Effects of lactoferrin and milk on adherence of Streptococcus uberis to bovine mammary epithelial cells.
OBJECTIVE
To determine whether lactoferrin (LF) or milk influenced adherence of Streptococcus uberis to bovine mammary epithelial cells.


METHODS
Three strains of S uberis from cows with mastitis, pooled milk samples from 3 clinically healthy Jersey cows early in the lactation period, and bovine mammary epithelial cells from a clonal cell line.


METHODS
Adherence of S uberis to bovine mammary epithelial cells in the presence of various concentrations of LF or milk and after pretreatment of bacteria with LF or milk was tested. Bacteria were cultured with mammary epithelial cell monolayers for 1 hour. The culture supernatant was removed, and the epithelial cells were lysed. Adherence index was calculated as number of colony-forming units (CFU) in the cell lysate divided by number of CFU in the supernatant times 10,000.


RESULTS
All 3 strains of S uberis were found to bind to purified LF and LF in milk. Addition of LF to the culture medium enhanced adherence of all 3 strains to mammary epithelial cells, whereas addition of milk enhanced adherence of 2 strains and decreased adherence of the third. Pretreatment of bacteria with LF or milk increased adherence of 1 of the strains but decreased adherence of the other 2. Increased adherence was antagonized by rabbit antibovine LF antibody.


CONCLUSIONS
Results suggest that LF may function as a bridging molecule between S uberis and bovine mammary epithelial cells, facilitating adherence of the bacteria to the cells.
Fang
W
W
Department of Animal Science, University of Tennessee, Knoxville 37996, USA.
Almeida
R A
RA
Oliver
S P
SP
D000473:Alkanes / Q000737:chemistry; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle; D015169:Colony Count, Microbial / Q000662:veterinary; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004847:Epithelial Cells / Q000382:microbiology / Q000502:physiology; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D007106:Immune Sera / Q000276:immunology; D007781:Lactoferrin / Q000276:immunology / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000382:microbiology* / Q000502:physiology; D008414:Mastitis, Bovine / Q000382:microbiology; D008892:Milk / Q000382:microbiology / Q000502:physiology*; D011817:Rabbits; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary; D013291:Streptococcus / Q000254:growth & development / Q000502:physiology*; D013499:Surface Properties
D000473:Alkanes; D007106:Immune Sera; D007781:Lactoferrin; C007932:n-hexadecane; D016650:Fluorescein-5-isothiocyanate