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

总结 对流感嗜血杆菌（Hi）的6种荚膜多糖（CP）型a、B、c、d、e和f的结构进行了鉴定。全身感染以H.流感病毒B型（HiB）。临界水平的血清IgG抗Hib CP通过补体介导的溶菌作用赋予型特异性免疫。Hib结合疫苗的广泛使用带来了群体免疫。Hib的这种近乎消除导致了其他Hi类型可能成为脑膜炎原因的猜测。例如，在巴西，Hib脑膜炎的发病率在开始Hib结合物免疫后的1年内下降了69%，而Hia脑膜炎的发病率增加了8倍。荷兰参考实验室报告说，A型仅在<4岁的儿童中观察到。 Hia和Hib CP的性质 根据其CP的结构，Hi可分为3个毒力组，每组2个：a型和B型;毒力最强的由中性糖、醇（核糖醇）和磷酸二酯组成; c型和f型由N-乙酰化氨基糖、单糖和磷酸二酯组成; d型和e型具有N-乙酰葡糖胺和N-乙酰甘露糖胺神经糖醛酸的重复单元。Hib和Hia对单独补体的杀菌作用比其他四种类型具有更大的抵抗力。乳鼠攻毒试验表明，Hib和Hia菌血症的半数感染量（ID_（50））均比其它两种菌血症的ID_（50）低几个对数。用B型或A型菌株鼻内攻击幼鼠，导致B型55 - 90%菌血症，A型35%菌血症。其他类型没有侵入性。 Hia引起的侵袭性疾病 在美国，无论是否接种Hib疫苗，Hia疾病的发病率都是恒定的。从1998年到2002年，疾病预防控制中心的新发感染项目对来自9个地点的约3500万人的数据进行了积极的基于实验室和人群的Hi疾病监测。1,743株侵袭性分离株中有17株为Hia。Hia是某些人群中脑膜炎的重要原因，例如白色山区阿帕奇印第安儿童，其Hia脑膜炎的年发病率为254例/100，000名儿童。Hammittet等人报道了阿拉斯加土著婴儿中爆发的侵袭性Hia疾病。在6个月期间，附近两个村庄记录了5例Hia病例。在巴西，Hia脑膜炎的发病率为0.16例/100，000人年。南非和加拿大马尼托巴的土著居民也报告了儿童Hia脑膜炎。 Hia疫苗 对于随机、双盲和对照试验而言，病例数太少。在没有有效性证据的情况下，将一个物种内的类型添加到疫苗中是有优先权的。几种肺炎球菌类型，脑膜炎球菌群Y和W135以及脊髓灰质炎病毒2型基于其安全性和免疫原性获得许可。Hia CP的结构、实验和临床特性与B型CP非常相似。越来越多的Hia侵袭性疾病的报告表明，开发Hia缀合物是必要的。将B型CP与蛋白质缀合的方法适用于Hia。 D-1，5-核糖醇磷酸是Hia和Hib CP的一种成分。本文报道了B. pumilus Sh 18含有聚-1，5-核糖醇磷酸作为主要组分，并且通过该PS缀合物在小鼠中诱导的抗体与Hia和Hib两者交叉反应。我们合成了含有8或12个重复单元的聚核糖醇磷酸酯链，末端酮基用于与氨氧基化BSA或破伤风类毒素缀合。将这些缀合物以2.5g/小鼠注射到小鼠中，3次，2周一次，一周后获得血清。ELISA证明了Hia和Hib的抗体，八聚体缀合物是比十二聚体缀合物更好的免疫原。其杀菌活性正在研究中。

Summary The structures of the 6 capsular polysaccharide (CP) types, a, b, c, d, e, and f of Haemophilus influenzae (Hi) have been elucidated. Systemic infections were due mostly to H. influenzae type b (Hib). A critical level of serum IgG anti-Hib CP confers type-specific immunity by complement-mediated bacteriolysis. Herd immunity followed wide spread usage of Hib conjugate vaccine. This near-elimination of Hib led to the speculation that other Hi types may emerge as causes of meningitis. For example, in Brazil, the incidence of Hib meningitis decreased 69% during 1 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 only observed in <4 year-olds. Properties of Hia and Hib CP Hi can be divided into 3 virulence groups of two, related to the structures of their CP: types a and b; 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 phosphodiester; types d and e have a repeat unit of an N-acetylglucosamine and N-acetylmannosamineuronic acid. Hib and Hia have greater resistance to the bactericidal effects of complement alone than the other four types. Challenge of infant rats showed that the 50% 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 a strains resulted in 55 to 90% bacteremia with type b, and 35% with type a strains. The other types were not invasive. Invasive Diseases Caused By Hia Rates of Hia disease have been constant in the US regardless of Hib vaccination. From 1998 to 2002, The Emerging Infections Program, of CDC conducted active laboratory- and population-based surveillance for Hi disease in data from 9 sites with approximately 35 million people. Seventeen of 1,743 invasive isolates were Hia. Hia is an important cause of meningitis in certain populations such as White Mountain Apache Indian children who have an annual incidence of 254 cases/100,000 children of Hia meningitis. Hammittet al. reported an out break of invasive Hia disease among Native Alaska infants. During a 6-month period in 2 nearby villages, 5 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 cases is too low for a randomized, double-blinded and controlled trial. There is precedence for adding types within a species to a vaccine without evidence for efficacy. Several pneumococcal types, meningococcal groups Y and W135, and poliovirus type 2 were licensed based upon their safety and immunogenicity. The structural, experimental and clinical properties of Hia CP resemble closely that of type b. The increasing number of reports of Hia invasive diseases suggest that development of a 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 antibodies induced in mice by this PS 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 BSA or tetanus toxoid. These conjugates were injected into mice, 3 times 2 weeks a part at 2.5g/mouse and sera obtained a week later. Elisa demonstrated antibodies to both Hia and Hib, with the octamer conjugate being a better immunogen than dodecamer conjugate. Their bactericidal activity is being studied.