SARS-CoV-2: Vaccines in the pandemic era

Coronavirus disease 2019(COVID-19),caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has caused millions of infections and deaths worldwide since its emergence in December 2019.As there is little or no natural immunity in the human population or specific anti-COVID-19 drugs,researchers from the government,academia and industry are developing vaccines at an unprecedented speed to halt the pandemic.In this review,the results of animal experiments and clinical trials on several vaccine technical platforms are summarized,and several challenges are also discussed to further promote the development,evaluation and application of vaccines during the challenging situation of the global pandemic.

Relationship between T-lymphocyte cytokine levels and sero-response to hepatitis B vaccines

AIM: To investigate the cellular defects by analyzing the (Th1/Th2) cytokine levels in vaccine responders and non-responders. METHODS: Peripheral blood mononuclear cell (PBMC) from responders and non-responders were stimulated with or with out recombinant HBsAg or PHA. Broad spectrum of cytokines viz (Th1) IFN-γ, IL-2, TNF-α, IL-12 and (Th2) IL-10, IL-4 were measured after in vitro stimulation with recombinant HBsAg and were compared with respective antibody titers. RESULTS: A significant decrease (P = 0.001) in Th1 and Th2 cytokines namely, IL-2, INF-γ, TNF-α and IL-10in non-responders was observed. The level of IL-4 was not significant between the three groups. Furthermore, despite a strong Th1 and Th2 cytokine response, the level of IL-12 was elevated in high-responders compared to other groups (P = 0.001) and demonstrated a positive correlation with anti-HBs titers and Th1 cytokine response. CONCLUSION: Our findings suggest that unrespon-siveness to recombinant hepatitis B vaccines (rHB) is multifactorial, including specific failure of antigen presentation or the lack of both T helper Th1 and Th2 response.

Comparison of three different recombinant hepatitis B vaccines:GeneVac-B,Engerix B and Shanvac B in high risk infants born to HBsAg positive mothers in India

AIM： To evaluate a low cost Indian recombinant hepatitis B vaccine GeneVac-B for its immunogenicity and safety in comparison to Engerix B and Shanvac B vaccine in high risk newborn infants born to （hepatitis B surface antigen） HBsAg positive mothers.METHODS： A total of 158 infants were enrolled in the study. Fifty eight infants were enrolled in the GeneVac-B group while 50 each were included for Engerix B and Shanvac B groups. A three-dose regimen of vaccination; at birth （within 24 h of birth）, 1st mo and 6 too. were adopted with 10 μg dosage administered uniformly in all the three groups. Clinical and immunological parameters were assessed for safety and immunogenicity of the vaccines, in all the enrolled infants.RESULTS： Successful follow up until seven months of age was achieved in 83% （48/58） for GeneVac-B, 76% （38/50） and 64% （32/50） for Engerix B and Shanvac B groups respectively. 100% seroconversion and seroprotection was achieved in all the three groups of infants. The geometric mean titers of anti-HBs one month after the completion of three dose of vaccination were 90.5, 80.9 and 72.5 mTU/mL in GeneVac-B, Engerix B and Shanvac B vaccine group respectively. Furthermore the level of anti-HBs increases with age of babies who were born to HBsAg positive mothers. The GMT values of anti-HBs were 226.7, 193.9 and 173.6 mIU/mL respectively in GeneVac-B, Engerix B and Shanvac B groups one year after the completion of the three doses of vaccine. No systemic reactions were reported in infants during the entire vaccination process of GeneVac-B and the other two vaccines. Clinical safety parameters remained within the normal limits throughout the study period.CONCLUSION： The study concludes that there is no significant difference between the three recombinant hepatitis B vaccines. Administration of these vaccines within 24 h of birth to babies, born to HBsAg positive mothers will reduce the incidence of HBV infection.

