A unique serine-rich repeat protein (Srr-2) and novel surface antigen (epsilon) associated with a virulent lineage of serotype III Streptococcus agalactiae.
Group B streptococci (GBS) are pathogens of both neonates and adults, with serotype III strains in particular being associated with invasive disease and meningitis. In this study, a novel GBS surface antigen, epsilon, was found to be co-expressed with the previously reported delta antigen on an identical subset of serotype III GBS. Expression of delta/epsilon on the surface of serotype III GBS was shown to distinguish the restriction digest pattern (RDP) III-3 and multilocus sequence typing (ST)-17 lineage. epsilon-Specific antibodies were reactive with a unique, high-molecular-mass, serine-rich repeat protein (Srr-2) found exclusively in RDP III-3 strains. The gene encoding Srr-2 was located within a putative accessory secretory locus that included secY2 and secA2 homologues and had a genetic organization similar to that of the secY2/A2 locus of staphylococci. In contrast, serotype III delta/epsilon-negative strains and strains representative of serotypes Ia, Ib, Ic and II shared a common Srr-encoding gene, srr-1, and an organization of the secY2/A2 locus similar to that of previously reported serotype Ic, delta/epsilon-negative serotype III and serotype V GBS strains. Representative serotype III delta/epsilon-positive strains had LD(90) values 3-4 logs less than those of serotype III delta/epsilon-negative strains in a neonatal mouse model of infection. These results indicate that the RDP III-3/ST-17 lineage expresses Srr-2 and is highly virulent in an in vivo model of neonatal sepsis.
Seifert
Kyle N
KN
Department of Biology, James Madison University, Harrisonburg, VA 22807, USA.
Adderson
Elisabeth E
EE
Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
Whiting
April A
AA
Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
Bohnsack
John F
JF
Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
Crowley
Paula J
PJ
Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
Brady
L Jeannine
LJ
Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis* / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004195:Disease Models, Animal; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013210:Staphylococcus / Q000235:genetics; D013290:Streptococcal Infections / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D016019:Survival Analysis; D037521:Virulence Factors / Q000032:analysis / Q000235:genetics*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; D037521:Virulence Factors; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins