Mass spectrometry-based study of chronic wasting disease (CWD) prions from experimentally infected elk

Authors: Silva, Christopher; Erickson-Beltran, Melissa; CASSMANN, ERIC - Iowa State University; Greenlee, Justin

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/28/2025
Publication Date: 8/20/2025
Citation: Silva, C.J., Erickson-Beltran, M.L., Cassmann, E.D., Greenlee, J.J. 2025. Mass spectrometry-based study of chronic wasting disease (CWD) prions from experimentally infected elk. American Chemical Society Abstracts. ACS Fall 2025/Abstract #4316725. https://doi.org/10.1021/scimeetings.5c11362.
DOI: https://doi.org/10.1021/scimeetings.5c11362

Interpretive Summary:

Technical Abstract: Wild and farmed elk are susceptible to chronic wasting disease (CWD), a cervid prion disease. Prions are molecular pathogens that propagate their pathology by inducing a natively expressed prion protein (PrPC) to adopt the prion conformation. A mass spectrometry-based analysis of the prions isolated from elk with methionine (M) or leucine (L) at position 132 (MM132, ML132, or LL132) that were experimentally infected with a common inoculum was conducted. Tryptic and chymotryptic digestion conditions were optimized to yield a set of peptides (TNMK, MLGSAMSRPL, LLGSAMSRPL, ENMYR, MMER, and VVEQMCITQYQR) that was suitable for a multiple reaction monitoring (MRM) method. These peptides were used to measure the extent of methionine oxidation, to determine the proportion of M and L in the prions from heterozygous elk (ML132), and to quantitate the prions in each sample. Brain tissue from MM132 animals contained the greatest amount of prions (5.4 × 102 ± 7 × 101 ng/g). ML132 animals contained ~ 35 % less (3.3 × 102 ± 6 × 101 or 3.6 × 102 ± 3 × 101 ng/g) even though they incubated the disease for a longer time. LL132 animals contained ~ 90 % less prions (0.7 × 102 ± 1 × 101, 0.2 × 102 ± 0.2 × 101, or 0.2 × 102 ± 0.5 × 101 ng/g), even though the animals incubated prions the longest of the three sets of animals. Even though the incubation period for ML132 animals is longer than that of MM132, the L132 polymorphism is a lesser component (43% ± 2% or 36% ± 3%) of the mixture. This set of peptides permits a quantification of the extent of methionine oxidation for all of the methionines in the samples. Thus, mass spectrometry can be used to characterize these molecular pathogens at a molecular level.