制备疫苗用W135/Y群脑膜炎球菌菌种的免疫原性及遗传稳定性观察

目的 为保证生产四价流脑(A、C、W135、Y群)结合疫苗质量一致性和可控性,对分离自国内的W135、Y群脑膜炎球菌CMCC(B)29037株和CMCC(B)29028株进行免疫原性及遗传稳定性观察.方法 将W135/Y群脑膜炎球菌工作种子批菌种分别连续传代至30代,并收获3、5、10、15、20、25及30代次菌液,对各代次菌进行免疫原性、抗原性、生化反应、毒性、毒力测定,并将30代次菌发酵培养后提取荚膜多糖进行质量分析.结果 CMCC(B)29037株和CMCC(B)29028株工作种子批菌种诱导小鼠产生总IgG抗体分别为1∶1114和1∶2229,杀菌抗体水平与IgG抗体间差异无统计学意义;试管凝集效价均达到1∶320,生化检定两菌株均发酵葡萄糖、麦芽糖,不发酵果糖、蔗糖、甘露醇和乳糖;两菌株的LD50均＞109,30代次内各代次菌的免疫原性、抗原性、生化反应和毒性均无差异.30代次菌液脑腔毒性测定显示均无病理改变,用第30代次菌生产的W135/Y群脑膜炎球菌荚膜多糖各项检定指标均合格.结论 分离自国内的CMCC(B)29037株和CMCC(B)29028株为脑膜炎球菌W135/Y群菌株,免疫原性、抗原性好,生化反应合格、安全性良好,连续传至30代次仍保持较好的安全性和免疫原性,30代次菌纯化的W135/Y群脑膜炎球菌荚膜多糖质量符合质控要求,可以用作四价流脑结合疫苗生产株.     

B群脑膜炎奈瑟菌外膜蛋白作为疫苗候选抗原的研究进展

目前获准上市的流脑疫苗主要有A群、A+C群以及A、C、W-135及Y群的四价混合疫苗,上述疫苗的有效免疫原成分均为脑膜炎球菌的荚膜多糖。而B群脑膜炎奈瑟菌的荚膜多糖因与人类N-乙酰神经氨酸聚合物结构相似,可能产生交叉反应,引起自身免疫病,不适合用作B群流脑的疫苗候选抗原。因此,研究者把焦点转向B群脑膜炎奈瑟菌外膜蛋白,目前报道的B群流脑疫苗外膜蛋白候选抗原主要包括fHBP、NspA、NHBA、NhhA、NadA、GNA1946、GNA1162、NMB0315等。本文就上述外膜蛋白作为B群流脑疫苗候选抗原的最新进展作一综述。     

A、C群脑膜炎球菌结合疫苗免疫原性研究

目的 研究A、C群脑膜炎球菌结合疫苗的免疫原性,包括剂量、免疫记忆及抗原相容性.方法 将不同剂量的A、C群脑膜炎球菌结合疫苗分别免疫小鼠,末次免疫后14 d采集血清测定血清抗体滴度,确定最佳免疫剂量后,再分别以单价A群和C群脑膜炎球菌结合疫苗及二价A、C群脑膜炎球菌结合疫苗同时对小鼠分别进行1、2、3针免疫,考察其针次效应和抗原相容性.结果 A、C群脑膜炎球菌结合疫苗中的A抗原和C抗原均以1.25 μg剂量免疫小鼠时,其免疫原性较好.A、C群脑膜炎球菌结合疫苗能够诱导小鼠产生免疫回忆应答,且在二价结合疫苗中的A群耦联物和C群耦联物配伍后无干扰作用,抗原相容性良好.结论 A、C群脑膜炎球菌结合疫苗具有较好的免疫原性和明显的免疫回忆应答,抗原相容性良好.     

