Adherence and internalization of Streptococcus uberis to bovine mammary epithelial cells are mediated by host cell proteoglycans

The role of cell glycosaminoglycans (GAC) on adherence and internalization of Streptococcus uberis to bovine mammary epithelial cells was evaluated by adherence/internalization competition assays, by removal of GAG from the h ost cell surface and by inhibition of GAG glycosylation in the host cell. H eparin (HEP), heparan sulfate (HSA), chondroitin sulfate A (CSA) and chondr oitin sulfate B (CSB) inhibited adherence and internalization of S. uberis in a dose-dependent manner. However, inhibition was lower with CSA and CSB than that observed with HEP and HSA. Adherence and internalization were als o inhibited upon treatment of mammary epithelial cells with GAG lyases. The greatest inhibition was observed with heparinase I. Tunicamycin, an inhibi tor of mammalian cell glycosylation of cell surface glycoproteins, markedly inhibited internalization of S. uberis into mammary epithelial cells. Diff erences between strains were observed. These results suggest that a HSA pro teoglycan receptor on the host cell surface may mediate S. uberis adherence to and internalization of bovine mammary epithelial cells. (C) 1999 Publis hed by Elsevier Science B.V. All rights reserved.