嵌合HAdV六邻体蛋白抗原表位的rFLU/HAdV/Hexon疫苗候选株构建及免疫效果研究

目的构建、拯救以PR8流感病毒为载体嵌合HAdV六邻体蛋白抗原表位的疫苗候选株,对其免疫原性及免疫保护性进行评价。方法应用反向遗传学技术,以流感病毒PR8为载体,将HAdV六邻体蛋白抗原表位的基因插入流感病毒非结构蛋白NS基因,构建重组质粒NS1-Hexon,将重组质粒与PR8流感病毒其他7个基因组质粒共转染COS-1/MDCK共培养细胞,成功拯救嵌合HAdV六邻体抗原表位重组疫苗候选株,命名为rFLU/HAdV/Hexon,通过HA、RT-PCR、IFA、Western blotting和电镜等方法对rFLU/HAdV/Hexon进行鉴定。rFLU/HAdV/Hexon经鸡胚培养、浓缩纯化后滴鼻免疫Balb/c小鼠,评价小鼠机体产生的体液免疫、细胞免疫和黏膜免疫应答,进一步采用PR8流感病毒和HAdV-3病毒攻击小鼠评价其免疫保护性。结果成功拯救出基于PR8流感病毒为载体嵌合HAdV六邻体蛋白抗原表位的rFLU/HAdV/Hexon疫苗候选株。rFLU/HAdV/Hexon疫苗株形态符合流感病毒典型特征,能够诱导小鼠机体产生高效价的针对PR8和HAdV-3的特异性抗体,肺鼻灌洗液可检测到高效价的sIgA抗体;攻毒实验结果显示,rFLU/HAdV/Hexon疫苗株免疫小鼠可明显减轻感染症状、有效降低肺鼻的病毒载量、显著改善肺组织的病理病变情况。结论研制的嵌合HAdV六邻体蛋白抗原表位的rFLU/HAdV/Hexon疫苗株是有发展前景的腺病毒候选疫苗株,为腺病毒疫苗的研究提供了新思路。     

甲型H7N9流感裂解疫苗制备及免疫保护效果的评价

目的构建、拯救重配甲型H7N9流感病毒疫苗候选株并制备甲型H7N9流感裂解疫苗,动物实验评价甲型H7N9流感裂解疫苗的免疫原性及免疫保护性效果。方法采用反向遗传学技术将A/Anhui/1/2013(H7N9)疫苗株的HA、NA基因和A/Puerto Rico/8/34(PR8)毒株的PB2、PB1、PA、NP、M、NS基因进行重配,转染细胞后筛选拯救甲型H7N9流感病毒疫苗候选株,制备rgPR8-H7N9流感裂解疫苗抗原。腹腔注射免疫Balb/c小鼠,检测血清IgG、IgG1、IgG2a、HI效价,进一步用野生株攻毒,评价rgPR8-H7N9流感裂解疫苗的免疫保护效果。结果成功拯救甲型H7N9流感病毒疫苗候选株rgPR8-H7N9。制备的重配甲型H7N9流感裂解疫苗对小鼠产生较高的HI抗体效价。IgG1/IgG2a亚型检测结果表明小鼠体内以诱导体液免疫为主。攻毒实验显示甲型H7N9流感裂解疫苗能够有效降低肺部的病毒载量,肺组织病变显著减轻、体质量下降后趋于稳定,疫苗剂量达到15μg即可全部存活。A/Anhui/1/2013(H7N9)野生株流感病毒攻毒,甲型H7N9流感裂解疫苗能够达到保护小鼠效果。结论成功拯救重配甲型H7N9流感病毒疫苗候选株rgPR8-H7N9,制备的甲型H7N9流感裂解疫苗具有较好的免疫原性及免疫保护性,为H7N9流感裂解疫苗的研发及进入临床研究提供了实验依据。     

减毒流感疫苗研究进展

目前流感疫苗研制已取得明显进步，但流感病毒仍然对全球公共卫生构成巨大威胁。传统的灭活流感疫苗（IIV）或减毒活流感疫苗（LAIV）接种是控制季节性流感的主要策略，但它不能对具有大流行潜力的新型流感病毒提供保护。且季节性流感病毒持续性抗原漂移，导致抗原不匹配，严重影响疫苗效力。因此，快速优化季节性流感疫苗生产和开发新的大流行流感疫苗，仍然是预防流感的重要任务。最近有报道质疑目前LAIV的有效性，因为它主要是针对疫苗中的甲型流感病毒（IAV），保护范围有限。因此，需要研究人员开发新型LAIV，以克服LAIV的局限性。基于质粒的反向遗传学的发现和应用是快速产生重配减毒流感病毒的关键技术，可用于开发新型、有效的LAIV。本文将对新型LAI的安全性、免疫原性和保护性进行阐述，并汇总有关LAIV研究方面的新进展，以启发流感疫苗研究新思路。     