Associated Bacteriostasis Research of Coptidis Rhizoma-Folium Isatidis and Coptidis Rhizoma-Flos Poprli against Escherichia coli O2

[Objective] The paper was to explore the combined inhibitory effect of rhizoma coptidis-folium isatidis and rhizoma coptidis-flos poprli against Escherichia coli O2.[Method] Contrast test of single and associated bacteriostasis against known serotype E. coli O2 was conducted using microcheckerboard method.[Result] The MIC of rhizoma coptidis, folium isatidis and flos poprli were 1/8 extracting liquid, 1/8 extracting liquid and 1/2 extracting liquid, respectively. When combined with folium isatidis or flos poprli, the MIC of rhizoma coptidis was 1/8 extracting liq-uid or 1/16 extracting liquid compared with single use. When combined with rhizoma coptidis, the MIC of folium isatidis and flos poprli were 1/8 extracting liquid and 1/16 extracting liquid.[Conclusion] When rhizoma coptidis was combined with folium isatidis or flos poprli, the FIC values were 2 and 0.625, performing independent action and additive effect, respectively.

Development of a Multi-Plex Electrochemiluminescent Assay for the Detection of Serum Antibody Responses to Meningococcal Conjugate Vaccines

Neisseria meningitidis is a gram negative diplococcal bacterium. Worldwide, N. meningitidis is the leading cause of bacterial meningitis and sepsis, with five serogroups (A, B, C, Y, and W-135) responsible for the majority of the disease. Multivalent (A, C, Y, and W-135) polysaccharide and conjugate vaccines have been licensed in the United States and elsewhere and are widely available. We have developed a multi-plexed electrochemiluminescent assay to quantitate serum antibody responses to meningococcal polysaccharides A, C, Y, and W-135 to allow for rapid evaluation of li- censed and investigational vaccines. A 96-well plate containing a carbon electrode arrayed with polysaccharides A, C, Y, and W-135 on separate spots within each well has been developed for simultaneous detection of polysaccharidespecific antibodies in serum samples from vaccinated individuals. The assay conditions were optimized using the anti-meningococcal serogroup A/C reference serum pool, CDC 1992 (NIBSC 99/706), through evaluation of plate types, coating polysaccharide concentrations, and blocking and serum diluent buffers. Comparison of single and multiplex assays demonstrated the sensitivity, specificity, and speed of the multi-plex format for the quantification of serum antibody responses to N. meningitidis polysaccharides A, C, Y and W-135.

Validation of Automated Dilution and Transfer Methods for Rapid Assessment of Functional Immune Responses to Meningococcal Vaccines

A high-throughput Serum Bactericidal Assay (SBA) was developed to monitor the functional antibody responses to capsular polysaccharide antigens from multiple serotypes of Neisseria meningitidis. This assay measures the ability of an antibody, aided by complement, to mediate killing of bacteria. Functional assays of this type are increasingly used in the quality control arena as potency release tests. Consequently, there has been an enhanced requirement for reproducibility in the performance of this type of assay. Assay validation is, therefore, important to facilitate understanding of the significance of values obtained, and to enable appropriate and informed use of the assay. This study involved the evaluation of the high-throughput serum bactericidal assay including the effects of different dilution and transfer techniques on assay performance. The results presented here demonstrate the repeatability, and the precision and ruggedness of the assay.

Protectivity of Freeze Dried Inactivated Rift Valley Fever Vaccine

Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and lessen or stop the spread of zoonotic diseases to humans. Animal vaccines that are both safe and efficacious are vital to modern culture. The vaccine should induce a strong, protective and prolonged immune response against the antigenic factor. In order to achieve these goals, novel vaccination techniques and an efficient adjuvant are required to render the vaccine immunogenically protective and trigger a strong immune response. Aim: Our study aims to promote and enhance the immunogenicity against RVF virus disease through lyophilized inactivated RVF vaccine through induction of early cellular, high and prolonged humeral immunity in vaccinated animals using cabopol as stabilizer and Saponin or normal saline as a diluent at time of vaccination. Moreover, manufacturing of these vaccines is easy to be done. Results: The gained results revealed that RVF freeze-dried vaccine with Carbopol that reconstituted using Saponin elicited better immune response than that reconstituted using normal saline (NaCl). The cell mediated immune response as represented by lymphocyte blastogenesis and phagocytic activity were markedly increased with high levels when we used Saponin as a diluent than that in group vaccinated with vaccine diluted with NaCl, on the other side the humeral immune response in group vaccinated using the Saponin as diluent is more detected and stayed within the protective level till the end of 11th month post vaccination (1.5 TCID50) while the immune response induced after using normal saline as a diluent stayed within the protective level till the end of 10th month post vaccination (1.8 TCID50). Conclusion: The use of Saponin as a diluent for reconstitution of the freeze dried RVF vaccine is preferable than the use of normal saline enhancing both sheep cellular and humeral immune response.

