Working Group on quality,safety and efficacy of typhoid Vi capsular polysaccharide conjugate,vaccines, Jeju,Republic of Korea, 5–7 September 2012

Typhoid fever is a gastrointestinal disease transmitted through the ingestion of contaminated water or food. The bacterium, Salmonella enterica subspecies enterica serovar Typhi is an important cause of illness and death in many poor countries where access to safe water and basic sanitation is limited. Humans are the only natural host and reservoir of S. Typhi. Typhoid fever causes around 21 million cases and at least 200,000 deaths per year. Currently, several groups are developing typhoid conjugate vaccines that are expected to be safe and effective in infancy or early childhood. The World Health Organization convened a meeting, in collaboration with the Korea Food and Drug Administration, with experts group in September 2012 to develop guidelines for regulatory evaluation of the quality, safety and efficacy of typhoid conjugate vaccines. This report summarizes collective views on scientific and technical issues that need to be considered in the guidelines.     

Immune suppression induced by Vi capsular polysaccharide is overcome by Vi-DT conjugate vaccine

The influence pre-exposure of mice to Vi capsular polysaccharide, purified from Salmonella enterica Serovar Typhi, on the subsequent immune response induced by a Vi-diphtheria toxoid (Vi-DT) conjugate was evaluated. Vi induced low anti Vi IgG titers with the dominant subclass being IgG3. The Vi-DT conjugate induced high titers of anti Vi IgG with the dominant subclass being IgG1 but with considerable quantities of IgG2a, IgG2b and IgG3. Priming of mice with Vi suppressed the response to a subsequent dose of conjugate and the suppression was overcome by a second dose of conjugate. Priming with conjugate prevented suppression of the anti Vi response and subsequent dosing with Vi raised titers back to previous levels but did not boost to new higher levels. The anti DT IgG response to one dose of conjugate was relatively strong and protracted and continued to rise for 12 weeks, compared to the response to one dose of DT which was poor and peaked at two weeks. The prolonged anti DT response was most likely due to the slow release of DT from the conjugate lattice as it degrades within the mouse resulting in a continuous stimulation of the immune response. The presence of increasing amounts of un-conjugated Vi, up to 50%, administered with the conjugate resulted in increasingly higher levels of both anti Vi and anti DT. Larger amounts of un-conjugated Vi inhibited the anti Vi response. These findings have implications for vaccine quality and a limit for un-conjugated polysaccharide should not exceed 50% and from a vaccine program perspective if the results presented here translate to humans then a Vi conjugate, once it becomes available, should replace Vi polysaccharide vaccines.     

Impact of vaccination against Haemophilus influenzae type b with and without a booster dose on meningitis in four South American countries

To inform World Health Organization recommendations regarding use of Haemophilus influenzae type b (Hib) vaccines in national immunization programs, a multi-country evaluation of trends in Hib meningitis incidence and prevalence of nasopharyngeal Hib carriage was conducted in four South American countries using either a primary, three-dose immunization schedule without a booster dose or with a booster dose in the second year of life. Surveillance data suggest that high coverage of Hib conjugate vaccine sustained low incidence of Hib meningitis and low prevalence of Hib carriage whether or not a booster dose was used.     

Immunogenicity and safety of a tetravalent E. coli O-antigen bioconjugate vaccine in animal models

BackgroundExtra-intestinal pathogenic Escherichia coli (ExPEC) are major human pathogens; however, no protective vaccine is currently available. We assessed in animal models the immunogenicity and safety of a 4-valent E. coli conjugate vaccine (ExPEC-4V, serotypes O1, O2, O6 and O25 conjugated to Exotoxin A from Pseudomonas aeruginosa (EPA)) produced using a novel in vivo bioconjugation method.MethodsThree doses of ExPEC-4V (with or without aluminum hydroxide) were administered to rabbits (2 μg or 20 μg per O-antigen, subcutaneously), mice (0.2 μg or 2 μg per O-antigen, subcutaneously) and rats (0.4 μg or 4 μg per O-antigen, intramuscularly). Antibody persistence and boostability were evaluated in rats using O6-EPA monovalent conjugate (0.4 μg O-antigen/dose, intramuscularly). Toxicity was assessed in rats (16 μg total polysaccharide, intramuscularly). Serum IgG and IgM antibodies were measured by ELISA.ResultsRobust antigen-specific IgG responses were observed in all animal models, with increased responses in rabbits when administered with adjuvant. O antigen-specific antibody responses persisted up to 168 days post-priming. Booster immunization induced a rapid recall response. Toxicity of ExPEC-4V when administered to rats was considered to be at the no observed adverse effect level.ConclusionsExPEC-4V conjugate vaccine showed good immunogenicity and tolerability in animal models supporting progression to clinical evaluation.     

