Transformation of nonencapsulated Streptococcus pneumoniae during systemic infection

Abstract Streptococcus pneumoniae (pneumococcus) is a principal cause of bacterial middle ear infections, pneumonia, and meningitis. Capsule-targeted pneumococcal vaccines have likely contributed to increased carriage of nonencapsulated S. pneumoniae (NESp). Some NESp lineages are associated with highly efficient DNA uptake and transformation frequencies. However, NESp strains lack capsule that may increase disease severity. We tested the hypothesis that NESp could acquire capsule during systemic infection and transform into more virulent pneumococci. We reveal that NESp strains MNZ67 and MNZ41 are highly transformable and resistant to multiple antibiotics. Natural transformation of NESp when co-administered with heat-killed encapsulated strain WU2 in a murine model of systemic infection resulted in encapsulation of NESp and increased virulence during bacteremia. Functional capsule production increased the pathogenic potential of MNZ67 by significantly decreasing complement deposition on the bacterial surface. However, capsule acquisition did not further decrease complement deposition on the relatively highly pathogenic strain MNZ41. Whole genome sequencing of select transformants demonstrated that recombination of up to 56.7 kbp length occurred at the capsule locus, along with additional recombination occurring at distal sites harboring virulence-associated genes. These findings indicate NESp can compensate for lack of capsule production and rapidly evolve into more virulent strains.

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The Capsular Serotype of Streptococcus pneumoniae Is More Important than the Genetic Background for Resistance to Complement

Infection and Immunity ◽

10.1128/iai.00740-10 ◽

2010 ◽

Vol 78 (12) ◽

pp. 5262-5270 ◽

Cited By ~ 36

Author(s):

Merit Melin ◽

Krzysztof Trzciński ◽

Seppo Meri ◽

Helena Käyhty ◽

Merja Väkeväinen

Keyword(s):

Streptococcus Pneumoniae ◽

Invasive Disease ◽

Relative Effect ◽

Clinical Isolates ◽

Complement C3 ◽

Bacterial Surface ◽

Complement Resistance ◽

Opsonophagocytic Killing ◽

Complement Deposition ◽

Phagocytic Killing

ABSTRACT The polysaccharide capsule of Streptococcus pneumoniae inhibits phagocytic killing by innate immune mechanisms. Certain serotypes are associated with invasive disease while others with a nasopharyngeal carriage. The invasiveness of serotypes may partly be explained by ability to resist deposition of complement (C3) on the bacterial surface and consequent opsonophagocytic killing. In our previous studies, we observed that clinical isolates of serotypes 1 and 5, which are rarely detected in asymptomatic carriage, were resistant to complement deposition and opsonophagocytosis, whereas serotypes 6B and 23F, both common in carriage, were more sensitive to deposition of C3 and opsonophagocytic killing. However, presence of significant variation in C3 deposition between isolates of the same serotype indicated that factors other than the capsule also affect complement resistance. To distinguish the relative effect of the capsular serotype and other virulence factors on C3 deposition, we compared capsule-switched mutants prepared in genetic backgrounds of pneumococcal strains TIGR4, 603, and 618. Clinical isolates which had the same multilocus sequence type but expressed different serotypes were also compared. We found that the serotype had a significant impact on complement resistance and that the more resistant the strain was to complement, the higher was the concentration of polysaccharide-specific antibodies required for opsonophagocytic killing. Comparison of strains expressing the same capsular polysaccharides in the different genetic backgrounds and various capsular mutants of the same strain suggests that while the genotype affects complement resistance, the serotype is the most important determinant. Differences between serotypes were more significant than the differences between strains.

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Transcriptional Regulation in the Streptococcus pneumoniae rlrA Pathogenicity Islet by RlrA

Journal of Bacteriology ◽

10.1128/jb.185.2.413-421.2003 ◽

2003 ◽

Vol 185 (2) ◽

pp. 413-421 ◽

Cited By ~ 84

Author(s):

David L. Hava ◽

Carolyn J. Hemsley ◽

Andrew Camilli

Keyword(s):

