Decrease in pneumococcal co-colonization following vaccination with the seven-valent pneumococcal conjugate vaccine

Understanding the epidemiology of pneumococcal co-colonization is important for monitoring vaccine effectiveness and the occurrence of horizontal gene transfer between pneumococcal strains. In this study we aimed to evaluate the impact of the seven-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal co-colonization among Portuguese children. Nasopharyngeal samples from children up to 6 years old yielding a pneumococcal culture were clustered into three groups: pre-vaccine era (n = 173), unvaccinated children of the vaccine era (n = 169), and fully vaccinated children (4 doses; n = 150). Co-colonization, serotype identification, and relative serotype abundance were detected by analysis of DNA of the total bacterial growth of the primary culture plate using the plyNCR-RFLP method and a molecular serotyping microarray-based strategy. The plyNCR-RFLP method detected an overall co-colonization rate of 20.1%. Microarray analysis confirmed the plyNCR-RFLP results. Vaccination status was the only factor found to be significantly associated with co-colonization: co-colonization rates were significantly lower (p = 0.004; Fisher''s exact test) among fully vaccinated children (8.0%) than among children from the pre-PCV7 era (17.3%) or unvaccinated children of the PCV7 era (18.3%). In the PCV7 era there were significantly less non-vaccine type (NVT) co-colonization events than would be expected based on the NVT distribution observed in the pre-PCV7 era (p = 0.024). In conclusion, vaccination with PCV7 resulted in a lower co-colonization rate due to an asymmetric distribution between NVTs found in single and co-colonized samples. We propose that some NVTs prevalent in the PCV7 era are more competitive than others, hampering their co-existence in the same niche. This result may have important implications since a decrease in co-colonization events is expected to translate in decreased opportunities for horizontal gene transfer, hindering pneumococcal evolution events such as acquisition of antibiotic resistance determinants or capsular switch. This might represent a novel potential benefit of conjugate vaccines.     

Pneumococcal antibody concentrations and carriage of pneumococci more than 3 years after infant immunization with a pneumococcal conjugate vaccine

Background

A 9-valent pneumococcal conjugate vaccine (PCV-9), given in a 3-dose schedule, protected Gambian children against pneumococcal disease and reduced nasopharyngeal carriage of pneumococci of vaccine serotypes. We have studied the effect of a booster or delayed primary dose of 7-valent conjugate vaccine (PCV-7) on antibody and nasopharyngeal carriage of pneumococci 3–4 years after primary vaccination.

Methodology/Principal Findings

We recruited a subsample of children who had received 3 doses of either PCV-9 or placebo (controls) into this follow-up study. Pre- and post- PCV-7 pneumococcal antibody concentrations to the 9 serotypes in PCV-9 and nasopharyngeal carriage of pneumococci were determined before and at intervals up to 18 months post-PCV-7. We enrolled 282 children at a median age of 45 months (range, 38–52 months); 138 had received 3 doses of PCV-9 in infancy and 144 were controls. Before receiving PCV-7, a high proportion of children had antibody concentrations >0.35 µg/mL to most of the serotypes in PCV-9 (average of 75% in the PCV-9 and 66% in the control group respectively). The geometric mean antibody concentrations in the vaccinated group were significantly higher compared to controls for serotypes 6B, 14, and 23F. Antibody concentrations were significantly increased to serotypes in the PCV-7 vaccine both 6–8 weeks and 16–18 months after PCV-7. Antibodies to serotypes 6B, 9V and 23F were higher in the PCV-9 group than in the control group 6–8 weeks after PCV-7, but only the 6B difference was sustained at 16–18 months. There was no significant difference in nasopharyngeal carriage between the two groups.

Conclusions/Significance

Pneumococcal antibody concentrations in Gambian children were high 34–48 months after a 3-dose primary infant vaccination series of PCV-9 for serotypes other than serotypes 1 and 18C, and were significantly higher than in control children for 3 of the 9 serotypes. Antibody concentrations increased after PCV-7 and remained raised for at least 18 months.     

