Real-Time Quaking-Induced Conversion Detection of Bovine Spongiform Encephalopathy Prions in a Subclinical Steer.

Soyoun Hwang,Justin J Greenlee,M Heather West Greenlee,Eric M Nicholson,Martin H Groschup,Anne Balkema-Buschmann

doi:10.3389/fvets.2017.00242

Abstract

Bovine spongiform encephalopathy (BSE) belongs to a group of fatal prion diseases that result from the misfolding of the cellular prion protein (PrPC) into a pathogenic form (PrPSc) that accumulates in the brain. In vitro assays such as serial protein misfolding amplification and real-time quaking-induced conversion (RT-QuIC) allow assessment of the conversion of PrPC to PrPSc. RT-QuIC can be used for the detection of prions in a variety of biological tissues from humans and animals. However, there is no such comparison of RT-QuIC data between BSE positive and presymptomatic cattle. Further, the current study assesses prion distribution in multiple brain regions of clinically ill or subclinical animals. Here, we compare RT-QuIC reactions seeded with brain samples collected from experimentally inoculated cattle that were clinically ill or subclinically affected with BSE. The results demonstrate RT-QuIC seeding in various brain regions of an animal with subclinical BSE despite being determined negative by immunohistochemistry. Bioassay of the subclinical animal and RT-QuIC of brainstem from inoculated knockout (PRNP−/−) cattle were used to confirm infectivity in the subclinical animal and determine that RT-QuIC reactions were not the result of residual inoculum, respectively. These results confirm that RT-QuIC is a highly sensitive prion detection assay that can detect prions in a steer prior to the onset of clinical signs of BSE.

Highlights

Bovine spongiform encephalopathy (BSE) belongs to a group of fatal neurologic diseases that result from the misfolding of the cellular prion protein (PrPC) into a pathogenic form (PrPSc) in the brain [1,2,3]
In the cattle clinically affected with BSE, PrPSc immunoreactivity was detected in all brain regions examined and corresponded with spongiform change
An animal inoculated with classical BSE (No 1) did not develop clinical illness and tested negative by standard diagnostics performed on brainstem despite a prolonged observation period of 31 months

Summary

Introduction

Bovine spongiform encephalopathy (BSE) belongs to a group of fatal neurologic diseases that result from the misfolding of the cellular prion protein (PrPC) into a pathogenic form (PrPSc) in the brain [1,2,3]. New prion detection tools relying on the in vitro amplification of PrPSc have been developed and include protein misfolding cyclic amplification (PMCA) [8,9,10] and the real-time quakinginduced conversion (RT-QuIC) assay [11,12,13,14,15,16,17,18]. Both of these approaches can amplify very low levels of PrPSc to levels that are readily detectable. The RT-QuIC assay has been shown to detect low levels of TSE infectivity and to detect human and animal prions in various tissues [11,12,13,14,15,16,17,18]

Methods

Results

Conclusion