Streptococcus Pneumoniae ◽

Transcriptional Activation ◽

Virulence Genes ◽

Systemic Infection ◽

Transcriptional Regulators ◽

Lung Infection ◽

Surface Proteins ◽

Microbial Pathogens ◽

Temporal Expression ◽

Bacterial Surface

ABSTRACT The proper temporal expression of virulence genes during infection is crucial to the infectious life cycle of microbial pathogens, particularly in pathogens that encounter a multitude of environments in eukaryotic hosts. Streptococcus pneumoniae normally colonizes the nasopharynges of healthy adults but can cause a range of diseases at a variety of host sites. Transcriptional regulators that are essential for full virulence of S. pneumoniae in different animal models have been identified. One such regulator, rlrA, is required for colonization of the nasopharynx and lung infection but is dispensable for systemic infection. Previous work has shown that rlrA lies in a 12-kb pathogenicity islet, divergently opposed to three putative sortase-anchored surface proteins and three sortase enzymes. In addition to rlrA, one of the putative surface proteins and one of the sortases have also been shown to be essential for lung infection. In this work, we demonstrate that RlrA is a positive regulator of all seven genes in the rlrA pathogenicity islet, with transcriptional activation occurring at four different promoters in the islet with AT-rich sequences. These promoters direct the expression of rlrA itself, the three sortases, rrgA, and rrgBC. These data are consistent with the model whereby the rlrA pathogenicity islet acts in an autonomous manner to alter the bacterial surface components that interact with the pulmonary and nasopharyngeal environments.

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Essential Role for Cellular Phosphoglucomutase in Virulence of Type 3 Streptococcus pneumoniae

Infection and Immunity ◽

10.1128/iai.69.4.2309-2317.2001 ◽

2001 ◽

Vol 69 (4) ◽

pp. 2309-2317 ◽

Cited By ~ 53

Author(s):

Gail G. Hardy ◽

Ashalla D. Magee ◽

Christy L. Ventura ◽

Melissa J. Caimano ◽

Janet Yother

Keyword(s):

Streptococcus Pneumoniae ◽

Critical Role ◽

Growth Environment ◽

Suppressor Mutations ◽

Capsule Production ◽

High Virulence ◽

Capsule Locus ◽

Cellular Pathways ◽

Type 3 ◽

Insertion Mutants

ABSTRACT Synthesis of the Streptococcus pneumoniae type 3 capsule requires the pathway glucose-6-phosphate (Glc-6-P) → Glc-1-P → UDP-Glc → UDP-glucuronic acid (UDP-GlcUA) → (GlcUA-Glc) n . The UDP-Glc dehydrogenase and synthase necessary for the latter two steps, and essential for capsule production, are encoded by genes (cps3D andcps3S, respectively) located in the type 3 capsule locus. The phosphoglucomutase (PGM) and Glc-1-P uridylyltransferase activities necessary for the first two steps are derived largely through the actions of cellular enzymes. Homologues of these enzymes, encoded by cps3M and cps3Uin the type 3 locus, are not required for capsule production. Here, we show that cps3M and cps3U also are not required for mouse virulence. In contrast, nonencapsulated isolates containing defined mutations in cps3D andcps3S were avirulent, as were reduced-capsule isolates containing mutations in pgm. Insertion mutants that lacked PGM activity were avirulent in both immunologically normal (BALB/cByJ) and immunodeficient (CBA/N) mice. In contrast, a mutant (JY1060) with reduced PGM activity was avirulent in the former but had only modestly reduced virulence in the latter. The high virulence in CBA/N mice was not due to the lack of antibodies to phosphocholine but reflected a growth environment distinct from that found in BALB/cByJ mice. The reduced PGM activity of JY1060 resulted in enhanced binding of complement and antibodies to surface antigens. However, decomplementation of BALB/cByJ mice did not enhance the virulence of this mutant. Suppressor mutations, only some of which resulted in increased capsule production, increased the virulence of JY1060 in BALB/cByJ mice. The results suggest that PGM plays a critical role in pneumococcal virulence by affecting multiple cellular pathways.

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Positive Correlation between Tyrosine Phosphorylation of CpsD and Capsular Polysaccharide Production in Streptococcus pneumoniae

Journal of Bacteriology ◽

10.1128/jb.185.20.6057-6066.2003 ◽

2003 ◽

Vol 185 (20) ◽

pp. 6057-6066 ◽

Cited By ~ 108

Author(s):

Matthew H. Bender ◽

Robert T. Cartee ◽

Janet Yother

Keyword(s):