脑膜炎奈瑟菌A群荚膜多糖与B群外膜蛋白复合物偶联物的制备和免疫原性

目的　脑膜炎奈瑟菌 (Nm)A群荚膜多糖与B群菌株 34 0 7或 5 42 85 2外膜蛋白复合物偶联 ,希望获得 1种对A和B群Nm感染皆有预防效果 ,并可提高A群荚膜多糖对婴幼儿免疫力的偶联物。方法　用饱和硫酸铵沉淀细菌培养上清液 ,沉淀物再经SephacrylS 30 0纯化获得外膜蛋白复合物。通过碳化二亚铵 (EDC)介导的缩合反应将B群外膜蛋白复合物与A群荚膜多糖偶联。偶联物、未偶联的荚膜多糖、B群外膜蛋白复合物及A群荚膜多糖和B群外膜蛋白复合物简单混合物按相同程序免疫小鼠获得抗体 ,经ELISA、杀菌力试验和Westernblotting测定了偶联物的免疫原性。结果　偶联物比未偶联的荚膜多糖或者荚膜多糖同B群外膜蛋白复合物简单混合抗原的免疫原性增强 2 1～32 0倍 ;其中以B群 34 0 7菌株的外膜蛋白复合物与A群荚膜多糖偶联的效果更好。偶联物免疫血清不仅对A群代表菌株 (2 90 19)和B群菌株 (34 0 7,5 42 85 2和 2 90 2 1)均有较强的杀菌活性 ,而且还对所试的具有不同菌型特征的其它 8株B群菌株仍有较强的交叉反应性。Westernblotting初步分析发现上述两种偶联物免疫的血清与各自的外膜蛋白复合物在相对分子质量约 42× 10 3 、39× 10 3 和 2 6× 10 3 处有相同的反应带 ,其中 42× 10 3 左右的条带为 1类外膜蛋白。结论     

分泌抗A群脑膜炎球菌多糖单克隆抗体的杂交瘤细胞系的建立

用A群脑膜炎球菌悬液免疫的BALB/c小鼠脾细胞与Sp2/0骨髓瘤细胞,经50％PEG处理进行融合。采用微量被动血凝试验(PHA)筛选及有限稀释法克隆化后,获得4株分泌抗A群脑膜炎球菌多糖单克隆抗体(McAb)的杂交瘤细胞系(WSA—C_(11),WSA—E_6,WSA—D_4,WSA—F_8),培养上清和诱生的小鼠腹水的特异性抗体的PHA和ELISA滴度分别为1.28—5.12×10~(-2)和1×10~(-5)—10~(-6)、4株McAb和PHA滴度均被A群脑膜炎球菌多糖抗原抑制,其血凝抑制滴度与所加抑制抗原的量成线性关系,4株McAb均与3株A群脑膜炎球菌菌株呈现强的玻片凝集反应,3株B群,2株C群,1株D群,及7株新群脑膜炎球菌菌株不发生效义玻片凝集反应。试验证明4株杂交瘤细胞所分泌的抗体是针对具有群特异性的A群脑膜炎球菌多糖抗原的。4株McAb具有很高的亲和力,经80～160倍稀释与A群脑膜炎球菌菌株仍呈现强的玻片凝集反应,而A群脑膜炎球菌诊断血清(Pc-Ab)高于10倍稀与本菌的玻片凝集反应明显减弱,McAc的细菌试管定量凝集反应滴度也较PcAb诊断血清高16～32倍。4株McAb均属小鼠IgM类。杂交瘤细胞系染色体计数为91～95条。4株条交瘤细胞在体外连续培养4个多月,40余代,经液氮冻存复苏后仍保持稳定的分泌抗体的能力。     

两株B群脑膜炎奈瑟氏菌脂寡糖减毒前后抗原性与毒性的检测

两株Ｂ群脑膜炎奈瑟氏菌脂寡糖减毒前后抗原性与毒性的检测孙银燕胡绪敬王君摘要脂寡糖（ＬＯＳ）是Ｂ群Ｎｍ的一种主要外膜抗原，用ＳｅｐｈａｃｒｙｌＳ－３００ＨＲ或ＳｅｐｈａｄｅｘＧ－７５凝胶层析方法从两株Ｂ群Ｎｍ（５４２８５２和３４０７）中提取获得了纯度较...     

