title: Characterization of chicken egg yolk immunoglobulins (IgYs) specific for the most prevalent capsular serotypes of mastitis-causing Staphylococcus aureus.
abstract: The objective of this in vitro study was to evaluate the potential of egg yolk immunoglobulins (IgYs) for treating mastitis caused by Staphylococcus aureus. Specific IgY against type 5 (IgY-T5), type 8 (IgY-T8) and type 336 (IgY-T336) S. aureus strains were obtained by immunizing hens with whole cell vaccines and the IgY produced were then purified to around 80% purity using a water dilution method coupled with salting out and ultra-filtration. Enzyme-linked immunosorbent assay indicated that the IgY specifically targeted the three homologous strains. A growth inhibition assay was performed in Columbia broth (non-encapsulated form) and phosphate-buffered saline (encapsulated form) for an 8h incubation. The results showed that IgY-T336 significantly inhibited (but only 1.5 log units; P<0.01) the growth of all three strains at 15 mg/ml in the Columbia broth. In contrast, the same concentrations of IgY-T5 and IgY-T8 did not show obvious bacteriostatic activity against the two homologous strains. In phosphate buffered saline, no inhibition of the two encapsulated strains was observed with IgY-T5, IgY-T8 and IgY-T336. However, IgY-T336 reduced live bacteria by 1.0 log unit against strain 336 compared with the control. An internalization test indicated that all of the specific IgY (at 5mg/ml) significantly (about 3.0 log units of the control; P<0.01) blocked the internalization of their homologous strains by bovine mammary epithelial cells (MAC-T cells) within 6h. These results suggested that research on the application of IgY as a treatment for mastitis caused by S. aureus should be focused on the internalization inhibition activity rather than on the growth inhibition activity of the IgY.
authors.affiliation: Department of Bioscience and Biotechnology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Lin-Hui
authors.initials: LH
authors.lastname: Wang
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Li
authors.forename: Li-Ji
authors.initials: LJ
authors.lastname: Jin
authors.forename: Jian-Song
authors.initials: JS
authors.lastname: You
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhou
authors.forename: Shu-Ying
authors.initials: SY
authors.lastname: Li
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Xu
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D000918:Antibody Specificity; D002417:Cattle; D002460:Cell Line; D002645:Chickens / Q000276:immunology; D004530:Egg Yolk / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007136:Immunoglobulins / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D008414:Mastitis, Bovine / Q000276:immunology / Q000382:microbiology; D015995:Prevalence; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary; D013211:Staphylococcus aureus / Q000187:drug effects / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; C016512:IgY; D007136:Immunoglobulins