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United States Department of Agriculture

Agricultural Research Service

Research Project: PREVENTION AND CHARACTERIZATION OF PERSISTENT COLONIZATION BY E. COLI O157:H7 AND OTHER SHIGA TOXIN-PRODUCING E. COLI (STEC) IN CATTLE Title: Fluorescence spectroscopy of the retina from scrapie-infected mice

Authors
item Bose, Sayantan -
item Schonenbrucher, Holger -
item Richt, Juergen -
item Casey, Thomas
item Rasmussen, Mark -
item Kehrli Jr, Marcus
item Petrich, Jacob -

Submitted to: Photochemistry and Photobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 21, 2013
Publication Date: July 1, 2013
Citation: Bose, S., Schonenbrucher, H., Richt, J.A., Casey, T., Rasmussen, M.A., Kehrli, Jr., M.E., Petrich, J.W. 2013. Fluorescence spectroscopy of the retina from scrapie-infected mice. Photochemistry and Photobiology. 89(4):864-868. Available: http://dx.doi.org/10.1111/php.12056.

Interpretive Summary: Scrapie is a fatal neurologic disease of sheep and goats, a type of transmissible spongiform encephalopathy (TSE), which is typically diagnosed in affected animals by examination of brain tissue after death. A diagnosis of scrapie results in condemnation of the sheep carcass at slaughter. The diagnostic platforms call for antibodies specific to prion proteins which appear to be the causative agents of TSE. These post-mortem tests are labor-intensive and require hours to days for completion which delays releasing or condemning suspect carcasses. Mice are often used as alternative animals for studying scrapie and other TSE diseases. This study utilizes fluorescence technology to examine retinal tissue of the mouse eye to diagnose scrapie. The retina is an extension of the central nervous system (CNS) and as such reflects certain pathologic changes present in brain tissue which produce characteristic optical signals when examined by fluorescence spectroscopy. The characteristic fluorescent signal is apparently a result of aggregated prions and other proteins in the CNS, including the retina. Retinal tissue from scrapie-affected mice had distinctly different fluorescence patterns from retina of healthy mice. The procedure described could be adapted to real-time examination of food animal eyes at the time of slaughter, greatly reducing the time required for testing carcasses post-slaughter.

Technical Abstract: Recently, we have proposed that the fluorescence spectra of sheep retina can be well correlated to the presence or absence of scrapie. Scrapie is the most widespread TSE (transmissible spongiform encephalopathy) affecting sheep and goats worldwide. Mice eyes have been previously reported as a model system to study age related accumulation of lipofuscin, which has been investigated by monitoring the increasing fluorescence with age covering its entire life-span. The current work aims at developing mice retina as a convenient model system to diagnose scrapie and other fatal TSE diseases in animals such as sheep and cows. The objective of the research reported here was to determine whether the spectral features are conserved among two different species, namely mice and sheep, and whether an appropriate small animal model system could be identified for diagnosis of scrapie based on the fluorescence intensity in retina. The results were consistent with the previous reports on fluorescence studies of healthy and scrapie infected retina of sheep. The fluorescence from the retinas of scrapie-infected sheep was significantly more intense and showed more heterogeneity than that from the retinas of uninfected mice. Although the structural characteristics of fluorescence spectra of scrapie infected sheep and mice eyes are slightly different, more importantly, murine retinas reflect the enhancement of fluorescence intensity upon infecting the mice with scrapie, which is consistent with the observations in sheep eyes.

Last Modified: 9/22/2014
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