A群脑膜炎球菌多糖结合物的免疫原性研究

目的：制备A群脑膜炎球菌多糖（PS）结合物，观察其免疫原性。方法：A群脑膜炎球菌多糖经溴化氰活化后共价接上己二酰肼手臂，在碳二亚胺催化下与精制破伤风类毒素（TT）偶联剂备结合物。单独多糖、多糖结合物和TT按相同程序免疫NIH小鼠，用ELISA法检测小鼠血清抗多糖抗体滴度和特异性及抗TT抗体滴度。结果：用上述实验方法制备的结合物具有多糖和蛋白质的抗原性，免疫小鼠可诱导高滴度的血清抗多糖IgG抗体，免疫2针后高滴度抗体至少持续存在3周。血清抗体可中和多糖。加强免疫提示有免疫记忆性。结合物还可诱导产生一定水平的TT抗体。结论：A群脑膜炎球菌多糖结合到TT上可明显增强多糖在小鼠中的免疫原性，为制备结合疫苗并研究其对婴幼儿的免疫原性提供了实验基础。     

双蛋白载体A、C群脑膜炎球菌多糖结合物的免疫效果观察

目的 比较和评价在A、C群脑膜炎球菌多糖结合物中应用两种蛋白作为载体的免疫效果.方法 构建不耐热肠毒素B亚单位(LTB)的克隆载体和表达载体.确定rLTB主要为可溶性表达.应用一步阳离子交换层析对rLTB进行纯化,获得较纯的目的蛋白.利用GM1-ELISA和非变性SDS-PAGE的方法确定纯化后的rLTB能够形成具有生物学活性的五聚体.最后利用化学方法(ADH方法)将通过基因工程手段获得的重组LTB五聚体蛋白与C群脑膜炎球菌多糖(GCMP)耦联,获得多糖蛋白结合物GCMP-rLTB.以单一蛋白破伤风类毒素(TT)为载体的A+C群脑膜炎球菌多糖蛋白结合物(GAMP-TT和GCMP-TT)及同时应用两种蛋白载体的A+C群脑膜炎球菌多糖蛋白结合物(GAMP-TT和GCMP-rLTB)分别通过腹腔注射途径免疫小鼠.应用ELISA方法分别检测小鼠血清中IgG水平.结果 单独以TT为载体的A+C群脑膜炎球菌多糖蛋白结合物(GAMP-TT和GC-MP-TT)和同时以两种蛋白作为载体的A+C群脑膜炎球菌多糖蛋白结合物(GAMP-TT和GCMP-rLTB)通过注射途径免疫小鼠,后者产生的血清多糖特异性IgG水平显著高于前者.结论 双蛋白载体在改善A、C群脑膜炎球菌多糖结合物疫苗的免疫原性方面具有明显优势.

Abstract：

Objective To evaluate the immunogenicity of group A and C meningococcal polysaccharides conjugates using different proteins as carriers. Methods Heat-labile enterotoxin B subunit (LTB)pentamer form was expressed in E. coli. The target protein was identified and purified by cation-exchange chromatography. Then biological activity of rLTB was tested using GM1-ELISA. GCMP was conjugated to rLTB with the chemical method (ADH). Furthermore, the mice were immunized with GAMp-TT/GCMP-TT conjugates and GAMP-TT/GCMP-rLTB conjugates via peritoneal. Finally the anti-polysaccharide antibody was detected. Results The GAMP-TT/GCMP-rLTB conjugate elicits remarkably higher serum antibodies in mice than GAMP-TT/GCMP-TT conjugate. Conclusion These results indicated that polysaccharide conjugates using different proteins as carriers were superior to those using only one protein as carrier.     

