Pneumococcal Capsular Polysaccharide Research Articles

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.

Development of a pneumococcal conjugate vaccine based on chemical conjugation of polysaccharide serotype 6B to PspA

The use of conjugate vaccines remains an effective intervention to prevent pneumococcal diseases. In order to expand vaccine coverage, the inclusion of pneumococcal proteins as carriers is a propitious alternative that has been explored over the past few years. In this study, pneumococcal surface protein A (PspA) clade 1, family 1 (PspA1) and clade 3, family 2 (PspA3) were used as carrier proteins for pneumococcal capsular polysaccharide serotype 6B (Ps6B). Employing an improved reductive amination chemistry, 50% of Ps6B was incorporated to each protein, PspA1 and PspA3. The effect of chemical modifications in Ps6B and PspA was assessed by an antigenicity assay and circular dichroism, respectively. Fragmentation and oxidation decreased the antigenicity of Ps6B while conjugation improved antigenicity. In the same manner, introduction of adipic acid dihydrazide (ADH) reduced PspA secondary structure content, which was partially restored after conjugation. Immunization of Ps6B-PspA1 and Ps6B-PspA3 conjugates in mice induced specific IgG antibodies against the Ps6B and the protein; and anti-PspA antibodies had functional activity against two pneumococcal strains with different serotypes. These results suggest that chemical coupling between Ps6B and PspA did not affect antigenic epitopes and support the further development of PspA as a carrier protein in pneumococcal conjugate vaccines to provide broader protection.

Impact of HIV-1 Infection and Antigen Class on T Follicular Helper Cell Responses to Pneumococcal Polysaccharide-Protein Conjugate Vaccine-13.

Pneumococcal infections are common and serious complications of HIV-1 disease. Prevention has been compromised by the limited magnitude and quality of Ab responses to T cell-independent type 2 pneumococcal capsular polysaccharides (PPS). The pneumococcal polysaccharide-protein conjugate vaccine-13 (PCV-13) contains PPS conjugated to the T cell-dependent protein (diphtheria toxoid [DT] [CRM197]). We investigated the differential response to PPS and DT by human Ab-secreting B cells (ASC) after immunization with PCV-13 in newly diagnosed healthy HIV+ and control adults. The numbers of PPS-specific IgG ASC increased significantly and similarly in HIV+ and controls. However, DT-specific IgG ASC increased in controls but not HIV+ subjects. To determine the cellular basis of these disparate responses to DT and PPS, we characterized the frequency and activation of T follicular helper (Tfh) cells, the predominant T cell subset providing B cell help. Expression of inducible T cell costimulator (ICOS), which sustains Tfh function and phenotype, increased significantly among controls, when compared with the HIV+ group. Increases in ICOS+ Tfh correlated with changes in T-dependent, DT-specific IgG ASC in controls but not in HIV+ In contrast, ICOS expression did not correlate with T cell-independent type 2 PPS-specific ASC in either group. Of note, upon optimized ex vivo stimulation, CD4 T cells from HIV+ subjects differentiated into Tfh cells and formed synapses with Raji B cells at frequencies similar to that of controls. In summary, PCV-13-induced increase in ICOS expression on Tfh was associated with responses to DT, which was compromised in recently diagnosed healthy HIV+ adults and can be restored ex vivo by providing effective Tfh-differentiating signals.

Prevalence and predictors of SARS-CoV-2 antibodies among solid organ transplant recipients with confirmed infection.

It remains uncertain whether immunocompromised patients including solid organ transplant (SOT) recipients will have a robust antibody response to SARS‐CoV‐2 infection. We enrolled all adult SOT recipients at our center with confirmed SARS‐CoV‐2 infection who underwent antibody testing with a single commercially available anti‐nucleocapsid antibody test at least 7 days after diagnosis in a retrospective cohort. Seventy SOT recipients were studied (56% kidney, 19% lung, 14% liver ± kidney, and 11% heart ± kidney recipients). Thirty‐six (51%) had positive anti‐nucleocapsid antibody testing, and 34 (49%) were negative. Recipients of a kidney allograft were less likely to have positive antibody testing compared to those who did not receive a kidney (p = .04). In the final multivariable model, the years from transplant to diagnosis (OR 1.26, p = .002) and baseline immunosuppression with more than two agents (OR 0.26, p = .03) were significantly associated with the antibody test result, controlling for kidney transplantation. In conclusion, among SOT recipients with confirmed infection, only 51% of patients had detectable anti‐nucleocapsid antibodies, and transplant‐related variables including the level and nature of immunosuppression were important predictors. These findings raise the concern that SOT recipients with COVID‐19 may be less likely to form SARS‐CoV‐2 antibodies.

