Pneumococcal Capsular Polysaccharide Research Articles

Identification and Quantification of a Pneumococcal Cell Wall Polysaccharide by Antibody-Enhanced Chromatography Assay

Multivalent pneumococcal vaccines have been developed successfully to combat invasive pneumococcal diseases (IPD) and reduce the associated healthcare burden. These vaccines employ pneumococcal capsular polysaccharides (PnPs), either conjugated or unconjugated, as antigens to provide serotype-specific protection. Pneumococcal capsular polysaccharides used for vaccine often contain residual levels of cell wall polysaccharides (C-Ps), which can generate a non-serotype specific immune response and complicate the desired serotype-specific immunity. Therefore, the C-P level in a pneumococcal vaccine needs to be controlled in the vaccine process and the anti C-P responses need to be dialed out in clinical assays. Currently, two types of cell-wall polysaccharide structures have been identified: a mono-phosphocholine substituted cell-wall polysaccharide C-Ps1 and a di-phosphocholine substituted C-Ps2 structure. In our effort to develop a next-generation novel pneumococcal conjugate vaccine (PCV), we have generated a monoclonal antibody (mAb) specific to cell-wall polysaccharide C-Ps2 structure. An antibody-enhanced HPLC assay (AE-HPLC) has been established for serotype-specific quantification of pneumococcal polysaccharides in our lab. With the new anti C-Ps2 mAb, we herein extend the AE-HPLC assay to the quantification and identification of C-Ps2 species in pneumococcal polysaccharides used for vaccines.

Mucosal adjuvanticity and mucosal booster effect of colibactin-depleted probiotic Escherichia coli membrane vesicles

ABSTRACT There is a growing interest in development of novel vaccines against respiratory tract infections, due to COVID-19 pandemic. Here, we examined mucosal adjuvanticity and the mucosal booster effect of membrane vesicles (MVs) of a novel probiotic E. coli derivative lacking both flagella and potentially carcinogenic colibactin (ΔflhDΔclbP). ΔflhDΔclbP-derived MVs showed rather strong mucosal adjuvanticity as compared to those of a single flagellar mutant strain (ΔflhD-MVs). In addition, glycoengineered ΔflhDΔclbP-MVs displaying serotype-14 pneumococcal capsular polysaccharide (CPS14+MVs) were well-characterized based on biological and physicochemical parameters. Subcutaneous (SC) and intranasal (IN) booster effects of CPS14+MVs on systemic and mucosal immunity were evaluated in mice that have already been subcutaneously prime-immunized with the same MVs. With a two-dose regimen, an IN boost (SC-IN) elicited stronger IgA responses than homologous prime-boost immunization (SC-SC). With a three-dose regimen, serum IgG levels were comparable among all tested regimens. Homologous immunization (SC-SC-SC) elicited the highest IgM responses among all regimens tested, whereas SC-SC-SC failed to elicit IgA responses in blood and saliva. Furthermore, serum IgA and salivary SIgA levels were increased with an increased number of IN doses administrated. Notably, SC-IN-IN induced not only robust IgG response, but also the highest IgA response in both serum and saliva among the groups. The present findings suggest the potential of a heterologous three-dose administration for building both systemic and mucosal immunity, e.g. an SC-IN-IN vaccine regimen could be beneficial. Another important observation was abundant packaging of colibactin in MVs, suggesting increased applicability of ΔflhDΔclbP-MVs in the context of vaccine safety.

Experience with 23-valent pneumococcal polysaccharide vaccine in patients with ankylosing spondylitis and psoriatic arthritis

