人呼吸道合胞病毒减毒活疫苗的研究进展

人呼吸道合胞病毒(Respiratory syncytial virus,RSV)是一种可引起严重下呼吸道疾病的病原体,易感人群为婴幼儿、老年人及免疫力低下者。目前尚无针对RSV的疫苗和特异而有效的抗病毒药物。研究发现,减毒活疫苗不产生疾病增强效应,在母传抗体的存在下仍可复制,且有较强的免疫原性,被认为是最有希望的RSV疫苗。就RSV减毒活疫苗的研究进展作一综述。     

评估首次接种人体的G蛋白缺失RSV减毒活疫苗的安全性、耐受性、脱落性和免疫原性：一项随机对照试验

正人呼吸道合胞病毒(RSV)是婴幼儿和老年人下呼吸道感染的主要原因。针对呼吸道合胞病毒的儿童疫苗不仅可以预防呼吸道合胞病毒在婴幼儿中的发病和死亡,还可以减少其在老年人群的传播。由一种缺失G附着蛋白的减毒RSV活疫苗组成的RSVΔG与宿主细胞的结合严重受损,在临床前研究中显示其传染性降低。用RSVΔG疫苗对棉鼠进行鼻内免疫可防止野生型RSV的复制,从而不会诱发继发性疾病。作者进行了首次人体试验,     

反向遗传学技术在流感病毒减毒活疫苗研究中的应用进展

流感病毒是一种威胁人类健康的重要病原体,具有季节流行性,可以引起暴发性感染,对公共卫生及经济带来打击。接种疫苗是目前保护人类免受流感病毒感染的最佳医疗干预措施。安全性与有效性的平衡是疫苗研发追求的目标,减毒活疫苗则能够实现两者平衡,有望在预防免疫中发挥巨大作用。随着反向遗传学技术的成熟,其在流感病毒减毒活疫苗的研发中也发挥着越来越大的作用,使减毒病毒株的构建更加简便,减毒方法更加多元。本文主要就反向遗传学技术在流感病毒减毒活疫苗研发中的应用进行简要综述。     

呼吸道合胞病毒非结构蛋白NS1、NS2的研究进展

呼吸道合胞病毒(reespiratory syncytial virus,RSV)是引起婴幼儿和老年人下呼吸道感染的重要病原体之一.由于该病毒的致病机理还不太清楚导致目前尚无有效治疗RSV的方法.研究表明,呼吸道合胞病毒的非结构蛋白NS1、NS2具有抗细胞凋亡的作用,同时可以逃避宿主免疫系统(IFN)对病毒的干扰,有利于病毒复制.敲除这两种基因的减毒活疫苗和袁达沉默NS1的小干扰RNA(siRNA)的质粒研究已经取得了一定的进展.对非结构蛋白功能的深入研究有助于了解RSV的致病机理,同时为预防和治疗RSV感染奠定理论基础.     

呼吸道合胞病毒mRNA疫苗的研究进展

呼吸道合胞病毒(respiratory syncytial virus, RSV)是引起急性呼吸道感染的主要病原体之一,给婴幼儿和老年人带来了沉重的疾病负担。自福尔马林灭活呼吸道合胞病毒疫苗(FI-RSV)失败以来,RSV疫苗研究进展缓慢。但近年随着对RSV F蛋白(fusion protein, F)结构研究的不断深入,RSV的候选疫苗取得了快速进展,RSV的候选疫苗种类也逐渐增多,包括RSV mRNA疫苗、重组载体疫苗、亚单位疫苗、病毒样颗粒疫苗、减毒活疫苗和嵌合疫苗等。其中,RSV mRNA疫苗具有成本低、免疫原性强、生产工艺简单、研发周期短、安全性高和易于标准化生产等特点,适合应对新发传染性疾病的防控。现就RSV疫苗的研究现状、RSV mRNA疫苗发展历程及临床研究进展作一概述。     

呼吸道合胞病毒疫苗研究进展

呼吸道合胞病毒(RSV)是引起婴幼儿支气管炎和肺炎的主要原因,并可致免疫缺陷病人显著发病和死亡,RSV疫苗已被WHO列为全球最优先发展的疫苗之一。经过几十年的研究,虽然取得了显著进展,但尚未有RSV疫苗上市。目前RSV疫苗的研究主要集中于亚单位疫苗、减毒活疫苗和DNA疫苗等,其中亚单位疫苗和减毒活疫苗被认为最有前途,已分别进行了的临床试验。     