Establishment and verification of a quantitative ELISA assay for detection of human serotype specific IgG against Streptococcus pneumoniae

Objective To establish a quantitative enzyme-linked immunosobent assay (ELISA) recommended by World Health Organization (WHO) for the detection of human serotype specific immunoglobulin G (IgG) against Streptococcus pneumoniae (Sp). Methods According to WHO′s operation manual for Enzyme linked immunosobent assay ELISA for the quantitative of Streptococcus pneumoniae serotype specific IgG (Pn PS ELISA), we established a ELISA method to detect serotype specific IgG against Sp in human serum specimens by using Sp capsular polysaccharide 4, 6B, 9V, 14, 18C, 19F, and 23F (purchased American Type Culture Collection, ATCC) as coating antigens and pneumococcal capsular polysaccharide antibody standard serum 007 sp (from National Institute for Biological Standards and Control, NIBSC) as standard serum. The accuracy and stability of the established method were evaluated using WHO′s calibration serum panel and internal quality control serum PnG. Results The concentration of 7 serotype specific coating antigens of Sp capsular polysaccharide (4, 6b, 9V, 14, 18C、19F and 23F) were determined and serotype specific IgG against Sp in human serum specimens were detected with the quantitative ELISA method established. More than 75% of measurements for 7 serotype specific Sp capsular polysaccharide IgG antibodies for 12 WHO calibration sera were within ± 40% of the measurement values assigned by reference laboratories of WHO, with an overall consistency rate of 86.9%, a correlation curve slope of 0.94, and an R2 of 0.99, respectively. In addition, the results of 20 consecutive internal quality control serum test showed that the coefficient of variation (CV) of different batches were less than 15%, which met the requirements of WHO intra-laboratory evaluation. Conclusion A quantitative ELISA method recommended by WHO for detection of serotype-specific Streptococcus pneumoniae IgG antibody in human serum was successfully established and verified. The accurate and stable method meet the requirements of disease surveillance and vaccine effect evaluation.

The human natural anti-αGal antibody targets common pathogens by broad-spectrum polyreactivity.

Naturally occurring antibodies are abundant in human plasma, but their importance in the defence against bacterial pathogens is unclear. We studied the role of the most abundant of such antibodies, the antibody against terminal galactose-α-1,3-galactose (anti-αGal), in the protection against pneumococcal infections (Streptococcus pneumonia). All known pneumococcal capsular polysaccharides lack terminal galactose-α-1,3-galactose, yet highly purified human anti-αGal antibody of the IgG class reacted with 48 of 91 pneumococcal serotypes. Anti-αGal was found to contain multiple antibody subsets that possess distinct specificities beyond their general reactivity with terminal galactose-α-1,3-galactose. These subsets in concert targeted a wide range of microbial polysaccharides. We found that anti-αGal constituted up to 40% of the total antibody reactivity to pneumococci in normal human plasma, that anti-αGal drives phagocytosis of pneumococci by human neutrophils and that the anti-αGal level was twofold lower in patients prone to pneumococcal infections compared with controls. Moreover, during a 48-year period in Denmark, the 48 anti-αGal-reactive serotypes caused fewer invasive pneumococcal infections (n=10927) than the 43 non-reactive serotypes (n=18107), supporting protection on the population level. Our findings explain the broad-spectrum pathogen reactivity of anti-αGal and support that these naturally occurring polyreactive antibodies contribute significantly to human protective immunity.