Effect of seven-valent pneumococcal conjugate vaccine on Staphylococcus aureus colonisation in a randomised controlled trial

Background

Heptavalent pneumococcal conjugate vaccine (PCV7) shifts nasopharyngeal colonisation with vaccine serotype pneumococci towards nonvaccine serotypes. Because of the reported negative association of vaccine serotype pneumococci and Staphylococcus aureus in the nasopharynx, we explored the effect of PCV7 on nasopharyngeal colonisation with S. aureus in children and parents.

Methodology/Principal Findings

This study was part of a randomised controlled trial on the effect of PCV7 on pneumococcal carriage, enrolling healthy newborns who were randomly assigned (1∶1∶1) to receive PCV7 (1) at 2 and 4 months of age (2) at 2, 4 and 11 months or (3) no PCV7 (controls). Nasopharyngeal colonisation of S. aureus was a planned secondary outcome. Nasopharyngeal swabs were obtained from all children over a 2-year period with 6-months interval and from one parent at the child''s age of 12 and 24 months and cultured for Streptococcus pneumoniae and S. aureus. Between July 2005 and February 2006, 1005 children were enrolled and received either 2-doses of PCV7 (n = 336), 2+1-doses (336) or no dose (n = 333) before PCV7 implementation in the Dutch national immunization program. S. aureus colonisation had doubled in children in the 2+1-dose group at 12 months of age compared with unvaccinated controls (10.1% versus 5.0%; p = 0.019). A negative association for co-colonisation of S. pneumoniae and S. aureus was observed for both vaccine serotype (adjusted odds ratio (aOR) 0.53, 95% confidence interval (CI) 0.38–0.74) and nonvaccine serotype pneumococci (aOR 0.67, 95% CI 0.52–0.88).

Conclusions/Significance

PCV7 induces a temporary increase in S. aureus colonisation in children around 12 months of age after a 2+1-dose PCV7 schedule. The potential clinical consequences are unknown and monitoring is warranted.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00189020","term_id":"NCT00189020"}}NCT00189020     

肺炎球菌结合疫苗研发策略

安全有效的肺炎球菌结合疫苗(pneumococcal conjugate vaccine, PCV)已成为预防婴幼儿肺炎球菌感染的主要手段。目前Prevenar7~?、Synflorix~?和Prevenar13~?的先后上市,仍不能满足全球婴幼儿及高危人群预防肺炎球菌感染的需求,这一需求促进了国内外对PCV疫苗的研发。各研究机构采用的结合技术各不相同,但在PCV制备中需考虑的因素有据可循。现对PCV研发策略中需考虑的血清型、多糖相对分子质量大小、载体蛋白、结合化学的选择,以及中间质控监测和结合物表征方法的选择等作一概述,为新型PCV研发提供参考。     

13价肺炎球菌结合疫苗在老年人群中的免疫原性研究

老年人群对肺炎球菌疫苗的免疫应答不同于婴幼儿,在对老年人群肺炎球菌疫苗免疫原性的研究中,临床试验设计和判定标准均有所不同。现将美国13价肺炎球菌结合疫苗(13-valent conjugated vaccine,PCV13)在老年人群免疫原性研究的临床资料进行归纳和分析,为国内肺炎球菌疫苗在老年人群中的临床研究提供参考。     

Rituximab and abatacept but not tocilizumab impair antibody response to pneumococcal conjugate vaccine in patients with rheumatoid arthritis

Introduction

The objective of the study was to investigate the impact of newer biologic treatments including rituximab, abatacept and tocilizumab on antibody response following pneumococcal vaccination using a 7-valent conjugate vaccine in patients with established rheumatoid arthritis (RA).