用多糖-破伤风类毒素结合苗制备抗流行性脑膜炎球菌多糖单克隆抗体

［摘要］目的研制抗A群奈瑟脑膜炎球菌荚膜多糖单克隆抗体（GAMP mAb）。方法以A群奈瑟脑膜炎球菌荚膜多糖 破伤风类毒素（GAMP TT）耦联物免疫BALB/c小鼠,用常规细胞融合与克隆化技术获得一株能稳定分泌抗GAMP mAb的杂交瘤细胞株（2E7）。采用秋水仙素阻断法测定其染色体数目,降植烷诱导法制备含该抗体的小鼠腹腔积液,辛酸 硫酸铵沉淀法纯化单克隆抗体,十二烷基硫酸钠 聚丙烯酰胺凝胶电泳（SDS PAGE）灰度扫描测定提取物纯度,改良过碘酸盐氧化法制备辣根过氧化物酶（HRP）标记抗GAMP mAb,并采用中和法及其抗原替代法对抗GAMP mAb的特异性进行初步的鉴定。结果所获得的杂交瘤细胞（2E7）具有很好的生长特性,染色体数目约为139.73条;抗体分泌量适中,Ig亚类为IgG1,提取物浓度1.76～2.32 mg•mL 1,纯度97.2%,标记抗GAMP mAb的效价为1：25 600;抗原替代实验与中和实验对其特异性考核,初步结果证实2E7 mAb具有很好的抗GAMP特异性。结论成功制备抗GAMP mAb,为GAMP TT疫苗的生产监测及产品质量控制提供了必要的物质基础。     

B族链球菌多糖—蛋白质结合物黏膜免疫小鼠血清IgG研究

目的探讨B族链球菌荚膜多糖-破伤风类毒素结合物（GBS-CPS-TT）,经不同免疫途径免疫小鼠的可行性及免疫剂量。方法经滴鼻、灌胃、皮下注射途径免疫小鼠,各组均免疫3次,每次免疫间隔时间2周,免疫后1周时采集血清,采用间接酶联免疫吸附实验（ELISA）检测血清中特异性IgG的抗体滴度。应用统计软件SPSS13.0对数据进行统计学分析,组间均数比较采用方差分析。结果 GBS-CPS-TT经滴鼻免疫、灌胃免疫和皮下注射均可以诱导产生特异性血清IgG抗体。IgG抗体滴度分别为：滴鼻5μg组（2.671±0.207）;滴鼻10μg组（2.911±0.263）;皮下注射5μg组（2.866±0.251）;灌胃10μg组（2.851±0.224）。滴鼻10μg组诱导产生的IgG抗体滴度明显高于滴鼻5μg组（P〈0.01）。结论 GBS-CPS-TT经滴鼻免疫小鼠后可产生系统性免疫应答。     

Comparison of the safety and immunogenicity of an investigational and a licensed quadrivalent meningococcal conjugate vaccine in children 2-10 years of age

Background

Routine administration of quadrivalent meningococcal conjugate vaccine to adolescents and certain high risk groups is recommended in the United States and Canada. We compared the immunogenicity and safety of an investigational quadrivalent meningococcal vaccine conjugated to CRM-197 (MenACWY-CRM) with a licensed quadrivalent vaccine conjugated to diphtheria toxoid (MCV4) in children aged 2–10 years.

Methods

Eligible 2–5-year-olds were randomized 1:2:2 to receive either 2 doses of MenACWY-CRM, or 1 dose of MenACWY-CRM or MCV4; 6–10-year-olds were randomized 1:1 to receive a single dose of MenACWY-CRM or MCV4. The primary immunogenicity assessment was seroresponse separately for the two age cohorts 28 days following a single dose of MenACWY-CRM or MCV4. Noninferiority and superiority criteria were predefined. Solicited injection-site and systemic reactions were collected for the 7 days postvaccination.

Results

A total of 2907 children were randomized to receive study vaccine. MenACWY-CRM met statistical superiority criteria vs. MCV4 for groups W and Y and was noninferior for group C in both age strata. For group A, noninferiority criteria were not met; the group A seroresponse rates for MenACWY-CRM and MCV4, respectively were 72% (95% confidence interval 68–75%) and 77% (73–80%) in 2–5-year-olds and 77% (73–80%) and 83% (79–86%) in 6–10-year-olds. When the two age strata were combined (2–10-year-old children), MenACWY-CRM was noninferior to MCV4 for all four groups, and statistically superior for groups C, W, and Y. Safety parameters were similar across age cohorts and vaccines groups.

