抗原致敏期缺损补体增强抗肿瘤免疫效应

目的 观察蛇毒因子(CVF)缺损补体对疫苗诱导的抗肿瘤免疫的影响.方法 用CVF分别在抗原的致敏期和免疫的效应期缺损补体,抗原OVA加完全弗氏佐剂(CFA)联合免疫C57BL/6小鼠,14 d后接种E.G7肿瘤细胞,评价补体缺损效果,观察肿瘤出现时间,记录小鼠肿瘤大小.结果 OVA CFA免疫的正常小鼠,在肿瘤接种14 d内能完全抑制肿瘤生长;抗原致敏期缺损补体,肿瘤接种21 d内能完全抑制肿瘤生长;免疫效应期缺损补体,肿瘤出现的时间与OVA CFA免疫的正常小鼠相似.结论 抗原致敏期补体缺损可能有利于抗肿瘤免疫.     

hCGβ-03d3基因免疫BALB／c小鼠选择性促进B细胞克隆扩增

评价分子佐剂C3d在基因免疫中选择性促进抗原特异性B细胞增殖作用。分别用质粒pCMV4-hcGβ-C3d3和pCMV4-hOGβ免疫BALB／c小鼠，免疫剂量为50pmol。间隔3周相同剂量加强免疫1次。加强免疫后第1周及第2周，MTT法分析各组小鼠脾脏B细胞和T细胞增殖；ELISPOT法分析两免疫组小鼠脾脏hcGβ抗原特异性IgG分泌细胞。结果显示在加强免疫后第1周及第2周，hCGβ-C3d3免疫组B细胞增殖能力显著高于hCGβ免疫组及正常对照组；而各组间T细胞增殖状况未见明显差异。hcGβ-C3d3免疫组较hCGβ免疫组小鼠脾细胞分泌IgG的量和分泌hCGβ抗体的细胞数量均明显增加。结果表明分子佐剂C3d对于B细胞具有选择性克隆扩增作用。     

髓系抑制性细胞在小鼠肝癌免疫逃逸中的作用

目的:研究荷瘤小鼠脾脏中髓系抑制性细胞(Myeloid-derived suppressor cells,MDSCs)比例的变化及在组织中的分布,探讨其在肝癌免疫逃逸中的作用。方法:采用肝癌细胞原位移植法建立小鼠原位肝癌模型,流式细胞仪检测正常小鼠和荷瘤小鼠7、14、21天脾脏中MDSCs的比例,免疫组织化学染色对其进行定位分析。结果:荷瘤小鼠脾脏中MDSCs的比例比正常小鼠显著增高(P0.05),而且随着荷瘤时间的延长,MDSCs的比例逐渐增加。正常小鼠脾脏中少量的MDSCs散在分布于红髓区,荷瘤后大量MDSCs主要聚积在边缘区及白髓区的动脉周围淋巴鞘。结论:小鼠脾脏中MDSCs的比例与肿瘤进展相关,且主要分布在脾脏胸腺依赖区。     

U14-CBE脂质体瘤苗诱导的细胞和体液免疫应答

目的 探讨脂质体瘤苗诱导的免疫应答,以探明细胞表面抗原(crude butanol extraction,CBE)-脂质体瘤苗诱导抗癌免疫的效应机制.方法 采用正丁醇法提取子宫颈癌U14-CBE,以卵磷脂(ePC)、磷脂酰乙醇胺(PE)和胆固醇(Chol)制成大单层脂质体,将CBE包裹入脂质体,制成CBE-脂质体瘤苗.分别于第0、7、14天将CBE-脂质体瘤苗腹腔接种于免疫Km小鼠体内,在免疫后的第7、14、24天处死小鼠,取组织称湿重,并行组织学、组织化学观察脾脏中由该脂质体瘤苗诱导的T细胞和B细胞的反应.结果 经U14-CBE脂质体和单纯CBE免疫的小鼠脾脏重量明显高于空白对照组和空白脂质体组(P<0.05),且CBE脂质体组脾重呈持续性增长,而单纯CBE组脾重于第14天达高峰,第24天又有所回落.组织学和组织化学染色显示脾脏中细动脉周围淋巴鞘(periarterial lymphatic sheath,PALS)和免疫母细胞数量增多、嗜派若宁大细胞增多以及淋巴小结增多、生发中心活性加强和浆细胞数量增多.结论 CBE-脂质体瘤苗既可引起显著的细胞免疫反应,也可引发体液免疫反应.     

