Challenges and opportunities for the implementation of the Three Rs in Canadian vaccine quality control

A case-study approach was used to identify opportunities and challenges to the implementation of the Three Rs in vaccine testing in Canada. Data was obtained through interviews with 16 Canadian stakeholders involved in the production, testing and evaluation of vaccines. Participants identified inconsistent regulatory testing requirements, the lack of biological functionality of some in vitro methods, the benchmarking of in vitro against in vivo assays, and high caution towards method changes as major challenges to implementation. Opportunities to implementation were identified as the desire for and steps taken towards harmonization of test methods between countries, collaborations on new method development, the poor performance of traditional animal methods, the domino effect of one regulatory authority accepting a method after another, and stakeholder concerns for the ethical care and use of animals used in vaccine testing. These results suggest that industry and the Canadian government are open to implementing the Three Rs in vaccine quality control, but methods adopted must be reliable and biologically relevant. Improving the harmonization of regulatory requirements will assist in furthering the implementation of alternative methods.     

Comparison of CRM197, diphtheria toxoid and tetanus toxoid as protein carriers for meningococcal glycoconjugate vaccines

Glycoconjugate vaccines are among the most effective and safest vaccines ever developed. Diphtheria toxoid (DT), tetanus toxoid (TT) and CRM₁₉₇ have been mostly used as protein carriers in licensed vaccines. We evaluated the immunogenicity of serogroup A, C, W-135 and Y meningococcal oligosaccharides conjugated to CRM₁₉₇, DT and TT in naïve mice. The three carriers were equally efficient in inducing an immune response against the carbohydrate moiety in immunologically naïve mice. The effect of previous exposure to different dosages of the carrier protein on the anti-carbohydrate response was studied using serogroup A meningococcal (MenA) saccharide conjugates as a model. CRM₁₉₇ showed a strong propensity to positively prime the anti-carbohydrate response elicited by its conjugates or those with the antigenically related carrier DT. Conversely in any of the tested conditions TT priming did not result in enhancement of the anti-carbohydrate response elicited by the corresponding conjugates. Repeated exposure of mice to TT or to CRM₁₉₇ before immunization with the respective MenA conjugates resulted in a drastic suppression of the anti-carbohydrate response in the case of TT conjugate and only in a slight reduction in the case of CRM₁₉₇. The effect of carrier priming on the anti-MenA response of DT-based conjugates varied depending on their carbohydrate to protein ratio. These data may have implications for human vaccination since conjugate vaccines are widely used in individuals previously immunized with DT and TT carrier proteins.     

1例破伤风皮试强阳性患者的护理

总结1例破伤风强阳性患者的护理,根据患者的具体症状我们采取了地塞米松,钙剂抗过敏及20%甘露醇静滴,50%硫酸镁湿热敷后用肝素钠湿敷,红外线照射消肿等针对性治疗护理措施,经精心治疗护理患者康复出院。     

加速度肌松仪的预刺激方式对维库溴铵药效测定的影响

目的：观察加速度肌松监测仪的预刺激方法对维库溴铵药效测定的影响。方法30名女性患者分为三组,各10例。在同一患者的两手均放置肌松监测,随机选其中一手作为对照手,先给5 s,50 Hz强直刺激,然后行AUTO I校准,再给20 min TOF监测。每分钟记录一次T1值,第20分钟T1值分别与前各次用配对t检验比较。患者另一手为试验手,分为3组,在AUTO I校准后分别给予20 min（组一）、1 min（组二）和6 min（组三）TOF刺激。组一每分钟记录一次T1值,第20分钟T1值分别与前各次用配对t检验比较。然后用累积剂量法测定同一患者两手的维库溴铵ED50、ED90、ED95和斜率（Probit/LOG）。用配对t检验行自身比较。结果在20 min TOF预刺激期间,对照手T1稳定,但试验手最初T1逐渐增加,第6分钟后稳定。维库溴铵的ED50、ED90、ED95和斜率在组一和组三两手间差异无统计学意义（P〉0.05）,组二则对照手数值明显小于试验手（P〈0.05）。结论5 s、50 Hz强直刺激可迅速使T1值稳定,否则需6 min才能使T1值稳定,当T1值稳定后,维库溴铵药效测定不受预刺激方法影响。     

Heat shock increases antigenic peptide generation but decreases antigen presentation

The heat shock response is a universal and highly conserved cellular response to stress. We describe here the effect of elevated temperature on the capacity of B cells to present antigen. Heat shock markedly affects the ability of these cells to process and present tetanus toxin to class II-restricted T cell clones. Inhibition of antigen presentation is due neither to a modification of antigen capture nor to a variation of major histocompatibility complex (MHC) class II molecule synthesis and cell surface expression. Stressed and nonstressed B cells are able to present peptides loaded at the cell surface with the same efficiency. Nevertheless, heat shock leads to an increase of antigen peptide generation in subcellular compartments; an enhancement of cathepsin B activity is also observed. These data suggest that such a stress induces a failure in the intracellular peptide loading onto MHC class II molecules.     

静脉吸毒致破伤风临床特点分析

目的比较分析静脉吸毒所致破伤风与常见的外伤引起的破伤风在临床表现、诊断、治疗上的不同点.方法 15例静脉吸毒所致破伤风与24例外伤引起的破伤风的临床特点和治疗方案进行比较分析.结果静脉吸毒所致破伤风与常见的外伤引起的破伤风相比,没有明确的外伤史,临床症状复杂,常合并其他血源性传染病.结论静脉吸毒所致破伤风有特殊的症状,在诊断和治疗上应分别对待.     

14型肺炎球菌荚膜多糖-破伤风类毒素结合疫苗研究

目的：探讨制备肺炎球菌荚膜多糖（PNCPS）－蛋白结合疫苗适宜条件。方法：采用碳二亚胺法将14型PNCPS与破伤风类毒素（TT）结合，将结合物免疫NIH小鼠，用ELISA法检测小鼠血清中抗14例PNCPS的IgG抗体滴度。结果：结合反应产率和结合物中多糖，蛋白含量的测定显示试验成功合成了14型PNCPS－TT结合物，该结合物具有14型PNCPS的血清学特异性，将之免疫小鼠诱生的抗14型PNCPS特异性IgG抗水平显著高于单纯14型PNCPS。结论：试验成功地合成了14型PNCPS－TT结合物，本试验采用的结合方法可行。     

Seroprotection associated with infant vitamin A supplementation given with vaccines is not related to antibody affinity to Hepatitis B and Haemophilus influenzae type b vaccines

Vaccines are usually assessed by analyses of their safety and immunogenicity to determine the effectiveness of eliciting antibody responses against target organisms. However, it is equally important to establish antibody affinity because of its specific role in protection from infection. Antibody affinity can be determined by comparisons of various antibody concentrations in dose–response curves. During a study on the immunogenicity of a pentavalent vaccine in 888 infants, antibody affinity analyses of the hepatitis B and Haemophilus influenzae type b components were investigated in infants given 15 mg RE vitamin A with their vaccination and those who were not given vitamin A. In this paper we present the results of 222 infants; a 25% sub-sample of the original study. Analyses were carried out using dilutions of serum samples from fitted values corresponding to optical densities from antibody detection assays. These were obtained from the ligand binding equation and mid point titres in dose–response curves were then calculated. Vitamin A supplementation had no effect on the midpoint titres of Hepatitis B and H. influenzae type b vaccine derived antibodies. The significant effect of vitamin A supplementation on the Hepatitis B vaccine component observed in a previous seroprotection analysis is probably due to the amount of antibodies since affinity was unaffected.