Molecular Characterization of Coxsackievirus B1 Strains Isolated from Patients with Hand Foot and Mouth Disease in Yunnan,Southwest China

Coxsackievirus(CV)B belongs to the species Enterovirus B,genus Enterovirus of the family Picornaviridae.Enterovirus B(EV-B)includes 63 serotypes:CVB1-6;CVA9;echoviruses E1-7,9,11-21,24-27,and 29-33;EV-B69,EV-B 73-75,EV-B77-88,EV-B 93,EV-B 97-101,EV-B 106-107.

Field Assessment of the Level of Protection Conferred by a Newly Prepared Combined Inactivated Vaccine against E. coli and P. multocida in Rabbit in Egypt

Pasteurellosis is the most prevalent, extremely contagious bacterial disease among domestic rabbits and is considered the leading cause of deaths in rabbits, resulting in enormous economic losses to the rabbit industry. Screening for bacterial agents causing mortalities in rabbits revealed the presence of Enterobacteriacae species in approximately 42% of studied cases, with E. coli the most commonly isolated organism. The present study was designed to evaluate the immune response of rabbits vaccinated with a locally prepared, combined inactivated vaccine of Pasteurella multocida and E. coli, adjuvanated with Montanide ISA70. A total of 370 rabbits, aged 2 - 3 weeks, were divided into four groups: (G1) vaccinated with a polyvalent P. multocida vaccine, (G2) vaccinated with a polyvalent E. coli vaccine, (G3) vaccinated with a combined inactivated Montanide ISA70 vaccine of P. multocida and E. coli, and (G4) kept as a non-vaccinated control group. All rabbits received two doses of 0.5 ml of the prepared vaccines, administered one month apart, and were then challenged with virulent strains of P. multocida and E. coli three weeks after the second vaccination. The prepared vaccines were evaluated by determining humoral immunity using indirect haemagglutination (IHA) test and ELISA. The potency of the vaccines was assessed through challenge and determination of LD50. Experimental findings on the prepared polyvalent combined inactivated P. multocida and E. coli vaccine indicated that it is a potent vaccine, producing the highest antibody titers and a 90% protection rate against challenges with virulent strains of P. multocida type A, D2, and E. coli types O157, O151 and O125. Thus, this vaccine is promising in addressing both P. multocida and E. coli problems in rabbits, farms, providing significant protection, and we recommend its commercial production to help rabbit producers control these two major bacterial infections.

广西南宁市5岁以下儿童细菌性脑膜炎病原学研究

目的 了解南宁市 5岁以下儿童细菌性脑膜炎的病原学特点和致病菌的药物敏感性情况。 方法 2 0 0 0年 11月至 2 0 0 2年 12月 ,在南宁市 (含邕宁、武鸣县 )所在乡镇卫生院以上的医疗机构进行监测 ,对发现疑似脑膜炎患儿采集脑脊液和血液进行细菌培养和采用Kirby Bauer纸片扩散法对病原菌进行药物敏感试验。 结果 共检测采自 12 72例病例的 12 12份脑脊液标本和 1193份血标本。分离出 63株致病菌 ,其中从脑脊液标本中检出 2 3株 ,从血液中检出 40株。脑脊液和血液培养检出最多的病原菌基本上一致 ,葡萄球菌最多 ,其次是肺炎双球菌、流感嗜血杆菌、肠杆菌科细菌。葡萄球菌对万古霉素、庆大霉素、苯唑西林及环丙沙星敏感率均在 80 %以上 ,而对青霉素和红霉素耐药率很高。沙门菌、大肠杆菌、阴沟肠杆菌等肠杆菌科细菌对环丙沙星、头孢菌素的敏感性较高。 结论 细菌性感染是南宁市婴幼儿脑膜炎致病因素之一。抗菌药物的选择使用应根据细菌药敏结果 ,以提高疗效 。