10. Kinetics of Post-Vaccination Seroprotection to S. Pneumonia for the Immune-Compromised and Vaccine-Naïve Populations

Background S. pneumonia infection presents a significant challenge, accounting for 20–38% of hospital-acquired pneumonia, and the leading cause of community-acquired pneumonia despite availability of effective vaccines. Incidence is highest in children under 2 years, the immunocompromised, and elderly. CDC has reported the emergence of antibiotic resistance in ~30% of cases, adding to risk of morbidity and mortality. Fewer than half of the elderly are vaccinated and vulnerable to infection on admission. Passive immunotherapy as an adjunct to vaccines may improve outcomes in such populations. The objective of this study was to evaluate whether seroprotective response induced with a pneumococcal conjugate vaccine could rapidly yield protective opsonic levels of antibody within anticipated duration of hospitalization.MethodsHealthy donors (n=30) were immunized with Prevnar. Blood was drawn on days 0, 3, 7, 10, 14, 21, and 28. Samples were pooled and tested for presence of functional opsonic antibodies recognizing capsular polysaccharides. Clearance mechanism of S. pneumonia was based on antibody recognition to pneumococcal capsular polysaccharide and opsonic titers used as an in vitro surrogate to evaluate the efficacy of vaccine.ResultsThere was little to no opsonic activity against most serotypes on day 0, except for low antibody activity with serotypes 1, 3, 4, and 5. Titers increased, with protective levels achieved by day 10 for most serotypes (except 14 and 18C), peaking at day 14 or after across serotypes (Figures 1 and 2). Average titers rose from log2 titer 2 on day 0 to log2 titer 8 on days 21 and 28. Titers against most serotypes reached log2 10 (titer 1024) or higher. Patients remained susceptible to nosocomial infection for at least 10 days post admission until protective titers are reached.OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V. N=2. OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 14, 18C, 19A, 19F, and 23F. N=2. ConclusionPatients with no prior history of vaccination (or inability to mount response) with Prevnar or pneumovax remain vulnerable to S. pneumonia infection even if vaccinated on entry, due to delayed kinetics in reaching protective titers. These patients may require prophylactic intervention of hyperimmune Ig with high opsonic titers to S. pneumonia, providing protection until vaccine response elicits protective antibodies.Disclosures All Authors: No reported disclosures

The level of naturally occurring anti-αGal antibody predicts antibody response to polysaccharide vaccination in HIV-infected adults.

In clinical practice, the capacity for producing anti-carbohydrate antibodies is regarded as an entity, but supportive evidence is lacking. We hypothesized that the outcome of the gold standard test for clinical assessment of this capacity, antibody response to polysaccharide vaccination, correlated with the level of the abundant naturally occurring anti-carbohydrate antibody, anti-αGal. To perform an exploratory study, 47 HIV-infected adults were recruited from a vaccine trial. Participants received a 23-valent pneumococcal capsular polysaccharide vaccine. Plasma samples obtained just before and median 4weeks after the vaccination were quantified for IgG anti-αGal antibody and IgG antibodies to polysaccharides present in the vaccine (serotypes 1, 7F and 19A) by solid-phase type immunoassays. The vaccination responses were assessed as a categorical variable (based on criteria defined by The American Academy of Allergy, Asthma & Immunology and the American College of Allergy, Asthma & Immunology) and as three different continuous variables (antibody increment, geometrical average and standard normal deviates of the achieved antibody concentrations). The baseline anti-αGal level predicted the vaccine response as a categorical variable (ROC-curve analysis, AUC=0.71; 95%CI: 0.55-0.86) and as the three continuous variables (eg slope of linear regression of geometrical average=0.37; 95%CI: 0.15-0.59). The correlation between the anti-αGal level and antibody responses to polysaccharide vaccination fits with a shared underlying capacity. Thus, the present study supports the notion of a measurable capacity for the production of anti-carbohydrate antibodies in each individual. Firm conclusions on the generalizability and clinical utility require further studies.

Decoding capsule synthesis in Streptococcus pneumoniae.