Methods

Patients with RA receiving rituximab, abatacept or tocilizumab as monotherapy or combined with methotrexate (MTX) participated in the study. Specific IgG antibodies against 23F and 6B serotypes were measured at vaccination and 4 to 6 weeks after vaccination using standardised ELISA. Geometric mean antibody levels (GML) were calculated. Antibody response (AR) was defined as the ratio between post- and pre-vaccination antibody levels and a positive antibody response (posAR) was AR ≥2.

Results

In total, 88 patients were enrolled in the study. Of 55 patients treated with rituximab, 26 (46%) were on concomitant MTX. Of patients receiving abatacept (n = 17) and tocilizumab (n = 16) biologic treatment was given in combination with MTX in 13 (76%) and 9 (56%) patients, respectively. Patients treated with rituximab had significantly lower AR compared to those on tocilizumab, as well as compared to previously reported RA patients on MTX and controls (spondylarthropathy patients treated with NSAIDs and/or analgesics). In total, 10.3% of patients on rituximab monotherapy and no patient on rituximab + MTX had posAR for both serotypes. For abatacept and tocilizumab the corresponding figures were 17.6% and 50%.

Conclusion

In this cohort of patients with established RA, treatment with rituximab and abatacept was associated with diminished antibody response but this was most pronounced for rituximab. Pneumococcal conjugate vaccine administrated during ongoing tocilizumab treatment seems to be associated with sufficient antibody response. Pneumococcal vaccination should preferably be encouraged before initiation of rituximab or abatacept treatment.

Trial registration

NCT00828997 and EudraCT EU 2007-006539-29.     

The association between antibody levels before and after 7-valent pneumococcal conjugate vaccine immunization and subsequent pneumococcal infection in chronic arthritis patients

IntroductionThe aim of present study is to inverstigate the association between antibody levels after vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) and subsequent serious pneumococcal infections in rheumatoid arthritis (RA) and spondylarthropathy (SpA) patients.MethodsA cohort of 497 patients (RA = 248 and SpA = 249) received a single dose of PCV7. At vaccination, patients were treated with methotrexate (MTX; n = 85), anti-tumour necrosis factor (anti-TNF) + MTX (n = 169), anti-TNF monotherapy (n = 158) and non-steroidal anti-inflammatory drugs (NSAIDs)/analgesics (n = 85). Antibody levels of serotypes 6B and 23B were analyzed before and 4 to 6 weeks after vaccination using standard enzyme-linked immunosorbent assay (ELISA). Serious pneumococcal infections (pneumonia/lower respiratory tract infection, meningitis, sepsis, septic arthritis) occurring within 4.5 years after vaccination were identified in the Skåne Healthcare Register using the International Classification of Diseases, tenth revision (ICD-10) codes. The association between post-vaccination antibody levels and protection against infections and determination of protective cutoff levels was explored using receiver operating characteristic (ROC) curves. Predictors of infection were studied using regression analyses.ResultsEighteen infections were registered in 15 patients before vaccination and 27 infections in 23 patients after vaccination. Patients with serious infections after vaccination had significantly lower post-vaccination antibody titres for both 6B (P = 0.04) and 23 F (P = 0.04). Post-vaccination antibody levels of at least 1.29 mg/L and 1.01 mg/L for 6B and 23, respectively, were associated with better protection from serious infections. Higher age, concomitant prednisolone but not MTX or anti-TNF were associated with such infections.ConclusionsPatients with more robust antibody responses after vaccination with pneumococcal conjugate vaccine were less likely to suffer from serious infections. High age and prednisolone at vaccination were associated with putative serious pneumococcal infections in this cohort.

Trial registration number

EudraCT EU 2007-006539-29 and {"type":"clinical-trial","attrs":{"text":"NCT00828997","term_id":"NCT00828997"}}NCT00828997. Registered 23 January 2009.     