内源性IL-12决定人PBMC产生干扰素γ的水平(英)

目的：ＩＦＮ－γ是由被有丝分裂原或抗原所激活的Ｔ细胞和ＮＫ细胞所产生，它具有广泛的免疫调节活性，现认为ＩＬ－１２（外源性）是诱导 ＩＦＮ－γ产生的强诱导剂，并可促进静息 ＣＤ４＋Ｔ细胞朝向 Ｔｈ１表型分化，即诱导细胞免疫。目的是为了解由ＰＢＭＣ产生的内源性ＩＬ－１２是否在体外可诱导ＩＦＮ－γ的产生及通过何机制诱导细胞免疫。方法：用抗ＣＤ３抗体、ＰＨＡ、抗ＣＤ３抗体加抗ＣＤ２８抗体和抗原（ＭＬＣ）来检测被刺激的ＰＢＭ细胞的ＩＦＮ－γ的产生，同时也用ＩＬ－１２和ＩＬ－１２Ｒβ１的中和抗体来抑制ＩＦＮ－γ的产生。结果：激活的人ＰＢＭ中ＩＦＮ－γ分泌依赖于内源性ＩＬ－１２的产生，而且激活的Ｔ细胞可诱导ＡＰＣ细胞产生ＩＬ－１２，此过程是通过Ｔ细胞表面的ＣＤ４０Ｌ和ＡＰＣ的ＣＤ４０相互作用而实现。结论：这些结果提示，内源性ＩＬ－１２在正常宿主抗细胞内抗原的感染反应中起重要作用，在某些形式的自身免疫性疾病和移植排斥反应的免疫病理发生中也起中心作用。

南宁市儿童流感嗜血杆菌、肺炎链球菌和脑膜炎奈瑟菌所致脑膜炎流行病学特征分析

目的 了解广西南宁市 5岁以下儿童流感嗜血杆菌 (Hi)、肺炎链球菌 (Sp)和脑膜炎奈瑟菌 (Nm)所致脑膜炎流行病学特征 ,为制订该病的预防对策提供依据。方法 2 0 0 0年 11月至 2 0 0 2年 12月对广西南宁市市区、市郊 15个乡镇、武鸣县 10个乡镇和邕宁县 14个乡镇的凡符合“疑似脑膜炎筛检标准”的 5岁以下患儿进行以病原学为依据的细菌性脑膜炎流行病学监测。结果 共评估了12 72例疑似脑膜炎患儿 ,发现Hi脑膜炎 3例、Sp脑膜炎 4例 ,未发现Nm脑膜炎病例 ;Hi、Sp脑膜炎年均发病率分别为 0 98/10万、1.30 /10万 ;Hi和Sp脑膜炎病例分布于邕宁县和南宁市区 ;Hi、Sp脑膜炎平均发病年龄分别为 11 7、5 8月龄 ;发病季节较分散 ;临床症状体征均较重 ,Hi和Sp脑膜炎各有 1例并发症发生 ,Sp脑膜炎病死 1例 ,均无后遗症发生 ;所分离的Hi和Sp菌株有对青毒素和复方新诺明耐药的现象 ;确诊患儿绝大多数居住于农村 ,均未接种过相应的疫苗。结论 虽然本次监测南宁市 5岁以下儿童Hi、Sp和Nm所致脑膜炎发病率均较低 ,但除采取针对呼吸道传染病的预防措施外 ,仍主张采取针对性的疫苗接种。

数据库管理系统在儿童细菌性脑膜炎流行病学监测中的应用

本文介绍Visual Foxpro6.0数据管理系统在儿童细菌性脑膜炎流行病学监测数据管理中的应用,充分体现了该系统功能强大,界面直观、科学及便于管理等优点,并对本监测的数据管理系统的局限性作了分析。本数据管理系统是用于流行病学研究数据管理的优良软件。