基于M2e的广谱流感疫苗及其免疫保护机制研究进展

疫苗接种是预防流感最有效和经济的手段.当前使用的流感疫苗主要是作用于特异性的流感病毒表面糖蛋白血凝素,只能对和疫苗株匹配的流行株提供保护,因此每年需要对疫苗株进行更新.研发能够预防不同亚型流感病毒的广谱疫苗成为流感疫苗研究的热点.M2e是甲型流感病毒保守片段,可作为广谱流感疫苗的候选抗原,是目前广谱流感疫苗研究的热点.本文将就M2e广谱流感疫苗及其免疫保护机制的研究进展作一综述.     

A型流感病毒M2蛋白疫苗的研究进展

流感是由流感病毒引起的一种呼吸道传染病.目前应用的流感疫苗主要是针对流感病毒的膜蛋白HA和NA,但HA和NA存在抗原漂移和抗原转变问题,需要不断改换制备疫苗用的毒株.解决办法之一是研制一种"通用型"流感疫苗.M2蛋白是流感病毒第三种跨膜蛋白,具有离子通道作用,而且其基因序列高度保守.用M2蛋白或M2蛋白胞外区免疫小鼠可以有效保护小鼠免受致死性病毒攻击.因此,M2蛋白被认为是一种潜在的具有交叉保护性抗原,可用于开发通用型甲型流感疫苗.     

流感疫苗株为载体的重组HAdV疫苗候选株构建及免疫效果

目的以冷适应、减毒流感活疫苗株为载体,构建并拯救喷鼻重组HAd V疫苗候选株,并评价其免疫效果,为腺病毒候选疫苗研制提供实验数据。方法应用反向遗传学技术,以冷适应、减毒流感活疫苗A/Ann Arbor/6/60ca(H2N2)株为骨架,与季节性流感病毒A/California/07/209疫苗株的血凝素(haemagglutination,HA)及插入HAd V六邻体蛋白抗优势原表位的2个重复序列经改造的神经氨酸酶(neuraminidase,NA)基因构建流感病毒八质粒系统,转染COS-1/MDCK细胞筛选疫苗候选株并鉴定;制备的候选疫苗株滴鼻免疫Balb/c小鼠,通过中和抗体、s Ig A黏膜抗体及细胞因子的测定评价其免疫原性,并用野生HAd V-7病毒株攻击评价免疫保护效果。结果成功拯救获得重组HAd V疫苗候选株,命名为rg Flu/HAd V-Ca,其形态符合流感病毒典型特征,可有效表达HAd V病毒Hexon优势表位,且具有冷适应、减毒表型。小鼠免疫后可产生针对HAd V-7及H1N1流感病毒的特异性中和抗体,肺鼻灌洗液中可检测到针对HAd V-7中和抗体s Ig A抗体,并可检测到脾淋巴细胞分泌HAd V-7特异性细胞因子IFN-γ、IL-4;攻毒实验显示,rg Flu/HAd V-Ca疫苗候选株可有效降低小鼠肺病毒载量。结论重组冷适应、减毒HAd V活疫苗株rg Flu/HAd V-Ca具有良好的免疫效果,为腺病毒候选疫苗的研制提供了新思路。     

用反向遗传技术产生冷适应致弱的重组A型人流感病毒的研究

目的 以鸡胚高度适应株A/PR/8/34株为重组流感病毒骨架,利用反向遗传技术拯救冷适应致弱的重组A型人流感病毒.方法 对冷适应、温度敏感、减毒的A/Ann Arbor/6/60(H2N2)流感病毒株的PB2基因片段,进行了全基因序列合成,同时人工引入PB2265(N265S)氨基酸的突变.PB2基因片段通过与改造后的转录/表达载体pAD3000连接,构建PB2基因的拯救载体.该重组质粒与PR8进行"7 1"组合的病毒拯救,共转染COS-1细胞.结果 经测序获得序列准确的拯救质粒pMDV-A-PB2,利用反向遗传技术成功拯救出了具有血凝性(1×25)的冷适应的重组A型流感病毒.结论 利用反向遗传技术成功拯救冷适应致弱的重组A型人流感病毒,该系统为深入研究甲型人流感病毒的基因功能和新型疫苗研发奠定了基础.     