Pneumococcus plays a primary role as a causative agent of pneumonia both in the general population and in patients with immuno-inflammatory rheumatic diseases (IVRS), including spondylarthritis (SpA). However, data on the immunogenicity, efficacy and safety of pneumococcal vaccines in patients with SpA are limited.The aim of the study. To study the immunogenicity, efficacy and safety of the 23-valent pneumococcal polysaccharide vaccine (PPV-23) in patients with ankylosing spondylitis (AS) and psoriatic arthritis (PsA), observed at the V.A. Nasonova Research Institute (Moscow, Russia).Materials and methods. 145 people were included in the study: 51 patients with AS, 25 with PsA, 69 in control group (СG) without IVR. The majority of patients (65.8%) received immunosuppressive therapy. PPV-23 was administered in an amount of one dose (0.5 ml) subcutaneously against the background of antirheumatic therapy, regardless of the activity of the main IVR. The level of antibodies (AT) to pneumococcal capsular polysaccharide was determined using the EIA PCP IgG kit (TestLine Clinical Diagnostics, Czech Republic) before vaccination and 1, 3 and 12 months after it. The clinical efficacy and safety of PPV-23 were also evaluated, including the effect on the activity of AS and PsA according to the dynamics of BASDAI and DAPSA indices.Results. After 1, 3 and 12 months after vaccination, the concentration of pneumococcal AT was significantly higher compared to baseline values, which indicates sufficient immunogenicity of PPV-23. The clinical efficacy of PPV-23 in patients with AS and PsA was 98.7%. In general, there was no negative effect of vaccination on the activity of the underlying disease. The frequency of postvaccinal reactions in patients and in СG was comparable.Conclusions. The obtained results of the study indicate sufficient immunogenicity, clinical efficacy and safety of PPV-23 in patients with AS and Ps A.

Streptococcus pneumoniae serotype 33G: genetic, serological, and structural analysis of a new capsule type.

Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen with the greatest burden of disease in Asia and Africa. The pneumococcal capsular polysaccharide has biological relevance as a major virulence factor as well as public health importance as it is the target for currently licensed vaccines. These vaccines have limited valency, covering up to 23 of the >100 known capsular types (serotypes) with higher valency vaccines in development. Here, we have characterized a new pneumococcal serotype, which we have named 33G. We detected serotype 33G in nasopharyngeal swabs (n = 20) from children and adults hospitalized with pneumonia, as well as healthy children in Mongolia. We show that the genetic, serological, and biochemical properties of 33G differ from existing serotypes, satisfying the criteria to be designated as a new serotype. Future studies should focus on the geographical distribution of 33G and any changes in prevalence following vaccine introduction.

Characterization of pneumococcal serotype 7F in vaccine conjugation

Streptococcus pneumoniae is a highly invasive bacterial pathogen that can cause a range of illnesses. Pneumococcal capsular polysaccharides (CPS) are the main virulence factors that causes invasive pneumococcal disease (IPD). Pneumococcal CPS serotype 7F along with a few other serotypes is more invasive and likely to cause IPD. Therefore, 7F is a target for pneumococcal vaccine development, and is included in the two recently approved multi-valent pneumococcal conjugated vaccines, i.e. VAXNEUVANCE and PREVNAR 20.To support process and development of our 15-valent pneumococcal conjugated vaccine (PCV15), chromatographic methods have been developed for 7F polysaccharide and conjugate characterization. A size-exclusion chromatography (SEC) method with UV, light scattering and refractive index detections was employed for concentration, size and conformation analysis. A reversed-phase ultra-performance liquid chromatography (RP-UPLC) method was used for analysis of conjugate monosaccharide composition and degree of conjugation. The collective information obtained by these chromatographic analysis provided insights into the pneumococcal conjugate and conjugation process.Graphical