人3型副流感病毒及其疫苗的研究进展

人3型副流感病毒(Human Parainfluenza Virus type 3,HPIV-3)是引起婴幼儿严重细支气管炎及肺炎等下呼吸道疾病的主要病原体,其在发达国家和发展中国家都造成了沉重的疾病负担。迄今,对HPIV-3感染的预防和治疗都还没有有效的疫苗和药物,因此WHO将HPIV-3疫苗列为未来重点研发的疫苗。近年来,随着重组技术和反向遗传学的发展,HPIV-3疫苗的研制取得了重要进展,部分疫苗已进入临床评价阶段。就HPIV-3的生物学特性如病毒结构特征、复制过程、流行病学特征,以及近年来传统冷适应减毒活疫苗、亚单位疫苗、以反向遗传学为基础的新型减毒活疫苗的研制成果及临床试验进展作简要综述。     

呼吸道合胞病毒载体疫苗研究进展

人呼吸道合胞病毒(human respiratory syncytial virus, RSV)是引起婴幼儿下呼吸道感染的最重要的病毒病原,RSV载体疫苗可在人细胞内从头合成,形成的蛋白质构象与RSV自然感染后表达的完全相同,不会导致抗原表位的丧失或变化,形成的免疫力更利于抵抗随后的自然感染;经黏膜途径免疫不会产生疾病增强作用,且能突破母传抗体的干扰,因而受到广泛关注。对近年来RSV载体疫苗的研究进展进行了综述。     

RSV初免后用表达RSV融合前F蛋白的副流感病毒载体加强免疫更有效

正人呼吸道合胞病毒(RSV)是一种重要的全球性儿童呼吸道病原体,目前缺乏已获许可的疫苗或合适的抗病毒药物治疗,针对RSV鼻内给药的儿童减毒活疫苗正处于研发之中。本文作者评估了一种序贯免疫策略,即RSV初次免疫后,用RSV或表达RSV融合前F蛋白的嵌合牛/人副流感病毒3型(rB/HPIV3)载体进行加强免疫。基因工程技术构建载体表达的F蛋白(DS-Cav1突变),提高了高免疫原性融合前F蛋白(pre-F)的构象稳定性。     

单克隆抗体在呼吸道合胞病毒感染诊断和防治中的应用

呼吸道合胞病毒 (RSV)是世界范围内婴幼儿下呼吸道感染的重要病原 ,目前尚无成熟疫苗应用于临床。展开对RSV被动免疫的研究显得尤为重要。单克隆抗体成为深入研究和防治RSV感染的有力武器。本文综述了单克隆抗体在RSV感染的诊断、预防和治疗中的应用     

Effectiveness of enteric immunization in the development of secretory immunoglobulin A response and the outcome of infection with respiratory syncytial virus.

Cotton rats were immunized via intranasal, intradermal, or enteric routes with respiratory syncytial virus (RSV) or a live recombinant vaccinia virus expressing the RSV F glycoprotein (vaccinia F). The animals were tested for the appearance of RSV-specific antibody responses in the serum, bronchoalveolar lavage, and nasal wash after immunization and for virus replication 4 days after intranasal challenge with RSV. RSV antibody response in the serum and respiratory tract was demonstrated in all immunization groups and was significantly increased after intranasal challenge with RSV. Immunoglobulin A (IgA) antibody response in bronchoalveolar lavage fluid after intranasal or enteric immunization was two- to threefold higher than that after intradermal immunization. Nasal-wash IgA antibody response was not significantly different among three immunization groups, although mean antibody titer was the highest in intranasal immunization group. Complete resistance to replication of RSV challenge was observed in the lungs of cotton rats immunized by the intranasal or enteric routes, whereas a low level of replication was detected in the lungs of rats immunized intradermally. Enteric or intradermal immunization conferred partial protection to the upper respiratory tract, but complete protection of the upper respiratory tract was observed in the intranasal immunization group. These observations suggest that while enteric immunization is quite effective in inducing antibody responses in the respiratory tract, the magnitude of antiviral immunity induced in the respiratory tract after intranasal immunization may be superior to that observed after enteric immunization.     

Replication-competent or attenuated, nonpropagating vesicular stomatitis viruses expressing respiratory syncytial virus (RSV) antigens protect mice against RSV challenge

Foreign glycoproteins expressed in recombinant vesicular stomatitis virus (VSV) can elicit specific and protective immunity in the mouse model. We have previously demonstrated the expression of respiratory syncytial virus (RSV) G (attachment) and F (fusion) glycoprotein genes in recombinant VSV. In this study, we demonstrate the expression of RSV F and G glycoproteins in attenuated, nonpropagating VSVs which lack the VSV G gene (VSVDeltaG) and the incorporation of these RSV proteins into recombinant virions. We also show that intranasal vaccination of mice with nondefective VSV recombinants expressing RSV G (VSV-RSV G) or RSV F (VSV-RSV F) elicited RSV-specific antibodies in serum (by enzyme-linked immunosorbent assay [ELISA]) as well as neutralizing antibodies to RSV and afford complete protection against RSV challenge. In contrast, VSVDeltaG-RSV F induced detectable serum antibodies to RSV by ELISA, but no detectable neutralizing antibodies, yet it still protected from RSV challenge. VSVDeltaG-RSV G failed to induce any detectable serum (by ELISA) or neutralizing antibodies and failed to protect from RSV challenge. The attenuated, nonpropagating VSVDeltaG-RSV F is a particularly attractive candidate for a live attenuated recombinant RSV vaccine.     