TNFSF14对STZ诱发Ⅰ型糖尿病的影响及其机制初探

目的:以链脲佐菌素(STZ)腹腔注射小鼠,建立Ⅰ型糖尿病动物模型,探讨TNFSF14在Ⅰ型糖尿病病理发生的作用。方法:以55 mg/kg的剂量,腹腔注射STZ于野生型(WT)和TNFSF14缺陷(TNFSF14 KO)小鼠体内,连续注射5 d,并在最后一次注射的当天开始测量血糖,根据情况每周测量2～3次;在指定的时间点处死小鼠,收集胰腺组织、脾脏和胰腺淋巴结。HE染色观察胰腺组织的病理情况;流式细胞术检测脾脏和胰腺淋巴结的淋巴细胞中T细胞亚群(CD3⁺T细胞、CD4⁺T细胞以及CD4⁺FoxP3⁺调节性T细胞)的频率。结果:连续5 d注射STZ后,WT组小鼠的血糖随即急剧上升,23 d后所有小鼠均超过了正常水平,而TNFSF14 KO小鼠的血糖值相对稳定,23 d后仍有80%的小鼠维持在正常血糖水平。HE染色显示,与WT小鼠相比,TNFSF14 KO小鼠的胰岛中淋巴细胞浸润明显减少,胰岛相对完整。流式细胞术结果表明,与WT组小鼠相比,TNFSF14 KO小鼠脾脏和胰腺淋巴结淋巴细胞中的CD3     

LEF-1协助TCF-1决定蛋白免疫应答中滤泡辅助T细胞的功能

目的 探讨在蛋白免疫应答中转录因子TCF-1与LEF-1在滤泡辅助T细胞的分化与功能中的地位。方法 对他莫昔芬诱导的条件敲除Tcf7与Lef1小鼠采用NP-KLH联合铝佐剂免疫或者NP-CGG联合完全弗氏佐剂免疫，分析应答过程中滤泡辅助T细胞的分化与功能，检测蛋白免疫应答中T细胞与B细胞TCF-1与LEF-1的表达量，并用脾脏嵌合小鼠模型验证TCF-1与LEF-1对于滤泡辅助T细胞功能的重要性。结果 Tcf7与Lef1敲除小鼠的滤泡辅助T细胞分化是正常的，而B细胞应答严重缺陷。同时，Tcf7敲除小鼠的B细胞应答也是缺陷的，而Lef1敲除小鼠的B细胞应答是完整的；TCF-1与LEF-1在滤泡辅助T细胞中大量表达，而在B细胞中不表达；脾脏嵌合小鼠模型提示，在有正常滤泡辅助T细胞的帮助下，B细胞中TCF-1与LEF-1的缺失不会导致B细胞应答缺陷。结论 在蛋白免疫应答中，TCF-1与LEF-1对于滤泡辅助T细胞的分化是不重要的，LEF-1协助TCF-1通过影响滤泡辅助T细胞的功能而影响B细胞应答。     