Humoral Immunodeficiency in two patients with Alagille Syndrome

IntroductionAlagille syndrome is an autosomal dominant entity caused by mutations that affect the Notch-Jagged1 signaling pathway. It is characterized by cholestasis due to poor bile ducts, congenital heart disease, skeletal abnormalities, ocular abnormalities and characteristic facial phenotype. We present 2 patients diagnosed with Alagille syndrome who presented associated immunodeficiency and required gammaglobulin treatment. Case 117-year-old male patient, who was liver transplanted at 19 months of the age. At 6 years of life, he underwent splenectomy secondary to immune thrombocytopenic purpura. He presented recurrent otitis and severe, large styes on the eyelids. He developed a first episode of pneumonia at 6. He received double kidney transplantation due to end-stage chronic kidney disease at 9. At the age of 10 laboratory results showed: IgG: 374 mg/dl IgM: 43 mg/dl IgE: 3 UI and IgA: 202 mg/dl. Functional responses against protein and polysaccharide antigens were absent. Lymphocytes populations were normal. He started treatment with intravenous gammaglobulin at 10 years of age. Case 27-year-old male patient with liver involvement, portal hypertension and portal vein cavernomas that evolved to hypersplenism with esophageal and gastric varices and gastrointestinal bleeding that required a splenorenal anastomosis and a stent. He presented a ventricular communication with a severe hypoplasia of the left pulmonary branch. He presented multiple infectious events including pneumococcal pneumonia. Laboratory showed pancytopenia secondary to hypersplenism, CD4 T lymphopenia (<250/uL)) with preserved CD4/CD8 ratio with normal lymphocyte proliferations, IgG: 450 mg/dl, IgM: 21 mg/dl, IgA: 136 mg/dl. A humoral response decay against global Pneumococcal capsular polysaccharide was observed. Variable response to protein antigen was present. Daily chemoprophylaxis with trimethoprim sulfamethoxazole was indicated but he repeated infectious episodes, then subcutaneous gammaglobulin was started. ConclusionsWe present2 patients diagnosed with Alagille syndromewith associated immunodeficiency. The NOTCH/Jagged 1 signaling pathway is of profound relevance to the process of somitogenesis and in the development of CD4 and CD8 lymphocytes. The immune compromise of patients with Alagille syndrome should be emphasized and eventually gammaglobulin treatment should be indicated.

Antibody enhanced HPLC for serotype-specific quantitation of polysaccharides in pneumococcal conjugate vaccine

Bacterial infection remains as one of the major healthcare issues, despite significant scientific and medical progress in this field. Infection by Streptococcus Pneumoniae (S. Pneumoniae) can cause pneumonia and other serious infectious diseases, such as bacteremia, sinusitis and meningitis. The pneumococcal capsular polysaccharides (CPS) that constitute the outermost layer of the bacterial cell are the main immunogens and protect the pathogen from host defense mechanisms. Over 90 pneumococcal CPS serotypes have been identified, among which more than 30 can cause invasive pneumococcal diseases that could lead to morbidity and mortality. Multivalent pneumococcal vaccines have been developed to prevent diseases caused by S. Pneumoniae. These vaccines employ either purified pneumococcal CPSs or protein conjugates of these CPSs to generate antigen-specific immune responses for patient protection. Serotype-specific quantitation of these polysaccharides (Ps) antigen species are required for vaccine clinical dosage, product release and quality control. Herein, we have developed an antibody-enhanced high-performance liquid chromatography (HPLC) assay for serotype-specific quantitation of the polysaccharide contents in multivalent pneumococcal conjugate vaccines (PCVs). A fluorescence-labeled multiplex assay format has also been developed. This work laid the foundation for a serotype-specific antigen assay format that could play an important role for future vaccine research and development.

Conjugation Mechanism for Pneumococcal Glycoconjugate Vaccines: Classic and Emerging Methods.

Licensed glycoconjugate vaccines are generally prepared using native or sized polysaccharides coupled to a carrier protein through random linkages along the polysaccharide chain. These polysaccharides must be chemically modified before covalent linking to a carrier protein in order to obtain a more defined polysaccharide structure that leads to a more rational design and safer vaccines. There are classic and new methods for site-selective glycopolysaccharide conjugation, either chemical or enzymatic modification of the polysaccharide length or of specific amino acid residues of the protein carrier. Here, we discuss the state of the art and the advancement of conjugation of S. pneumoniae glycoconjugate vaccines based on pneumococcal capsular polysaccharides to improve existing vaccines.

A highly immunogenic vaccine platform against encapsulated pathogens using chimeric probiotic Escherichia coli membrane vesicles

