Background

Current pneumococcal vaccines based on capsular polysaccharides are expensive and their coverage are limited to only few serotypes from >95 that are known, which led to a selective pressure that causes serotype replacement. Therefore, protein based vaccines have been investigated as an alternative and the virulence factor pneumolysin (Ply) is a promising candidate. This work aims at developing the production and purification process of the recombinant detoxified Ply (PdT), since reaching high recovery and purity of the antigen is essential for the development of affordable and safety vaccines.

Methods

E. coli + PdT cultivation was performed in 10L-bioreactor with auto-induction medium. After biomass suspensions, cells were lysed by chemical and physical methods. Different buffers were evaluated to enhance PdT solubility. After centrifugation, the supernatant was applied to chromatography steps. Protein concentration was measured by Lowry and BCA and PdT purity by densitometry of SDS-PAGE bands.

Results

The cultivation yielded 544 g wet biomass. The lysis and clarification processes promoted 94% recovery of soluble protein in bis-tris buffer pH 7.0. The chromatography steps allowed achieving < 50% PdT recovery.

Conclusions

Additional chromatography steps and process optimization will be evaluate in order to increase recovery, thus diminishing costs, and reach purity higher than 95%.

Background

SSI Diagnostica manufactures polyclonal pneumococcus antisera, which is used by vaccine manufacturers in their QC. In this comparing assay we investigate the immunological differences between the monoclonal antibodies and polyclonal antisera using the IMMAGE 800 Immunochemistry System, Beckman Coulter.

Methods

Monoclonal and polyclonal antibodies against the 23-valent vaccine serotypes were evaluated in the routine Immunochemistry QC analysis (IMMAGE 800).

Affinity were analysed using specific polysaccharides from ATCC performing standard curves from 0.5 to 5µg/mL. Specificity were analysed using an antigen pool containing 50µg/mL of each of the 23 valent vaccine serotypes from ATCC.

Results

Monoclonal and Polyclonal antisera against serotype 1, 3, 5, 9V and 19A were evaluated undiluted and diluted. The monoclonal antibodies are overall lacking affinity (instrument response) compared with polyclonal antisera, which made it difficult to make an acceptable standard curve giving trouble passing the QC accept criteria set by vaccine manufactures.

Additional data for specificity and the last 18 antibodies will follow on the poster if abstracts is accepted.

Conclusions

The comparison between the pneumococcus monoclonal antibodies and polyclonal antisera, revealed that there is a detectable immunological difference and affinity between the polyclonal pneumococcal sera and the monoclonal pneumococcal sera analyzed in the immune nephelometric assays.

Background

Pneumococcal conjugate vaccines (PCVs) reduced the incidence of pneumococcal disease. We performed a systematic literature review of the cost-effectiveness of PCVs within East and Southeast Asia.

Methods

We reviewed the MEDLINE and EMBASE databases through 10/11/2019 to identify studies evaluating the cost-effectiveness of PCVs in East and Southeast Asia. Study characteristics, clinical outcomes, cost outcomes, and cost-effectiveness results were extracted, while studies without at least one analysis in East and Southeast Asia were excluded.

Results

We included 32 studies: 3 multi-setting studies and 29 single-setting studies. Within these studies, there were a total of 55 separate analyses comparing pneumococcal vaccination strategies. A PCV (PCV7/10/13) was compared to no vaccination in 45 (81.8%) analyses, and the vaccine was considered cost-effective in 86.7% (39/45) (Table 1). PCV13 and PCV10 were evaluated in 9 (16.4%) analyses. The results comparing PCV10 with PCV13 were heavily dependent on the study funder and modeling assumptions but independent studies found PCV13 cost-effective compared to PCV10 due to broader serotype coverage.

Conclusions

PCVs are generally cost-effective against no vaccination in Asia. This study will support decision-makers in Asia as they consider the clinical and economic value of introducing PCV NIPs and considering higher valent vaccines.

Background

Research data management for field studies in rural Africa poses unique challenges. Data management in the Pneumococcal Vaccine Schedules (PVS) trial in The Gambia uses the following innovative procedures to maintain data integrity and validity with large numbers of observations where there is no electricity or internet.

Methods

•Confirming residential status and identity of infants in the study area in a continuously updated live sampling frame of over 10,000 births per year.

•User prompts and decision rules for group allocation for over 10,000 births per year and correct vaccine administration according to village of residence for over 50,000 PCV doses per year.

