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United States Department of Agriculture

Agricultural Research Service

Title: Application of Raman Spectroscopy to Analyse the Cryptosporidium Parvum Oocyst Wall and Suture Constituents

Authors
item Jayasundera, Shalini - USDA-ARS
item Schmidt, Walter
item Shelton, Daniel
item Fayer, Ronald
item Adar, Fran - JOBIN YVON HORIBA

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 24, 2006
Publication Date: June 15, 2006
Citation: Jayasundera, S., Schmidt, W.F., Shelton, D.R., Fayer, R., Adar, F. 2006. Application of raman spectroscopy to analyse the cryptosporidium parvum oocyst wall and suture constituents [abstract]. Eastern Analytical Symposium. Somerset, New Jersey, November 13-16, 2006. Abstract #553, p. 58.

Interpretive Summary: A protozoan parasite spread by fecal contamination of livestock, pets, wildlife and humans causes diarrhea in humans and/or other animals. Chlorinated water kills the microbes present in water, except the protozoan that exist as oocysts are not adversely affected by bleach. For the protozoa to be infectious, they have to emerge from the oocyst through a suture opening in the wall of the oocyst. Using Raman spectroscopy and Raman imaging results, the site of the suture opening is assigned to a breaking of S-S- bonds each breakage forming two open H-S-bonds. Simple reduction-oxidation chemistry can explain the mechanism through which the oocyst can be made vulnerable to standard municiple water practices, precluding the case in Minneapolis, MN in which 400,000 people caught the infection.

Technical Abstract: The protozoan parasite Cryptosporidium parvum, associated with diarrheal disease in humans, livestock, companion animals, and wildlife, infects drinking water. Fecal contamination is the ultimate source of the oocyst, found in surface waters throughout the United States. The parasite has so far shown resistance to the many disinfecting chemicals used on bacteria and viruses due to the protective oocyst wall. A suture in the wall opens and the organisms exit the oocyst to initiate infection in the mammal that ingested the oocyst. Identification of the oocyst wall physical and chemical composition can provide a rational basis for designing processes which will reduce or eliminate oocysts from drinking water. In this study we used Raman spectroscopy to identify markers/binding sites on the oocysts wall structure. Our preliminary studies have identified the structural features consistent with amides, amines, aromatics, carbohydrates, ureas and sulfur. A raman image created by mapping the intensities at specific frequencies in an area of a microscopic TV capture of an oocysts layer was used to determine the changes in the localized chemical structure of the oosysts wall. The representative spectra extracted from the map showed changes at different localized positions of the oocysts walls. Our results show that the chemical properties of the oocyst wall are not uniform and that unique features exist in the localized structure. Molecular studies of oocysts walls will provide information on structural and/or conformational changes that will occur and mechanisms by which the walls are weakened when the oocysts opens. This will enable the development of potential chemical treatments to counteract the parasitical effect.

Last Modified: 4/17/2014
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