F4ac-fimbrial-binding proteins in porcine milk and the absorption of colostral proteins by piglets
Date
2008
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
F4 positive enterotoxigenic Escherichia coli (ETEC) is the most common pathogen causing neonatal diarrhea in piglets. The pathogenesis requires the attachment of ETEC to the intestinal brush border, mediated by F4 fimbria. Colostral anti-F4 antibodies and some non-immunoglobulin porcine skim milk proteins can bind F4 and prevent colonization and infection by F4-positive ETEC. Little is known, however, about the F4-binding ability of porcine milk fat globule membrane (MFGM) proteins. In addition, the knowledge of the absorption of porcine colostral proteins into the blood of neonatal piglets is limited, despite the well accepted concept that in neonatal piglets, protein absorption from the intestine is non-selective.
In this study, the ability of porcine MFGM proteins to bind purified F4ac (one of the three subtypes of F4 fimbriae) was investigated. Porcine MFGM proteins were first separated by 2D SDS-PAGE and subsequently identified by mass spectrometry. Overlay western Blot was then employed to demonstrate the interaction between porcine MFGM proteins and purified F4ac. Several proteins from porcine MFGM reacted with F4ac, and of these, lactadherin, butyrophilin, adipophilin, and acyl-CoA synthetase 3 reacted strongly. The biological function of these proteins in vivo was not investigated but it is possible that their interaction with F4ac positive ETEC interferes with bacterial attachment and colonization.
In order to investigate protein absorption by neonatal piglets after natural suckling, the protein profiles of the plasma of pre-suckling and 24 h post-suckling neonatal piglets were studied by 2D SDS-PAGE. Those plasma proteins that increased prominently after suckling were then identified by mass spectrometry. Only immunoglobulins were unequivocally determined to be absorbed, because they were absent before suckling and present in large quantity in plasma 24 h after suckling. The absorption of other colostral proteins was either equivocal or not detectable by our detection methods. These results suggest that, unlike immunoglobulins, major non-immunoglobulin proteins in porcine colostrum may not be absorbed into systemic circulation in substantial amounts.
Description
Keywords
protein absorption, fimbrial-binding proteins, F4 fimbria, Enterotoxigenic Escherichia coli, porcine milk, milk fat globule membrane
Citation
Degree
Master of Science (M.Sc.)
Department
Veterinary Pathology
Program
Veterinary Pathology