Vaccines against infectious diseases should elicit potent and long-lasting immunity, ideally even in those with age-related decline in immune response. Here we report a rational polysaccharide vaccine platform using probiotic Escherichia coli-derived membrane vesicles (MVs). First, we constructed a probiotic E. coli clone harboring the genetic locus responsible for biogenesis of serotype 14 pneumococcal capsular polysaccharides (CPS14) as a model antigen. CPS14 was found to be polymerized and mainly localized on the outer membrane of the E. coli cells. The glycine-induced MVs displayed the exogenous CPS14 at high density on the outermost surface, on which the CPS14 moiety was covalently tethered to a lipid A-core oligosaccharide anchor. In in vivo immunization experiments, CPS14+MVs, but not a mixture of free CPS14 and empty MVs, strongly elicited IgG class-switch recombination with a Th1/Th2-balanced IgG subclass distribution without any adjuvant. In addition, CPS14+MVs were structurally stable with heat treatment and immunization with the heat-treated MVs-elicited CPS14-specific antibody responses in mouse serum to levels comparable to those of non-treated CPS14+MVs. Notably, the immunogenicity of CPS14+MVs was significantly stronger than those of two currently licensed vaccines against pneumococci. The CPS14+MV-elicited humoral immune responses persisted for 1 year in both blood and lung. Furthermore, the CPS14+MV vaccine was widely efficacious in mice of different ages. Even in aged mice, vaccination resulted in robust production of CPS14-specific IgG that bound to the pneumococcal cell surface. Taken together, the present probiotic E. coli MVs-based vaccine platform offers a promising, generalizable solution against encapsulated pathogens.

Effect of FcRn antagonism on protective antibodies and to vaccines in IgG-mediated autoimmune diseases pemphigus and generalised myasthenia gravis

Antagonism of the neonatal Fc receptor (FcRn) by efgartigimod has been studied in several autoimmune diseases mediated by immunoglobulin G (IgG) as a therapeutic approach to remove pathogenic IgGs. Whereas reduction of pathogenic titres has demonstrated efficacy in multiple autoimmune diseases, reducing total IgG could potentially increase infection risk in patients receiving FcRn antagonists. The objective of this study was to analyse the effect of FcRn antagonism with efgartigimod on existing protective antibody titres and the ability to mount an immune response after vaccine challenge. Serum levels of total IgG and protective antibodies against tetanus toxoid (TT), varicella zoster virus (VZV), and pneumococcal capsular polysaccharide (PCP) were measured in all patients enrolled in an open-label trial of efgartigimod for the treatment of pemphigus. Vaccine specific-responses were assessed by measuring changes in IgG titres in patients with generalised myasthenia gravis (gMG) who were treated with efgartigimod and who received influenza, pneumococcal, or coronavirus disease 2019 (COVID-19) vaccines during participation in the double-blind trial ADAPT or open-label extension, ADAPT+ (n = 17). FcRn antagonism reduced levels of protective anti-TT, anti-VZV, and anti-PCP antibodies and total IgG to a similar extent; anti-TT and anti-VZV titres remained above minimally protective thresholds for the majority of patients, (10/12) 83% and (14/15) 93% respectively. Protective antibodies returned to baseline values upon treatment cessation. Antigen-specific IgG responses to influenza, pneumococcal, and COVID-19 immunisation were detected in patients with gMG who received these vaccines while undergoing therapy with efgartigimod. In conclusion, FcRn antagonism with efgartigimod did not hamper generation of IgG responses but did transiently reduce IgG titres of all specificities.

High-Performance Anion-Exchange chromatography with conductivity detection method for simultaneous determination of nitrogen and phosphorus in polysaccharides

Capsular polysaccharides of Streptococcus pneumoniae contain a characteristic mix of monosaccharides in their structure resulting in immunologically distinct serotypes. Pneumococcal capsular polysaccharides include sugars such as hexoses, uronic acids, hexosamines, methyl pentoses, other functional groups are attached to the sugars are N and O-acetyl groups, nitrogen and phosphorus. Most of these components can be quantified using different colorimetric methods. However, available methods for quantifying nitrogen and phosphorus are not sensitive enough and laborious. We report a highly sensitive high-performance anion-exchange chromatography-conductivity detector (HPAEC-CD) method for quantifying nitrogen and phosphorus present in pneumococcal capsular polysaccharides. The method is reliable, robust and reproducible with no interference. The LOQ for nitrogen and phosphorus of 3.125 and 62.5 ng/mL, respectively, is highly critical for estimating low levels of total nitrogen and total phosphorus. We have implemented this method to quantify total nitrogen in Typhoid Vi polysaccharide and phosphorus in Haemophilus influenzae type-b polysaccharide. This method has greater application for quantification of nitrogen and phosphorus present in low concentrations in polysaccharide vaccines/biologicals.

