Immunogenicity of a five-microgram dose of hepatitis B vaccine

The immunogenicity of a 5-μg dose of vaccine (H-B-Vax, MSD) was evaluated in 50 young adults (17–19 years). Results were compared to our previous studies using similarly prepared vaccines using 20 μg and 10 μg per dose with the same trial protocol in a comparable population. Seroconversion rates for the 5-μg doses of vaccine were 80% after the first dose and 98% after the second dose. The remaining participants did not develop anti-HBs in the course of the trial. These results are not significantly different from those observed in the 10-μg and 20-μg studies. The increase of anti-HBs titers was slower for the 5-μg group. High geometric mean titers were observed after booster vaccination, but lower for the 5μg (3,591 mIU/ml) than for 10 μg (9,277 mIU/ml) and 20 μg (12,975mIU/ml) doses. It is concluded that 5-μg dose of the vaccine is effectively immunogenic for young adults.     

国产乙型肝炎疫苗不同剂量免疫效果的研究

本文报道应用上海生物制品研究所生产的乙型肝炎(血源)疫苗对上海、山东8～11岁的血清乙肝标志均阴性的学龄儿童,随机分至5μg、10μg和 20μg三组,按0、1、6月免疫程序接种,全程后 3月(即首针后 9月)三组的 Anti-HBs阳转率分别为 94.4％、99.1％和 90.4％。GMT(几何均数滴度)RIA S/N 在107.1～140.6之间;24月时阳转率仍在90.9～96.5％之间,S/N 在89.1～118.8之间。S/N≥10 者5μg、10μg和 20μg各为 90.0％、94.0％和 86.4％,无显著性差异。     

Subcutaneous administration of inactivated hepatitis B vaccine by automatic jet injection

To assess the feasibility of jet injection for mass immunization against hepatitis B virus, inactivated, alum-adsorbed hepatitis B vaccine (Merck, Sharp, and Dohme Research Laboratories, West Point, PA) was administered subcutaneously by automatic jet injection to 19 volunteers lacking antibody to hepatitis B surface antigen (anti-HBs). Three 20-μg doses were given at 0, 1, and 6 months. Of 19 volunteers, 5 (26%) developed anti-HBs by 1 month after the first injection, and 15 of 19 (79%) were anti-HBs-positive 6 to 8 weeks after the first booster administration. Following the second booster, 16 of 19 (84%) recipients had detectable anti-HBs. Possible systemic reactions were limited to low-grade fever (37.8°C) in one volunteer following one injection, and mild lethargy in a second recipient. Local reactions to jet injection of vaccine occurred more frequently, with indurated, nodular lesions 3–10 mm in diameter developing at the site of 19 of 57 (33%) vaccine injections, compared with 2 of 57 (3%) saline placebo injections. Such nodules were generally painless. Sore arms were noted in 11 of 57 (19%) vaccine injections. With the exception of frequent but minor local reactions, subcutaneous administration of inactivated hepatitis B vaccine by automatic jet injection is safe, and results in vaccine immunogenicity approximating that associated with intramuscular needle injection.     

Characterization and long-term persistence of immune response following two doses of an AS03A-adjuvanted H1N1 influenza vaccine in healthy Japanese adults

Background Long-term persistence of immune response and safety of two doses of an A/California/07/2009 H1N1 pandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based Adjuvant System) administered 21 d apart was evaluated in Japanese adults [NCT00989612]. Methods One-hundred healthy subjects aged 20-64 y (stratified [1:1] into two age strata 20-40 y and 41-64 y) received 21 d apart, two doses of AS03-adjuvanted 3.75μg haemagglutinin (HA) H1N1 2009 vaccine. Immunogenicity data by haemagglutination inhibition (HI) assay six months after the first vaccine dose (Day 182) and microneutralization assay following each of the two vaccine doses (Days 21 and 42) and at Day 182 are reported here. Results Persistence of strong HI immune response was observed at Day 182 that met the US and European regulatory thresholds for pandemic influenza vaccines (seroprotection rate: 95%; seroconversion rate: 93%; geometric mean fold-rise: 20). The neutralizing antibody response against the A/Netherlands/602/2009 strain (antigenically similar to vaccine-strain) persisted for at least up to Day 182 (vaccine response rate: 76%; geometric mean titer: 114.4) and paralleled the HI immune response at all time points. No marked difference was observed in HI antibody persistence and neutralising antibody response between the two age strata. The vaccine had a clinically-acceptable safety profile. Conclusion Two priming doses of H1N1 2009 pandemic influenza vaccine induced an immune response persisting for at least six months after the first vaccine dose. This could be beneficial in evaluating the importance and effect of vaccination with this AS03-adjuvanted pandemic influenza vaccine.     