Streptococcus pneumoniae synthesizes >100 types of capsular polysaccharides (CPSs). While the diversity of the enzymes and transporters involved is enormous, it is not limitless. In this review, we summarized the recent progress on elucidating the structure-function relationships of CPSs, the mechanisms by which they are synthesized, how their synthesis is regulated, the host immune response against them and the development of novel pneumococcal vaccines. Based on the genetic and structural information available, we generated provisional models of the CPS repeating units that remain unsolved. In addition, to facilitate cross-species comparisons and assignment of glycosyltransferases, we illustrated the biosynthetic pathways of the known CPSs in a standardized format. Studying the intricate steps of pneumococcal CPS assembly promises to provide novel insights for drug and vaccine development as well as improve our understanding of related pathways in other species.

Structural, biosynthetic and serological cross-reactive elucidation of capsular polysaccharides from Streptococcus pneumoniae serogroup 28

Capsular polysaccharides (CPS) are the key virulent factors in the pathogenesis of Streptococcus pneumoniae. The previously unknown CPS structures of the pneumococcal serotype 28F and 28A were thoroughly characterized by NMR spectroscopy, chemical analysis and AF4-MALS-dRI. The following repeat unit structures were determined: -4)[α-l-Rhap-[4-P-2-Gro]]-(1-3)-α-d-Sug-[6-P-Cho]-(1-3)-β-l-Rhap-[2-OAc]-(1-4)-β-d-Glcp-(1-; 28F: Sug = Glcp, Mw: 540.5 kDa; 28A: Sug = GlcpNAc, Mw: 421.9 kDa; The correlation of CPS structures with biosynthesis showed that glycosyltransferase WciU in serotypes 28F and 28A had different sugar donor specificity toward α-d-Glcp and α-d-GlcNAcp, respectively. Furthermore, latex agglutination tests of de-OAc and de-PO4 CPS were conducted to understand cross-reactions between serogroup 28 with factor antiserum 23d. Interestingly, the de-OAc 28F and 28A CPS can still weakly react with factor antiserum 23d, while de-PO4 CPS did not react with factor antiserum 23d. This indicated that OAc group could affect the affinity and P-2-Gro was crucial for cross-reacting with factor antiserum 23d.

A Japanese nationwide survey of 23-valent pneumococcal capsular polysaccharide vaccine (PPSV23) revaccination coverage rate among elderly adults aged 65 and older and physician’s attitude

ABSTRACT In July 2017, the Japanese Association for Infectious Diseases issued guidance for the administration of the PPSV23 revaccination. Despite increasing recognition of its protective benefits, levels of PPSV23 revaccination coverage rate in Japanese elderly population are unclear at present. Here, we report the results of a survey to know PPSV23 revaccination rates among elderly patients aged 65 and older. We asked an array of questions related to PPSV23 revaccination to Elderly adults and doctors across Japan via Web-based surveys in June 2018. The sampled population consisted of 5,085 men and women aged 65 and older. The PPSV23 revaccination coverage rate was estimated by survey questions regarded vaccination counts, intervals, and vaccine type. In addition, 400 internal medicine physicians were surveyed and asked about their reasons for recommending PPSV23 revaccination to elderly patients. In total, 1,648 elderly adults had received at least one PPSV23 dose; of these, 58 had received it at least twice (revaccination coverage rate: 3.5%). The most commonly cited justification for revaccination with PPSV23 among the surveyed physicians was that the benefits of revaccination exceed the risks of revaccination. In addition, multivariate analysis showed revaccinated status was most strongly associated with recommendations from peers (e.g. spouse, family, friends) among elderly subjects. This study reports PPSV23 revaccination coverage rate among Japanese adults aged 65 and older for the first time and concludes that the coverage rate is very low.

Quality Improvement of Capsular Polysaccharide in Streptococcus pneumoniae by Purification Process Optimization.