A prospective study of the infant gut microbiome in relation to vaccine response.

The establishment of the gut microbiome plays a key symbiotic role in the developing immune system; however, its influence on vaccine response is yet uncertain. We prospectively investigated the composition and diversity of the early-life gut microbiome in relation to infant antibody response to two routinely administered vaccines. Eighty-three infants enrolled in the New Hampshire Birth Cohort Study were included in the analysis. We collected blood samples at 12 months of age and assayed the isolated serum to quantify total IgG and measured antibody to pneumococcal capsular polysaccharide and tetanus toxoid. Stool samples were collected from infants at 6 weeks of age and sequenced using 16S rRNA, and a subset of 61 samples were sequenced using shotgun metagenomics sequencing. We observed differences in beta diversity for 16S 6-week stool microbiota and pneumococcal and tetanus IgG antibody responses. Metagenomics analyses identified species and metabolic pathways in 6-week stool associated with tetanus antibody response, in particular, negative associations with the relative abundance of Aeriscardovia aeriphila species and positive associations with the relative abundance of species associated with CDP-diacylglycerol biosynthesis pathways. The early gut microbiome composition may influence an infant's vaccine response. Early intestinal microbiome acquisition plays a critical role in immune maturation and in both adaptive and innate immune response in infancy. We identified associations between early life microbiome composition and response to two routinely administered vaccines-pneumococcal capsular polysaccharide and tetanus toxoid-measured at approximately 1 year of age. Our findings highlight the potential impact of the gut microbiome on infant immune response that may open up opportunities for future interventions.

Immunogenicity, Safety, and Clinical Effectiveness of the 23-Valent Pneumococcal Polysaccharide Vaccine in Patients With Spondyloarthritis (Preliminary Data)

Background. Immunosuppressive drugs are widely used for the treatment of patients with spondyloarthritis (SpA) to effectively control the activity of the disease. At the same time, the use of these drugs is associated with an increased risk of developing infections of the upper and lower respiratory tract, which can be prevented by vaccination. The aim of the study was to evaluate the immunogenicity, safety, and clinical efficacy of the 23-valent pneumococcal polysaccharide vaccine (PPV-23) in patients with SpA. Material and methods. The study included 54 patients with SpA: 39 with ankylosing spondylitis, and 15 with psoriatic arthritis. Most patients had a history of two or more cases of lower respiratory tract infections, 2 patients reported a monthly exacerbation of chronic sinusitis, one patient reported the development of otitis every 2–3 months. 72% of patients received immunosuppressive therapy at the time of inclusion in the study. PPV-23 was administered in the amount of 1 dose (0.5 ml) against the background of ongoing antirheumatic therapy. The level of antibodies to pneumococcal capsular polysaccharide was determined using the EIA PCP IgG kit (TestLine Clinical Diagnostics s.r.o., Czech Republic) at baseline, after 1, 3, and 12 months after vaccination. The tolerability of PPV-23, the effect of vaccination on SpA activity (according to the dynamics of the BASDAI index), and the incidence of upper and lower respiratory tract infections were assessed. Results. The concentration of antibodies to pneumococcal capsular polysaccharide was significantly higher 1, 3, and 12 months after vaccination compared to baseline. There was no negative effect of vaccination on the activity of SpA and the emergence of «new» autoimmune disorders. The vaccine was well tolerated by 76% of patients., Only one patient developed pneumonia during the observation period. Patients suffering from frequent sinusitis and otitis reported the absence of these infections after vaccination. Conclusions. Preliminary results of the study indicate sufficient immunogenicity, safety, and clinical efficacy of PPV-23 in patients with SpA.

Sex Influences Age-Related Changes in Natural Antibodies and CD5+ B-1 Cells.