注射DNA编码的一种病毒蛋白通过异源性保护来抵抗流感

甲型流感病毒和人免疫缺陷病毒的囊膜蛋白在不同分离株间变异很大,能诱导中和抗体产生的疫苗对不断变化的新分离株没有保护作用,而对保守的病毒抗原具有特异性的细胞毒性T淋巴细胞(CTL)则能对不同的病毒株起反应。在活体内这种CTL的产生通常要求有抗原的内源表达,就象发生在病毒感染时的情况一样。作者将编码甲型流感病毒A/PR/8/34(H1N1)株的核蛋白(NP)的cDNA插入细菌质粒DNA井置于劳斯氏肉瘤病毒或巨细胞病毒启动子的控制之下。将构建的质粒DNA直接注射进BALB/C小鼠的四头肌,结果导致NP特异的CTL的产生并能在随后提供针对甲型流感病毒异源毒株A/HK/68(H3N2)感染的保护。这两种流感病毒毒株的分离时间间隔34年,其表面抗原分属不同的亚型。作者还分别进行了细胞免疫和体液     

呼吸道合胞病毒样颗粒疫苗制备及免疫效果研究

目的利用昆虫表达系统表达以流感病毒基质蛋白M1为骨架制备的嵌合呼吸道合胞病毒(RSV)融合蛋白F和表面糖蛋白G蛋白的呼吸道合胞病毒样颗粒(RSV-F/G VLPs)疫苗候选株,并滴鼻免疫Balb/c小鼠,评价其免疫原性与免疫保护性。方法通过基因重组技术制备以流感基质蛋白M1为骨架,并嵌合RSV F/G蛋白的RSV-F/G VLPs,经超滤浓缩、蔗糖密度梯度离心纯化VLP,滴鼻免疫Balb/c小鼠,检测血清抗体IgG、IgG1、IgG2a,黏膜sIgA效价以及细胞因子IL-4、INF-γ等,评价候选疫苗的免疫原性;二免后2周RSV A2株攻毒,通过检测小鼠体质量变化,肺病毒载量及肺病理切片来评价候选疫苗的免疫保护性。结果成功制备了RSV-F VLPs、RSV-G VLPs疫苗抗原,动物实验结果证实,候选疫苗株RSV-F/G VLPs可刺激机体产生特异性Th1型细胞免疫及黏膜免疫;攻毒实验结果表明候选疫苗株RSV-F/G VLPs针对RSV A2株的攻击可以产生一定的保护效果。结论成功制备了RSV-F VLPs、RSV-G VLPs候选疫苗抗原,并通过动物实验证明RSV-F/G VLPs具有良好的免疫原性和免疫保护性,为发展新型RSV疫苗提供实验依据。     

小鼠MIP-1α真核表达质粒的构建及在HSV-Ⅱ核酸疫苗中的应用

目的：构建小鼠巨噬细胞炎性蛋白-1α（MIP-1α）的真核表达质粒,观察其作为分子佐剂对单纯疱疹病毒Ⅱ型（HSV-Ⅱ）DNA疫苗免疫效果的影响.方法：以LPS刺激RAW264.7细胞提取总RNA.采用RT-PCR扩增出MIP-1α基因的全部编码序列,利用克隆载体pUCm-T,将其亚克隆入pcDNA3中,构建出小鼠MIP-1α的真核表达质粒Pm;将其转染COS-7细胞,并用Boyden趋化小室法检测MIP-1α的生物学活性.然后用其与HSV-ⅡgD的DNA疫苗一起免疫BALB/c小鼠,检测免疫小鼠的特异性抗体、脾T细胞增殖反应及病毒攻击小鼠后对小鼠的保护率,观察MIP-1α对HSV-Ⅱ DNA疫苗免疫效果的影响.结果：成功构建了小鼠MIP-1α的重组真核表达质粒;免疫BALB/c小鼠发现,其作为分子佐剂可加强HSV-ⅡgDNA疫苗的免疫效果.结论：小鼠MIP-1α可作为HSV-Ⅱ gD DNA疫苗的分子佐剂,为研制新型有效的HSV-Ⅱ DNA疫苗提供一定的依据.     

