Cross Reacting Polysaccharides (H. influenzae types a and b, and B. pumilus)

这份报告的调查员已经退休了。目前还没有关于进展的报告。以下是去年的报告。 在b型流感嗜血杆菌(Hib)结合疫苗广泛使用后产生了群体免疫，而Hib的几乎消除导致了人们猜测其他类型的流感嗜血杆菌(Hi)可能会成为脑膜炎的原因。例如，在巴西，在开始接种Hib结合免疫后的第一年里，Hib脑膜炎的发病率下降了69%，而Hib脑膜炎的发病率增加了8倍。荷兰参考实验室报告说，a型仅见于4岁以下的儿童。 Hia和Hib Cp的性质。 根据其CP结构，HI可分为三个毒力群，每两个毒力群。毒性最强的类型a和b由中性糖、醇(核糖醇)和磷酸二酯组成；类型c和f由N-乙酰化氨基糖、单糖和磷酸二酯组成；以及(3)类型d和e具有N-乙酰氨基葡萄糖和N-乙酰甘露糖醛酸的重复单元。与其他四种类型相比，Hib和Hia能抵抗补体单独的杀菌作用。对幼年大鼠的攻击试验表明，对Hib和Hia菌血症的半数感染剂量(ID50)均比其他类型低几个对数。B型和a型幼鼠鼻腔攻击后，b型菌血症发生率为55%~90%，a型菌血症发生率为35%，其余类型均为非侵袭性。 人类免疫缺陷病毒引起的侵袭性疾病。 尽管接种了Hib疫苗，但在美国，Hia病的发病率保持不变。从1998年到2002年，美国疾病控制与预防中心的新发感染计划在9个地点、约3500万人的数据中进行了积极的实验室和基于人群的Hi疾病监测。在1743株侵袭性分离物中，有17株为Hia，这是某些人群脑膜炎的重要原因，如白山阿帕奇印第安人儿童，每年每100,000名儿童中有254例Hia脑膜炎。Hammitt等人。(Pediatr Infect Dis J 2005；24：453)报告在阿拉斯加土著婴儿中暴发侵袭性Hia病。在两个邻近村庄的6个月期间，记录了5例HIA病例。在巴西，据报告出血性脑膜炎发病率为0.16例/100,000人年。南非和加拿大马尼托巴省的当地居民也报告了儿童患有Hia脑膜炎。 HIA疫苗。 HIA病例的数量太低，不适合随机、双盲、对照试验。然而，在没有有效性证据的情况下，在疫苗中添加一个物种的类型是有先例的。例如，几种肺炎球菌类型，包括脑膜炎球菌Y组和W135组以及脊髓灰质炎病毒2型，是根据其安全性和免疫原性发放许可证的。HIA CP的结构、实验和临床特征与b型非常相似，越来越多的HIA侵袭性疾病的报告表明HIA结合物的开发是必要的。B型CP与蛋白质偶联的方法适用于HIA。D-1，5-核糖醇磷酸是Hia和Hib的CPS的一种成分。我们报道了短小芽孢杆菌Sh18胞壁多糖(PS)的主要成分是聚-1，5-核糖醇磷酸，用这种结合物在小鼠体内诱导的抗体与Hia和Hib均发生交叉反应。我们合成了含有8个或12个重复单元的聚核糖醇磷酸链，末端的酮基用于与氨基氧基化的牛血清白蛋白(BSA或破伤风类毒素)偶联。我们将结合物以2.5g/只的速度注射到小鼠体内，每隔2周注射三次，一周后获得血清。酶联免疫吸附试验证实了抗Hia和Hib的抗体，八聚体结合物比十二聚体结合物具有更好的免疫原性。一些被测试的血清对A型和B型都显示出杀菌活性，这与它们的ELISA值大致相关。 其他结构和配方正在研究中。作为天然多糖疫苗的替代品，我们正在开发一种针对HIA的结合疫苗，方法是通过化学合成由葡萄糖-核糖醇-磷酸重复单元组成的衣壳材料的片段。到目前为止，我们已经合成了葡萄糖-核糖醇单元，并能够组装重复单元的二聚体。构建更高成员的磷酸二酯连接的寡糖正在进行中。

The investigator for this report has retired. There is no report on progress. Following is last year's report. Herd immunity followed widespread use of the Haemophilus influenzae type b (Hib) conjugate vaccine, and the near-elimination of Hib led to speculation that other Haemophilus influenzae (Hi) types may emerge as causes of meningitis. For example, in Brazil, the incidence of Hib meningitis decreased by 69 percent during the first year after initiation of Hib conjugate immunization while the incidence of Hia meningitis increased 8-fold. The Netherlands Reference Laboratory reported that type a was observed only in children younger than 4 years old. Properties of Hia and Hib CP. Hi may be classified into three virulence groups of two, related to their CP structures. Types a and b, which are the most virulent, are composed of a neutral sugar, an alcohol (ribitol), and a phosphodiester; types c and f are composed of an N-acetylated aminosugar, a monosaccharide, and a phosphodiester; and (3) types d and e have a repeat unit of an N-acetylglucosamine and N-acetylmannosamineuronic acid. Compared with the other four types, Hib and Hia are resistant to the bactericidal effects of complement alone. Challenge of infant rats showed that the 50 percent infective dose (ID50) for bacteremia of both Hib and Hia was several logs lower than of the other types. Intranasal challenge of infant rats with type b or type a resulted in 55 to 90 percent bacteremia with type b and 