Natural Abs are primarily produced by B-1 cells and are essential for protection against Streptococcus pneumoniae The incidence and mortality rate for pneumococcal infection increases dramatically after age 65, disproportionately affecting males in both human and murine systems. To date, there is a significant gap in our understanding of the relationship among sex, aging, natural IgM efficacy, and the natural IgM repertoire. Our investigation demonstrates that the protective capacity of serum IgM against pneumococcal infection is maintained in IgM obtained from aged female mice but absent in IgM from aged male mice. To understand this difference in protective capacity, we examined serum Ig, discovering that the protective change was not associated with shifts in levels of phosphorylcholine (PC)- or pneumococcal capsular polysaccharide serotype 3-specific IgM. Interestingly, we observed that aged females have an increase in the total number of CD5+ B-1 cells, higher serum IL-5 levels, and a larger percentage of aged female CD5+ B-1 cells that express CD86 as compared with aged males. Furthermore, single-cell IgM repertoire analysis from peritoneal PC+, splenic PC+, and bone marrow CD5+ B-1 cell subsets demonstrated greater diversity with age and a higher level of germline status in female mice than previously observed in studies of aged male mice. Aged female CD5+ B-1 cells also expressed higher levels of transcripts associated with cell activity and self-renewal, such as Nanog and Hmga2 Taken together, these data indicate that females maintain a more diverse and active CD5+ B-1 cell pool and natural IgM repertoire, which has implications for sex-related susceptibility to infection and disease.

Impact of Janus kinase inhibitors on antibody response to 13-valent pneumococcal conjugate vaccine in patients with rheumatoid arthritis.

To evaluate the antibody response to 13-valent pneumococcal conjugate vaccine (PCV13) in patients with rheumatoid arthritis receiving Janus kinase inhibitors (JAKIs). Fifty-three patients receiving methotrexate (MTX; n = 10), JAKI (n = 20), or MTX + JAKI (n = 23) were vaccinated with PCV13. Serum concentrations of immunoglobulin G (IgG) antibodies to 13 pneumococcal serotype capsular polysaccharides were quantified before and 4-6 weeks after vaccination. Positive antibody response was defined as a 2-fold or more increase in IgG concentrations from prevaccination levels. After vaccination, IgG concentrations significantly increased in all treatment groups (P <0.001), but fold increases (postvaccination to prevaccination ratios) were different among treatment groups (9.30 for MTX, 6.36 for JAKI, and 3.46 for combination therapy). Positive antibody response rates were comparable between the MTX group (90%) and the JAKI group (95%) but lower in the MTX + JAKI group (52.2%). In a multivariable logistic regression analysis, the combination therapy was the only factor associated with a reduced antibody response to PCV13. No severe adverse events were observed in any treatment group. Although JAKIs do not impair PCV13 immunogenicity in rheumatoid arthritis patients, the combination of MTX with JAKI can reduce the antibody response in this patient population.

Study Protocol for Preventing Early-Onset Pneumonia in Young Children Through Maternal Immunisation: A Multi-Centre Randomised Controlled Trial (PneuMatters).

Background: Preventing and/or reducing acute lower respiratory infections (ALRIs) in young children will lead to substantial short and long-term clinical benefits. While immunisation with pneumococcal conjugate vaccines (PCV) reduces paediatric ALRIs, its efficacy for reducing infant ALRIs following maternal immunisation has not been studied. Compared to other PCVs, the 10-valent pneumococcal-Haemophilus influenzae Protein D conjugate vaccine (PHiD-CV) is unique as it includes target antigens from two common lower airway pathogens, pneumococcal capsular polysaccharides and protein D, which is a conserved H. influenzae outer membrane lipoprotein.Aims: The primary aim of this randomised controlled trial (RCT) is to determine whether vaccinating pregnant women with PHiD-CV (compared to controls) reduces ALRIs in their infants' first year of life. Our secondary aims are to evaluate the impact of maternal PHiD-CV vaccination on different ALRI definitions and, in a subgroup, the infants' nasopharyngeal carriage of pneumococci and H. influenzae, and their immune responses to pneumococcal vaccine type serotypes and protein D.Methods: We are undertaking a parallel, multicentre, superiority RCT (1:1 allocation) at four sites across two countries (Australia, Malaysia). Healthy pregnant Australian First Nation or Malaysian women aged 17–40 years with singleton pregnancies between 27+6 and 34+6 weeks gestation are randomly assigned to receive either a single dose of PHiD-CV or usual care. Treatment allocation is concealed. Study outcome assessors are blinded to treatment arms. Our primary outcome is the rate of medically attended ALRIs by 12-months of age. Blood and nasopharyngeal swabs are collected from infants at birth, and at ages 6- and 12-months (in a subset). Our planned sample size (n = 292) provides 88% power (includes 10% anticipated loss to follow-up).Discussion: Results from this RCT potentially leads to prevention of early and recurrent ALRIs and thus preservation of lung health during the infant's vulnerable period when lung growth is maximum. The multicentre nature of our study increases the generalisability of its future findings and is complemented by assessing the microbiological and immunological outcomes in a subset of infants.Clinical Trial Registration: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374381, identifier: ACTRN12618000150246.

