title: Identification of secretory immunoglobulin A antibody targets from human milk in cultured cells infected with enteropathogenic Escherichia coli (EPEC).
abstract: Enteropathogenic Escherichia coli (EPEC) uses a type III secretion system (T3SS) to inject effectors into host cells and alter cellular physiology. The aim of the present study was to identify targets of human secretory immunoglobulin A (sIgA) antibodies from the proteins delivered by EPEC into HEp-2 cells after infection. Bacterial proteins delivered into EPEC-infected cells were obtained in sub-cellular fractions (cytoplasmic, membrane, and cytoskeleton) and probed with sIgA antibodies from human milk and analyzed by Western blotting. These sIgA antibodies reacted with Tir and EspB in the cytoplasmic and membrane fractions, and with intimin in the membrane fraction mainly. The sIgA also identified an EPEC surface-associated Heat-shock protein 70 (Hsp70) in HEp-2 cells infected with EPEC. Purified Hsp70 from EPEC was able to bind to HEp-2 cells, suggesting adhesive properties in this protein. EspC secreted to the medium reacted strongly with the sIgA antibodies. An EPEC 115 kDa protein, unrelated to the EspC protein, was detected in the cytoplasm of infected HEp-2 cells, suggesting that this is a new protein translocated by EPEC. The results suggest that there is a strong host antibody response to Tir and intimin, which are essential proteins for attaching and effacing (A/E) pathogen mediated disease.
authors.affiliation: Departamento de Salud Publica, Facultad de Medicina, Universidad Nacional Autónoma de México, D. F. 04510, Mexico.
authors.forename: Sandra
authors.initials: S
authors.lastname: Gavilanes-Parra
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mendoza-Hernández
authors.forename: María E
authors.initials: ME
authors.lastname: Chávez-Berrocal
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Girón
authors.forename: Gabriel
authors.initials: G
authors.lastname: Orozco-Hoyuela
authors.forename: Angel
authors.initials: A
authors.lastname: Manjarrez-Hernández
mesh_terms: D054308:Enteropathogenic Escherichia coli / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000276:immunology*; D056945:Hep G2 Cells; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000276:immunology*; D008895:Milk, Human / Q000276:immunology*; D037521:Virulence Factors / Q000276:immunology
chemical_list: D029968:Escherichia coli Proteins; D007071:Immunoglobulin A, Secretory; D037521:Virulence Factors
keywords: Antigens; EPEC; Enteropathogenic Escherichia coli; Human milk; Secretory IgA antibodies