Increased Nasopharyngeal Bacterial Titers and Local Inflammation Facilitate Transmission of Streptococcus pneumoniae

ABSTRACTThe transmission of the bacteriumStreptococcus pneumoniae(the pneumococcus) marks the first step toward disease development. To date, our ability to prevent pneumococcal transmission has been limited by our lack of understanding regarding the factors which influence the spread of this pathogen. We have previously developed an infant mouse model of pneumococcal transmission which was strictly dependent on influenza A virus (IAV) coinfection of both the experimentally colonized “index mice” and the naive cohoused “contact mice.” Here, we sought to use this model to further elucidate the factors which facilitateS. pneumoniaetransmission. In the present report, we demonstrate that increasing the nasopharyngeal load ofS. pneumoniaein the colonized index mice (via the depletion of neutrophils) and inducing a proinflammatory response in the naive cohoused contact mice (as demonstrated by cytokine production) facilitatesS. pneumoniaetransmission. Thus, these data provide the first insights into the factors that help mediate the spread ofS. pneumoniaethroughout the community.IMPORTANCEStreptococcus pneumoniae(the pneumococcus) is a major cause of worldwide morbidity and mortality and is a leading cause of death among children under the age of five years. Transmission ofS. pneumoniaemarks the first step toward disease development. Therefore, understanding the factors that influence the spread of pneumococci throughout the community plays an essential role in preventing pneumococcal disease. We previously developed the first reproducible infant mouse model for pneumococcal transmission and showed that coinfection with influenza virus facilitates the spread ofS. pneumoniae. Here, we show that increasing the bacterial load in the nasal cavity of colonized individuals as well as inducing an inflammatory response in naive “contact cases” facilitates the spread of pneumococci. Therefore, this study helps to identify the factors which must be inhibited in order to successfully prevent pneumococcal disease.

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Influenza-Induced Inflammation Drives Pneumococcal Otitis Media

Infection and Immunity ◽

10.1128/iai.01278-12 ◽

2013 ◽

Vol 81 (3) ◽

pp. 645-652 ◽

Cited By ~ 43

Author(s):

Kirsty R. Short ◽

Patrick C. Reading ◽

Lorena E. Brown ◽

John Pedersen ◽

Brad Gilbertson ◽

...

Keyword(s):

Otitis Media ◽

Middle Ear ◽

Influenza A ◽

Pneumococcal Disease ◽

Influenza Viruses ◽

Dependent Manner ◽

Proinflammatory Response ◽

Content Type ◽

Infant Mouse ◽

Human Middle Ear

ABSTRACTInfluenza A virus (IAV) predisposes individuals to secondary infections with the bacteriumStreptococcus pneumoniae(the pneumococcus). Infections may manifest as pneumonia, sepsis, meningitis, or otitis media (OM). It remains controversial as to whether secondary pneumococcal disease is due to the induction of an aberrant immune response or IAV-induced immunosuppression. Moreover, as the majority of studies have been performed in the context of pneumococcal pneumonia, it remains unclear how far these findings can be extrapolated to other pneumococcal disease phenotypes such as OM. Here, we used an infant mouse model, human middle ear epithelial cells, and a series of reverse-engineered influenza viruses to investigate how IAV promotes bacterial OM. Our data suggest that the influenza virus HA facilitates disease by inducing a proinflammatory response in the middle ear cavity in a replication-dependent manner. Importantly, our findings suggest that it is the inflammatory response to IAV infection that mediates pneumococcal replication. This study thus provides the first evidence that inflammation drives pneumococcal replication in the middle ear cavity, which may have important implications for the treatment of pneumococcal OM.