脑膜炎奈瑟菌ACPS-BOMPC偶联物的免疫原性、安全性和稳定性

目的：评价脑膜炎奈瑟菌（Nm)A群荚膜多糖和B 群外膜蛋白复合物（ACPS－BOMPC）偶联物的免疫原性，安全性和稳定性，方法：通过小鼠和家兔免疫试验，ELISA和杀菌力试验，测定了偶联物的免疫原性和稳定性，通过小鼠和豚鼠毒性试验及热原性试验测定了BOMPC与偶联物的安全性。结果：免疫后87．5％的小鼠抗偶联物的抗体滴度达到1：7240－1：20480；81．25％小鼠抗偶联物蝇的ACPS抗体滴度达1：320以上，偶联后抗ACPS的抗体滴度比未偶联的ACPS的抗体滴度提高了8－128倍，偶联物免疫家兔产生了较高的抗体滴度，5个月未见抗ACPS－BOMPC抗体滴度明显下降；动物实验初步证明偶联物对B群Nm菌株有一定的保护作用；偶联物具有较好的稳定性，对小鼠，豚鼠无毒性。结论：所制备的ACPS－BOMPC偶联物具有较好的免疫原性，动物实验安全且稳定，有可能成为一种有效的抗Ａ群和抗B群Nm感染的疫苗。     

B群Nm 3407菌株外膜蛋白复合物(OMPC)的提取及免疫原性

目的 Ｂ群脑膜炎奈瑟氏菌Ｎｍ荚膜多糖作为菌苗候选成分效果不理想，有些非荚膜的抗原成分存在血清型和亚型的限制，为了能提取一种免疫原性强，并具有广泛的抗原交叉反应性的Ｂ群Ｎｍ外膜蛋白复合物（ｏｕｔｅｒ ｍｅｍｂｒａｎｅ ｐｒｏｔｅｉｎ ｃｏｍｐｌｅｘ，ＯＭＰＣ）以研制更有效的Ｂ群Ｎｍ菌苗提供依据。方法 比较了从病人分离的Ｂ群Ｎｍ３４０７菌株提取ＯＭＰＣ的３种方法，用ＥＬＩＳＡ、杀菌力试验、小鼠免疫试验     

Current status of meningococcal group B vaccine candidates: capsular or noncapsular?

Meningococcal meningitis is a severe, life-threatening infection for which no adequate vaccine exists. Current vaccines, based on the group-specific capsular polysaccharides, provide short-term protection in adults against serogroups A and C but are ineffective in infants and do not induce protection against group B strains, the predominant cause of infection in western countries, because the purified serogroup B polysaccharide fails to elicit human bactericidal antibodies. Because of the poor immunogenicity of group B capsular polysaccharide, different noncapsular antigens have been considered for inclusion in a vaccine against this serogroup: outer membrane proteins, lipooligosaccharides, iron-regulated proteins, Lip, pili, CtrA, and the immunoglobulin A proteases. Alternatively, attempts to increase the immunogenicity of the capsular polysaccharide have been made by using noncovalent complexes with outer membrane proteins, chemical modifications, and structural analogs. Here, we review the strategies employed for the development of a vaccine for Neisseria meningitidis serogroup B; the difficulties associated with the different approaches are discussed.     

Multicenter comparison of Neisseria meningitidis serogroup C anti-capsular polysaccharide antibody levels measured by a standardized enzyme-linked immunosorbent assay.

A standardized enzyme-linked immunosorbent assay (ELISA) was used by 11 laboratories to measure levels of total serum antibody to Neisseria meningitidis serogroup C capsular polysaccharide in 16 unpaired pre- and postvaccination serum samples. Twelve serum samples were from adults, and four were from children aged 2, 3, 5, and 9. The between-laboratory coefficient of variation for pre- and postvaccination sera ranged from 16 to 59% and 11 to 21%, respectively. The average percent difference (absolute value) from the between-laboratory means for all prevaccination sera measured by each laboratory was 24%, whereas the average percent difference was 13% for all postvaccination sera. A postvaccination quality control serum was diluted three times to give optical densities on the high, middle, and low portions of the standard reference curve. The three dilutions were assayed by the 11 laboratories a total of 241 times and yielded an overall coefficient of variation of 20%. Antibody-binding inhibition curves showed that the standardized ELISA was specific for N. meningitidis serogroup C capsular polysaccharide antibody. Fifty percent inhibition of seven serum samples was obtained after reaction with an average concentration of 0.9 micrograms of meningococcal serogroup C polysaccharide per ml; an average of 93% inhibition was obtained with 50 micrograms of polysaccharide per ml. The acceptance and use of this standardized ELISA will reduce between-laboratory assay variability and ensure a more accurate and reproducible assessment of immunogenicity for vaccines under development.     

