Transcriptional and Proteomic Profiles of Group B Streptococcus Type V Reveal Potential Adherence Proteins Associated with High-Level Invasion

Abstract

Group B Streptococcus (GBS) is an opportunistic organism that can harmlessly colonize the human gut, vagina, and rectum but can also cause pneumonia, sepsis, and meningitis in neonates born to colonized mothers. We have shown previously that growth rate and oxygen level regulate the ability of GBS to invade eukaryotic cells in vitro. Herein we extend and expand on these observations to show that GBS type V, an emergent serotype, grown in a chemostat at a cell mass-doubling time (t d ) of 1.8 h with oxygen invaded human ME-180 cervical epithelial cells in large numbers compared with those grown at the same t d without oxygen or at a slower t d of 11.0 h. The fact that several GBS type V cell wall-associated and membrane proteins were expressed exclusively under the invasive growth condition prompted an investigation, using genomics and proteomics, of all upregulated genes and proteins. Several proteins with potential roles in adherence were identified, including an undefined surface antigen (SAG1350), a lipoprotein (SAG0971), penicillin-binding protein 2b (SAG0765), glyceraldehyde-3-phosphate dehydrogenase (SAG0823), and an iron-binding protein (SAG1007). Mouse antisera to these five proteins inhibited binding of GBS type V to ME-180 cells by >85%. Recombinant undefined surface antigen (SAG1350), lipoprotein (SAG0971), and penicillin-binding protein 2b (SAG0765) each bound to ME-180 cells in a dose-dependent fashion, confirming their ability to act as ligands.Collectively, these data increase the number of potential GBS adherence factors and also suggest a role for these surface-associated proteins in initial pathogenic events.Group B Streptococcus (GBS) is a facultative anaerobe that can persist in both poorly and well-oxygenated tissues in humans. It commonly colonizes the anaerobic environments of the rectum and the vagina but can also colonize, grow, and disseminate from the oxygen-rich lungs of a newborn and cause pneumonia, life-threatening sepsis, and meningitis. That the presence of oxygen during growth is positively associated with the ability of GBS to invade human cells was recently demonstrated in vitro with GBS grown in a chemostat, where nutrient conditions are precisely controlled (17). In addition to oxygen, the rate of growth also influences invasiveness, as shown by the fact that GBS grown in a chemostat at a cell mass-doubling time (t d ) of 1.8 h invaded respiratory epithelial cells in significantly greater numbers than did those grown at a relatively slower t d of 11.0 h (25).Newly described genes such as those encoding the penicillinbinding protein (PBP) (ponA) (19), superoxide dismutase (sodA) (33), the delta subunit of RNA polymerase (18), glutamine transporter (glnQ) (40), and RogB, a transcriptional regulator of GBS (12), add to a growing list of GBS virulence factors. Indeed, the sequencing of GBS genomes from several serotypes (41), including types V and III (8, 42), and technologies such as DNA microarray and proteomic analysis now allow global approaches to revealing the complex natu...

CsrRS and Environmental pH Regulate Group B Streptococcus Adherence to Human Epithelial Cells and Extracellular Matrix

“…These include proteins that bind to host cells, such as serine-rich repeat family proteins (32,50) and BibA (36), as well as proteins that bind specifically to components of host ECM, such as fibrinogen, fibronectin, and laminin (4,10,31,37,38,43,48). Some enzymes and transport binding proteins also have been suggested to be involved in GBS adherence through various mechanisms (16,22,27,29,47). GBS pili also have been shown to contribute to adherence, although recent work suggests that adherence and biofilm formation may be exclusively functions of PI-2a pili and not of PI-1 or PI-2b pili (30).…”

Role of Pilus Proteins in Adherence and Invasion of Streptococcus agalactiae to the Lung and Cervical Epithelial Cells

“…Cell viability and count were determined by 0.4% trypan blue (Sigma) exclusion and hemocytometer counts as described (11). Spent medium was replaced every 2-3 days and 1 day before use.…”

“…The differences in serotype distribution among various populations may also reflect differences in pathogenesis among the serotypes. Several promising vaccine candidates like capsular polysccharide (Cps); surface protein, such as ␣ and ␤ components of the C protein complex, Rib; surface immunogenic protein (Sip); and C5a peptidase have been identified to develop a vaccine against GBS and have been reviewed in detail recently (7)(8)(9)(10)(11). Despite the many studies that are focused on developing a GBS vaccine using conventional approaches, including the cultivation of pathogens and the identification of highly immunogenic and protective antigens using standard biochemical and microbiological techniques, little success has been achieved in terms of developing a vaccine that is globally effective (7).…”

“…The analysis of multiple genomes of GBS revealed tremendous diversity and identified candidates that are not shared by all of the strains sequenced but provide general protection when combined (12). The sequencing of GBS genomes from several serotypes (13), including types, Ia, V, and III (14,15), and technologies such as DNA microarray and proteomics are now treated as global approaches for vaccine development (7,11,16,17).…”

Fever temperature enhances mechanisms of survival of Streptococcus agalactiae within human endothelial cells

“…The clinical scenario concerning invasive diseases caused by GBS underlies the ability of this pathogen to bypass and/or injure endothelial cells to gain access to the blood stream. Previous studies demonstrated that the GBS-endothelial cell interaction process is a phenomenon of prime importance in the etiology of diseases caused by GBS, but an understanding of these events at the (7,8). Many factors that allow this microorganism to persist and thrive in human tissues remain unidentified.…”