Chinchilla and murine models of upper respiratory tract infections with respiratory syncytial virus

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the elderly. While the primary infection is the most serious, reinfection of the upper airway throughout life is the rule. Although relatively little is known about either RSV infection of the upper respiratory tract or host mucosal immunity to RSV, recent literature suggests that RSV is the predominant viral pathogen predisposing to bacterial otitis media (OM). Herein, we describe mouse and chinchilla models of RSV infection of the nasopharynx and Eustachian tube. Both rodent hosts were susceptible to RSV infection of the upper airway following intranasal challenge; however, the chinchilla proved to be more permissive than the mouse. The chinchilla model will likely be extremely useful to test the role of RSV in bacterial OM and the efficacy of RSV vaccine candidates designed to provide mucosal and cytotoxic T-lymphocyte immunity. Ultimately, we hope to investigate the relative ability of these candidates to potentially protect against viral predisposal to bacterial OM.     

Recombinant baculovirus-based vaccine expressing M2 protein induces protective CD8<Superscript>+</Superscript> T-cell immunity against respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is an important cause of acute lower respiratory tract disease in infants, young children, immunocompromised individuals, and the elderly. However, despite ongoing efforts to develop an RSV vaccine, there is still no authorized RSV vaccine for humans. Baculovirus has attracted attention as a vaccine vector because of its ability to induce a high level of humoral and cellular immunity, low cytotoxicity against various antigens, and biological safety for humans. In this study, we constructed a recombinant baculovirus- based vaccine expressing the M2 protein of RSV under the control of cytomegalovirus promoter (Bac_RSVM2) to induce CD8⁺ T-cell responses which play an important role in viral clearance, and investigated its protective efficacy against RSV infection. Immunization with Bac_RSVM2 via intranasal or intramuscular route effectively elicited the specific CD8⁺ T-cell responses. Most notably, immunization with Bac_RSVM2 vaccine almost completely protected mice from RSV challenge without vaccine-enhanced immunopathology. In conclusion, these results suggest that Bac_RSVM2 vaccine employing the baculovirus delivery platform has promising potential to be developed as a safe and novel RSV vaccine that provides protection against RSV infection.     

Dual role of respiratory syncytial virus glycoprotein fragment as a mucosal immunogen and chemotactic adjuvant

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract disease in infancy and early childhood. Despite its importance as a pathogen, there is no licensed vaccine to prevent RSV infection. The G glycoprotein of RSV, a major attachment protein, is a potentially important target for protective antiviral immune responses and has been shown to exhibit chemotactic activity through CX3C mimicry. Here, we show that sublingual or intranasal immunization of a purified G protein fragment of amino acids from 131 to 230, designated Gcf, induces strong serum IgG and mucosal IgA responses. Interestingly, these antibody responses could be elicited by Gcf even in the absence of any adjuvant, indicating a novel self-adjuvanting property of our vaccine candidate. Gcf exhibited potent chemotactic activity in in vitro cell migration assay and cysteine residues are necessary for chemotactic activity and self-adjuvanticity of Gcf in vivo. Mucosal immunization with Gcf also provides protection against RSV challenge without any significant lung eosinophilia or vaccine-induced weight loss. Together, our data demonstrate that mucosal administration of Gcf vaccine elicits beneficial protective immunity and represents a promising vaccine regimen preventing RSV infection.     

Single intranasal immunization with recombinant adenovirus-based vaccine induces protective immunity against respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract disease in infancy and early childhood. Despite its importance as a pathogen, there is no licensed vaccine against RSV. The G glycoprotein of RSV, a major attachment protein, is a potentially important target for protective antiviral immune responses. Here, a recombinant replication-deficient adenovirus-based vaccine, rAd/3xG, expressing the soluble core domain of G glycoprotein (amino acids 130 to 230) engineered by codon optimization and tandem repetition for higher-level expression, was constructed and evaluated for its potential as an RSV vaccine in a murine model. A single intranasal immunization with rAd/3xG provided potent protection against RSV challenge which lasted for more than 10 weeks. Strong mucosal immunoglobulin A responses were also induced by a single intranasal immunization but not by intramuscular or oral administration of rAd/3xG. Interestingly, neither gamma interferon- nor interleukin-4-producing CD4 T cells directed to I-E^d-restricted epitope were detected in the lungs of rAd/3xG-immune mice upon challenge, whereas priming with vaccinia virus expressing RSV G (vvG) elicited strong Th1/Th2 mixed CD4 T-cell responses. Lung eosinophilia and vaccine-induced weight loss were significantly lower in the rAd/3xG-immune group than in the vvG-primed group. Together, our data demonstrate that a single intranasal administration of rAd/3xG elicits beneficial protective immunity and represents a promising vaccine regimen against RSV infection.     

