IMPACT OF M49, MRP, ENN, AND C5A PEPTIDASE PROTEINS ON COLONIZATION OF THE MOUSE ORAL MUCOSE BY STREPTOCOCCUS-PYOGENES

Resistance to phagocytosis is a hallmark of virulent Streptococcus pyo genes (group A streptococcus), Surface bound C5a peptidase reduces rec ruitment of phagocytes to the site of infection, and hyaluronic acid c apsules and/or the M protein limit the uptake of streptococci, In this study the relative impact of M and M-like proteins and the C5a peptid ase on the virulence of a serotype M49 strain was assessed. The capaci ties of isogenic strains with an insertion mutation in emm49; with a d eletion mutation in scpA49 (C5a peptidase gene); and,vith a deletion t hat removes all three M-like genes, mrp49, emm49, and enn49, to coloni ze mice and resist phagocytosis were compared. Experiments confirmed r esults obtained in an earlier study, which showed that the M49 protein was not required for in vitro resistance to phagocytosis, and also sh owed that the M protein was not required for colonization of mice. Fai lure to produce all three M-like proteins, M49, Mrp, and Enn49, signif icantly reduced the ability of these streptococci to resist phagocytos is in vitro but did not significantly alter the persistence of strepto cocci on the oral mucosa, In vitro experiments indicate that M+ strept ococci are phagocytized by polymorphonuclear leukocytes that have been activated with phorbol-12-myristate 13-acetate or recombinant human C 5a, This observation may explain the finding that expression of M49 pr otein is not essential for short-term colonization of the mouse oral m ucosa.