Persistence of antibody response 1.5 years after vaccination using 7-valent pneumococcal conjugate vaccine in patients with arthritis treated with different antirheumatic drugs

Introduction

The aim of this study was to explore the persistence of an antibody response 1.5 years after vaccination with 7-valent pneumococcal conjugate vaccine in patients with rheumatoid arthritis (RA) or spondyloarthropathy (SpA) treated with different antirheumatic drugs.

Methods

Of 505 patients initially recruited, data on current antirheumatic treatment and blood samples were obtained from 398 (79%) subjects after mean (SD, range) 1.4 (0.5; 1 to 2) years. Antibody levels against pneumococcal serotypes 23F and 6B were analyzed by using enzyme-linked immunosorbent assay (ELISA). Original treatment groups were as follows: (a) RA receiving methotrexate (MTX); (b) RA taking anti-TNF monotherapy; (c) RA taking anti-TNF+MTX; (d) SpA with anti-TNF monotherapy; (e) SpA taking anti-TNF+MTX; and (f) SpA taking NSAID/analgesics. Geometric mean levels (GMLs; 95% CI) and proportion (percentage) of patients with putative protective antibody levels ≥1 mg/L for both serotypes, calculated in different treatment groups, were compared with results 4 to 6 weeks after vaccination. Patients remaining on initial treatment were included in the analysis. Possible predictors of persistence of protective antibody response were analysed by using logistic regression analysis.

Results

Of 398 patients participating in the 1.5-year follow up, 302 patients (RA, 163, and SpA, 139) had unchanged medication. Compared with postvaccination levels at 1.5 years, GMLs for each serotype were significantly lower in all groups (P between 0.035 and <0.001; paired-sample t test), as were the proportions of patients with protective antibody levels for both serotypes (P < 0.001; χ² test). Higher prevaccination antibody levels for both serotypes 23F and 6B were associated with better persistence of protective antibodies (P < 0.001). Compared with patients with protective antibody levels at 1.5 years, those not having protective antibody levels were older, more often women, had longer disease duration and higher HAQ and DAS, and had a lower proportion of initial responders to both serotypes.Concomitant anti-TNF treatment and MTX were identified as negative predictors of the persistence of protective antibodies among RA patients (P = 0.024 and P = 0.065, respectively). Only age 65 years or older (P = 0.017) and not antirheumatic treatment was found to be a negative predictor of protective antibodies in patients with SpA.

Conclusions

After initial increase, 1.5 years after pneumococcal vaccination with 7-valent conjugate vaccine, postvaccination antibody levels decreased significantly, reaching levels before vaccination in this cohort of patients with established arthritis treated with different antirheumatic drugs. MTX and anti-TNF treatment predicted low persistence of protective immunity among patients with RA. To boost antibody response, early revaccination with conjugate vaccine might be needed in patients receiving potent immunosuppressive remedies.

Trial registration number

EudraCT EU 2007-006539-29 and {"type":"clinical-trial","attrs":{"text":"NCT00828997","term_id":"NCT00828997"}}NCT00828997.     

Invasive pneumococcal disease in Portugal prior to and after the introduction of pneumococcal heptavalent conjugate vaccine

The rates of invasive pneumococcal disease (IPD), serotype distribution and antimicrobial susceptibility prior to and after the introduction of the heptavalent pneumococcal conjugate vaccine in Portuguese children were evaluated. The changes in incidence of IPD in children under 1 year old between the two periods of the study was not significant (P=0.53), despite the 21% decline. In children under 18 years old there was a 27.7% decrease in vaccine serotypes. All nonvaccine serotypes increased 71.4%. The decrease in vaccine serotypes was more impressive during the first year of life (-54.8%) than for children between 1 and 5 years of age (-19.1%). Among children under 1 year old, penicillin nonsusceptible isolates declined between the two periods of the study (47.2% vs. 25.0%) (P=0.03), as did those of cefotaxime and ceftriaxone nonsusceptible isolates. No changes were observed for isolates nonsusceptible to tetracycline and macrolides. The serotypes of these nonsusceptible isolates differed after the introduction of vaccine (P=0.01). Multiresistance increased 57.1% after the introduction of vaccine. Multiresistant isolates with vaccine serotype declined 42.9% (P<0.001), and nonvaccine serotypes appeared during the vaccination period (P<0.001). These findings suggest a replacement of vaccine serotypes by nonvaccine serotypes, mainly among nonsusceptible isolates.     