A Novel Pneumococcal Surface Protein K of Nonencapsulated Streptococcus pneumoniae Promotes Transmission among Littermates in an Infant Mouse Model with Influenza A Virus Coinfection.

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 nonvaccine serotypes, including NESp, has been highlighted as a challenge in treatment strategy, but the virulence of NESp is not well understood. Protective strategies against NESp colonization and transmission between children require particularly urgent evaluation. NESp lacks capsules, a major virulence 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 coinfection. 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.

Evaluation of effectiveness, safety and cost-benefit of the 23– valent pneumococcal capsular polysaccharide vaccine for HIV-Infected patients

IntroductionDue to the lack of understanding of the protective effects and safety of 23-valent pneumococcal polysaccharide vaccine (PPV23) in immune-deficient populations, the vaccination rate of PPV23 among HIV-infected patients is still very low in China. The main objectives of this study were to determine whether the efforts to assess measures for the prevention of pneumococcal pneumonia are still worthwhile, and provide designated vaccination program of HIV-infected persons for government policy based on. Methods60 HIV-infected adults in Lanshan county who had never been vaccinated with any pneumococcal vaccine were enrolled in this study, voluntary vaccination of PPV23 and One-year follow-up after vaccination can be completed. Result76.67% patients (46/60) had serologic response at 12 months after vaccine, CD4 count(≤500 cells/ul or > 500 cells/ul) and Month from diagnosis to first antiviral therapy (≤1 month or > 1 month) were related to antibody responses (p < 0.05).In this study, PPV23 was well tolerated, no adversereaction was reported.11 Streptococcus pneumoniae pneumonia (9.17%,11/120) occurred in the Unvaccinated group and 1 case(1.67%,1/60)in the vaccination group within one year after vaccination(Fisher's exact probability, P = 0.225). The VE was 81.79%. The per capita benefit was 39.32 dollars, thebenefit-costratio = 1.19. There are significant statistical differences between the vaccinated group and the non-vaccinated group in outpatient costs (p < 0.05, 95 %CI: 9.29–32.11), Medicine costs (p = 0.017, 95 %CI: 2.47–24.44), and disease related indirect costs (p = 0.038, 95 %CI: 0.93–33.63) within one year of vaccination. ConclusionOur study results showed that PPV23 can be safely and effectively administered to HIV-1 infected individuals and effectively preventing Streptococcal pneumonia. Considering the cost-benefit of vaccination among HIV-infected persons, as it has been reported in our study, it is necessary to promote the widespread use of the vaccine among HIV-infected persons in the future.

Isolation and Characterization of Human Monoclonal Antibodies to Pneumococcal Capsular Polysaccharide 3.