Respiratory syncytial virus (RSV) F, G, M2 (22K), and N proteins each induce resistance to RSV challenge, but resistance induced by M2 and N proteins is relatively short-lived.

The ability of recombinant vaccinia viruses that separately encoded 9 of the 10 known respiratory syncytial virus (RSV) proteins to induce resistance to RSV challenge was studied in BALB/c mice. Resistance was examined at two intervals following vaccination to examine early (day 9) as well as late (day 28) immunity. BALB/c mice were inoculated simultaneously by the intranasal and intraperitoneal routes with a recombinant vaccinia virus encoding one of the following RSV proteins: F, G, N, P, SH, M, 1B, 1C, or M2 (22K). A parainfluenza virus type 3 HN protein recombinant (Vac-HN) served as a negative control. One half of the mice were challenged with RSV intranasally on day 9, and the remaining animals were challenged on day 28 postvaccination. Mice previously immunized by infection with RSV, Vac-F, or Vac-G were completely or almost completely resistant to RSV challenge on both days. In contrast, immunization with Vac-HN, -P, -SH, -M, -1B, or -1C did not induce detectable resistance to RSV challenge. Mice previously infected with Vac-M2 or Vac-N exhibited significant but not complete resistance on day 9. However, in both cases resistance had largely waned by day 28 and was detectable only in mice immunized with Vac-M2. These results demonstrate that F and G proteins expressed by recombinant vaccinia viruses are the most effective RSV protective antigens. This study also suggests that RSV vaccines need only contain the F and G glycoproteins, because the immunity conferred by the other proteins is less effective and appears to wane rapidly with time.     

Cytotoxic T-cell response to respiratory syncytial virus in mice.

The role of the humoral and cellular arms of the immune response in protection against respiratory syncytial virus (RSV) infection and in the pathogenesis of the severe forms of this disease is poorly understood. The recent demonstration that some inbred mouse strains can be infected with RSV has opened the way to a detailed investigation of RSV immunity. We report here the finding of major histocompatibility complex-restricted, RSV-specific memory cytotoxic T cells in the spleens of BALB/c and C57BL mice after intranasal infection; these T cells recognize the Long, A2, and 8/60 (human) strains of RSV. Both K and D locus major histocompatibility complex alleles can restrict the cytotoxic response; however, in the two haplotypes tested, Dd is a low-responder allele and Kb is a nonresponder allele for RSV. UV-inactivated RSV (when given intraperitoneally) can prime mice for development of cytotoxic T cell memory, restimulate cytotoxic T cell cultures in vitro, and form a target for the cytotoxic cells.     

Assembly and immunological properties of Newcastle disease virus-like particles containing the respiratory syncytial virus F and G proteins

Human respiratory syncytial virus (RSV) is a serious respiratory pathogen in infants and young children as well as elderly and immunocompromised populations. However, no RSV vaccines are available. We have explored the potential of virus-like particles (VLPs) as an RSV vaccine candidate. VLPs composed entirely of RSV proteins were produced at levels inadequate for their preparation as immunogens. However, VLPs composed of the Newcastle disease virus (NDV) nucleocapsid and membrane proteins and chimera proteins containing the ectodomains of RSV F and G proteins fused to the transmembrane and cytoplasmic domains of NDV F and HN proteins, respectively, were quantitatively prepared from avian cells. Immunization of mice with these VLPs, without adjuvant, stimulated robust, anti-RSV F and G protein antibody responses. IgG2a/IgG1 ratios were very high, suggesting predominantly T(H)1 responses. In contrast to infectious RSV immunization, neutralization antibody titers were robust and stable for 4 months. Immunization with a single dose of VLPs resulted in the complete protection of mice from RSV replication in lungs. Upon RSV intranasal challenge of VLP-immunized mice, no enhanced lung pathology was observed, in contrast to the pathology observed in mice immunized with formalin-inactivated RSV. These results suggest that these VLPs are effective RSV vaccines in mice, in contrast to other nonreplicating RSV vaccine candidates.