Enzyme-linked immunosorbent assay for detection of serum antibody in children vaccinated with Japanese encephalitis vaccine

Serum antibodies in children who had been vaccinated with Japanese encephalitis (JE) vaccine were measured by enzyme-linked immunosorbent assay (ELISA) and neutralization (N) and hemagglutination-inhibition (HI) tests. Of 20 serum samples obtained after two shots of JE vaccine in the first year, all but one showed positive titers in the ELISA and N test, but five showed negative titers in the HI test. All 12 serum samples obtained after booster immunization with JE vaccine in the second year showed positive and considerably higher titers in all three tests. Moreover, a high correlation was found between the ELISA, N and HI titers. These results indicate that the ELISA is useful for detecting antibodies in subjects immunized with JE vaccine.     

Automated capillary Western dot blot method for the identity of a 15-valent pneumococcal conjugate vaccine

Simple Western is a new technology that allows for the separation, blotting, and detection of proteins similar to a traditional Western except in a capillary format. Traditionally, identity assays for biological products are performed using either an enzyme-linked immunosorbent assay (ELISA) or a manual dot blot Western. Both techniques are usually very tedious, labor-intensive, and complicated for multivalent vaccines, and they can be difficult to transfer to other laboratories. An advantage this capillary Western technique has over the traditional manual dot blot Western method is the speed and the automation of electrophoresis separation, blotting, and detection steps performed in 96 capillaries. This article describes details of the development of an automated identity assay for a 15-valent pneumococcal conjugate vaccine, PCV15–CRM197, using capillary Western technology.     

伤寒Vi多糖结合疫苗免疫小鼠后的抗体类型及动态分析

伤寒Vi多糖结合疫苗和Vi多糖疫苗分别免疫小鼠,分离血清,采用间接ELISA法测定不同时点血清中特异性IgA、IgM、IgG及其亚类(IgG1、IgG2a、IgG3)的抗体滴度。结果显示,免疫一针后,Vi多糖结合疫苗组的IgG抗体GMT值明显升高,第二针有加强效应(P<0.01);所测3种IgG亚型中IgG2a抗体滴度升高明显;Vi多糖和结合疫苗免疫小鼠后,血清中IgA和IgM抗体滴度均有显著升高,但无加强应答。显示Vi多糖结合疫苗在诱导小鼠血清IgG应答方面有加强效应。     

A calicheamicin conjugate with a fully humanized anti-MUC1 antibody shows potent antitumor effects in breast and ovarian tumor xenografts

Murine CTM01 is an internalizing murine IgG(1) monoclonal antibody that recognizes the MUC1 antigen expressed on many solid tumors of epithelial origin. Calicheamicin conjugates of this antibody have previously been shown to be potent, selective antitumor agents in preclinical models. A conjugate has now been made with a genetically engineered human version of this antibody, hCTM01. The hCTM01 is an IgG(4) isotype, has an immunoaffinity approximately 30% higher than mCTM01 by competitive RIA, and is efficiently internalized into target cells. The hCTM01-NAc-gamma calicheamicin DM amide conjugate, referred to as CMB-401, shows targeted killing of MUC1-expressing cells in vitro and produces pronounced dose-related antitumor effects over an 8-fold dose range against a MUC1-expressing, ovarian xenograft tumor, OvCar-3. The specificity of CMB-401 was confirmed by comparing its antitumor effects with those of an isotype-matched nonspecific conjugate against the MX-1 breast carcinoma. CMB-401, given either ip or iv, was highly active in these models in single and multiple dose regimens and gave complete regressions at the highest doses examined with good overall therapeutic ratios. CMB-401 also gave good antitumor effects at similar doses with a cisplatin-resistant MUC1-expressing cell line.     