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Infant Mouse Model for the Study of Shedding and Transmission during Streptococcus pneumoniae Monoinfection

Infection and Immunity ◽

10.1128/iai.00416-16 ◽

2016 ◽

Vol 84 (9) ◽

pp. 2714-2722 ◽

Cited By ~ 29

Author(s):

M. Ammar Zafar ◽

Masamitsu Kono ◽

Yang Wang ◽

Tonia Zangari ◽

Jeffrey N. Weiser

Keyword(s):

Streptococcus Pneumoniae ◽

Mouse Model ◽

Influenza A ◽

Carrier State ◽

High Ratio ◽

New Host ◽

Content Type ◽

Infant Mouse ◽

Colonization Density ◽

Pneumococcal Colonization

One of the least understood aspects of the bacteriumStreptococcus pneumoniae(pneumococcus) is its transmission from host to host, the critical first step in both the carrier state and the disease state. To date, transmission models have depended on influenza A virus coinfection, which greatly enhances pneumococcal shedding to levels that allow acquisition by a new host. Here, we describe an infant mouse model that can be utilized to study pneumococcal colonization, shedding, and transmission during bacterial monoinfection. Using this model, we demonstrated that the level of bacterial shedding is highest in pups infected intranasally at age 4 days and peaks over the first 4 days postchallenge. Shedding results differed among isolates of five different pneumococcal types. Colonization density was found to be a major factor in the level of pneumococcal shedding and required expression of capsule. Transmission within a litter occurred when there was a high ratio of colonized “index” pups to uncolonized “contact” pups. Transmission was observed for each of the well-colonizing pneumococcal isolates, with the rate of transmission proportional to the level of shedding. This model can be used to examine bacterial and host factors that contribute to pneumococcal transmission without the effects of viral coinfection.

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Comparison of Immunogenicity and Protection of Two Pneumococcal Protein Vaccines Based on PsaA and PspA

Infection and Immunity ◽

10.1128/iai.00916-17 ◽

2018 ◽

Vol 86 (6) ◽

Cited By ~ 5

Author(s):

Jinfei Yu ◽

Bo Li ◽

Xiaorui Chen ◽

Jingcai Lu ◽

Dandan Wang ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Pneumococcal Disease ◽

Bacterial Load ◽

Survival Rates ◽

Mucosal Vaccine ◽

High Morbidity ◽

Content Type ◽

Single Protein ◽

Specific Igg ◽

Children Under 5

ABSTRACTStreptococcus pneumoniaeis a major cause of invasive pneumococcal disease, septicemia, and meningitis that can result in high morbidity rates in children under 5 years old. The current polysaccharide-based vaccines can provide type-specific immunity, but a broad-spectrum vaccine would provide greater coverage. Therefore, developing pneumococcal-protein-based vaccines that can extend to more serum types is highly important. In this study, we vaccinated mice via the subcutaneous (s.c.) route with a systemic vaccine that is a mixture of fusion protein PsaA-PspA23 and a single protein, PspA4, with aluminum hydroxide as an adjuvant. As a comparison, mice were immunized intranasally with a mucosal vaccine that is a mixture of PspA2-PA-BLP (where PA is protein anchor and BLP is bacterium-like particle) and PspA4-PA-BLP, via the intranasal (i.n.) route. The two immunization processes were followed by challenge withStreptococcus pneumoniaebacteria from two different PspA families. Specific IgG titers in the serum and specific IgA titers in the mucosa were determined following immunizations. Bacterial loads and survival rates after challenge were compared. Both the systemic vaccine and the mucosal vaccine induced a significant increase of IgG against PspAs. Only the mucosal vaccine also induced specific IgA in the mucosa. The two vaccines provided protection, but each vaccine showed an advantage. The systemic vaccine induced higher levels of serum antibodies, whereas the mucosal vaccine limited the bacterial load in the lung and blood. Therefore, coimmunizations with the two types of vaccines may be implemented in the future.

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Type I Interferon Signaling Is a Common Factor Driving Streptococcus pneumoniae and Influenza A Virus Shedding and Transmission

mBio ◽

10.1128/mbio.03589-20 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Tonia Zangari ◽

Mila B. Ortigoza ◽

Kristen L. Lokken-Toyli ◽

Jeffrey N. Weiser

Keyword(s):