•Weekly synchronisation of data to a central server (up to 400 trial enrolments, 2500 PCV doses and 800 clinical presentations per week monitoring residence of 300,000 population).

•Weekly update of a back-end relational database combining variables from five different applications.

•Linkage of demographic identity details to patients presenting to health facilities using family geneology and photographs.

•Remote data viewing for off-site external trial monitoring, query and resolution audit trail, as well as trial staff real-time viewing of data.

Results

Interactive experience of the data systems will be available at the conference.

Conclusions

Those systems are working properly for PVS data collection.

Background

Mushrooms are white rot fungi regarded as one of the well-known food possessing various kinds of biopharmaceuticals compounds. Pleurotus ostreatus is an edible mushroom with history of medicinal uses.

Methods

Phytochemical constituents of the methanol extract were quantified while pure isolate of Streptococcus pneumoniae was obtained using standard protocols. The effect of the extract on cellular immune responses was assessed by Phagocytosis Evaluation and Nitroblue Tetrazolium Tests. In vivo study against Streptococcal infection was evaluated using the neutrophil adhesion, carbon clearance and Hemagglutination titre tests in mice.

Results

Methanol extracts of Pleurotus revealed the presence of flavonoids (6.41%), alkaloids (10.01%), saponins (2.02%), phenols (1.55%), carbohydrate (14.05%), and proteins (45.09%). The percentage stimulation of the polymorphonuclear neutrophils (PMNs) was obtained as 53% for (500mg/ml), while the Nitroblue Tetrazolium test score ranged from 58.00±9.64 for 500mg/ml to 27.33±4.84 for 125mg/ml. Significant number of PMNs adhered to nylon fibre while antibody titre and phagocytic index increased in concentration dependent manner.

Conclusions

Pleurotus ostreatus has high carbohydrate and protein contents. It showed a significant stimulation of the cell mediated and humoral immunity against Streptococcus pneumoniae infections.

Background

Pneumococcal protein vaccines have been proposed as better serotype-independent alternatives to already used polysaccharide-based vaccines in order to increase coverage. PspA and PdT were genetically fused and protected mice against lethal challenge, offered higher cross protection against different strains and showed greater opsonophagocytosis rate than co-administered proteins. As juxtaposed fusion was unstable, flexible (PspA-FL-PdT) and rigid (PspA-RL-PdT) linkers were inserted between antigens to increase stability. This work aimed to produce stable hybrid molecules and evaluate their antigenicity.

Methods

The two constructs were cloned into E. coli and clones were cultivated in defined culture media. Hybrids were purified from soluble fraction using chromatography and stability was evaluated by Western blot. Mice were immunized, antibody production was evaluated by ELISA, and aspiration lethal challenge was performed.

Results

High purity was obtained for both molecules (>95%). Hybrids were stable for at least 12 months at -20°C, and PspA-FL-PdT was stable at 4°C for this period. Although both hybrids elicited high antibody levels, only PspA-RL-PdT protected mice against lethal challenge. New immunization assay is being conducted to evaluate protein dose for immunization and bacterial concentration at challenge.

Conclusions

Promising protection and stability were achieved, but further investigation is still needed to formulate a new protein based vaccine.

Background

Commercially licensed pneumococcal vaccines provide effective immunity against specific serotypes but have their own limitations. They fail to induce memory, require multiple doses and lead to serotype replacement. Pneumococcal Capsular polysaccharides (PCP) serve as major virulence factors, but are weakly immunogenic. In order to make this subunit based vaccine more effective; Poly lactide polymeric particles entrapping pneumococcal polysaccharide and its homologous conserved surface protein SP0845 were formulated and were immunologically evaluated.

Methods

PCP type 1, type 5 and recombinant SP0845 protein was entrapped in polymeric nanoparticles using double emulsion solvent evaporation method. In vivo studies were performed in BALB/c mice to evaluate cytokines and antibody response. ELISPOT assay was performed to enumerate antigen specific antibody secreting splenic cells in immunized mice.

Results

Pneumococcal capsular polysaccharide type 1 and 5 entrapped in PLA polymeric particles induced higher IgM and IgG memory antibody response than their soluble counterparts. Immunogenicity of SP0845 protein (tag free) was enhanced by delivering it using poly-lactide polymeric nanoparticles. Number of PCP type 1 specific IgG secreting cells detected in the spleen of mice immunized with PCP-1 entrapped nanoparticles were higher as compared to its soluble form.