miR-106b表达下调介导疟疾红内期疫苗免疫保护性下降

目的探讨miR-106b在疟疾红内期感染后控制疫苗免疫保护性随时间逐渐降低中的作用。方法 C57BL/6小鼠通过尾静脉接种约氏疟原虫P.yoelii 17XNL感染的红细胞,接种小鼠给予氯喹控制红内期感染的发生。接种完成后不同时间点(30 d、90 d、180 d)首先检测小鼠免疫保护性,ELISA检测小鼠血清抗红内期疟原虫抗体滴度,q RT-PCR检测血清miR-106b表达情况。然后,通过流式细胞技术检测脾脏B细胞TACI(transmembrane activator and CAML interactor)表达变化。最后通过体外培养B细胞,加入miR-106b mimic后检测B细胞TACI表达变化。结果免疫后30 d小鼠可产生100%的免疫保护,免疫后90 d小鼠在i RBC攻击后第3天均出现感染,而免疫后180 d小鼠在i RBC攻击后第2天均出现感染。同时,免疫后180 d与30 d相比抗体滴度明显下降(P<0.01),并且小鼠血清中miR-106b的表达也呈现明显的下降趋势。流式细胞分析发现免疫后180 d小鼠脾脏记忆性B细胞(memory B cells,MBCs)表面TACI表达比免疫30 d及90 d小鼠均出现明显下降(P<0.01)。体外培养B细胞加入miR-106b mimic后TACI表达增高。结论疟原虫红内期感染后控制疫苗保护性降低与血清中miR-106b及脾脏MBCs表面TACI表达降低有关,提高miR-106b的浓度可增加MBCs表面TACI的表达。     

hCGβ-C3d3基因免疫BALB/c小鼠选择性促进B细胞克隆扩增

评价分子佐剂C3d在基因免疫中选择性促进抗原特异性B细胞增殖作用。分别用质粒pCMV4-hCG-βC3d3和pCMV4-hCGβ免疫BALB/c小鼠,免疫剂量为50 pmol。间隔3周相同剂量加强免疫1次。加强免疫后第1周及第2周,MTT法分析各组小鼠脾脏B细胞和T细胞增殖;ELISPOT法分析两免疫组小鼠脾脏hCGβ抗原特异性IgG分泌细胞。结果显示在加强免疫后第1周及第2周,hCG-βC3d3免疫组B细胞增殖能力显著高于hCGβ免疫组及正常对照组;而各组间T细胞增殖状况未见明显差异。hCG-βC3d3免疫组较hCGβ免疫组小鼠脾细胞分泌IgG的量和分泌hCGβ抗体的细胞数量均明显增加。结果表明分子佐剂C3d对于B细胞具有选择性克隆扩增作用。     

BET蛋白抑制剂JQ1对MRL/lpr狼疮小鼠外周B细胞分化的影响北大核心CSCD

目的:探讨BET蛋白抑制剂JQ1对MRL/lpr狼疮小鼠外周B细胞分化的影响及其治疗作用。方法:12周龄MRL/lpr小鼠分别腹腔注射JQ150 mg/(kg·d)或10%DMSO;每2周检测24 h尿蛋白定量;6周后检测血清中尿素氮(BUN)、肌酐(Cr)、补体C3、补体C4、抗ds-DNA抗体、ANA及IgG、IgG1、IgG2a、IgM等免疫球蛋白水平;PAS染色观察肾脏组织病理学改变,免疫荧光染色观察IgG和C3免疫复合物沉积情况。利用流式细胞术检测小鼠B细胞各亚群细胞的比例;RT-qPCR检测脾脏prdm1 mRNA表达水平。结果:与DMSO组相比,JQ1治疗组小鼠24 h尿蛋白定量显著减少,血清BUN、Cr水平明显降低,补体C3、C4水平明显升高,抗ds-DNA抗体、ANA以及IgG、IgG1、IgG2a和IgM等免疫球蛋白水平明显降低;此外,JQ1治疗组小鼠肾小球、肾血管的病理损害程度均明显减轻,肾脏IgG和C3免疫复合物沉积显著减少。同时,JQ1治疗组小鼠脾脏、淋巴结、外周血B细胞中浆细胞和记忆B细胞亚群的比例显著下降;JQ1治疗亦显著抑制狼疮小鼠B细胞内调节浆细胞分化的关键转录因子prdm1 mRNA表达。结论:BET蛋白抑制剂JQ1对MRL/lpr狼疮小鼠具有显著的治疗作用,通过抑制Blimp1表达进而调节浆细胞分化可能是其发挥治疗作用的机制之一。BET蛋白可能是SLE治疗的新靶标。     