Streptococcus Pneumoniae ◽

Respiratory Tract ◽

Influenza A Virus ◽

Influenza A ◽

Common Factor ◽

Type I ◽

Upper Respiratory Tract ◽

Content Type ◽

Infant Mouse ◽

Upper Respiratory

ABSTRACT The dynamics underlying respiratory contagion (the transmission of infectious agents from the airways) are poorly understood. We investigated host factors involved in the transmission of the leading respiratory pathogen Streptococcus pneumoniae. Using an infant mouse model, we examined whether S. pneumoniae triggers inflammatory pathways shared by influenza A virus (IAV) to promote nasal secretions and shedding from the upper respiratory tract to facilitate transit to new hosts. Here, we show that amplification of the type I interferon (IFN-I) response is a critical host factor in this process, as shedding and transmission by both IAV and S. pneumoniae were decreased in pups lacking the common IFN-I receptor (Ifnar1−/− mice). Additionally, providing exogenous recombinant IFN-I to S. pneumoniae-infected pups was sufficient to increase bacterial shedding. The expression of IFN-stimulated genes (ISGs) was upregulated in S. pneumoniae-infected wild-type (WT) but not Ifnar1−/− mice, including genes involved in mucin type O-glycan biosynthesis; this correlated with an increase in secretions in S. pneumoniae- and IAV-infected WT compared to Ifnar1−/− pups. S. pneumoniae stimulation of ISGs was largely dependent on its pore-forming toxin, pneumolysin, and coinfection with IAV and S. pneumoniae resulted in synergistic increases in ISG expression. We conclude that the induction of IFN-I signaling appears to be a common factor driving viral and bacterial respiratory contagion. IMPORTANCE Respiratory tract infections are a leading cause of childhood mortality and, globally, Streptococcus pneumoniae is the leading cause of mortality due to pneumonia. Transmission of S. pneumoniae primarily occurs through direct contact with respiratory secretions, although the host and bacterial factors underlying transmission are poorly understood. We examined transmission dynamics of S. pneumoniae in an infant mouse model and here show that S. pneumoniae colonization of the upper respiratory tract stimulates host inflammatory pathways commonly associated with viral infections. Amplification of this response was shown to be a critical host factor driving shedding and transmission of both S. pneumoniae and influenza A virus, with infection stimulating expression of a wide variety of genes, including those involved in the biosynthesis of mucin, a major component of respiratory secretions. Our findings suggest a mechanism facilitating S. pneumoniae contagion that is shared by viral infection.

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Immunization with Pneumococcal Surface Protein K of Nonencapsulated Streptococcus pneumoniae Provides Protection in a Mouse Model of Colonization

Clinical and Vaccine Immunology ◽

10.1128/cvi.00456-15 ◽

2015 ◽

Vol 22 (11) ◽

pp. 1146-1153 ◽

Cited By ~ 12

Author(s):

Lance E. Keller ◽

Xiao Luo ◽

Justin A. Thornton ◽

Keun-Seok Seo ◽

Bo Youn Moon ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Mouse Model ◽

Pneumococcal Disease ◽

Surface Protein ◽

Antibody Isotype ◽

Content Type ◽

Mouse Immunization ◽

Escape Mutants

ABSTRACTCurrent vaccinations are effective against encapsulated strains ofStreptococcus pneumoniae, but they do not protect against nonencapsulatedStreptococcus pneumoniae(NESp), which is increasing in colonization and incidence of pneumococcal disease. Vaccination with pneumococcal proteins has been assessed for its ability to protect against pneumococcal disease, but several of these proteins are not expressed by NESp. Pneumococcal surface protein K (PspK), an NESp virulence factor, has not been assessed for immunogenic potential or host modulatory effects. Mammalian cytokine expression was determined in anin vivomouse model and in anin vitrocell culture system. Systemic and mucosal mouse immunization studies were performed to determine the immunogenic potential of PspK. Murine serum and saliva were collected to quantitate specific antibody isotype responses and the ability of antibody and various proteins to inhibit epithelial cell adhesion. Host cytokine response was not reduced by PspK. NESp was able to colonize the mouse nasopharynx as effectively as encapsulated pneumococci. Systemic and mucosal immunization provided protection from colonization by PspK-positive (PspK+) NESp. Anti-PspK antibodies were recovered from immunized mice and significantly reduced the ability of NESp to adhere to human epithelial cells. A protein-based pneumococcal vaccine is needed to provide broad protection against encapsulated and nonencapsulated pneumococci in an era of increasing antibiotic resistance and vaccine escape mutants. We demonstrate that PspK may serve as an NESp target for next-generation pneumococcal vaccines. Immunization with PspK protected against pneumococcal colonization, which is requisite for pneumococcal disease.

