A Heparin Purification Process Removes Spiked Transmissible Spongiform Encephalopathy Agent

Area of Science:

• Veterinary Medicine
• Biochemistry
• Public Health

Background:

• Bovine heparin was removed from the US market in 2000 due to concerns about Bovine Spongiform Encephalopathy (BSE).
• Current US heparin supply relies solely on porcine sources, highlighting the need for alternative sources like bovine heparin.
• Ensuring the safety of bovine heparin requires evaluating its manufacturing process for the removal of BSE agents.

Purpose of the Study:

• To assess the efficacy of a standard heparin purification protocol in removing prion surrogates.
• To investigate the potential for reintroducing bovine heparin into the US market safely.
• To identify optimal conditions for prion removal during bovine heparin manufacturing.

Main Methods:

• A four-step bench-scale heparin purification protocol was employed, mimicking industrial processes.
• Hamster 263K scrapie, a surrogate for the BSE agent, was spiked into the process.
• Residual abnormal prion protein (PrP^TSE) was quantified using real-time quaking-induced conversion (RT-QuIC) assays and infectivity was assessed via animal bioassays.

Main Results:

• The purification process demonstrated a reduction in infectivity by 3.6 log₁₀ and removed 3.4 log₁₀ of PrP^TSE seeding activity.
• Sodium hydroxide (NaOH) treatment emerged as the most effective step for prion removal.
• Further optimization of NaOH treatment, particularly at pH 12.5, showed removal of up to 5.2 log₁₀ of PrP^TSE seeding activity.

Conclusions:

• A basic heparin manufacturing process can significantly reduce prion contamination.
• Alkaline treatment conditions, including concentration, duration, and temperature, can be optimized for enhanced prion removal.
• These findings support the potential for the safe reintroduction of bovine heparin in the USA.