SARS康复者M抗原特异性记忆性T细胞免疫应答的探讨

目的探讨SARS患者康复后,外周血单个核细胞(PBMCs)中是否存在SARS-CoVM抗原特异性T细胞。方法从完全康复期SARS患者和健康人外周血中分离PBMCs,体外经M混合多肽刺激后,采用酶联免疫吸附试验(ELISA)、酶联免疫斑点试验(ELISpot)及流式细胞仪检测技术,分析抗原特异性T淋巴细胞的反应性。结果在未经任何抗原刺激的情况下,PBMCs几乎不分泌IFN-γ。当SARS-CoVM混合多肽刺激后,SARS康复期患者的PBMCs分泌大量的IFN-γ,并可检测出高频率的IFN-γ产生细胞。与健康刺激组及康复期SARS患者未刺激组相比,差异显著(P<0.05)。流式结果显示,SARS康复期患者PBMCs经M多肽刺激后,分别有0.11%CD4+和0.16%CD8+T淋巴细胞分泌IFN-γ。根据IFN-γ和IL-2的表达与否,可将CD4+T细胞分为三个亚群IFN-γ-IL-2+、IFN-γ+IL-2+和IFN-γ+IL-2-。结论SARS-CoV感染后,机体可以产生针对SARS-CoVM蛋白的抗原特异性细胞免疫反应,其免疫记忆可以在体内维持很长时间。

疑似脑膜炎患儿脑脊液改变与临床表现关系的流行病学研究

目的 了解疑似脑膜炎患儿脑脊液改变程度与其临床表现的关系。 方法 将纳入细菌性脑膜炎监测系统疑似脑膜炎病例根据脑脊液改变的程度分成 3组 ,统计其临床表现 ,并进行流行病学统计、分析。 结果 3组病例均以≤ 2 4月龄段为主 ,尤以CSF培养阳性组为高 ,男性发病的比例高于女性 ;除抽搐外 ,临床表现普遍有CSF培养阳性组高于异常组 ,异常组高于正常组的特点 ;≤ 2 4月龄段患儿囟门膨突的构成比高于 2 5～ 36月龄段 ,而≥ 3项临床表现的构成比后者则高于前者 ;异常组女性的囟门膨突的构成比高于男性 ;≥ 3项临床表现以异常组及CSF培养阳性组的夏季为最高 ;农村患儿临床表现构成比高于城市患儿 ;采样前不用抗菌素者抽搐的构成比高于采样前使用抗菌素者 ,但总的来说两种情况患儿的临床表现差异并不明显。 结论 CSF改变程度与临床表现的关系呈正相关 ,抽搐不是脑膜炎特异性的表现 ,对于农村患儿。

南宁市疑似脑膜炎患儿抗生素使用情况调查分析

目的 了解南宁地区疑似脑膜炎患儿抗生素的使用情况 ,以求规范、合理使用抗生素。 方法 使用统一的调查表格收集符合筛选标准的疑似脑膜炎患儿的相关资料 ,并进行流行病学统计、分析。 结果 共评估了 12 72例脑膜炎疑似患儿 ,使用的抗生素以青霉素类 ( 75 0 0 % )和头孢菌素类 ( 64 2 3 % )为主 ;排前五位的是 :青霉素( 3 9 15 % )、头孢噻肟 ( 3 6 16% )、氨苄西林 ( 10 3 8% )、头孢拉定 ( 7 70 % )和头孢唑啉 ( 7 2 3 % )。 5 0 %以上的病例在就诊期间使用了 2种或 2种以上的抗生素 ,3 4 98%的病人在就诊前已使用了抗生素 ,注射途径给药的抗生素占 71 18% ;就诊期间注射给药的抗生素占 98 2 7%。年长儿青霉素使用率 ( 4 4 88% )较年龄较小的婴幼儿 ( 3 6 95 % )高 ,而新生儿较1个月以上的幼儿的头孢塞肟、氨苄西林、阿莫西林 -舒巴坦和头孢曲松的使用率高。脑脊液生化、常规异常和 /或血白细胞升高组抗生素使用率 ( 92 5 2 5 )较正常组 ( 83 165 )高。 结论 本调查中疑似脑膜炎患儿的抗生素治疗往往以引起该病的主要病原菌为依据 ,以经验用药为主 ,建议对类似病人应尽可能做病原学检查以指导治疗 ;