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A novel pneumococcal surface protein K of nonencapsulated Streptococcus pneumoniae promotes transmission among littermates in an infant mouse model with influenza A virus co-infection

Infection and Immunity ◽

10.1128/iai.00622-21 ◽

2022 ◽

Author(s):

Hideki Sakatani ◽

Masamitsu Kono ◽

Denisa Nanushaj ◽

Daichi Murakami ◽

Saori Takeda ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Mouse Model ◽

Influenza A ◽

Capsular Polysaccharide ◽

Surface Protein ◽

Nasal Colonization ◽

Infant Mouse ◽

Key Factor ◽

Protective Strategy ◽

New Hosts

We established an infant mouse model for colonization and transmission by nonencapsulated Streptococcus pneumoniae (NESp) strains to gain important information about its virulence among children. Invasive pneumococcal diseases have decreased dramatically since the worldwide introduction of pneumococcal capsular polysaccharide vaccines. Increasing prevalence of non-vaccine serotypes including NESp has been highlighted as a challenge in treatment strategy, but the virulence of NESp is not well understood. Protective strategy against NESp colonization and transmission between children require particularly urgent evaluation. NESp lacks capsules, a major virulent factor of pneumococci, but can cause a variety of infections in children and older people. PspK, a specific surface protein of NESp, is a key factor in establishing nasal colonization. In our infant mouse model for colonization and transmission by NESp strains, NESp could establish stable nasal colonization at the same level as encapsulated serotype 6A in infant mice, and could be transmitted between littermates. Transmission was promoted by NESp surface virulence factor PspK and influenza virus co-infection. However, PspK-deletion mutants lost the ability to colonize and transmit to new hosts. Promotion of NESp transmission by influenza was due to increased susceptibility of the new hosts. PspK was a key factor not only in establishment of nasal colonization, but also in transmission to new hosts. PspK may be targeted as a new candidate vaccine for NESp infection in children.

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Antibodies to Streptococcus pneumoniae Capsular Polysaccharide Enhance Pneumococcal Quorum Sensing

mBio ◽

10.1128/mbio.00176-11 ◽

2011 ◽

Vol 2 (5) ◽

Cited By ~ 22

Author(s):

Masahide Yano ◽

Shruti Gohil ◽

J. Robert Coleman ◽

Catherine Manix ◽

Liise-anne Pirofski

Keyword(s):

Monoclonal Antibodies ◽

Streptococcus Pneumoniae ◽

Quorum Sensing ◽

Direct Effect ◽

Pneumococcal Disease ◽

Effector Cell ◽

Capsular Polysaccharide ◽

Genetic Exchange ◽

Content Type ◽

Specific Antibodies

ABSTRACTThe use of pneumococcal capsular polysaccharide (PPS)-based vaccines has resulted in a substantial reduction in invasive pneumococcal disease. However, much remains to be learned about vaccine-mediated immunity, as seven-valent PPS-protein conjugate vaccine use in children has been associated with nonvaccine serotype replacement and 23-valent vaccine use in adults has not prevented pneumococcal pneumonia. In this report, we demonstrate that certain PPS-specific monoclonal antibodies (MAbs) enhance the transformation frequency of two differentStreptococcus pneumoniaeserotypes. This phenomenon was mediated by PPS-specific MAbs that agglutinate but do not promote opsonic effector cell killing of the homologous serotypeinvitro. Compared to the autoinducer, competence-stimulating peptide (CSP) alone, transcriptional profiling of pneumococcal gene expression after incubation with CSP and one such MAb to the PPS of serotype 3 revealed changes in the expression of competence (com)-related and bacteriocin-like peptide (blp) genes involved in pneumococcal quorum sensing. This MAb was also found to induce a nearly 2-fold increase in CSP2-mediated bacterial killing or fratricide. These observations reveal a novel, direct effect of PPS-binding MAbs on pneumococcal biology that has important implications for antibody immunity to pneumococcus in the pneumococcal vaccine era. Taken together, our data suggest heretofore unsuspected mechanisms by which PPS-specific antibodies could affect genetic exchange and bacterial viability in the absence of host cells.IMPORTANCECurrent thought holds that pneumococcal capsular polysaccharide (PPS)-binding antibodies protect against pneumococcus by inducing effector cell opsonic killing of the homologous serotype. While such antibodies are an important part of how pneumococcal vaccines protect against pneumococcal disease, PPS-specific antibodies that do not exhibit this activity but are highly protective against pneumococcus in mice have been identified. This article examines the effect of nonopsonic PPS-specific monoclonal antibodies (MAbs) on the biology ofStreptococcus pneumoniae. The results showed that in the presence of a competence-stimulating peptide (CSP), such MAbs increase the frequency of pneumococcal transformation. Further studies with one such MAb showed that it altered the expression of genes involved in quorum sensing and increased competence-induced killing or fratricide. These findings reveal a novel, previously unsuspected mechanism by which certain PPS-specific antibodies exert a direct effect on pneumococcal biology that has broad implications for bacterial clearance, genetic exchange, and antibody immunity to pneumococcus.