Safety and immunogenicity of an alum-adjuvanted whole-virion H7N9 influenza vaccine: a randomized,blinded, clinical trial

ObjectivesA case of H7N9 influenza virus infection was first identified in China in 2013. This virus is considered to have high pandemic potential. Here we developed an H7N9 influenza vaccine containing an aluminium adjuvant and evaluated the safety and immunogenicity of the vaccine.MethodsFrom October 2017 through August 2018 we conducted a randomized, double-blinded, single-centre phase I clinical trial in China among 360 participants aged ≥12 years. All participants received two doses of the vaccine (7.5, 15 or 30 μg haemagglutinin antigen) or placebo at an interval of 21 days. Adverse event data were collected for 30 days after vaccination. Serum samples were collected on days 0, 21 and 42 for the haemagglutinin inhibition (HI) antibody assay.ResultsA total of 347 participants (347/360, 96.4%) completed the study. The proportions of vaccine-related adverse events after one injection were 56.7% (34/60) in the 7.5-μg group, 86.7% (52/60) in the 15-μg group and 86.7% (52/60) in the 30-μg group. The proportions of adverse events after two injections were less than those reported after the first dose. None of the serious adverse events were related to the vaccine. After receiving two doses of the 7.5-μg vaccine, the proportion of participants achieving an HI titre of ≥40 was 98.2% (55/56, 95%CI 72.3~100.0%), with a geometric mean titre (GMT) of 192.6 (95%CI 162.9~227.8).ConclusionsThe alum-adjuvanted H7N9 whole-virion inactivated vaccine was safe and strongly immunogenic in a population aged ≥12 years.     

Characterization of candidate adenovirus 37 by SDS-polyacrylamide gel electrophoresis of virion pplypeptides and DNA restriction site mapping

The immunogenic effect of inactivated hepatitis B vaccine (Merck Heptavax B) was evaluated in 202 seronegative healthy medical personnel. Three inoculations of vaccine were given at 1-month intervals. Of 116 vaccinees who received a 40-μg dose, 39% had an anti-HBs response 1 month after the first dose, 88% 1 month after the second dose, and 99% 1 month after the third dose. Of 86 vaccinees who received a 20-μg dose, 40% had an anti-HBs response 1 month after the first dose, 79% after the second dose, and 95% after the third dose. These results confirm the high immunogenic effect of a 20-μg dose of vaccine.     

Pre-S_2抗原在乙肝疫苗中的免疫作用的探讨

比较三种乙型肝炎血源疫苗和一种重组DNA(r-DNA)疫苗诱导Pre-S_2抗体阳性率与阻断乙型肝炎病毒母婴传播的有效率,其中rDNA疫苗不含有Pre-S_2蛋白,免疫后不产生Pre-S_2抗体,加热灭活疫苗按3μg与6μg两种剂量免疫后,半数以上对象均可产生Pre-S_2抗体,甲醛一步法灭活疫苗免疫后有30％婴儿产生Pre-S_2抗体。阻断母婴传播的有效率分别为:rDNA疫苗72.2％,甲醛一步法灭活疫苗70.1％,加热灭活疫苗3μg组35.6％,6μg组71.9％。疫苗免疫效果同HBsAg含量有关,似同Pre-S_2蛋白关系不明显。免疫后抗HBs阳性率与反映抗HBs含量的S/N值均同Pre-S_2抗体阳性率没有明显联系。Pre-S_2蛋白似非决定乙肝疫苗有效率的主要成分,而疫苗中的S蛋白含量对疫苗的免疫效果起十分重要作用。     

Myelin basic protein stimulates insulin and glucagon secretion from rat pancreatic islets in vitro and in vivo