Cross-reactive protection against influenza A virus by a topically applied DNA vaccine encoding M gene with adjuvant

The skin is rich with immunocompetent cells and therefore immunization through the skin is an attractive alternative to the invasive vaccination methods currently used. In this study the backs of mice were gently shaved, hydrated, and painted with a DNA vaccine encoding influenza M protein with adjuvant. The immunized mice were then challenged with two mouse-adapted strains of the influenza virus A: A/PR/8/34 (H1N1) and A/Udorn/72 (H3N2). This adjuvanated and topically applied DNA vaccine efficiently induced cytotoxic as well as humoral immune response and provide cross-reactive protection against several strains of influenza A virus. For better protection against virus infection, it will be necessary to select and combine the DNA vaccine with an appropriate adjuvant.     

Protective Efficacy of the Conserved NP,PB1, and M1 Proteins as Immunogens in DNA- and Vaccinia Virus-Based Universal Influenza A Virus Vaccines in Mice

The conventional hemagglutinin (HA)- and neuraminidase (NA)-based influenza vaccines need to be updated most years and are ineffective if the glycoprotein HA of the vaccine strains is a mismatch with that of the epidemic strain. Universal vaccines targeting conserved viral components might provide cross-protection and thus complement and improve conventional vaccines. In this study, we generated DNA plasmids and recombinant vaccinia viruses expressing the conserved proteins nucleoprotein (NP), polymerase basic 1 (PB1), and matrix 1 (M1) from influenza virus strain A/Beijing/30/95 (H3N2). BALB/c mice were immunized intramuscularly with a single vaccine based on NP, PB1, or M1 alone or a combination vaccine based on all three antigens and were then challenged with lethal doses of the heterologous influenza virus strain A/PR/8/34 (H1N1). Vaccines based on NP, PB1, and M1 provided complete or partial protection against challenge with 1.7 50% lethal dose (LD₅₀) of PR8 in mice. Of the three antigens, NP-based vaccines induced protection against 5 LD₅₀ and 10 LD₅₀ and thus exhibited the greatest protective effect. Universal influenza vaccines based on the combination of NP, PB1, and M1 induced a strong immune response and thus might be an alternative approach to addressing future influenza virus pandemics.     

Immunization with a low dose of hemagglutinin-encoding plasmid protects against 2009 H1N1 pandemic influenza virus in mice

A vaccine against the novel pandemic influenza virus (2009 H1N1) is available, but several problems in preparation of vaccines against the new emerging influenza viruses need to be overcome. DNA vaccines represent a novel and powerful alternative to conventional vaccine approaches. To evaluate the ability of a DNA vaccine encoding the hemagglutinin (HA) of 2009 H1N1 to generate humoral responses and protective immunity, BALB/c mice were immunized with various doses of 2009 H1N1 HA-encoding plasmid and anti-HA total IgG, hemagglutination inhibition antibodies and neutralizing antibodies were assayed. The total IgG titers against HA correlated positively with the doses of DNA vaccine, but immunization with either a low dose (10 μg) or a higher dose (25-200 μg) of HA plasmid resulted in similar titers of hemagglutination inhibition and neutralizing antibodies, following a single booster. Further, 10 μg plasmid conferred effective protection against lethal virus challenge. These results suggested that the DNA vaccine encoding the HA of 2009 H1N1 virus is highly effective for inducing neutralizing antibodies and protective immunity. DNA vaccines are a promising new strategy for the rapid development of efficient vaccines to control new emerging pandemic influenza viruses.     

A DNA vaccine expressing PB1 protein of influenza A virus protects mice against virus infection

Although influenza DNA vaccine research has focused mainly on viral hemagglutinin and has led to promising results, other virion proteins have also shown some protective potential. In this work, we explored the potential of a DNA vaccine based on the PB1 protein to protect BALB/c mice against lethal influenza A virus infection. The DNA vaccine consisted of pTriEx4 plasmid expressing PB1. As a positive control, a pTriEx4 plasmid expressing influenza A virus HA was used. Two weeks after three subcutaneous doses of DNA vaccine, the mice were challenged intranasally with 1 LD₅₀ of A/Puerto Rico/8/34 (H1N1) virus, and PB1- and HA-specific antibodies, survival rate, body weight change, viral mRNA load, infectious virus titer in the lungs, cytokines IL-2, IL-4 and IL-10, and granzyme-B were measured. The results showed that (i) the PB1-expressing DNA vaccine provided a fair protective immunity in the mouse model and (ii) viral structural proteins such as PB1 represent promising antigens for DNA vaccination against influenza A.     