ABSTRACTThe current pneumococcal capsular polysaccharide (PPS) conjugate vaccine (PCV13) is less effective against Streptococcus pneumoniae serotype 3 (ST3), which remains a major cause of pneumococcal disease and mortality. Therefore, dissecting structure-function relationships of human ST3 pneumococcal capsular polysaccharide (PPS3) antibodies may reveal characteristics of protective antibodies. Using flow cytometry, we isolated PPS3-binding memory B cells from pneumococcal vaccine recipients and generated seven PPS3-specific human monoclonal antibodies (humAbs). Five humAbs displayed ST3 opsonophagocytic activity, four induced ST3 agglutination in vitro, and four mediated both activities. Two humAbs, namely, C10 and C27, that used the same variable heavy (VH) and light (VL) chain domains (VH3-9*01/VL2-14*03) both altered ST3 gene expression in vitro; however, C10 had fewer VL somatic mutations, higher PPS3 affinity, and promoted in vitro ST3 opsonophagocytic and agglutinating activity, whereas C27 did not. In C57BL/6 mice, both humAbs reduced nasopharyngeal colonization with ST3 A66 and a clinical strain, B2, and prolonged survival following lethal A66 intraperitoneal infection, but only C10 protected against lethal intranasal infection with the clinical strain. After performing VL swaps, C10VH/C27VL exhibited reduced ST3 binding and agglutination, but C27VH/C10VL binding was unchanged. However, both humAbs lost the ability to reduce colonization in vivo when their light chains were replaced. Our findings associate the ability of PPS3-specific humAbs to reduce colonization with ST3 agglutination and opsonophagocytic activity, and reveal an unexpected role for the VL in their functional activity in vitro and in vivo. These findings also provide insights that may inform antibody-based therapy and identification of surrogates of vaccine efficacy against ST3.IMPORTANCE Despite the global success of vaccination with pneumococcal conjugate vaccines, serotype 3 (ST3) pneumococcus remains a leading cause of morbidity and mortality. In comparison to other vaccine-included serotypes, the ST3 pneumococcal capsular polysaccharide (PPS3) induces a weaker opsonophagocytic response, which is considered a correlate of vaccine efficacy. Previous studies of mouse PPS3 monoclonal antibodies identified ST3 agglutination as a correlate of reduced ST3 nasopharyngeal colonization in mice; however, neither the agglutinating ability of human vaccine-elicited PPS3 antibodies nor their ability to prevent experimental murine nasopharyngeal colonization has been studied. We generated and analyzed the functional and in vivo efficacy of human vaccine-elicited PPS3 monoclonal antibodies and found that ST3 agglutination associated with antibody affinity, protection in vivo, and limited somatic mutations in the light chain variable region. These findings provide new insights that may inform the development of antibody-based therapies and next-generation vaccines for ST3.

Immunogenicity, safety and efficacy of 23-valent pneumococcal polysaccharide vaccine in patients with inflammatory joint diseases (preliminary data)

Intoduction.Currently, for the treatment of patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA), basic anti-inflammatory drugs and biological drugs are widely used to effectively control the activity of the disease. However, the use of these drugs is associated with an increased risk of developing comorbid infections, some of which can be prevented by vaccination. Objective. To evaluate the immunogenicity, safety, and clinical efficacy of the 23-valent pneumococcal polysaccharide vaccine (PPV-23) in patients with RA and SpA.Materials and methods. The study included 122 patients: 79 - with RA, 43-with SpA. Most patients had a history of two or more cases of lower respiratory tract infections, 2 patients reported a monthly exacerbation of chronic sinusitis, one patient reported the development of otitis media every 2-3 months. At the time of inclusion in the study, most patients received immunosuppressive therapy. PPV-23 was administered in an amount of 1 dose (0.5 ml) subcutaneously against the background of anti-rheumatic therapy. The level of antibodies to pneumococcal capsular polysaccharide was determined using the EIA PCP IgG kit (TestLine Clin-ical Diagnostics s.r.o., Czech Republic) before vaccination, 1, 3 and 12 months after vaccination. In addition, the tolerance of PPV-23, the frequency of pneumonia, and the effect on the activity of RA and SpA were evaluated (according to the dynamics of DAS28 and BASDAI).Results.At 1, 3, and 12 months after vaccination, the concentration of antibodies to pneumococcal capsular polysaccharide was significantly higher than the baseline values, which indicates sufficient immunogenicity of PPV-23. There was no negative effect of vaccination on the activity of the underlying disease and the occurrence of new autoimmune disorders. In the majority of patients (67% - RA, 81.4% - SpA), the tolerance of the vaccine was good. During the follow-up period, none of the patients developed pneumonia. Patients suffering from frequent sinusitis and otitis media reported the absence of these infections after vaccination.Conclusion.Preliminary results of the study indicate sufficient immunogenicity, safety, and clinical efficacy of PPV-23 in patients with RA and SpA.