Cell Wall ◽

Streptococcus Pneumoniae ◽

Tyrosine Phosphorylation ◽

Capsular Polysaccharide ◽

Kinase Inhibitor ◽

Tyrosine Phosphatase ◽

Regulatory System ◽

Capsule Production ◽

Capsule Locus ◽

Ladder Pattern

ABSTRACT CpsA, CpsB, CpsC, and CpsD are part of a tyrosine phosphorylation regulatory system involved in modulation of capsule synthesis in Streptococcus pneumoniae and many other gram-positive and gram-negative bacteria. Using an immunoblotting technique, we observed distinct laddering patterns of S. pneumoniae capsular polysaccharides of various serotypes and found that transfer of the polymer from the membrane to the cell wall was independent of size. Deletion of cps2A, cps2B, cps2C, or cps2D in the serotype 2 strain D39 did not affect the ability to transfer capsule to the cell wall. Deletion of cps2C or cps2D, which encode two domains of an autophosphorylating tyrosine kinase, resulted in the production of only short-chain polymers. The function of Cps2A is unknown, and the polymer laddering pattern of the cps2A deletion mutants appeared similar to that of the parent, although the total amount of capsule was decreased. Loss of Cps2B, a tyrosine phosphatase and a kinase inhibitor, resulted in an increase in capsule amount and a normal ladder pattern. However, Cps2B mutants exhibited reduced virulence following intravenous inoculation of mice and were unable to colonize the nasopharynx, suggesting a diminished capacity to sense or respond to these environments. In D39 and its isogenic mutants, the amounts of capsule and tyrosine-phosphorylated Cps2D (Cps2D∼P) correlated directly. In contrast, restoration of type 2 capsule production followed by deletion of cps2B in Rx1, a laboratory passaged D39 derivative containing multiple uncharacterized mutations, resulted in decreased capsule amounts but no alteration in Cps2D∼P levels. Thus, a factor outside the capsule locus, which is either missing or defective in the Rx1 background, is important in the control of capsule synthesis.

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Analysis of the Polysaccharide Capsule of the Systemic Pathogen Streptococcus iniae and Its Implications in Virulence

Infection and Immunity ◽

10.1128/iai.01484-06 ◽

2006 ◽

Vol 75 (3) ◽

pp. 1255-1264 ◽

Cited By ~ 63

Author(s):

Beth A. Lowe ◽

Jesse D. Miller ◽

Melody N. Neely

Keyword(s):

Capsular Polysaccharide ◽

Virulent Strain ◽

Systemic Disease ◽

Systemic Infection ◽

Streptococcus Iniae ◽

Capsule Production ◽

Commensal Strain ◽

Capsule Locus ◽

In The Beginning ◽

Severe Systemic Disease

ABSTRACT Systemic pathogens have developed numerous strategies for evading the defenses of the host, permitting dissemination and multiplication in various tissues. One means of survival in the host, particularly in the bloodstream, has been attributed to the ability to avoid phagocytosis via capsular polysaccharide. To further define the virulence capacity of Streptococcus iniae, a zoonotic pathogen with the ability to cause severe systemic disease in both fish and humans, we performed an analysis of the capsule locus. The initial analysis included cloning and sequencing of the capsule synthesis operon, which revealed an approximately 21-kb region that is highly homologous to capsule operons of other streptococci. A genetic comparison of S. iniae virulent strain 9117 and commensal strain 9066 revealed that the commensal strain does not have the central region of the capsule operon composed of several important capsule synthesis genes. Four 9117 insertion or deletion mutants with mutations in the beginning, middle, or end of the capsule locus were analyzed to determine their capsule production and virulence. Virulence profiles were analyzed for each mutant using three separate criteria, which demonstrated the attenuation of each mutant in several tissue environments. These analyses also provided insight into the different responses of the host to each mutant strain compared to a wild-type infection. Our results demonstrate that capsule is not required for all host environments, while excess capsule is also not optimal, suggesting that for an “ideal” systemic infection, capsule production is most likely regulated while the bacterium is in different environments of the host.

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Key Role of Capsular Polysaccharide in the Induction of Systemic Infection and Abortion by Hypervirulent Campylobacter jejuni

Infection and Immunity ◽

10.1128/iai.00001-17 ◽

2017 ◽

Vol 85 (6) ◽

Cited By ~ 8

Author(s):

Orhan Sahin ◽

Samantha A. Terhorst ◽

Eric R. Burrough ◽

Zhangqi Shen ◽

Zuowei Wu ◽

...