Immunoglobulin-A antibodies in upper airway secretions may inhibit intranasal influenza virus replication in mice but not protect against clinical illness

Mice immunized intranasally with a formalin-inactivated A/PR/8/34 (H1N1) influenza whole virus vaccine adjuvanted with cholera toxin, outer membrane vesicles from group B meningococci or formalin-inactivated whole cell Bordetella pertussis were protected against replication of the homologous virus in the nasal cavity. Only some mice were protected against clinical illness measured as weight loss and lowered body temperature. All mice immunized subcutaneously with one-tenth the intranasal vaccine dose without adjuvant were protected against clinical illness but not against local mucosal viral replication. Replicating virus was primarily found in animals with low concentrations of immunoglobulin (Ig)-A antibodies in saliva regardless of concentrations of IgG antibodies in serum. Clinical illness was seen only in those with low serum antibodies regardless of antibody levels in saliva. Nonreplicating nasal vaccines may not be sufficiently protective unless they also have a substantial influence on systemic immunity.     

Induction of antibody response by DNA immunization of newborn baboons against influenza virus.

Previous studies showed that DNA immunization of newborn mice with plasmids expressing influenza virus antigens induced protective immunity. We have now extended the study of neonatal responsiveness to DNA vaccines to nonhuman primates. Baboons immunized as neonates with plasmids expressing type A influenza virus hemagglutinin (HA) and nucleoprotein (NP) in doses ranging from 40 microg to 1 mg per plasmid per dose developed virus-specific humoral responses. The titer and kinetics of appearance of virus-specific IgG antibodies were dose dependent. Specific antibodies were detected by enzyme-linked immunosorbent assay (ELISA) as early as 1 month after birth in baboons immunized with the highest and intermediate doses of vaccine. Virus-neutralizing antibodies were detected in the group of baboons immunized with the highest dose. The specificity of virus-neutralizing antibodies was found to be directed against homologous determinants of HA; however, the IgG antibodies also cross-reacted with HA of a drift variant. Thus, DNA vaccination of newborn baboons with a prototype vaccine against influenza virus resulted in induction of specific humoral immunity.     

Immunization with plasmid DNA encoding influenza A virus nucleoprotein fused to a tissue plasminogen activator signal sequence elicits strong immune responses and protection against H5N1 challenge in mice

DNA vaccination is an effective means of eliciting both humoral and cellular immunity. Most of influenza vaccines targeted at hemagglutinin (HA) show efficient immunogenicity for protecting subjects against influenza virus infection. However, major antigenic variations of HA may facilitate the virus in developing resistance against such vaccines. DNA vaccines encoding conserved antigens protect animals against diverse viral subtypes, but their potency requires further improvement. In the present study, a DNA vaccine encoding the conserved nucleoprotein (NP) with a tissue plasminogen activator (tPA) signal sequence (ptPAs/NP) was generated, and immune responses were examined in vaccinated mice. A higher level of NP expression and secretion was observed in lysates and supernatants of the cells transfected with ptPAs/NP when compared to a plasmid encoding the wild-type full-length NP (pflNP). Immunofluorescence studies showed the cytoplasmic localization of the NP protein expressed from ptPAs/NP, but not from pflNP. In mice, the ptPAs/NP vaccine elicited higher levels of the NP-specific IgG and CD8(+) T cell-stimulating responses than that of pflNP. Vaccination with ptPAs/NP efficiently cleared the homologous H5N1 influenza virus in the infected lungs and induced partial cross-protection against heterologous, highly pathogenic H5N1 strains in mice. Our results may contribute to the development of protective immunity against diverse, highly pathogenic H5N1 virus subtypes.     

Induction of humoral and cellular immunity against influenza virus by immunization of newborn mice with a plasmid bearing a hemagglutinin gene

Neonates and infants display an intrinsic disability to mount protective immune responses to influenza viruses or conventional influenza vaccines. We investigated the ability of naked DNA to prime protective immune responses by inoculating newborn and adult mice with a plasmid (pHA) expressing hemagglutinin (HA) from the neurovirulent strain A/WSN/33 of influenza virus. Continuous exposure to small doses of antigen subsequent to neonatal DNA immunization led to effective priming of specific B and Th cells, rather than tolerance induction. The pHA immunization of adult mice primed a strongly biased Th1 response, whereas in neonates it induced a mixed Th1/Th2 response. In contrast to the effect of live-virus immunization, DNA immunization of neonates was followed by enhanced cytotoxic T lymphocyte responses subsequent to challenge with A/WSN/33 influenza virus. Mice immunized as neonates or adults with pHA plasmid exhibited significant increases in survival and decreases in virus lung titers following lethal challenge with the A/WSN/33 virus or the A/PR8/34 drift variant. Our results demonstrate that DNA vaccination is an efficient and safe means to generate broad humoral and cellular immune responses to influenza viruses, during the earliest stages of postnatal life.