FCA和FICA可增强淋巴滤泡捕捉抗原的能力

目的　探讨向体内注入非抗原类物质能否引起反应性淋巴滤泡形成 ,观察体内注入FCA(完全弗式佐剂 )、FICA(不完全弗式佐剂 )对滤泡树突状细胞 (FDC)捕捉抗原的能力有无影响。方法　将FCA、FI CA分别注入小鼠足底 ,数日后取出腘淋巴结 ,应用PNA B法及PAP免疫组化法染色 ,采取三维重塑方法 ,统计淋巴滤泡、FDC细胞群数量。结果　注入FCA、FICA后第 5日出现初级淋巴滤泡 ,第 3 5日数量达到高峰 ,之后逐渐减退。同时 ,滤泡树突状细胞 (FDC)与B细胞聚集同步出现。结论　动物体内注入有丝分裂物质FCA、FICA引起引流淋巴结内次级淋巴滤泡形成 ,初级滤泡形成过程中B细胞聚集与FDC形成是同步发生的     

Increased immunogenicity and induction of class switching by conjugation of complement C3d to pneumococcal serotype 14 capsular polysaccharide

Previous studies have demonstrated an adjuvant effect for the C3d fragment of complement C3 when coupled to T-dependent protein antigens. In this study, we examined the antibody response to covalent conjugates of C3d and a T-independent antigen, the capsular polysaccharide of serotype 14 Streptococcus pneumoniae (PPS14). We prepared a conjugate of mouse C3d and PPS14 and compared its immunogenicity with that of a conjugate of PPS14 and ovalbumin (OVA). When BALB/c mice were immunized with PPS14-C3d, there was a significant increase in serum anti-PPS14 concentrations compared with either native PPS14 or control PPS14-glycine conjugates. This was accompanied by a switch in anti-PPS14 from predominantly immunoglobulin M (IgM) to IgG1 by day 25 following primary immunization. Following secondary immunization with PPS14-C3d, there was a marked booster response and a further increase in the ratio of IgG1 to IgM anti-PPS14. Although the primary antibody response to the PPS14-OVA conjugate exceeded that induced by immunization with PPS14-C3d, serum anti-PPS14 concentrations after a second injection of PPS14-C3d were nearly identical to those induced by secondary immunization with PPS14-OVA. Experiments with athymic nude mice suggested that T cells were not required for the adjuvant effect of C3d on the primary immune response to PPS14 but were necessary for enhancement of the memory response after a second injection of PPS14-C3d. These studies show that the adjuvant effects of C3d extend to T-independent antigens as well as T-dependent antigens. As a means of harnessing the adjuvant potential of the innate immune system, C3d conjugates may prove useful as a component of vaccines against encapsulated bacteria.     

Immunization of aged mice with a pneumococcal conjugate vaccine combined with an unmethylated CpG-containing oligodeoxynucleotide restores defective immunoglobulin G antipolysaccharide responses and specific CD4+-T-cell priming to young adult levels