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Protection against Streptococcus pneumoniae Invasive Pathogenesis by a Protein-Based Vaccine Is Achieved by Suppression of Nasopharyngeal Bacterial Density during Influenza A Virus Coinfection

Infection and Immunity ◽

10.1128/iai.00530-16 ◽

2016 ◽

Vol 85 (2) ◽

Cited By ~ 12

Author(s):

M. Nadeem Khan ◽

Qingfu Xu ◽

Michael E. Pichichero

Keyword(s):

T Cells ◽

Streptococcus Pneumoniae ◽

Influenza A Virus ◽

Influenza A ◽

Passive Transfer ◽

Bacterial Density ◽

Content Type ◽

Adult Mice ◽

Significant Difference ◽

Colonization Density

ABSTRACTAn increase inStreptococcus pneumoniaenasopharynx (NP) colonization density during a viral coinfection initiates pathogenesis. To mimic naturalS. pneumoniaepathogenesis, we commensally colonized the NPs of adult C57BL/6 mice withS. pneumoniaeserotype (ST) 6A or 8 and then coinfected them with mouse-adapted H1N1 influenza A virus (PR/8/34).S. pneumoniaeestablished effective commensal colonization, and influenza virus coinfection causedS. pneumoniaeNP density to increase, resulting in bacteremia and mortality. We then studied histidine triad protein D (PhtD), anS. pneumoniaeadhesin vaccine candidate, for its ability to prevent invasiveS. pneumoniaedisease in adult and infant mice. In adult mice, the efficacy of PhtD vaccination was compared with that of PCV13. Vaccination with PCV13 led to a greater reduction ofS. pneumoniaeNP density (>2.5 log units) than PhtD vaccination (∼1-log-unit reduction). However, no significant difference was observed with regard to the prevention ofS. pneumoniaebacteremia, and there was no difference in mortality. Depletion of CD4+T cells in PhtD-vaccinated adult mice, but not PCV13-vaccinated mice, caused a loss of vaccine-induced protection. In infant mice, passive transfer of antisera or CD4+T cells from PhtD-vaccinated adult mice led to a nonsignificant reduction in NP colonization density, whereas passive transfer of antisera and CD4+T cells was needed to cause a significant reduction in NP colonization density. For the first time, these data show an outcome with regard to prevention of invasiveS. pneumoniaepathogenesis with a protein vaccine similar to that which occurs with a glycoconjugate vaccine despite a less robust reduction in NP bacterial density.

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Two regulatory factors of Vibrio cholerae activating the mannose-sensitive haemagglutinin pilus expression is important for biofilm formation and colonization in mice

Microbiology ◽

10.1099/mic.0.001098 ◽

2021 ◽

Vol 167 (10) ◽

Author(s):

Mengting Shi ◽

Yue Zheng ◽

Xianghong Wang ◽

Zhengjia Wang ◽

Menghua Yang

Keyword(s):

