新型疫苗佐剂的研究进展

与传统的灭活或活体疫苗相比,由基因工程重组抗原或化学合成多肽组成的现代疫苗往往存在免疫原性弱等问题,需要新型的免疫佐剂来增强其作用。尽管传统的铝盐佐剂是目前唯一全球公认的人用佐剂,但存在激发细胞免疫应答能力差等不足,因此,需要研发更为安全有效的人用新型佐剂,尤其是安全无毒、能够刺激较强细胞免疫应答的佐剂,以及适合粘膜疫苗、DNA疫苗和癌症疫苗的免疫佐剂。分析阐述了新型佐剂研究状况和佐剂发展方向,并进一步对新型佐剂的临床前和临床试验研究以及已批准上市的新型疫苗佐剂进行了综述。     

Secretory delivery of heterologous proteins in attenuated <Emphasis Type="Italic">Vibrio anguillarum</Emphasis> for potential use in vaccine design

To synthesize and secrete heterologous proteins in an attenuated Vibrio anguillarum strain for potential multivalent live vaccine development, different antigen-delivery systems based on bacterial-originated secretion signal peptides (SPs) were designed and identified in this work. Four SPs were derived from hemolysin of Escherichia coli, RTX protein of V. cholerae, hemolysin of V. anguillarum, zinc-metalloprotease of V. anguillarum, respectively, and their abilities to support secretion of green fluorescent protein (GFP) in an attenuated V. anguillarum strain MVAV6203 were assayed. Immunodetection of GFP showed that the capability of the tested signal leaders to direct secretion of GFP varied greatly. Although all the four signal peptide-fused GFPs could be expressed correctly and trapped intracellularly in recombinant strains, only the EmpA signal peptide could confer efficient secretion to GFP. For the investigation of its potential application in live bacteria carrier vaccines, a heterologous protein EseB of Edwardsiella tarda was fused to the SP(empA) antigen-delivery system and introduced into the strain MVAV6203. Further analysis of EseB demonstrated that the constructed SP(empA) antigen-delivery system could be used to secrete foreign protein in attenuated V. anguillarum and be available for carrier vaccines development.     

A recombinant mimetics of the HIV-1 gp41 prehairpin fusion intermediate fused with human IgG Fc fragment elicits neutralizing antibody response in the vaccinated mice

HIV-1 gp41 prehairpin fusion intermediate (PFI) composed of three N-terminal heptad repeats (NHR) plays a crucial role in viral fusion and entry and represents an attractive target for anti-HIV therapeutics (e.g., enfuvirtide) and vaccines. In present study, we constructed and expressed two recombinant gp41 PFI mimetics, designated N46Fd and N46FdFc. N46Fd consists of N46 (residues 536-581) in gp41 NHR and foldon (Fd), a trimerization motif. N46FdFc is composed of N46Fd fused with human IgG Fc fragment as an immunoenhancer. We immunized mice with N46 peptide, N46Fd and N46FdFc, respectively, and found that only N46FdFc elicited neutralizing antibody response in mice against infection by HIV-1 strains IIIB (clade B, X4), 92US657 (clade B, R5), and 94UG103 (clade A, X4R5). Anti-N46FdFc antibodies inhibited PIE7 binding to PFI, blocked gp41 six-helix bundle formation, and suppressed HIV-1 mediated cell-cell fusion. These findings provide an important clue for developing recombinant gp41 PFI mimetics-based HIV vaccines.     

Patterns of circulating hepatitis B surface antigen variants among vaccinated children born to hepatitis B surface antigen carrier and non-carrier mothers