Induction of a protective capsular polysaccharide antibody response to a multiepitope DNA vaccine encoding a peptide mimic of meningococcal serogroup C capsular polysaccharide

Systemic infection by encapsulated organisms, such as Neisseria meningitidis, is a major cause of morbidity and mortality worldwide, especially in individuals less than 2 years of age. Antibodies directed at the capsular polysaccharide are shown to be protective against disease by inducing complement-dependent bactericidal activity. The current polysaccharide vaccine has been shown to be poorly immunogenic in high-risk groups and this is probably related to its T-independent properties. An alternative approach to eliciting a T-dependent serum immunoglobulin G (IgG) antibody response to encapsulated pathogens is DNA vaccination. We assessed the immunogenicity of a multiepitope DNA vaccine encoding a T-cell helper epitope and a peptide mimic of N. meningitidis serogroup C. The DNA construct induced a significant anti-polysaccharide antibody response that was bactericidal. Mice immunized with the DNA construct were subsequently protected against challenge with a lethal dose of N. meningitidis serogroup C.     

Effect of O acetylation of Neisseria meningitidis serogroup A capsular polysaccharide on development of functional immune responses

The importance of O-acetyl groups to the immunogenicity of Neisseria meningitidis serogroup A polysaccharide (PS) was examined in studies using human sera and mouse immunization. In 17 of 18 postimmunization human sera, inhibition enzyme-linked immunosorbent assay indicated that the majority of antibodies binding to serogroup A PS were specific for epitopes involving O-acetyl groups. Studies with mice also showed an essential role for O-acetyl groups, where serum bactericidal titers following immunization with de-O-acetylated (de-O-Ac) conjugate vaccine were at least 32-fold lower than those following immunization with O-Ac PS-conjugate vaccine and 4-fold lower than those following immunization with native capsular PS. Inhibition studies using native and de-O-Ac PS confirmed the specificity of murine antibodies to native PS. The dramatic reduction in immunogenicity associated with removal of O-acetyl groups indicates that O acetylation is essential to the immunogenic epitopes of serogroup A PS. Since levels of bactericidal antibodies are correlated with protection against disease, O-acetyl groups appear to be important in protection.     

Anti-idiotypic antibody as a potential candidate vaccine for Neisseria meningitidis serogroup B

Sepsis and meningitis caused by Neisseria meningitidis serogroup B (NMGB) are serious diseases in infants and young adults, but no effective vaccine is available. The capsular polysaccharide (PS) of NMGB has poor immunogenicity and a structural similarity to polysialic acid (PSA) on neuronal tissue that may elicit autoantibodies. Using HmenB3, a protective and nonautoreactive monoclonal antibody (MAb) to NMGB capsular PS, we produced an anti-idiotypic MAb, Naid60, which mimics the capsular PS of NMGB. We produced an anti-anti-idiotypic MAb, MoB34, by using the immunogenic site on Naid60 responsible for inducing the anti-NMGB PS antibody response. MoB34 elicited the complement-mediated killing of representative strains of serogroup B meningococci. MoB34 did not bind to CHP-134, a neuroblastoma cell line expressing alpha(2-8) PSA, or to mouse brain cryosections at a high concentration. Naid60-keyhole limpet hemocyanin immunization inhibited the growth of live NMGB in intraperitoneally challenged mice; in contrast, three of five control mice developed bacteremia. Thus, Naid60 has an immunogenic site that elicits antibodies with bactericidal activity against NMGB and no autoimmunity to PSA. We suggest that the immunogenic region of Naid60 is a candidate for the development of a new vaccine against NMGB.     

Development and characterization of an anti-idiotype antibody to the capsular polysaccharide of Neisseria meningitidis serogroup C.

