Surface fibrils (fimbriae) of Actinomyces viscosus T14V.

Surface antigens of Actinomyces viscosus T14V were released from cell walls by digestion with lysozyme. These were separated by ion-exchange and gel filtration chromatography into fractions rich in carbohydrate or protein. The former contained a polysaccharide high in 6-deoxytalose, along with a peptide fragment from the cell wall. In the protein-rich fractions, material of high molecular weight was present, which contained some carbohydrate and up to 14.3% nitrogen. Aspartic acid, threonine, glutamic acid, lysine, alanine, and glycine were detected in these fractions, along with smaller amounts of 10 other amino acids. Most of the alanine was present as the L isomer and thus was not from peptidoglycan. Electron microscopy of the high-molecular-weight material revealed long fibrils, 3.5 to 4.5 nm in diameter, which resembled those seen on bacterial cells. V-specific antiserum, prepared by absorbing anti-A. viscosus T14V serum with cell walls of the avirulent strain (A. viscosus T14AV), did not react with the 6-deoxytalose polysaccharide but reacted well with isolated fibrils, and this was not inhibited by 6-deoxytalose.