Identification of Escherichia coli F4ac-binding proteins in porcine milk fat globule membrane.

F4ac-positive enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal mucosa to cause diarrhea in piglets. Prevention of bacterial attachment to the intestinal mucosa is the most effective defense against ETEC-induced diarrhea. Porcine milk fat globule membranes (MFGM) were shown to be able to inhibit attachment of ETEC to the intestinal brush border; however, the specific components of porcine MFGM that inhibited attachment of ETEC to enterocytes were not identified. Accordingly, the purpose of this study was to identify F4ac-binding MFGM proteins by overlay Western blot and affinity chromatography. The proteome of porcine MFGM was characterized and the following F4ac-binding proteins were detected by overlay Western blot and affinity chromatography: lactadherin, butyrophilin, adipophilin, acyl-CoA synthetase 3, and fatty acid-binding protein 3. The biological function of these proteins was not investigated but it is possible that their interaction with F4ac fimbria interferes with bacterial attachment and colonization.

Les Escherichia coli entérotoxinogénique (ETEC) positif pour F4ac doivent s'attacher à la muqueuse intestinale pour causer la diarrhée chez les porcelets. L'empêchement de l'attachement bactérien à la muqueuse intestinale est le moyen de défense le plus efficace contre la diarrhée induite par les ETEC. Les membranes de globules de gras de lait porcin (MFGM) ont été montré comme étant capable d'inhiber l'attachement des ETEC à la bordure en brosse intestinale; toutefois, les composantes spécifiques des MFGM porcines qui inhibaient l'attachement des ETEC aux entérocytes ne furent pas identifiées. Ainsi, le but de la présente étude était d'identifier les protéines des MFGM liant F4ac par immunobuvardage par superposition et chromatographie d'affinité. Le protéome des MFGM porcine fut caractérisé et les protéines liant F4as suivantes furent détectées par immunobuvardage par superposition et chromatographie d'affinité : lactadhérine, butyrophiline, adipophiline, acyl-CoA synthétase 3, et la protéine 3 liant les acides gras. La fonction biologique de ces protéines ne fut pas étudiée mais il est possible que leur interaction avec les fimbriae F4ac interfère avec l'attachement bactérien et la colonisation.(Traduit par Docteur Serge Messier).

Thymic epithelial tumor with heart metastasis in a horse.

Thymic malignancy is rare in horses. Thymic epithelial tumor was diagnosed in an 18-year-old mare with invasion and metastasis to the pericardium and heart. At necropsy, the cranial thoracic cavity was obliterated by a large mass located in the thymic region and the right atrium was also expanded and effaced by a similar mass. Histologically, the neoplasm was composed of sheets of spindle cells with intraparenchymal Hassall's corpuscles and formation of pseudorosettes around blood vessels compatible with type A thymic epithelial tumor according to World Health Organization classification. The neoplastic cells were diffusely immunoreactive for cytokeratin and negative for vimentin, S100, neuron specific enolase, glial fibrillar acidic protein, chromogranin A, synaptophysin, CD3 and CD79a markers. To the authors' knowledge, cardiac invasion and distinct histological pattern of pseudorosette formation have not been described in equine thymic epithelial tumors previously.

Hepatic lobe torsion in a horse.

A 4-year-old Belgian mare was presented with a 1-week history of fever, suspected of being caused by peritonitis. The mare died before the diagnostic procedures had been completed; postmortem examination revealed torsion of the left medial lobe of the liver, resulting in diffuse necrosis of liver tissue and severe peritoneal effusion.

Identification of lipopolysaccharide-binding proteins in porcine milk.

Septicemia and endotoxemia initiated by bacterial lipopolysaccharide (LPS) are relatively common in suckling and weaned piglets. Maternal milk is a source of both nutrition and immune protection for piglets. Passive transfer of colostral antibodies is necessary for protection of neonatal piglets against diseases, but the concentration of immunoglobulins in milk rapidly declines during the 1st wk of lactation in all mammals. We hypothesized, therefore, that nonimmunoglobulin substances in milk contribute to the innate protection of neonates against septicemia during the suckling period. Using LPS-affinity chromatography for isolation of LPS-binding proteins and liquid chromatography-mass spectrometry for their identification, we identified in porcine milk the following proteins with LPS-binding capacity: lactoferrin, soluble CD14, serum amyloid A, alpha-S1 casein, beta-casein, and kappa-casein. For lactoferrin, alpha-S1 casein, and kappa-casein, in vitro pepsin digestion did not inhibit LPS-binding activity, whereas combined digestion with pepsin and pancreatin abolished it. The biologic functions of these LPS-binding proteins and peptides were not determined.

Identification by mass spectroscopy of F4ac-fimbrial-binding proteins in porcine milk and characterization of lactadherin as an inhibitor of F4ac-positive Escherichia coli attachment to intestinal villi in vitro.

Enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal surface to cause diarrhea. Milk and colostrum play an important role in protecting suckling piglets against ETEC through their constituent antibodies as well as non-immunoglobulin factors. We used affinity chromatography and liquid chromatography-mass spectrometry to identify lactadherin, beta-casein, whey acidic protein, lipoprotein lipase, and several structural cellular proteins as non-immunoglobulin F4ac fimbriae-binding porcine milk proteins. To determine their potential biological relevance in a digestive environment, we treated porcine milk with pepsin or pepsin-pancreating in vitro, and found that pepsin digestion did not interfere with the F4-binding capacity of lactadherin as well as it revealed a cryptic F4-binding site(s) in alpha-S(1) casein and heart fatty acid binding protein. We also demonstrated that lactadherin interfered with attachment of F4ac-positive ETEC to porcine small intestinal villi in vitro and that this interference was carbohydrate dependent. Thus, our evidence suggests that lactadherin and the other F4-binding milk proteins, together with other defense components of milk, could play a role in protection of neonatal piglets against ETEC induced diarrhea.

Coinfection with bovine viral diarrhea virus and Mycoplasma bovis in feedlot cattle with chronic pneumonia.

Chronic, antibiotic-resistant pneumonia, sometimes with concurrent polyarthritis, occurs in feedlot cattle in western Canada. The prevalence of Mycoplasma bovis, bovine viral diarrhea virus, and Haemophilus somnus was determined by using immunohistochemical staining of lung and heart tissue from 2 groups of animals with this history. Mycoplasma bovis antigen was present in 44/48 cases submitted between 1995 and 1998 (retrospective group) and 15/16 of cases from 1999 (prospective group), and was associated with pulmonary necrosis. Bovine viral diarrhea virus antigen was present in association with microscopic vascular lesions in 31/48 retrospective and 9/16 of prospective cases. Types Ib and II bovine viral diarrhea virus were isolated from 4/16 prospective cases. Haemophilus somnus antigen was present in heart, lung, or both of 15/48 retrospective and 8/16 prospective cases. The results suggest that there may be synergism between bovine viral diarrhea virus and M. bovis in this pneumonia with arthritis syndrome.