Conclusions

Entrapment of pneumococcal antigens in polymeric particles significantly improves their antibody response.

Background

A Pneumococcal conjugate vaccine containing 14 serotypes (polysaccharide serotypes 1,3,4,5,6B,7F,9V,14,18C,19A,19F,22F,23F, and 33F - all separately conjugated to CRM₁₉₇ and formulated) was manufactured and tested for safety and immunogenicity in rabbits.

Methods

A Phase 1 safety and immunogenicity study was completed in 24 healthy adults. A separate Phase2 safety and immunogenicity study in 12 to 23 month old toddlers was conducted with two dose (0 and day 60) administration. The study had two arms (60 in each arm) with Prevnar13 as comparator.

Results

The PCV14 was well tolerated in toddlers and no SAE were reported. The IgG GMC for all serotypes post second dose were ≥ 0.35 mcg/mL in the PCV14 group. GMFR (depending on serotype) ranged from 4.31 to 57.72. In the Prevnar13 group (depending on serotype) GMFR ranged from 4.19 to 77.86. The MOPA indicated that the proportion (%) of subjects with tires ≥1:8 in the PCV14 group was 86.21 to 98.28 while in Prevnar13 group the range was from 98.33 to 100.

Conclusions

PCV14 was safe, well tolerated in adults and toddlers, and was immunogenic with GMC and MOPA titres well above the defined seroprotection criteria. Clinical studies in infants in larger target population are planned.

Background

In remote communities of northern Australia, we previously demonstrated that the onset of otitis media (OM) in Aboriginal infants was preceded by acquisition of bacterial pathogens that colonise the nasopharynx (NP) soon after birth. We aimed to determine safety and effectiveness of mixed vaccine schedules against early infection due to non-typeable Haemophilus influenzae and Streptococcus pneumoniae.

Methods

In an open-label controlled trial, we randomised (1:1:1) Aboriginal infants at 28 to 38 days of age, to either Prevenar13™ (P, PCV13) at 2-4-6 months of age (_PPP), Synflorix™ (S, PHiD-CV10) at 2-4-6 months (_SSS), or Synflorix at 1-2-4 months plus Prevenar13 at 6 months (SSSP). Primary outcomes (assessor-blinded) were immunogenicity at 7 months of age against pneumococcal serotypes 3, 6A, and 19A, and protein D (GMCs and proportions of infants with IgG > 0·35 µg/mL or > 100 EL.U/mL, respectively). Secondary immunogenicity outcomes at 2 and 4 months are also reported.

Results

A 4-dose early 1-2-4-6 month combination schedule of Synflorix plus Prevenar13 (SSSP) provided superior overall immune protection against serotypes 3, 6A, 19A, and protein D, compared to standard 3-dose 2-4-6 month schedules (_SSS or _PPP).

Conclusions

These vaccines can be combined safely and effectively within this primary schedule, with no evidence of immune suppression.

Background

Australian Aboriginal children are at high risk of early infection withStreptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi). We evaluated immunogenicity against 10 shared serotypes of a 4-dose combination schedule of PHiD-CV10 at 1-2-4 months plus PCV13 at 6 months, compared with standard 2-4-6 month schedules.

Methods

Infants were allocated (1:1:1) at 28 to 38 days of age, to 3-dose schedules of PCV13 (P) or PHiD-CV10 (S) at 2-4-6 months (_PPP or _SSS), or a combination schedule at 1-2-4-6 months (SSSP). Immunogenicity was measured at 2, 4, and 7 months.

Results

At 2 months the SSSP combination was superior to pre-vaccination (VTs other than 6B, 19F, or 23F). At 4 months SSSP was superior to _PPP (9 VTs) and _SSS (7 VTs), and _SSS was superior to _PPP (8 VTs). At 7 months, SSSP was superior to _PPP (1, 6B, 9V, 19F and 23F) and _SSS (8 VTs), and _PPP was superior to _SSS (8 VTs). OPA supports the SSSP schedule, particularly against 1, 6B, and 23F.

Conclusions

The 1-2-4-6 month schedule (SSSP) was superior at 2, 4, and 7 months of age compared to _SSS or _PPP, particularly for 1, 6B, and 23F at 7 months. At 4 months, _SSS was superior to _PPP.

Background

Widespread use of the 13-valent pneumococcal conjugate vaccine (PCV13) in infants and the associated indirect protection in adults has highlighted the significant burden of pneumococcal disease caused by serotypes unique to 23-valent pneumococcal polysaccharide vaccine (PPSV23) in older adults.