Keyword(s):

Guinea Pig ◽

Campylobacter Jejuni ◽

Capsular Polysaccharide ◽

Systemic Infection ◽

The United States ◽

Content Type ◽

Model Following ◽

Capsule Production ◽

Guinea Pig Model

ABSTRACT Campylobacter jejuni is a zoonotic pathogen, and a hypervirulent clone, named clone SA, has recently emerged as the predominant cause of ovine abortion in the United States. To induce abortion, orally ingested Campylobacter must translocate across the intestinal epithelium, spread systemically in the circulation, and reach the fetoplacental tissue. Bacterial factors involved in these steps are not well understood. C. jejuni is known to produce capsular polysaccharide (CPS), but the specific role that CPS plays in systemic infection and particularly abortion in animals remains to be determined. In this study, we evaluated the role of CPS in bacteremia using a mouse model and in abortion using a pregnant guinea pig model following oral challenge. Compared with C. jejuni NCTC 11168 and 81-176, a clone SA isolate (IA3902) resulted in significantly higher bacterial counts and a significantly longer duration of bacteremia in mice. The loss of capsule production via gene-specific mutagenesis in IA3902 led to the complete abolishment of bacteremia in mice and abortion in pregnant guinea pigs, while complementation of capsule expression almost fully restored these phenotypes. The capsule mutant strain was also impaired for survival in guinea pig sera and sheep blood. Sequence-based analyses revealed that clone SA possesses a unique CPS locus with a mosaic structure, which has been stably maintained in all clone SA isolates derived from various hosts and times. These findings establish CPS as a key virulence factor for the induction of systemic infection and abortion in pregnant animals and provide a viable candidate for the development of vaccines against hypervirulent C. jejuni.

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Blindness as an uncommon complication of Streptococcus pneumoniae systemic infection

Intensive Care Medicine ◽

10.1007/s00134-018-5486-0 ◽

2018 ◽

Vol 45 (2) ◽

pp. 263-265 ◽

Cited By ~ 1

Author(s):

R. Clere-Jehl ◽

H. Merdji ◽

D. Derhy ◽

J. Helms

Keyword(s):

Streptococcus Pneumoniae ◽

Systemic Infection ◽

Uncommon Complication

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Susceptibility of immunodeficient mice to aerosol and systemic infection with virulent strains of Francisella tularensis

Microbial Pathogenesis ◽

10.1016/j.micpath.2004.02.003 ◽

2004 ◽

Vol 36 (6) ◽

pp. 311-318 ◽

Cited By ~ 46

Author(s):

Wangxue Chen ◽

Rhonda KuoLee ◽

Hua Shen ◽

J Wayne Conlan

Keyword(s):

Francisella Tularensis ◽

Systemic Infection ◽

Immunodeficient Mice ◽

Virulent Strains

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d-Alanylation of Teichoic Acids Promotes Group A Streptococcus Antimicrobial Peptide Resistance, Neutrophil Survival, and Epithelial Cell Invasion

Journal of Bacteriology ◽

10.1128/jb.187.19.6719-6725.2005 ◽

2005 ◽

Vol 187 (19) ◽

pp. 6719-6725 ◽

Cited By ~ 162

Author(s):

Sascha A. Kristian ◽

Vivekanand Datta ◽

Christopher Weidenmaier ◽

Rita Kansal ◽

Iris Fedtke ◽

...

Keyword(s):

Bacterial Infections ◽

Group A Streptococcus ◽

Teichoic Acid ◽

Systemic Infection ◽

Human Neutrophils ◽

Invasive Infection ◽

Bacterial Surface ◽

Innate Defense ◽

Group A ◽

Antimicrobial Peptide Resistance

ABSTRACT Group A streptococcus (GAS) is a leading cause of severe, invasive human infections, including necrotizing fasciitis and toxic shock syndrome. An important element of the mammalian innate defense system against invasive bacterial infections such as GAS is the production of antimicrobial peptides (AMPs) such as cathelicidins. In this study, we identify a specific GAS phenotype that confers resistance to host AMPs. Allelic replacement of the dltA gene encoding d-alanine-d-alanyl carrier protein ligase in an invasive serotype M1 GAS isolate led to loss of teichoic acid d-alanylation and an increase in net negative charge on the bacterial surface. Compared to the wild-type (WT) parent strain, the GAS ΔdltA mutant exhibited increased susceptibility to AMP and lysozyme killing and to acidic pH. While phagocytic uptake of WT and ΔdltA mutants by human neutrophils was equivalent, neutrophil-mediated killing of the ΔdltA strain was greatly accelerated. Furthermore, we observed the ΔdltA mutant to be diminished in its ability to adhere to and invade cultured human pharyngeal epithelial cells, a likely proximal step in the pathogenesis of invasive infection. Thus, teichoic acid d-alanylation may contribute in multiple ways to the propensity of invasive GAS to bypass mucosal defenses and produce systemic infection.

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