PASSIVE PROTECTION OF MICE AGAINST GROUP-A STREPTOCOCCAL PHARYNGEAL INFECTION BY LIPOTEICHOIC ACID

Previous studies have shown that lipoteichoic acid (LTA) of group A st reptococci plays a central role in the adherence of these organisms to epithelial cells. In this study, intranasal instillation of purified LTA but not deacylated LTA in mice blocked colonization and prevented death after intranasal challenge infection with group A streptococci. Bacteria pretreated with rabbit antisera against LTA also failed to co lonize or infect mice after intranasal challenge. In vitro studies sho wed that LTA and M protein inhibited adherence of type 24 streptococci to mouse pharyngeal cells. Passive intranasal administration of purif ied type 24 M protein protected mice from death after challenge infect ion with type 24 streptococci but had no significant effect on pharyng eal colonization. Surface LTA and M protein may mediate adherence of s treptococci to mouse pharyngeal cells, and blocking adherence with LTA prevents colonization and infection in this animal model.