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Microbial adhesion of Cryptosporidium parvum: identification of a colostrum-derived inhibitory lipid
Joann Schmidt1, Mark S Kuhlenschmidt
1Department of Pathobiology, College of Veterinary Medicine, University of Illinois; Urbana, IL 61802, USA.
Abstract:
We previously described an unidentified lipid purified from calf small intestine that inhibits the in vitro adhesion of Cryptosporidium parvum sporozoites to host cells [Johnson JK, Schmidt J, Gelberg HB, Kuhlenschmidt MS. Microbial adhesion of Cryptosporidium parvum sporozoites: purification of an inhibitory lipid from bovine mucosa. J Parasitol 2004;90:980-90]. Intestinal mucosa from some calves, however, failed to yield this bioactive lipid. Accordingly, we examined other potential sources, especially dietary sources, of the inhibitory lipid and discovered it was principally derived from bovine colostrum. Interestingly, fresh colostrum yielded little or no inhibitory lipid, however, the lipid was found in relatively large quantities following incubation of colostrum with the aqueous fraction of calf intestinal contents. Using FAB-MS and NMR analysis, the sporozoite inhibitory lipid (SIL) was identified as oleic acid, a monounsaturated fatty acid likely released from colostrum triglycerides and phospholipids by digestion in the lumen of the calf small intestine. Oleic acid dose-dependently inhibited in vitro sporozoite-host cell adhesion with an inhibitory constant (IC(50)) of approximately 5 microM. Comparison of oleic acid with other C-18 fatty acids revealed linolenic, but not stearic acid, also displayed potent inhibitory activity. Neither linolenic nor oleic acid, however, affect either sporozoite or host cell viability at concentrations that inhibit sporozoite adhesion. These results suggest certain colostrum-derived long-chain fatty acids may serve as natural inhibitors of the early steps in C. parvum sporozoite-host cell interactions.
Insights
Oleic acid from bovine colostrum inhibits Cryptosporidium parvum sporozoite adhesion to host cells. This fatty acid, identified as the sporozoite inhibitory lipid (SIL), offers a potential natural strategy against parasite infection.
Area of Science:
- Parasitology
- Biochemistry
- Microbiology
Background:
- An unidentified lipid from calf small intestine previously inhibited Cryptosporidium parvum sporozoite adhesion.
- Some calves lacked this bioactive lipid in their intestinal mucosa, necessitating a search for alternative sources.
Purpose of the Study:
- To identify the source and structure of the lipid inhibiting Cryptosporidium parvum sporozoite adhesion.
- To investigate the potential of dietary sources, particularly bovine colostrum, for this inhibitory lipid.
Main Methods:
- Lipid analysis using Fast Atom Bombardment Mass Spectrometry (FAB-MS) and Nuclear Magnetic Resonance (NMR).
- In vitro assays to measure inhibition of sporozoite-host cell adhesion.
- Testing of various C-18 fatty acids for inhibitory activity and assessment of host/sporozoite viability.
Main Results:
- The sporozoite inhibitory lipid (SIL) was identified as oleic acid, a monounsaturated fatty acid.
- Oleic acid, derived from colostrum triglycerides and phospholipids, dose-dependently inhibited sporozoite adhesion with an IC(50) of approximately 5 microM.
- Linolenic acid also showed inhibitory activity, while stearic acid did not. Neither oleic nor linolenic acid affected cell viability at inhibitory concentrations.
Conclusions:
- Bovine colostrum is a primary source of the inhibitory lipid, oleic acid.
- Oleic acid and potentially other long-chain fatty acids from colostrum can naturally inhibit early-stage Cryptosporidium parvum infection by preventing sporozoite adhesion.
- These findings suggest a dietary-based approach to controlling Cryptosporidium parvum infections.