Conclusions

MenACWY-CRM and MCV4 were immunogenic and well tolerated in children aged 2–10 years. Seroresponse to MenACWY-CRM was statistically noninferior to MCV4 for all groups, and statistically superior for groups C, W, and Y.

Trial registration

Clinicaltrials.gov identifier: NCT00616421.     

半球中风病人眼球同向偏视的临床研究：附141例分析

对２８４例（左１４９例，右１３５例）壳核出血病人中１４１例眼球同向偏视的发生率、偏视程度及持续时间进行了分析。发现右半球病变眼症发生率非常明显地高于左侧者（Ｐ＜０．００５），右半球同向偏视的程度和持续时间亦大于和长于左侧者，说明眼球运动中枢支配的不对称性。右半球较集中，右半球较弥散。视觉空间注意力的左右半球差异可能是产生这种不对称性的生理学基础。     

Impact of pneumococcal vaccination in children on serotype distribution in adult community-acquired pneumonia using the serotype-specific multiplex urinary antigen detection assay

The aim of the study was to compare the distribution of the vaccine-serotypes covered by pneumococcal conjugate vaccines (PCV7 and PCV13) in adult patients with pneumococcal community-acquired pneumonia in Germany between the periods 2002–2006 and 2007–2011 using a novel serotype-specific multiplex urinary antigen detection assay (SSUA). Vaccination of children started with PCV7 in 2007, which was replaced by PCV13 in 2010. Following confirmation of the accuracy of SSUA in long-term stored urine samples from 112 patients with confirmed pneumonia and known pneumococcal serotype, urine samples of 391 CAPNETZ patients with documented pneumococcal pneumonia (i.e. positive BinaxNOW^® Streptococcus pneumoniae urine antigen test) but unknown serotype were tested for the 13 vaccine-serotypes using SSUA. The proportion of PCV7-serotypes significantly decreased in adult patients with pneumonia from 30.6% (2002–6) to 13.3% (2007–11, p < 0.001); in bacteremic pneumonia, PCV7-serotypes completely disappeared (3/14 versus 0/19, p = 0.058). Conversely, pneumococcal serotypes included by PCV13 remained stable during study period with a coverage of 61.5% (2002–06) and 59.7% (2007–11) in non-bacteremic pneumonia and 79% (for both periods) in bacteremic pneumonia, mainly due to an increase in pneumococcal serotypes 1, 3 and 7F during the second period. Thus, implementation of PCV7 in children in Germany in 2007 was associated with a significant decrease in vaccine-serotypes covered by PCV7 in adult patients with non-bacteremic pneumococcal pneumonia and with an elimination of PCV7 vaccine-serotypes in bacteremic pneumococcal pneumonia. PCV13 coverage remained high up to 2011, mainly due to an increase in serotypes 1, 3 and 7F.German Clinical Trials Register: DRKS00005274.     

A population-based analysis to determine the impact of the 13-valent pneumococcal conjugate vaccine on community-acquired pneumonia in British Columbia,Canada

BackgroundPneumonia is a leading cause of morbidity and mortality globally. We determined the impact of 13-valent pneumococcal conjugate vaccine (PCV13) use on community-acquired pneumonia (CAP) rates eight years after the vaccine was introduced in the infant immunization program.MethodsUsing diagnostic codes from administrative databases, we calculated the overall and age-specific CAP incidence per month (2000–2018). Changes in the CAP incidence before and after the PCV13 vaccine program introduction were evaluated using negative binomial regression model adjusting for 7-valent pneumococcal conjugate vaccine program.ResultsThe PCV13 vaccine infant immunization program was associated with declining CAP incidence among children aged 0–2 years (adjusted Incidence Rate Ratio (aIRR): 0.91; 95% CI: 0.87–0.96). Overall CAP incidence did not decrease in those aged 3–5 years (0.98; 95% CI: 0.93–1.04), 6–17 years (1.02; 95% CI: 0.97–1.08), 18–49 years (1.02; 95% CI:0.98–1.05), 50–64 years (1.07; 95% CI: 1.04–1.11), ≥65 years (1.05; 95% CI:1.02–1.08).ConclusionsThe PCV13 infant immunization program is temporally associated with a reduction in CAP incidence in vaccine target age group. However, no significant decrease in CAP incidence in other age groups warrants further study of the etiology of CAP to develop and implement effective prevention programs.