Polysaccharide (PS)-protein conjugate vaccines, in contrast to purified PS vaccines, recruit CD4+-T-cell help and restore defective PS-specific humoral immunity in the immature host. Surprisingly, in the immunocompromised, aged host, anti-PS responses to conjugate vaccines are typically no better than those elicited by purified PS vaccines. Although aging leads to defects in multiple immune cell types, diminished CD4+-T-cell helper function has recently been shown to play a dominant role. We show that in response to immunization with purified pneumococcal capsular PS serotype 14 (PPS14) in saline, the T-cell-independent immunoglobulin G (IgG) anti-PPS14 response in aged mice was comparable to that in young mice. In contrast, the T-cell-dependent IgG anti-PPS14 response to a soluble conjugate of PPS14 and pneumococcal surface protein A (PspA) (PPS14-PspA) in saline was markedly defective. This was associated with defective priming of PspA-specific CD4+ T cells. In contrast, immunization of aged mice with PPS14-PspA combined with an unmethylated CpG-containing oligodeoxynucleotide (CpG-ODN) restored IgG anti-PPS14 responses to young adult levels, which were substantially higher than those observed using purified PPS14. This was associated with enhanced PspA-specific CD4+-T-cell priming. Similarly, intact Streptococcus pneumoniae capsular type 14, which contains Toll-like receptor (TLR) ligands, also induced substantial, though modestly reduced, T-cell-dependent (TD) IgG ant-PPS14 responses in aged mice. Spleen and peritoneal cells from aged and young adult mice made comparable levels of proinflammatory cytokines in response to CpG-ODN, although cells from aged mice secreted higher levels of interleukin-10. Collectively, these data suggest that inclusion of a TLR ligand, as an adjuvant, with a conjugate vaccine can correct defective TD IgG anti-PS responses in elderly patients by augmenting CD4+-T-cell help.     

Complement dependency of splenic localization of pneumococcal polysaccharide and conjugate vaccines

The immune response to polysaccharides is initiated when polysaccharides bind complement factor C3d, and these polysaccharide-C3d complexes subsequently localize on splenic marginal zone B cells strongly expressing CD21 (complement receptor 2). Infants and children under the age of 2 years have low or absent expression of CD21 on their marginal zone B cells, and consequently do not adequately respond to polysaccharides. In contrast, polysaccharide-protein conjugate vaccines are able to induce antibodies at this young age. Conjugate vaccines apparently overcome the necessity for CD21-C3d interaction for an antipolysaccharide immune response. We demonstrate in a rat model that localization of pneumococcal polysaccharides on splenic marginal zone B cells indeed is complement dependent. We also show that pneumococcal conjugates do not specifically localize on splenic marginal zone B cells and that splenic localization of polysaccharide conjugates is independent of the presence of complement. Thus, the induction of antipolysaccharide antibodies by conjugate vaccines apparently can occur independently of CD21-C3d interaction. These basic findings may explain the effectiveness of conjugated vaccines in young children and may open the way for their application in other patient groups.     

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。     

Depletion of complement has distinct effects on the primary and secondary antibody responses to a conjugate of pneumococcal serotype 14 capsular polysaccharide and a T-cell-dependent protein carrier

Complement activation plays a critical role in the immune response to T-cell-dependent and T-cell-independent antigens. However, the effect of conjugation of T-cell-dependent protein carriers to T-cell-independent type 2 antigens on the requirement for complement in the humoral immune response to such antigens remains unknown. We studied the role of complement activation on the antibody response of BALB/c mice immunized with the T-cell-independent type 2 antigen serotype 14 pneumococcal capsular polysaccharide (PPS14), either in unmodified form or conjugated to ovalbumin (OVA). In mice immunized with either PPS14 or PPS14-OVA, depletion of endogenous complement at the time of primary immunization by treatment with cobra venom factor (CVF) diminished serum anti-PPS14 concentrations after primary immunization but enhanced antibody responses after secondary immunization. The secondary immunoglobulin G (IgG) anti-PPS14 antibody response after immunization with PPS14-OVA was especially enhanced by complement depletion, was observed at doses as low as 0.2 mug of antigen, and was maximal when CVF was administered within 2 days of immunization. The avidity and opsonophagocytic functions of IgG anti-PPS14 antibodies were comparable in mice immunized with PPS14-OVA with or without complement depletion. Serum anti-PPS14 antibody concentrations were near normal, and the enhancing effects of CVF treatment on the secondary anti-PPS14 antibody response were also apparent in splenectomized mice immunized with PPS14-OVA. These results demonstrate that complement activation can have distinct effects on the primary and secondary antibody responses to a T-cell-independent type 2 antigen, either unmodified or conjugated to a T-cell-dependent protein carrier. These differences should be taken into consideration when using complement to modulate the immune response to vaccines.     

