Molecular composition of diphtheria toxoid produced using semi-synthetic and meat extract-based broths

The use of semi-synthetic broths for cultivation of Corynebacterium diphtheriae instead of a meat extract-based broth avoids the presence of highly undesirable bovine meat antigens in the diphtheria toxoid. As information on the composition of casein digest-based broths used for the production of diphtheria toxoid is scarce, we have now developed one. The composition of a casein-based medium that supports vigorous bacterial growth as well as high toxin production is described below. The comparative analysis of the toxoids, produced using the meat-based Pope–Lingood and the casein digest-based broths, showed considerable differences in their molecular composition. The variance of weight distribution of toxoid-containing molecular complexes was smaller when the semi-synthetic broth was used. Normal human therapeutic IgG recognizes some of the proteins in the meat-based medium but does not react with any components of the semi-synthetic medium. While precipitation at the isoelectric point of the diphtheria toxoid produced by culturing the C. diphtheriae strain in the semi-synthetic medium resulted in a preparation meeting the requirement for purity (more than 1500 limit floculation Lf/mg protein nitrogen PN), the toxoid produced in the Pope–Lingood broth failed to meet this requirement in some cases, even after a second purification step using ultrafiltration.     

保存温度和时间对狂犬病疫苗效力稳定性的影响

对人用精制狂犬病疫苗和浓缩狂犬疫苗分析在－33℃,2－8℃,25℃,37℃保存0－6个月进行效力的稳定性观察,结果表明随存放时间及温度增加,两者的生物活性均有不同程度的降低。在2－8℃条件下疫苗的效力明显比其它温度稳定（P＜0．02）;精制疫苗与浓缩疫苗比较,其效力有更稳定的趋势。     

中枢神经系统靶向性CuZn—SOD的构建和表达

SOD对中风等由氧自由基毒性引起的神经性紊乱有保护作用,但因血脑屏障使血液中的SOD不能进入中枢神经系统。靶向性SOD可能是进入该系统的途径之一。将人CuZn-SODcDNA与破伤风毒素C部分基因融合,分别整合进pET－22b（＋）及pFastBacHTb载体中,并分别在E.coli及粉纹夜蛾Tn-5B1-4细胞中表达。表达产物分子量为68kD,与理论计算值。蛋白质印迹实验证实,其表达产物能与人CuZn－SOD多克隆抗人本及抗破伤毒素全毒互抗体有免疫反应。在Tn细胞中高效表达,表达产物占可溶性总蛋白质的20％,表达产物有SOD活性,且具有逆行轴突运输的能力。这为靶向性SOD的进一步应用创造了条件。     

中枢神经系统靶向性Mn-SOD的克隆和在大肠杆菌中的表达研究

靶向性超氧化物歧化酶(SOD)是治疗氧自由基引起神经细胞损伤所致疾病等的有效途径.将破伤风毒素C部分（tetanus toxin fragment C,TTC）基因与编码Mn-SOD的cDNA融合克隆进pET-22b(+)载体,1 mmol/L异丙基-D-硫代半乳糖（IPTG）诱导在大肠杆菌中表达.SDS-聚丙烯酰胺凝胶电泳(PAGE)图谱可见约71 ku有表达产物条带,与理论计算值相符;蛋白质印迹（Western blot）分析显示,表达产物与抗Mn-SOD及破伤风毒素的多抗有免疫反应,而且表达产物用邻苯三酚自氧化法测定具有SOD活性.融合蛋白可作为有效的试剂靶向性输送Mn-SOD到神经元细胞,这为进一步研究靶向性SOD的治疗中枢神经系统的相关疾病提供了基础.     

Effects of testosterone and corticosterone on immunocompetence in the zebra finch

The original immunocompetence handicap hypothesis (ICHH) suggested that testosterone has a handicapping effect in males by both promoting the development of sexual signals and suppressing immune function. A modified version, the stress-linked ICHH, has recently proposed that testosterone is immunosuppressive indirectly by increasing production of corticosterone. To test both the original and stress-mediated versions of the ICHH, we implanted male zebra finches taken from lines selected for divergent maximum stress-induced levels of corticosterone (high, low and control) with either empty or testosterone-filled implants. Their humoral and cell-mediated immune responses were then assessed by challenge with diphtheria:tetanus vaccine and phytohemagglutinin respectively. We found no effect of the hormone manipulations on either PHA or tetanus antibody responses, but found a significant interaction between titers of both testosterone and corticosterone on diphtheria secondary antibody response; antibody response was greatest in individuals with high levels of both hormones. There was also a significant interactive effect between testosterone treatment group and corticosterone titer on body mass; the body mass of males in the elevated testosterone treatment group decreased with increasing corticosterone titer. These results suggest that, contrary to the assumption of the stress-mediated version of the ICHH, high plasma levels of corticosterone are not immunosuppressive, but are in fact immuno-enhancing in the presence of high levels of plasma testosterone. Equally, the central assumption of the ICHH that testosterone is obligately immunosuppressive is also not supported. The same individuals with the highest levels of both hormones and consequently the most robust antibody response also possessed the lowest body mass.     