Levels of pneumococcal conjugate vaccine coverage and indirect protection against invasive pneumococcal disease and pneumonia hospitalisations in Australia: An observational study

BackgroundThere is limited empiric evidence on the coverage of pneumococcal conjugate vaccines (PCVs) required to generate substantial indirect protection. We investigate the association between population PCV coverage and indirect protection against invasive pneumococcal disease (IPD) and pneumonia hospitalisations among undervaccinated Australian children.Methods and findingsBirth and vaccination records, IPD notifications, and hospitalisations were individually linked for children aged <5 years, born between 2001 and 2012 in 2 Australian states (New South Wales and Western Australia; 1.37 million children). Using Poisson regression models, we examined the association between PCV coverage, in small geographical units, and the incidence of (1) 7-valent PCV (PCV7)-type IPD; (2) all-cause pneumonia; and (3) pneumococcal and lobar pneumonia hospitalisation in undervaccinated children. Undervaccinated children received <2 doses of PCV at <12 months of age and no doses at ≥12 months of age. Potential confounding variables were selected for adjustment a priori with the assistance of a directed acyclic graph.There were strong inverse associations between PCV coverage and the incidence of PCV7-type IPD (adjusted incidence rate ratio [aIRR] 0.967, 95% confidence interval [CI] 0.958 to 0.975, p-value < 0.001), and pneumonia hospitalisations (all-cause pneumonia: aIRR 0.991 95% CI 0.990 to 0.994, p-value < 0.001) among undervaccinated children. Subgroup analyses for children <4 months old, urban, rural, and Indigenous populations showed similar trends, although effects were smaller for rural and Indigenous populations. Approximately 50% coverage of PCV7 among children <5 years of age was estimated to prevent up to 72.5% (95% CI 51.6 to 84.4) of PCV7-type IPD among undervaccinated children, while 90% coverage was estimated to prevent 95.2% (95% CI 89.4 to 97.8). The main limitations of this study include the potential for differential loss to follow-up, geographical misclassification of children (based on residential address at birth only), and unmeasured confounders.ConclusionsIn this study, we observed substantial indirect protection at lower levels of PCV coverage than previously described—challenging assumptions that high levels of PCV coverage (i.e., greater than 90%) are required. Understanding the association between PCV coverage and indirect protection is a priority since the control of vaccine-type pneumococcal disease is a prerequisite for reducing the number of PCV doses (from 3 to 2). Reduced dose schedules have the potential to substantially reduce program costs while maintaining vaccine impact.

In an observational study, Jocelyn Chan and colleagues investigate associations between pneumococcal conjugate vaccine coverage and incidence of invasive pneumococcal disease and pneumonia among children under 5 years in Australia.     

Development of a solid-phase immunoenzyme method for determining the antibody level in the blood sera of persons vaccinated with influenza vaccine

To control the effectiveness of vaccination against influenza, the optimum conditions for making the enzyme-linked immunosorbent assay (ELISA) with a view to determine the level of anti-influenza antibodies in human blood sera have been established. The kinetics of influenza virus adsorption in the wells of ELISA polystyrene plates and the kinetics of the interaction between the immobilized antigen and species-specific peroxidase-labeled antibodies have been studied. The method has been shown to be more sensitive than the hemagglutination inhibition test in the determination of seroconversion in persons immunized with influenza vaccine.     

Use of pneumococcal vaccine in patients with renal pathology

The use of pneumococcal polysaccharide vaccine in patients with chronic renal pathology has proved to be expedient as it prevents the development of pneumococcal infection. However, active immunosuppressive therapy and massive proteinuria result in decreased duration of antibody persistence, which makes in necessary to repeat the injection of the vaccine 20-22 months after the first vaccination.