Role of complement receptor type 2 and endogenous complement in the humoral immune response to conjugates of complement C3d and pneumococcal serotype 14 capsular polysaccharide

Conjugation of the complement fragment C3d to both T-cell-dependent (TD) protein and T-cell-independent type 2 (TI-2) polysaccharide antigens enhances the humoral immune response in mice immunized with either type of antigen. However, the ability of C3d-protein conjugates to enhance the antibody response in mice deficient in complement receptor types 1 and 2 (CR1 and CR2) has raised questions about the role of C3d-CR2 interactions in the adjuvant effect of C3d. In this study, we examined the role of CR2 binding and endogenous complement activation in the antibody response to conjugates of C3d and serotype 14 pneumococcal capsular polysaccharide (PPS14). To block binding of PPS14-C3d conjugates to CR2, mice were immunized with a mixture of vaccine and (CR2)2-immunoglobulin G1 (IgG1). Mice receiving (CR2)2-IgG1 at the time of primary immunization had a marked reduction in the primary anti-PPS14 antibody response but an enhanced secondary anti-PPS14 response, suggesting that C3d-CR2 interactions are required for the primary response but can have negative effects on the memory response. Further, compared with mice receiving PPS14-C3d having a high C3d/PPS14 ratio, mice immunized with PPS14-C3d with low C3d/PPS14 ratios had an enhanced secondary antibody response. Treatment of mice with cobra venom factor to deplete complement had insignificant effects on the antibody response to PPS14-C3d. Experiments with CBA/N xid mice confirmed that PPS14-C3d conjugates retain the characteristics of TI-2 rather than TD antigens. Thus, the adjuvant effect of C3d conjugated to PPS14 requires C3d-CR2 interactions, does not require activation of endogenous complement, and is not mediated by TD carrier effects.     

Surface plasmon resonance analysis of antipolysaccharide antibody specificity: responses to meningococcal group C conjugate vaccines and bacteria

Antibody (Ab) responses to polysaccharides (PS), such as Neisseria meningitidis group C PS (MCPS), are characterized as being thymus independent and are restricted with regard to clonotype and isotype expression. PS conjugated to proteins, e.g., MCPS coupled with tetanus toxoid or the diphtheria toxin derivative CRM197, elicit thymus-dependent responses. The present study developed a surface plasmon resonance approach to evaluate Ab responses to MCPS conjugate vaccines, including either O-acetylated (OAc+) or de-O-acetylated (OAc-) forms of the PS. The results were generally consistent with those obtained by enzyme-linked immunosorbent assay and showed that sera from mice immunized with conjugate vaccines contain Abs that bind more effectively to OAc+ and OAc- MCPS than sera from mice immunized with fixed bacteria. The data suggest a critical shared or overlapping epitope recognized by all the conjugate vaccine immune sera and strategies for assessing polyclonal Ab avidity.     

Preclinical evaluation of group B Neisseria meningitidis and Escherichia coli K92 capsular polysaccharide-protein conjugate vaccines in juvenile rhesus monkeys.