Mouse Model ◽

Vibrio Cholerae ◽

Biofilm Formation ◽

Type Species ◽

Wild Type ◽

Expression Library ◽

Content Type ◽

Genomic Expression ◽

Infant Mouse ◽

Link Type

Vibrio cholerae the causative agent of cholera, uses a large number of coordinated transcriptional regulatory events to transition from its environmental reservoir to the host intestine, which is its preferred colonization site. Transcription of the mannose-sensitive haemagglutinin pilus (MSHA), which aids the persistence of V. cholerae in aquatic environments, but causes its clearance by host immune defenses, was found to be regulated by a yet unknown mechanism during the infection cycle of V. cholerae . In this study, genomic expression library screening revealed that two regulators, VC1371 and VcRfaH, are able to positively activate the transcription of MSHA operon. VC1371 is localized and active in the cell membrane. Deletion of vc1371 or VcrfaH genes in V. cholerae resulted in less MshA protein production and less efficiency of biofilm formation compared to that in the wild-type strain. An adult mouse model showed that the mutants with vc1371 or VcrfaH deletion colonized less efficiently than the wild-type; the VcrfaH deletion mutant showed less colonization efficiency in the infant mouse model. The findings strongly suggested that the two regulators, namely VC1371 and VcRfaH, which are involved in the regulation of MSHA expression, play an important role in V. cholerae biofilm formation and colonization in mice.

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Streptococcus pneumoniae Transmission Is Blocked by Type-Specific Immunity in an Infant Mouse Model

mBio ◽

10.1128/mbio.00188-17 ◽

2017 ◽

Vol 8 (2) ◽

Cited By ~ 13

Author(s):

Tonia Zangari ◽

Yang Wang ◽

Jeffrey N. Weiser

Keyword(s):

Streptococcus Pneumoniae ◽

Mouse Model ◽

Pneumococcal Conjugate Vaccine ◽

Herd Immunity ◽

Mechanistic Explanation ◽

Epidemiological Studies ◽

Contributing Factors ◽

Infant Mouse ◽

Major Benefit

ABSTRACT Epidemiological studies on Streptococcus pneumoniae show that rates of carriage are highest in early childhood and that the major benefit of the pneumococcal conjugate vaccine (PCV) is a reduction in the incidence of nasopharyngeal colonization through decreased transmission within a population. In this study, we sought to understand how anti- S. pneumoniae immunity affects nasal shedding of bacteria, the limiting step in experimental pneumococcal transmission. Using an infant mouse model, we examined the role of immunity (passed from mother to pup) on shedding and within-litter transmission of S. pneumoniae by pups infected at 4 days of life. Pups from both previously colonized immune and PCV-vaccinated mothers had higher levels of anti- S. pneumoniae IgG than pups from non-immune or non-vaccinated mothers and shed significantly fewer S. pneumoniae over the first 5 days of infection. By setting up cross-foster experiments, we demonstrated that maternal passage of antibody to pups either in utero or post-natally decreases S. pneumoniae shedding. Passive immunization experiments showed that type-specific antibody to capsular polysaccharide is sufficient to decrease shedding and that the agglutinating function of immunoglobulin is required for this effect. Finally, we established that anti-pneumococcal immunity and anti-PCV vaccination block host-to-host transmission of S. pneumoniae . Moreover, immunity in either the donor or recipient pups alone was sufficient to reduce rates of transmission, indicating that decreased shedding and protection from acquisition of colonization are both contributing factors. Our findings provide a mechanistic explanation for the reduced levels of S. pneumoniae transmission between hosts immune from prior exposure and among vaccinated children. IMPORTANCE Rates of carriage of the bacterial pathogen Streptococcus pneumoniae are highest among young children, and this is the target group for the pneumococcal conjugate vaccine (PCV). Epidemiological studies have suggested that a major benefit of the PCV is a reduction in host-to-host transmission, which also protects the non-vaccinated population (“herd immunity”). In this study, we examined the role of anti-pneumococcal immunity on nasal shedding and transmission of the pathogen using an infant mouse model. We found that shedding is decreased and transmission is blocked by anti-pneumococcal immunity and PCV vaccination. Additionally, transmission rates decreased if either the infected or contact pups were immune, indicating that reduced shedding and protection from the establishment of colonization are both contributing factors. Our study provides a mechanistic explanation for the herd immunity effect seen after the introduction of PCV and identifies potential points of intervention, which may have implications for future vaccine development.

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