Author
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HARP, JAMES |
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Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/29/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Cryptosporidium parvum is an intestinal parasite that causes diarrhea in young calves, and is a major cause of economic loss to producers. Cryptosporidium is also a significant contaminant of water supplies, and has caused large outbreaks of human disease. We are studying means of controlling Cryptosporidium infection in calves to reduce both economic losses and potential contamination of the environment. We have performed studies in mice and rats to develop a better understanding of the way Cryptosporidium infects the intestinal lining of young animals. We determined that giving some forms of sugar to infant mice drastically reduces infection with the parasite. This discovery will help us to understand the ways in which young animals, such as newborn calves, become resistant to infection with Cryptosporidium. This knowledge will help us develop vaccines and treatments to prevent disease in calves. This will benefit dairy and beef producers, as well as American consumers by reducing the cost of raising beef and dairy calves. Technical Abstract: Cryptosporidium parvum is a significant cause of diarrheal disease in humans and economically important livestock species, especially young ruminants. There is no effective treatment available for this protozoan parasite. Mechanisms of intestinal colonization by C. parvum are not well understood, but it has been suggested that the parasite may utilize a lectin-like receptor. We used an infant mouse model to test whether high sugar concentrations in the intestine would affect in vivo colonization with C. parvum. We found that sucrose, administered orally to mice at the time of challenge with C. parvum, significantly reduced infection. Significant reduction of infection was also seen in mice given isomaltose. Preincubation of oocysts with sucrose prior to oral challenge of mice had no effect on infectivity of oocysts; thus sucrose was not directly toxic to the parasite. Histologic examination of intestinal sections of mice treated with sucrose or isomaltose, but not other sugars, showed marked vacuolation of small intestinal epithelium 1 day after treatment. Three days after treatment, tissue appeared normal. Cryptosporidium parvum infection was accompanied by changes in expression of intestinal disaccharidases (sucrase and lactase) which are partially reversed by sugar treatment. Thus sucrose, and to a lesser extent isomaltose, reduced in vivo colonization with C. parvum, and altered epithelial cell morphology and expression of disaccharidases in intestines of infected mice. |