A monoclonal anti-idiotypic antibody (Ab2) whose antibody combining site contained a surrogate image of the meningococcal group C capsular polysaccharide was developed. To accomplish this, a monoclonal antibody against the group C capsular polysaccharide was developed by the fusion of splenocytes from mice immunized with Neisseria meningitidis group C strain MP13 with Sp2/0-Ag14 plasmacytoma cells. Monoclonal antibody 1E4, an immunoglobulin M isotype, demonstrated binding to the serogroup C polysaccharide in enzyme-linked immunosorbent assay (ELISA). Monoclonal antibody 1E4 reacted with 30 of 30 group C strains and 1 of 36 group B strains in immunodot assay, slide agglutination, inhibition ELISA, and bactericidal assay. This monoclonal antibody was selected as idiotype (Ab1) for the development of hybridomas producing an anti-idiotype antibody. One of the hybridomas developed, designated 6F9, was capable of over 70% inhibition of 1E4 in binding in the meningococcal C polysaccharide-specific ELISA. Studies with convalescent human serum demonstrated 100% inhibition of a serogroup C-specific ELISA with 200 micrograms of 6F9 per ml and 50% inhibition of this ELISA was achieved with 50 micrograms of 6F9 per ml. Monoclonal anti-idiotype antibodies (Ab3) with specificities similar to Ab1, 1E4 were generated from BALB/c mice immunized with the Ab2 (6F9). Immunization of rabbits with 6F9 resulted in an immunoglobulin G response which was significantly greater than that of control to a titer of 1:160. These studies indicate that monoclonal 6F9 contained a surrogate image on the combining antibody site which mimicked meningococcal C polysaccharide. This surrogate image is capable of evoking antibodies to the meningococcal C polysaccharide in syngenic and xenogenic species.     

Immunogenicity and antigenic heterogeneity of a human transferrin-binding protein in Neisseria meningitidis.

Growing Neisseria meningitidis on an iron restriction medium induces the synthesis of new outer membrane proteins, some of them true iron-regulated outer membrane proteins (IROMPs) and others synthesized because of the stress produced by the iron restriction. Some of these proteins are antigenic and can be considered for the development of vaccines; this is especially desirable in the case of N. meningitidis serogroup B, for which polysaccharide vaccines are not efficient. The antigenicity of N. meningitidis 37- and 70-kDa IROMPs has been studied previously; in this work, we studied the immunogenicity and antigenic heterogeneity of another IROMP, the human transferrin-binding protein 2 (TBP2), which seems to be indispensable for meningococcal growth inside the host. Mice were inoculated with purified outer membrane vesicles (blebs) from 5 selected N. meningitidis strains, and the five serum samples obtained were analyzed for anti-TBP2 antibodies by using the homologous strain and for cross-reactivity with the TBP2 of the 4 other selected strains and another 35 heterologous N. meningitidis strains. The TBP2s of the 5 strains tested were all immunogenic in mice to various degrees depending on the strain, and all five TBP2s shared one or more epitopes with heterologous strains (as shown by the cross-reactivities of the five serum samples), although the number of cross-reacting strains was very variable, ranging from 2 for strain V002 to 35 for strain P391. This suggests that the TBP2 epitopes of different strains differ in nature or in their accessibility to the immune system. Under the iron restriction conditions used, all strains synthesized a non-TBP2 antigenic 56-kDa protein thought to be a stress protein.     

Production of polyclonal and monoclonal antibodies against group A, B, and C capsular polysaccharides of Neisseria meningitidis and preparation of latex reagents.

Polyclonal and monoclonal antibodies against capsular polysaccharides of Neisseria meningitidis serogroups A, B, and C were produced in order to develop immunological reagents allowing both the detection of soluble antigens during meningococcal meningitis and antigenic serogrouping of N. meningitidis cultures. The performance characteristics of monoclonal and polyclonal antibody latex reagents were compared. For the detection of soluble polysaccharide antigen, polyclonal antibody latex reagent was selected for N. meningitidis A and C. The latex reagent prepared with polyclonal antibodies against N. meningitidis B could not detect capsular polysaccharide even at 1 mg/ml. The monoclonal antibody B latex reagent which detected 100 ng of polysaccharide per ml was therefore chosen. For the serogroup identification of N. meningitidis, the use of a confirmatory test results in an overall specificity of 100% with polyclonal or monoclonal antibody latex reagents.     

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.