Methods

This study evaluated the safety and immunogenicity of sequential administration of PCV13 followed by PPSV23 either 8 weeks (Group#1) or 26 weeks (Group#2) later in adults ≥50 years old. Serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) were measured prior and 30 days postvaccination.

Results

Proportions of participants reporting any AE were comparable between both groups. More participants in Group#1 (81.9%) reported injection site AEs following PPSV23 than Group#2 (64.0%). At Week 12, OPA GMTs to 12 shared serotypes between PPSV23 and PCV13 in Group#1 were noninferior to Group#2; OPA GMTs to 6 serotypes unique to PPSV23 were superior in Group#1 than Group#2. Overall, OPA GMTs for all tested serotypes were comparable by Week 30, after both groups had received PCV13 and PPSV23.

Conclusions

Sequential administration of PCV13 followed by PPSV23 at 2-month or 6-month intervals was generally well-tolerated. Serotype-specific OPA GMTs were comparable, regardless of dosing interval. Administration of PPSV23 did not hinder immune responses induced by PCV13.

Background

Burden of community acquired pneumonia (CAP) among infants is high in India. Pneumococcal Conjugate Vaccination(PCV) has been introduced in India since 2017 in a phased manner. Our aim was to study the effect of PCV on radiological findings of chest in infants hospitalized with WHO-defined CAP.

Methods

Prospective, hospital-based pneumonia surveillance in four districts of North India. Infants(2-11 months) hospitalized with CAP from index districts with<14 days of symptoms were recruited. Clinical data was abstracted. Chest X-rays(CXRs) were interpreted by a panel of three independent blinded radiologists.

Results

From May,2017-October,2018, 282 (22.7% females) infants with PCV vaccination (cases) and 570 (29.8% females) without PCV vaccination (controls) with interpretable CXRs were analyzed. Primary end point pneumonia (PEP)+other infiltrate (OI) were found in 43(15.2%) cases and 140(24.7%) controls (p=0.001); OI in 30(10.6%) cases and 69(12.1%) controls (p=0.5) and normal CXR in 209(74.1%) cases and 361(63.3%) controls (p=0.001). There was one death among cases whose CXR showed OI. There were 22 deaths among controls whose CXRs showed PEP + OI in 12(54.6%); OI in 3(13.6%) and normal 7(31.8%). Crude odds ratio for death (cases) was 0.088 (95 %: CI 0.012-0.66).

Conclusions

Among hospitalized patients of CAP, radiological findings differ by PCV vaccination status in infants.

Background

One approach of novel mucosal vaccines is the use of chitosan, which has shown potential as a versatile and effective coating material on nanoparticles (NPs) for improving efficacy. Various mechanisms are recognised to lead to improved immune response, however it is unclear how variations of chitosan molecules with differing properties affects the immunogenicity on dendritic cells (DCs). This study investigated the effects of different chitosan on the coating properties on PLGA NPs and subsequent immunogenicity.

Methods

Chitosans with varying molecular properties were coated onto PLGA NPs. The resulting NPs were characterised for size and zeta potential, quantification of chitosan adsorption on the NP surface, and immunogenicity through expression of CD40, CD86.

Results

PLGA NPs with different chitosan coatings exhibited differing particle characteristics, degrees of adsorption, and subsequent surface adsorption of model antigen protein. The relationship between the amount of chitosan adsorbed onto the particle surface and the resulting NP size increase differed for each chitosan. As expected, the surface charge also varied greatly, and the chitosans exhibited a concentration dependent immunogenicity.

Conclusions

Coating PLGA NPs with differing forms of chitosan, including salt form, degree of quaternisation, molecular weight, oligomerisation, carboxymethylation, all contribute to NPs containing unique characteristics and immunogenicity.

Background

We previously validated a multiplex, ECL-based assay to quantify serotype-specific IgG to 15 serotypes included in an investigational PCV. To address challenges of maintaining the clinical assay for measurement of vaccine-induced antibodies in Phase 3 and beyond, we established a proficiency panel, the first of its kind for Merck serology assays.

Methods

The proficiency panel consists of 32 biobroker serum samples selected for antibody concentrations that span the quantifiable range for all vaccine serotypes. Baseline values were established across 12 months and were utilized in reagent stability and technology transfer protocols.

Results

Stability results support use of critical reagents for 2 years, extending expiry for plates and secondary antibody and allowing for flexible storage temperatures for secondary antibody. The technology transfer passed pre-specified acceptance criteria using manual methods, when compared against baseline values established using automation, enabling assay validation using both manual and automated methods.