Generation of potent mouse monoclonal antibodies to self-proteins using T-cell epitope “tags”

Immunization of mice or rats with a "non-self" protein is a commonly used method to obtain monoclonal antibodies, and relies on the immune system''s ability to recognize the immunogen as foreign. Immunization of an antigen with 100% identity to the endogenous protein, however, will not elicit a robust immune response. To develop antibodies to mouse proteins, we focused on the potential for breaking such immune tolerance by genetically fusing two independent T-cell epitope-containing sequences (from tetanus toxin (TT) and diphtheria toxin fragment A (DTA)) to a mouse protein, mouse ST2 (mST2). Wild-type CD1 mice were immunized with three mST2 tagged proteins (Fc, TT and DTA) and the specific serum response was determined. Only in mice immunized with the T-cell epitope-containing antigens were specific mST2 serum responses detected; hybridomas generated from these mice secreted highly sequence-diverse IgGs that were capable of binding mST2 and inhibiting the interaction of mST2 with its ligand, mouse interleukin (IL)-33 (mIL-33). Of the hundreds of antibodies profiled, we identified five potent antibodies that were able to inhibit IL-33 induced IL-6 release in a mast cell assay; notably one such antibody was sufficiently potent to suppress IL-5 release and eosinophilia infiltration in an Alternaria alternata challenge mouse model of asthma. This study demonstrated, for the first time, that T-cell epitope-containing tags have the ability to break tolerance in wild-type mice to 100% conserved proteins, and it provides a compelling argument for the broader use of this approach to generate antibodies against any mouse protein or conserved ortholog.     

The protective effect of immunisation against diphtheria, pertussis and tetanus (DPT) in relation to sudden infant death syndrome

Epidemiological evidence indicates infants immunised against diphtheria, pertussis and tetanus (DPT) are at decreased risk of sudden infant death syndrome (SIDS). Asymptomatic whooping cough and pyrogenic toxins of Staphylococcus aureus have been implicated in the aetiology of SIDS. The objectives of the present study were: (1) to determine if the DPT vaccine induced antibodies cross-reactive with the staphylococcal toxins; (2) to determine if antibodies to the pertussis toxin (PT) and the staphylococcal toxins were present in the sera of women during late pregnancy; (3) to examine the effects of infant immunisation on levels of antibodies to PT and the staphylococcal toxins; (4) to assess the effects of changes in immunisation schedules in the UK on the incidence and age distribution of SIDS. Enzyme-linked immunosorbent assays (ELISA) were used to measure binding of rabbit or human IgG to the DPT vaccine, PT, toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxins A (SEA), B (SEB) and C (SEC). Neutralisation activity of anti-DPT serum was assessed by a bioassay for induction of nitric oxide from human monocytes by the staphylococcal toxins. Anti-DPT serum bound to the DPT vaccine, PT and each of the staphylococcal toxins. It also reduced the ability of the four toxins to induce nitric oxide from monocytes. In pregnant women, levels of IgG to PT, SEC and TSST-1 decreased significantly in relation to increasing weeks of gestation while antibodies to SEA and SEB increased. In infants' sera there were significant correlations between levels of IgG bound to DPT and IgG bound to PT, TSST-1 and SEC but not SEA or SEB. Antibody levels to the toxins in infants declined with age; sera from infants < or = 2 months of age had higher levels of IgG bound to the toxins than those older than 2 months. This pattern was observed for infants whose immunisation schedules began at 2 months of age or 3 months of age. The decrease in IgG bound to the toxins was, however, less for those immunised at 2 months. The decrease in SIDS deaths after the change in immunisation schedules was greatest in the 4-6-month age range. While DPT immunisation might prevent some unexplained infant deaths due to asymptomatic whooping cough, these data indicate that immunisation with DPT also induces antibodies cross-reactive with pyrogenic staphylococcal toxins implicated in many cases of SIDS. Passive immunisation of infants who have low levels of these antibodies might reduce further the numbers of these infant deaths.     

BCG—PPD的制备及应用

用三氯醋酸(TCA)和硫酸铵(AS)综合法,由卡介菌苗(BCG)培养滤液中提纯制得卡介菌素纯蛋白衍生物(BCG—PPD)。BCG—PPD的纯度和结核菌素纯蛋白衍生物国际标准(PPD-S)及中国标准(PPD—C)相近,高于加拿大标准(PPD—CT68)和丹麦标准(PPD—RT23)。在BCG免疫豚鼠中,BCG—PPD的皮肤迟发型变态反应(DTH)大于结核菌素纯蛋白衍生物(PPD)的DTH反应。在结核菌感染豚鼠组中,BCG—PPD的DTH反应小于PPD的DTH反应.在检查333名新生儿接种BCG12周后的免疫     

人破伤风类毒素免疫血浆筛选试验中两种抗体检测方法的比较

应用酶联免疫法(ELISA)和间接血凝法(IHA)对1014份破伤风类毒素全程免疫后人血浆进行抗体水平检测,比较两者的收浆率、收浆符合率以及与动物实验的相关性。结果表明两者收浆率均达80%。ELISA法与IHA法的合格浆符合率达92%,与动物实验的相关性更好。ELISA法操作简便快速,结果判读客观明确,优于传统的IHA法,可作为人破伤风类毒素免疫血浆筛选的常规方法。     

三种免疫制剂对真鲷弧菌病的免疫保护性

菌体疫苗按不同的方式对真鲷进行免疫2周后,对实验鱼均具有免疫保护性,免疫保护性最好的免疫组,免疫保护率在初次免疫后高达60%,强化免疫后免疫保护率可提高到80%;粗制LPS经去毒处理后初次免疫真鲷,不同浓度的LPS对实验鱼具有不同程度的免疫保护性,强化免疫后,免疫保护率均有明显的提高,浓度越高,免疫保护性越强,对真鲷的免疫保护率最高可达90%,最小弧菌产生的外毒素经福尔马林灭活后制成毒素苗,这种毒素苗能产生较好的免疫保护性,其免疫保护率可达80%,这表明外毒素不仅是最小弧菌产生的毒力因子,同时也是菌体产生的有效保护性抗原。