Enemy at the gates： dendritic cells and immunity to mucosal pathogens

Dendritic cells （DC） are diverse and specialized hematopoietic cells serving as an essential bridge between innate and adaptive immunity. DC exist in all lymphoid and nonlymphoid organs and are amongst the first responders to infection at epithelial surfaces including mucosal tissues. DC of the lung, gut, and vaginal mucosa display different phenotypes and functions reflecting each unique tissue and, in contrast to their counterparts in spleen and lymph nodes, are constantly exposed to both harmful and benign factors of their environments. Mucosal DC recognize and respond to pathogens through engagement of pattern recognition receptors, and activated DC migrate to draining lymph nodes to induce adaptive immune responses. The specialized function of DC aids in the induction of immunity and pathogen control at the mucosa. Such specialization includes the potent antiviral interferon response of plasma- cytoid DC to viral nucleic acids, the ability of mucosal DC to capture organisms in the gut lumen, the capacity of DC to cross-present antigen from other infected cells, and the ability of mucosal DC to initiate lgA class switching in B cells. DC plasticity is also critical in the immune response to mucosal pathogens, as DC can respond to the microen- vironment and sense pathogen-induced stress in neighboring epithelial cells. Finally, DC interact with each other through crosstalk to promote antigen presentation and T-cell immunity. Together, these processes condition mucosal DC for the induction of a tailored immune response to pathogens.

Human IgG Fc promotes expression, secretion and immunogenicity of enterovirus 71 VP1 protein

Enterovirus （EV71） can cause severe neurological diseases, but the underlying pathogenesis remains unclear. The capsid protein, viral protein 1 （VP1）, plays a critical role in the pathogenicity of EVT1. High level expression and secretion ofVP 1 protein are necessary for structure, function and immunogenicity in its natural conformation. In our previous studies, 5 codon-optimized VP 1 DNA vaccines, including wt-VP 1, tPA-VP 1, VP l-d, VP 1-hFc and VP 1 - mFc, were constructed and analyzed. They expressed VP1 protein, but the levels of secretion and immunogenicity of these VP1 constructs were significantly different （P〈0.05）. In this study, we further investigated the protein lev- els of these constructs and determined that all of these constructs expressed VP1 protein. The secretion level was increased by including a tPA leader sequence, which was further increased by fusing human IgG Fc （hFc） to VP1. VP 1-hFc demonstrated the most potent immunogenicity in mice. Furthermore, hFc domain could be used to purify VPI-hFc protein for additional studies.

Roles and relevance of mast cells in infection and vaccination

In addition to their well-established role in allergy mast cells have been described as contributing to functional regulation of both innate and adaptive immune responses in host defense. Mast cells are of hematopoietic origin but typically complete their differentiation in tissues where they express immune regulatory functions by releasing diverse mediators and cytokines. Mast cells are abundant at mucosal tissues which are portals of entry for common infectious agents in addition to allergens. Here, we review the current understanding of the participation of mast cells in defense against infection. We also discuss possibilities of exploiting mast cell activation to provide adequate adjuvant activity that is needed in high-quality vaccination against infectious diseases.

Immunogenicity of Lyophilized MVA Vaccine for HIV-1 in Mice Model

Highly attenuated modified vaccinia Ankara（MVA） is sensitive to repeat freeze-thaw cycle and easy to lose activity. In order to make the activity of MVA vaccine remain stable during its manufacturing, storage, and administration, the lyophilization as a good option could be resorted to; through screening, the right stabilizer composition and its production procedure were obtained. The final moisture content of freezing-dried recombinant MVA-HIV vaccine was lower than 3%. It can be reconstituted quickly and shows regular physical appearance and stable potency. In vivo functional experiment, mice were divided randomly into the liquid vaccination group, the lyophilized vaccination group, and the control group. Having been DNA vaccine priming, the mice were boosted with a dose of 10^7 pfu MVA- HIV vaccine, which produced indistinguishable antibody titer and cytotoxic T-lymphocyte（CTL） level compared with those of liquid vaccination group （ P 〉 0.05 ）. These results demonstrate that lyophilized MVA vaccine can induce high immunogenicity in mice.