been modeled in several in vitro assays, including serial protein misfolding amplification (sPMCA), amyloid seeding, and real time quaking induced conversion (RT-QuIC). Because RT-QuIC measures formation of amyloid fibrils in real time, it can be used to estimate the rate of seeded conversion. Here we use samples from deer infected with chronic wasting disease (CWD) in RT-QuIC to show that serial dilution of prion seed is linearly related to the rate of amyloid formation over a range of 10-3 to 10-8 µg. We then used an amyloid formation rate standard curve derived from a bioassayed reference sample (CWD+ brain homogenate) to estimate the prion seed concentration and infectivity in tissues, body fluids and excreta. Using these methods we estimate that urine and saliva from CWD-infected deer contain between 1 and 5 LD50 per 10 ml, respectively. Thus, over the 1 to 2 year course of infection, a substantial environmental reservoir of CWD prion contamination accumulates.
Posted on: Mon, 13 Oct 2014 04:49:06 +0000
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