Conclusions

Establishing a proficiency panel requires selection of appropriate samples, in large volume, and at least one year of testing to establish baseline values. This upfront investment enabled (1) expiry extension for critical reagents, resulting in overall time and cost savings, and (2) successful technology transfer and partial validation in another laboratory using both manual and automated methods.

Background

The objective of this study is to quantify the epidemiologic and economic burden of pneumococcal disease attributable to 15-valent pneumococcal conjugate vaccine (PCV15) serotypes in Canada.

Methods

A published Markov model was adapted to estimate the burden of PCV15 serotypes in a cohort of unvaccinated Canadian adults aged 65 and older who were tracked from 2015 until death. The Markov model included the following health states: no pneumococcal disease, invasive pneumococcal diseases (IPD), non-bacteremic pneumococcal pneumonia (NBPP) and death. Economic burden was estimated from a publicly funded health care payer perspective, by multiplying the number of inpatient/outpatient visits by the cost per inpatient/outpatient visits.

Results

The model resulted in an estimated 7,834 cases of IPD and 110,372 cases of NBPP hospitalizations. Of these, there were 1,684 cases of IPD related deaths and 8,444 cases of NBPP related death. Total lifetime discounted healthcare costs attributable to PCV15 serotypes were estimated to be approximately $874.6 million. 38.5% of these costs ($337.1 million) were attributable to serotypes 22F and 33F and 22.2% were attributable to serotype 3.

Conclusions

The serotypes included in PCV15 contribute considerably to the health and economic burden of pneumococcal disease among older adults in Canada.

Background

This analysis quantifies the epidemiologic and economic burden of pneumococcal disease attributable to 15-valent pneumococcal conjugate vaccine (PCV15) serotypes in a hypothetical cohort of US adults aged 65 years and older in the US.

Methods

A Markov model was used to estimate pneumococcal disease cases, deaths and costs attributable to PCV15 serotypes. A cohort of unvaccinated adults aged ≥65 years from 2017 were tracked until death. Economic burden was estimated from a payer perspective, by multiplying the number of inpatient/outpatient visits by the cost per inpatient/outpatient visits. Costs were discounted at 3% per year.

Results

An estimated 74,956 cases of IPD; 10,336 cases of IPD related deaths; 2,286,581 cases of NBPP hospitalizations and 135,566 cases of NBPP related deaths were attributable to PCV15 serotypes in adults aged ≥65 years in the U.S. Total lifetime discounted healthcare costs attributable to PCV15 serotypes were estimated to be approximately $19.9 million. 36.3% of these cases, deaths and costs were attributable to serotypes 22F and 33F and 42.4% were attributable to serotype 3.

Conclusions

PCV15 serotypes contribute to substantial health and economic burden of pneumococcal disease among older adults (aged ≥65 years) in the U.S., majority of which is attributable to the serotypes 3, 22F, and 33F.

Background

There is growing evidence that S. pneumoniae vaccines that are currently used to prevent specific infections also have heterologous effects on other infections or pathologies. Here we report a patient who improved his chronic dermatitis dramatically after pneumococcal immunization.

Methods

A 45-year-old adult patient was evaluated for a possible infectious or immune cause of a treatment resistant, disabling dermatitis of 4 years duration. No identifiably infectious cause was ever found. Immunity, including antibodies against S. pneumoniae, were normal. He was given a 13-valent conjugate vaccine followed by the 23-valent polysaccharide six weeks later.

Results

The patient had a complete clearing of lesion without additional medication after he was given the 23-valent pneumococcal polysaccharide vaccine. Improvement lasted 2 years. No medications were needed to maintain his healthy skin. After 2 years, dermatitis recurred. It cleared after a repeat 13-valente conjugate vaccine administration.

Conclusions

S. pneumoniae polysaccharide vaccine can improve conditions unrelated to pneumococcal infections. This effect is not dependent on having a detectable specific antibody deficiency involving S. pneumoniae antibodies.

Background

HIV infection increases the risk of pneumococcal disease (PD). Sequential vaccination with pneumococcal conjugate vaccine (PCV) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for prevention of PD. V114, an investigational 15-valent PCV, contains all serotypes in PCV13 plus serotypes 22F and 33F. This phase 3 trial evaluated immunogenicity and safety of V114 or PCV13 followed 8 weeks later by PPSV23 in HIV-infected adults.

