EFFECT OF ANTIBODIES ON THE CHAIN-LENGTH AND GROWTH OF STREPTOCOCCUS-SOBRINUS

Passive immunization has been suggested as a method to prevent coloniz ation of teeth by mutans streptococci. However, the mechanism of actio n of antibodies, both polyclonal and monoclonal, is not clear. In this study we investigated the effect of polyclonal antibodies (pAbs) and a monoclonal antibody (OMVU10) on the chain length and growth of Strep tococcus sobrinus. During growth in broth S. sobrinus formed significa ntly longer chains in the presence of pAbs in comparison to pre-immune serum (p<0.01), but pAbs did not influence the growth rate of S. sobr inus in broth. OMVU10 did not influence the growth rate nor the chain length. In order to study the effect of the antibodies on adhesion and growth on a surface, S. sobrinus was grown on hydroxyapatite discs in the presence of two other bacteria, Streptococcus oralis and Actinomy ces viscosus. No effect of the antibodies was found on the total culti vable count of the three bacteria after growth on hydroxyapatite discs . However, the morphology of the S. sobrinus microcolonies was differe nt after growth in the presence of both pAbs and OMVU10. The colonies were less dense and chains of S. sobrinus could be seen using a confoc al laser microscope. After growth in the presence of the control antib odies, the colonies were dense and no long chains could be observed. I t was concluded that pAbs influenced the chain length, in broth and on hydroxyapatite discs, and the colony morphology of S. sobrinus on hyd roxyapatite discs, whereas OMVU10 influenced the colony morphology of S. sobrinus on hydroxyapatite discs.