Monoclonal antibodies evoked by the free oligopeptide (Gly)5 reacting specifically with peptidoglycan from staphylococci

Characterization of a monoclonal antibody that binds to an epitope on soluble bacterial peptidoglycan fragments

We employed an inhibition-type enzyme-linked immunosorbent assay (ELISA) to characterize a murine immunoglobulin M monoclonal antibody (MAb) that bound soluble macromolecular peptidoglycan (PG). With this ELISA, the MAb was capable of detecting soluble PG concentrations of less than 10 ng/ml. Enzymatic digestion of PG reduced binding by more than 100-fold, implying that the epitope recognized by this antibody depended on repeating subunits within the glycan backbone. Additionally, the MAb bound to epitopes on both O-acetylated and non-O-acetylated PG fragments from gram-negative bacteria, as well as PG fragments from Staphylococcus aureus and PG fragments released into the medium by a number of gram-positive and gram-negative bacteria.

Staphylococcus aureus exopolysaccharide in vivo demonstrated by immunomagnetic separation and electron microscopy

Staphylococcus aureus strains were separated from mastitis milk samples without cultivation by using monodisperse magnetic polymer particles coated with polyclonal antiserum against an encapsulated S. aureus strain. Exopolysaccharide was verified by transmission electron microscopy and the serum soft-agar culture technique. Capsular polysaccharide was found on virtually all clinical isolates. Surface protein A and S. aureus-specific cell wall components were masked when the strains were cultured on an exopolysaccharide-promoting medium. Masking of surface determinants was dependent on their concentration on the bacterial surface as well as on exopolysaccharide abundance. The polysaccharide layer on in vivo bacteria was reduced markedly after just one transfer from milk to blood agar plates but was reexpressed after culturing was done on a capsule-generating medium.