The R28 protein of Streptococcus pyogenes is related to several group B streptococcal surface proteins, confers protective immunity and promotes binding to human epithelial cells.
The R28 protein is a surface molecule expressed by some strains of Streptococcus pyogenes (group A streptococcus). Here, we present evidence that R28 may play an important role in virulence. Sequence analysis demonstrated that R28 has an extremely repetitive sequence and can be viewed as a chimera derived from the three surface proteins Rib, alpha and beta of the group B streptococcus (GBS). Thus, the gene encoding R28 may have originated in GBS. The R28 protein promotes adhesion to human epithelial cells, as shown by experiments with an R28-negative mutant and by the demonstration that antibodies to highly purified R28 inhibited adhesion. In a mouse model of lethal intraperitoneal S. pyogenes infection, antibodies to R28 conferred protective immunity. However, the virulence of an R28-negative mutant was similar to that of the parental strain in the intraperitoneal infection model. Together, these data indicate that R28 represents a novel type of adhesin expressed by S. pyogenes and that R28 may also act as a target for protective antibodies at later stages of an infection. We consider the hypothesis that R28 played a pathogenetic role in the well-known epidemics of childbed fever (puerperal fever), which were caused by S. pyogenes. A role for R28 in these epidemics is suggested by epidemiological data.
Stålhammar-Carlemalm
M
M
Department of Laboratory Medicine, Lund University, Sölvegatan 23, 22362 Lund, Sweden.
Areschoug
T
T
Larsson
C
C
Lindahl
G
G
D000818:Animals; D000942:Antigens, Bacterial; D001422:Bacterial Adhesion / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002584:Cervix Uteri / Q000166:cytology / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D005810:Multigene Family; D010538:Peritonitis / Q000382:microbiology; D011995:Recombination, Genetic; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000473:pathology; D014774:Virulence / Q000235:genetics
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; C081277:Rib protein, Streptococcus agalactiae