Hepatitis B virus (HBV) variants that possessed missense mutation within the neutralization epitope of the major S antigen as defined by amino acid residues (aa#) 124–147, termed the a determinant variants, were identified through a population-based serosurvey of 2,305 children of the vaccinated birth cohorts born after 1986. Data on the 678 nucleotides encoding the S antigen of HBV were available for 75 HBV strains that were collected from 63 vaccinated children and 12 unvaccinated or incompletely vaccinated children, and 21 HBV strains from 25 unvaccinated adults. Among the diverse patterns of one to three amino acid substitutions within the a determinant, 145-Arg occurred most frequently (5/14); other variants were: 126-Ala, 127-Thr, 126-Ser/131-Asn/133-Thr, 129-His, 129-Arg, 123-Asn/131-Ile, 133-Leu, 141-Glu, and 141-Arg/144-Ala. Only one of these variants occurred in the 16 hepatitis B surface antigen (HBsAg)-carrier children born to HBsAg-negative mothers, whereas 12 of these variants occurred in the 20 (50%) children born to HBsAg-positive mothers. In addition, early administration of HBV vaccine within the noenatal period increased the likelihood of the emergence of these variants to 64.7% (11/17). Five of the 21 (23.8%) unvaccinated HBsAg-carrier adults harbored the a determinant variants possessing mutations within aa# 125–136, i.e. the putative first loop formed by the cysteine disulfide bonds. Vaccinated children were likely to harbor HBV variants possessing mutations involving altered charge of side chains and/or its hydrophobicity of amino acid residues within the putative second loop between aa#140 and 146. Our data suggest that emergence of these HBV S gene mutants in the phase of HBV vaccination program would be most common among populations in whom perinatal/vertical transmission of HBV is most common, i.e. southeast Asian and the Taiwanese.     

载体介导的刚地弓形虫MIC疫苗的研制现状

刚地弓形虫引起的弓形虫病是一种严重危害人类健康的人兽共患寄生虫病,采用疫苗防治该病是当前研究的热点领域之一。MIC抗原是一种有效的疫苗候选分子,本研究综述了鼠伤寒沙门菌、卡介苗、格登链球菌、腺病毒血清型5和假狂犬病毒等载体介导的刚地弓形虫MIC疫苗的研制现状。     

Concise synthesis of the pentasaccharide O-antigen of Escherichia coli O83:K24:H31 present in the Colinfant vaccine

A block synthetic approach is presented for the synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O83:K24:H31 strain, present in the “Colifant” vaccine. The target pentasaccharide has been synthesized by coupling a disaccharide with a trisaccharide in excellent yield. Yields are quite satisfactory in all intermediate steps. A concise synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O83:K24:H31 strain, present in the COLINFANT vaccine is presented. The target pentasaccharide has been synthesized following a block synthetic strategy by coupling a disaccharide with a trisaccharide in excellent yield.     

结核分枝杆菌蛋白亚单位疫苗与疫苗诱导的T细胞免疫记忆研究进展

牛分枝杆菌减毒活疫苗--卡介苗(bacillus Calmette-Guérin,BCG)对预防严重的儿童结核病有效,但其免疫保护效率随儿童年龄增长而降低。BCG不能提供终身免疫保护可能与其诱导的记忆性T细胞主要是寿命较短的效应记忆性T细胞有关。新型结核分枝杆菌蛋白亚单位疫苗将有效的抗原有机组合起来,在适宜的疫苗佐剂辅助下诱导Th1型免疫应答。动物实验表明,增加抗原谱可有效提高亚单位疫苗的保护效率。更重要的是,亚单位疫苗在体内持续时间较短,可诱导寿命较长的中央记忆性T细胞,提供比BCG更持久的免疫保护力。记忆性T细胞的分化受抗原特性与剂量、细胞因子、转录因子及雷帕霉素等的调控。对亚单位疫苗及其诱导的免疫记忆进行研究将对新型结核分枝杆菌疫苗的设计与评价产生积极影响。     

固有免疫学的研究进展及其对研制新型免疫佐剂的启示

近年来,亚单位疫苗、DNA重组疫苗、合成肽疫苗等新型疫苗不断涌现,这些疫苗纯度高、特异性强。但其分子小,免疫原性较差,难以诱导机体产生有效的免疫应答,需添加佐剂来增强其免疫原性或增强宿主对抗原的保护性应答。免疫学的研究阐明了固有免疫如何调节适应性免疫。随着固有免疫学的发展和生化技术的提高,开发特异性更强、生物安全性更高的免疫佐剂越来越受到重视。对佐剂的分类、作用机理,固有免疫学的研究进展进行了综述,并就未来发展趋势提出自己的观点,为临床应用和进一步研制高效、低毒的免疫佐剂提供了参考。