Methods

Eligible HIV-infected adults aged ≥18 years, pneumococcal vaccine naïve and receiving antiretroviral therapy were randomized 1:1 to receive either V114 or PCV13 followed by PPSV23. Randomization was stratified by CD4 cell count. Serotype-specific opsonophagocytic activity (OPA) and immunoglobulin G (IgG) antibodies were measured immediately prior and 30 days after each vaccination.

Results

Enrollment of study participants has been completed. Safety outcomes and serotype-specific OPA geometric mean titers and IgG geometric mean concentrations following vaccination with V114 or PCV13 will be summarized by vaccination group (primary). Sub-group analysis will include CD4 strata if there are more than 10 participants per group. Summaries of safety and immunogenicity outcomes following PPV23 will also be provided.

Conclusions

Findings will demonstrate whether immunization with V114 or PCV13 followed by PPSV23 is well-tolerated and immunogenic in HIV-infected adults.

Background

A 1+1 pneumococcal conjugate vaccine (PCV) schedule would increase its affordability for low and middle-income countries. The Vietnam Pneumococcal Trial II includes infants randomised to receive a 1+1 schedule of PCV10 or PCV13 at 2 and 12 months of age. This study measured the immunogenicity of a single dose of either PCV given at 2 months of age.

Methods

Serotype-specific IgG was measured at 3 and 12 months of age in PCV-vaccinated and unvaccinated controls using a WHO ELISA method.

Results

At 3 months, both vaccinated groups had higher antibody levels than controls for 7/10 serotypes (all except 6B, 14, 23F). The PCV10 group had higher antibody levels than the PCV13 group for 5/10 serotypes. Similar results were seen at 12 months, with higher antibody levels for all serotypes in the PCV10 group and 8/10 serotypes (all except 6V, 23F) in the PCV13 group compared with controls and higher antibody levels in the PCV10 than the PCV13 group for 7/10 serotypes.

Conclusions

A single dose of PCV in infancy is immunogenic and likely to provide some direct protection until the time of the booster dose. There may be a difference in the degree of protection offered by different PCVs.

Background

Coupling polysaccharides to protein-carriers enables generation of robust anti-polysaccharide response in a T-dependent manner. One mechanism is via engagement of polysaccharide-specific T-helper cells; it is unclear if carrier-specific T-helper cells (T_carrier) play any role. We study the role of T_carrier in priming and boost/recall of antibody response.

Methods

Rag1^-/- mice were adoptively transferred with B cells from naïve mice or mice primed with 5-valent Multiple Antigen Presenting System (MAPS) PS-protein vaccine, with or without CD4⁺ T cells from naïve or carrier-primed mice, prior vaccination with 5-valent MAPS. Serum anti-polysaccharide IgG was compared between groups pre- and post-vaccination. Separately, wild-type mice were primed with type4-pneumolysoid MAPS and exposed to heat-killed wild-type or pneumolysin^-/- type4 pneumococci for comparison of recalled anti-type4 polysaccharide response.

Results

For 3/5, and 4/5 polysaccharides, carrier-primed T cells, compared to unprimed T cells, enhanced vaccine-induced anti-polysaccharide IgG production by naïve B cells (priming) or memory B cells (recall), respectively. Priming mice with type4-pneumolysoid MAPS vaccine resulted in significantly higher recalled anti-type4 polysaccharide IgG after exposure to a pneumolysin-producing vs. pneumolysin-deficient strain.

Conclusions

T_carrier facilitates priming and boosting of anti-polysaccharide response. Using pneumococcal proteins as vaccine carriers may lead to higher antibody level recall during active pneumococcal infection or colonization.

Background

Conjugation of polysaccharide to a carrier protein has enhanced immunogenicity and efficacy of the vaccine. Carrier proteins, such as TT, DT and CRM₁₉₇, are most commonly used. Co-administration of a conjugate vaccine and its corresponding carrier protein antigen may induce carrier enhancement or suppression on vaccine immunogenicity, referred as immune interference. In this study, we investigated the effect of preexistence of anticarrier immunity or co-administration of pneumococcal polysaccharide conjugate vaccine and carrier protein on anti-polysaccharide immunity.

Methods

In-house 13-valent pneumococcal polysaccharide conjugate vaccine (PCV13) with TT as carried protein and in-house DTaP vaccine were used in this study. Prevnar 13 from Pfizer^® was used as positive control. Group of New Zealand white rabbits were immunized intramuscularly with DTaP and followed by in-house PCV13. A second group were given DTaP and in-house PCV13 simultaneously. Geometric mean IgG anti-TT and anti-polysaccharide concentrations were analyzed by indirect ELISA.

