ADHERENCE OF STREPTOCOCCUS-UBERIS TO BOVINE MAMMARY EPITHELIAL-CELLS AND TO EXTRACELLULAR-MATRIX PROTEINS

Adherence of an encapsulated (UT 101) and a non-encapsulated (UT 102) strain of Streptococcus uberis to a bovine mammary epithelial cell lin e (MAC-T) and to extracellular matrix proteins (ECMP) including fibron ectin, collagen and laminin was investigated. S. uberis was co-culture d at 4 degrees C with MAC-T cell monolayers. Both strains of S. uberis adhered to MAC-T cells. However, the nonencapsulated strain of S. ube ris adhered better to MAC-T cells than the encapsulated strain. Preinc ubation of MAC-T cells with lipoteichoic acid (LTA) and/or treatment o f S. uberis with antibodies directed against the carboxyl-terminal hal f of type 24 M protein reduced adherence of both strains of S. uberis to MAC-T cells. Adherence to ECMP was measured by incubating bis-carbo xyethyl-carboxyfluorescein acetomethyl ester (BCECF-AM) labelled S. ub eris in 96-well plates coated with fibronectin, collagen or laminin. B oth strains adhered to ECMP, however, the encapsulated strain adhered better to ECMP than the non-encapsulated strain. Results of this inves tigation demonstrated that both strains of S. uberis evaluated were ca pable of adhering to bovine mammary epithelial cells and to ECMP. Adhe rence of S. uberis to mammary epithelium may be an extremely important mechanism in the establishment and progression of bovine intramammary infections.