35 percent with type a. The other types were not invasive. Invasive diseases caused by Hia. Rates of Hia disease have remained constant in the United States despite Hib vaccination. From 1998 to 2002, the Emerging Infections Program of the CDC conducted active laboratory- and population-based surveillance for Hi disease in data from nine sites with approximately 35 million people. Seventeen of 1,743 invasive isolates were Hia, which is an important cause of meningitis in certain populations such as White Mountain Apache Indian childrenwith an annual incidence of 254 cases/100,000 children of Hia meningitis. Hammitt et al. (Pediatr Infect Dis J 2005;24:453) reported an outbreak of invasive Hia disease among Native Alaska infants. During a 6-month period in two proximate villages, five Hia cases were documented. In Brazil, an incidence of Hia meningitis of 0.16 cases/100,000 person-years was reported. South Africa and native populations in Manitoba Canada also report Hia meningitis in children. Hia vaccine. The number of Hia cases is too low for a randomized, double-blinded, controlled trial. Yet, precedent exists for adding types within a species to a vaccine without evidence for efficacy. For example, the licensing of several pneumococcal types, including meningococcal groups Y and W135 and poliovirus type 2, was based on their safety and immunogenicity. The structural, experimental, and clinical properties of Hia CP closely resemble those of type b, and the increasing number of reports of Hia-invasive disease suggests that development of an Hia conjugate is warranted. Methods for conjugating type b CP to a protein are applicable to Hia. D-1,5-ribitolphosphate is a constituent of the CPs of Hia and Hib. We reported that the cell wall polysaccharide (PS) of B. pumilus Sh18 contains a poly-1,5-ribitolphosphate as a major component and that antibodies induced in mice by such conjugate cross-reacted with both Hia and Hib. We synthesized polyribitolphosphate chains containing either 8 or 12 repeat units, with the terminal keto groups used for conjugation to aminooxylated bovine serum albumin (BSA or tetanus toxoid. We injected the conjugates into mice, three times at 2-week intervals at 2.5 g/mouse and obtained sera a week later. ELISA demonstrated antibodies to both Hia and Hib, with the octamer conjugate a better immunogen than the dodecamer conjugate. Some of the tested sera showed bactericidal activity against both type a and type b as roughly correlated with their ELISA values. Other constructs and formulations arebeing studied. As an alternative to the native polysaccharide-based vaccine, we are developing a conjugate vaccine against Hia by chemically synthesizing fragments of its capsular material which is built up by glucosyl-ribitol-phosphate repeating units. So far we have synthesized the glucosyl-ribitol unit and were able to assemble a dimer of the repeating unit. Construction of higher-membered phosphodiester-linked oligosaccharides is in progress.