We reported the first use of group B meningococcal conjugate vaccines in a nonhuman primate model (S. J. N. Devi, C. E. Frasch, W. Zollinger, and P. J. Snoy, p. 427-429, in J. S. Evans, S. E. Yost, M. C. J. Maiden, and I. M. Feavers, ed., Proceedings of the Ninth International Pathogenic Neisseria Conference, 1994). Three different group B Neisseria meningitidis capsular polysaccharide (B PS)-protein conjugate vaccines and an Escherichia coli K92 capsular polysaccharide-tetanus toxoid (K92-TT) conjugate vaccine are here evaluated for safety and relative immunogenicities in juvenile rhesus monkeys with or without adjuvants. Monkeys were immunized intramuscularly with either B PS-cross-reactive material 197 conjugate, B PS-outer membrane vesicle (B-OMV) conjugate, or N-propionylated B PS-outer membrane protein 3 (N-pr. B-OMP3) conjugate vaccine with or without adjuvants at weeks 0, 6, and 14. A control group of monkeys received one injection of the purified B PS alone, and another group received three injections of B PS noncovalently complexed with OMV. Antibody responses as measured by enzyme-linked immunosorbent assay varied among individual monkeys. All vaccines except B PS and the K92-TT conjugate elicited a twofold or greater increase in total B PS antibodies after one immunization. All vaccines, including the K92-TT conjugate, elicited a rise in geometric mean B PS antibody levels of ninefold or more over the preimmune levels following the third immunization. Antibodies elicited by N-pr. B-OMP3 and B-OMV conjugates were directed to the N-propionylated or to the spacer-containing B PS antigens as well as to the native B PS complexed with methylated human serum albumin. None of the vaccines caused discernible safety-related symptoms.     

Characterization of a recombinant pneumolysin and its use as a protein carrier for pneumococcal type 18C conjugate vaccines.

Pneumolysin from Streptococcus pneumoniae was expressed in Escherichia coli as a glutathione S-transferase fusion protein and purified by affinity and hydroxylapatite chromatography. The purified recombinant pneumolysin (rPL), with a molecular mass of 53 kDa, had a specific activity of 3 x 10(5) hemolytic units per mg of protein on rabbit erythrocytes and reacted identically in immunodiffusion with the antisera against native pneumolysin. The rPL was used as a protein carrier to prepare conjugate vaccine with pneumococcal type 18C polysaccharide (PS18C). The PS18C was directly coupled to rPL by reductive animation or was indirectly coupled to rPL via a spacer molecule, adipic acid dihydrazide. The conjugates were nontoxic for mice and guinea pigs at 100 micrograms per dose. The immunogenicity and protective efficacy of both conjugates were tested in mice. A single dose of either of the vaccines elicited a rise in immunoglobulin G antibody production; after two booster injections of the vaccines, statistically significant booster responses (P < 0.001) to both rPL and PS18C were produced. The sera containing the antibodies to rPL were capable of neutralizing the hemolytic activity of rPL to rabbit erythrocytes and the cytotoxicity of rPL to bovine pulmonary endothelial cells. Immunization with the conjugate vaccines conferred statistically significant protection in mice against lethal challenge with type 18C pneumococci.     

Immunogenicity of conjugate vaccines consisting of pneumococcal capsular polysaccharide types 6B, 14, 19F, and 23F and a meningococcal outer membrane protein complex.

In an effort to prepare pneumococcal (Pn) capsular polysaccharide (Ps) vaccines that would be immunogenic in infants, covalent conjugates were prepared for Pn types 6B, 14, 19F, and 23F. Each Ps type was covalently bound to an outer membrane protein complex from Neisseria meningitidis serogroup B and evaluated for immunogenicity in mice and infant monkeys. The conjugates induced specific anti-Ps antibody responses in mice and in infant rhesus and African green monkeys; a conjugate of 6B and outer membrane protein complex was immunogenic at Ps doses as low as 20 ng. Although low levels of the Pn group-common cell wall polysaccharide were present in all type-specific Ps preparations, anti-cell wall polysaccharide responses induced by covalent conjugates were < 1% of the total anti-Ps response after two doses of vaccine. In contrast, the anti-cell wall polysaccharide response of a noncovalent conjugate represented 41% of the anti-Ps response after two doses. Relative T-cell dependence, a requirement for the human target population of infants less than 18 months old, was demonstrated for all four Pn Ps conjugates in an athymic mouse model. Therefore, these Pn Ps-outer membrane protein complex conjugate vaccines are excellent candidates for evaluation in human infants.