Streptococcus pneumoniae is the causative agent of many diseases, most notably pneumonia. Most of the currently used vaccines to protect against this pathogen employ pneumococcal capsular polysaccharides (CPSs) as antigens, but purifying CPS of sufficient quality has been challenging. A purification process for CPS comprising conventional methods such as ultrafiltration, CTAB precipitation, and chromatography was previously established; however, this method resulted in high cell wall polysaccharide (CWPS) contamination, especially for serotype 5. Thus, a better purification method that yields CPS of a higher quality is needed for vaccine development. In this study, we significantly reduced CWPS contamination in serotype 5 CPS by improving the ultrafiltration and CTAB precipitation steps. Moreover, by applying an acid precipitation process to further remove other impurities, serotype 5 CPS was obtained with a lower impurity such as decreased nucleic acid contamination. This improved method was also successfully applied to 14 other serotypes (1, 3, 4, 6A, 6B, 7F, 9V, 11A, 14, 18C, 19A, 19F, 22F, and 23F). To assess the immunogenicity of the CPS from the 15 serotypes, two sets of 15-valent pneumococcal conjugate vaccines were prepared using the previous purification method and the improved method developed here; these vaccines were administered to a rabbit model. Enzyme-linked immunosorbent assay and opsonophagocytic assay demonstrated higher immunogenicity of the conjugate vaccine prepared using CPS produced by the improved purification process.

In vitro and in vivo characterization of the interaction, proinflammatory, immunomodulatory and antigenic properties of capsular polysaccharide from Streptococcus pneumoniae serotype 1

Pneumococcal capsular polysaccharide (PCP) is the major virulence determinant of Streptococcus pneumoniae (pneumococcus). Strains devoid of the capsule are avirulent or highly attenuated. PCP is present in soluble form and on pneumococci in infected individuals. The present study was undertaken to study the interaction of PCP from serotype 1 (PCP1) with immune cells, and its proinflammatory, immunomodulatory and antigenic properties. Binding of PCP1 to the surface of immune cells led to proinflammatory cytokine production which was not cell line or cytokine restricted. HEK293T transfectants expressing TLR1 and TLR2 produced IL-8 upon stimulation with PCP1, untransfected cells did not do so. PCP1 failed to induce TNF-α production from RAW264.7 cells when pre-incubated with a TLR2 blocking antibody. The surface binding of PCP1 was abrogated in the presence of TLR2 blocking antibody. PCP1 failed to bind TLR2 deficient RAW264.7 cells and induce TNF-α production. Unlike PCP1, alkali-treated PCP1 failed to stimulate RAW264.7 cells to produce TNF-α indicating the importance of alkali-sensitive moieties like O-acetyl groups. Alkali-treated PCP1 elicited lower anti-PCP1 antibody response. Mice experiments suggested that alkali-sensitive groups are significant target of protective antibodies in PCP1 immunized mice. Our findings demonstrate that PCP1 is an important modulator of immune response against pneumococci.

A Japanese nationwide survey of 23-valent pneumococcal capsular polysaccharide vaccine (PPSV23) coverage among patients with chronic medical condition aged 50 and older

ABSTRACT The 23-valent capsular polysaccharide pneumococcal vaccine (PPSV23) was introduced in Japan’s routine immunization schedule October 2014. It was recommended for adults aged 65 years (including those ≥65 during the transition period), and for adults 60–64 with cardiac, renal, or respiratory dysfunction equivalent to Level 1 physical disability. Several studies have shown that patients aged 50+ with chronic medical conditions (CMC) are at elevated risk of pneumococcal infection. Nonetheless, PPSV23 vaccination rates among this population remains low. In our study, we report the results of a survey investigation into PPSV23 vaccination rates among Japanese patients aged 50+ with CMC. Patients aged 50+ comprised the patient population (n = 5,078) and internal medicine physicians comprised the doctor population (n = 400) located all over Japan were asked an array of questions relevant to PPSV23 immunization in June 2018 via Web-based surveys. PPSV23 coverages among chronic patients aged 50–59, 60–64, and 65+ years were respectively 1.3%, 2.9%, and 37.8%. The high disease-specific PPSV23 rates seen in the 65+ group was 50.0% and 49.4%, for chronic liver disease and chronic lung disease, respectively. Doctors most frequently cited a lack of municipal subsidies as justification for recommending the vaccine to patients with CMC aged 50–64 years, and deference to patients’ wishes as justification for patients with CMC aged 65+. In conclusion, PPSV23 has poor coverage among Japanese adults aged 50–64 with CMC. Doctors and local authorities need to raise public awareness to improve the vaccination rate, given the high risk of pneumococcal infectious disease among patients with CMC.