Results

Anti-polysaccharide concentration of groups of preexistence of anti-TT or co-administration of PCV13 and DTaP was not statistically significant different from that of control, although anti-TT concentration was significantly increased in both these two groups.

Conclusions

Neither preexistence of anti-TT immunity, nor co-administration of conjugate vaccine and its corresponding carrier protein, has immune interreference on anti-polysaccharide immune response.

Background

Subject recruitment and retention are crucial factors contributing to the success of clinical trials. We describe the experience from a clinical trial of
pneumococcal conjugate vaccines currently underway in Ho Chi Minh City.

Methods

Subject recruitment and retention are crucial factors contributing to the success of clinical trials. We describe the experience from a clinical trial of
pneumococcal conjugate vaccines currently underway in Ho Chi Minh City.

Results

2,501 subjects were recruited at 2 months of age. To date 1,612 subjects have completed their final 24 month visit. The last 24 month visit is due in May 2020. We have a current withdrawal rate of 7.8%. The most common reason for withdrawal is moving outside the study area. Withdrawal rates and reasons by study group will be presented at the conference

Conclusions

Recruiting subjects who intend to remain in the study area is a challenge for clinical trials involving follow up of children over a number of years. Involving staff from subjects' local health clinics helps to keep the withdrawal rate down.

Background

Streptococcus pneumoniae(Spn) is a leading cause of invasive bacterial diseases. Despite the use of polysaccharide-based vaccines, Spn remains a major cause of invasive disease due to reasons including the increase in non-vaccine serotypes. Recent efforts focus on the development of protein-based vaccines for broad immunity. Previous studies showed that CD4+ T cells particularly Th17 cells are critical in host clearance of Spn and we showed domain 4 pneumolysin(D4Ply) activated CD4+ T cells including Th17 which were inversely associated with Spn carriage.

Methods

We now examined CD4+ T cell epitopes from D4Ply that activate Th17/Th1 cells in nasopharynx-associated lymphoid tissue(NALT) from children and adults. A number of peptides spanning whole length D4Ply were tested for capacity to activate T cells by cell proliferation (CFSE staining), intracellular cytokine staining and cytokine array.

Results

We identified several immunodominant epitopes that activated marked Th1/Th17 responses in NALT and PBMC, as demonstrated by intracellular cytokine staining and increased IFNg and IL17A levels in cell culture. CD4+ T cell proliferative response and cytokine production activated by peptide pools could be enhanced by an adjuvant Endocine.

Conclusions

Identification of immuno-dominant CD4+ T cell epitopes eliciting marked Th17 response offers great potential for peptides-based vaccine against pneumococcal infection in humans.

Background

We have previously reported that pneumococcal colonization increases lung and systemic protective immune responses. Live attenuated bacteria may be a good strategy for adult vaccination, particularly for those with chronic lung disease.

Methods

Single-blind RCT (superiority design). Healthy adults (age 18 to 50 years) were randomised 1:1:1:1 to be nasally vaccinated twice (two weeks interval) with either saline, wild-type 6B (BHN418) or a genetically modified strain (A1 or A2 – double mutants constructed on the BHN418 backbone). After 6 months, participants were challenged with wild-type 6B to assess protection against colonization acquisition.

Results

No Serious Adverse Events reported. 202 participants were assessed for eligibility, 148 randomised and 126 completed the study as per modified intention to treat. Rates of carriage acquisition following challenge with wild-type 6B were as follow: saline (negative control): 17/32 (47%), wild-type 6B (positive control): 9/31 (29%), A1: 9/30 (30%) and A2: 16/33 (49%).

Conclusions

Protection following nasal inoculation with attenuated strain (A1) was comparable to 6B wild-type. Attenuation in virulence by genetic modification may allow the development and safe use of live nasal vaccines whilst providing broad coverage against pneumococcal infection and improved lung immunity.

Background

Streptococcus pneumoniae is the most common cause of community acquired pneumonia despite robust vaccinations. With ~100 serotypes (ST) in circulation, surveillance is crucial to estimate the ST specific disease burden and assess vaccine efficacy/coverage. To address these needs, we have developed a high throughput multiplex Pneumococcal Urine Antigen Detection (PnUAD) assay for the quantitation of 15 serotype specific polysaccharides (Ps) in human urine.

Methods

PnUAD was qualified based on the assay precision, ruggedness, specificity, accuracy, limit of detection, selectivity and dilutional linearity. Test samples were individual or pooled normal human urine spiked with full-length vaccine grade polysaccharides or fragmented polysaccharides (<150 kDa).

Results

PnUAD was determined to be serotype specific, precise (<15% RSD), accurate (80%-127% recovery throughout the quantifiable range), and dilutable (<2-fold dilution bias per 10-fold dilution) for each of the 15 Pn serotypes. The PnUAD was also determined to be highly sensitive (LLOQ ranging between 0.0020 – 0.0781 ng/mL across the 15 serotypes), and selective (consistent PnPs recovery for each ST when spiked into different pre-dilutions of urine).

Conclusions

PnUAD met all performance expectations, and is considered qualified to detect serotype specific PnPs in human urine in subjects from epidemiology studies or vaccine clinical trials.

Background

Our laboratory has the task of developing and characterizing the reference seeds of 25 serotypes of clinical isolates donated by the Pedro Kourí Tropical Medicine Institute, cultivating them in liquid culture media, free of animal origin and complying with GMP. S. pneumoniae is a microorganism with special nutritional requirements for its growth and is very sensitive to conservation processes. The proper conservation of the strains directly impacts the production of vaccines.

Methods

Each isolation strain was grown in solid medium supplemented with 10% sheep blood and subsequently liquid medium. 15% glycerol was used as a cryoprotective additive. The characterization consisted of: viability, cultural characteristics of the colony, purity, Gram staining, growth potential in liquid medium, Identity (biochemical and serological tests). Each batch was made a file with all the documentation that guarantees compliance with the BPM.

Results

Of the 25 strains worked, it was possible to recover 24 and develop batches of reference seeds that met the required quality specifications and the controls after freezing were positive, indicating that there was no involvement in the process

Conclusions

The batches elaborated and characterized fulfilled the quality requirements necessary to constitute reference seed lots for the stage of development and production of vaccines.

Background

Reduced dose vaccination with pneumococcal conjugate vaccines may protect against infection. We sought to examine the relationship between the dose of polysaccharide in conjugate vaccines (PCVs) and immunogenicity.

Methods

A systematic review of English publications that evaluated variable dose immunogenicity of PCVs in humans was performed in Medline and Embase databases (Ovid SP) in August 2019. Results were synthesised descriptively due to the heterogeneity of product valency, content and vaccine schedule.

Results

We identified 1691 articles after de-duplication; 9 studies met our inclusion criteria; 2 in adults, 6 in children and 1 in both. Doses of polysaccharide evaluated ranged from 0.44 mcg to 17.6 mcg. Thirty days after vaccination following a single dose or 2p+1 schedule, all doses tested in infants achieved mean IgG concentrations (GMCs) above the acceptable correlate of protection (COP; 0.35 mcg) and only three GMCs' 95% confidence intervals crossed the COP. All doses tested in adults achieved GMCs that were comparable to those considered protective in children who have received 3 standard vaccine doses.

Conclusions

For some products, the mean antibody concentrations induced for some pneumococcal serotypes increased with increasing doses of the polysaccharide but the functional significance of these is uncertain.

Background

We previously found that higher nasopharyngeal (NP) antibody levels to vaccine candidate proteins PhtD, PcpA and Ply significantly correlated with reduced risk of AOM (Xu et al Clin Micro Infect 2017).

Methods

Mucosal NP IgA and IgG antibody levels to PhtD, PcpA, and PlyD were measured by ELISA from stringently-defined otitis prone (sOP) and non-otitis prone (NOP) children from Rochester NY at 7 specific time points between age 6 and 36 months old when they were healthy. Logistic regression modeling was used to determine if age-specific antibody levels could be used as a biomarker to identify the sOP child.

Results

Mucosal PhtD IgA, PcpA IgG and IgA, and PlyD IgA antibody levels were significantly lower among sOP children across the age span studied. Age-specific PhtD IgA levels during health proved a suitable biomarker to distinguish sOP from NOP (p< 0.001), AUC=0.81, sensitivity 0.84, specificity and 0.7. PhtD IgA predicted sOP status with average accuracy of 84% without knowledge of prior NP colonization or AOM infection history.

Conclusions

Age-specific mucosal PhtD IgA levels may be a useful biomarker to define children who are more likely to become otitis prone.