The effect of myelin basic protein on insulin and glucagon secretion from rat pancreatic islets was studied in vivo and in vitro. The myelin basic proteins isolated from bovine, human and rat brains all stimulated insulin secretion in a similar fashion. In a static incubation of isolated pancreatic islets, myelin basic protein at doses of 15.6–250 μg in a 0.5-ml reaction volume (1.7 times 10^-8 to 2.7 times 10^-5 M) significantly stimulated hormone release. Maximal stimulation, obtained at the 250-μg dose, was 6.5-fold greater than control for insulin secretion and 6.7-fold greater than control for glucagon secretion. In the case of glucagon no saturation was observed, but saturation was obvious for insulin release at doses of myelin basic protein of 62.5–250μg, larger doses causing permeabilization of the islet membranes as indicated by leakage of acid phosphatase. At a 100-μg dose the time course of insulin secretion induced by myelin basic protein indicated a fast initial release, and after the first 2 h only a little more insulin was released. At the lower doses of myelin basic protein (11 and 33μg) the secretion rate was nearly constant after the first hour. Significant stimulation of glucagon release by myelin basic protein was seen after 60 min, the rate of release being roughly constant at 33-and 100-μg doses thereafter. At the 11-μg dose significant stimulation of hormone release was observed only after a 4-h incubation. Lowering the temperature from 37 to 27 and 20°C reduced both basal and stimulated hormone secretion, the extent of stimulation over the basal level remaining the same at all temperatures only for insulin secretion at a dose of myelin basic protein of 100 μg. A dose of 10 mg myelin basic protein injected intravenously into anaesthetized rats resulted 15 min after injection in a circulating concentration of myelin basic protein of 34.7 μg ml^-1 (1.7 times 10^-6 M) as measured by our radioimmunoassay. It stimulated insulin secretion (P < 0.01), having no significant effect on plasma glucagon levels. Since myelin basic proteins have been shown to display fusogenic properties in cell-free membrane systems, we propose that myelin basic protein exerts its hormone-releasing effect by aggregating and fusing the hormone-containing vesicles to the cell plasma membranes.     

Immunogenicity and safety of the influenza A/H1N1 2009 inactivated split-virus vaccine in young and older adults: MF59-adjuvanted vaccine versus nonadjuvanted vaccine

Since initial reports in April 2009, the pandemic influenza A (H1N1) virus has spread globally. Influenza vaccines are the primary method for the control of influenza and its complications. We conducted a multicenter clinical trial to evaluate the immunogenicity and safety of H1N1 vaccine (Green Cross Co.) in young adults (18 to 64 years) and the elderly (≥ 65 years) using a two-dose regimen, with the doses administered 21 days apart. Three different regimens of hemagglutinin antigen were comparatively analyzed: 3.75 μg (MF59 adjuvanted) versus 7.5 μg (MF59 adjuvanted) versus 15 μg (nonadjuvanted) in young adults and 3.75 μg (MF59 adjuvanted) versus 7.5 μg (MF59 adjuvanted) in the elderly. In young adults, all three vaccine regimens met the European Agency for the Evaluation of Medicinal Products (EMA) criteria after the first dose. In the elderly, on day 21 after the first dose, the rates of seroprotection and seroconversion were significantly higher for the 7.5-μg dose of MF59 adjuvanted vaccine than for the 3.75-μg dose (58.0% versus 44.3% [P = 0.03] and 53.7% versus 37.2% [P < 0.01], respectively). After the second dose, the geometric mean titer (GMT) increment was blunted with a 15-μg dose of nonadjuvanted vaccine, whereas the GMT increased about 2-fold with MF59 adjuvanted vaccines. In conclusion, a single 7.5-μg dose of MF59 adjuvanted vaccine would have a practical advantage over a two-dose, 3.75-μg, MF59 adjuvanted vaccine priming schedule. Following a two-dose priming schedule, the increase in hemagglutinin inhibition titers was higher with MF59 adjuvanted vaccine than with nonadjuvanted vaccine.     

乙肝疫苗无（低）应答加大剂量再免疫效果分析

目的探讨乙肝疫苗接种后无（低）应答者加大剂量再免疫的效果,以提高乙肝疫苗预防接种的保护率。方法对近3年已完成标准乙肝疫苗免疫接种程序至少一年、复查乙肝病毒标志物均为阴性的健康人群,随机地接受3种再免疫方案,按常规程序（0、1、6个月）予肌肉注射。A组40例：进口重组乙肝疫苗（安在时）,每次剂量40μg;B组40例：安在时,每次剂量20μg;C组40例：国产重组乙肝疫苗,每次剂量20μg。在首针乙肝疫苗接种前及接种后第1、2、7个月（T1、T2、T7）采血检测抗-HBs。结果T1时,进口40μg组、进口20μg组和国产20μg组复种后应答率分别为45．0％（18／40）、37．5％（15／40）和30．0％（12／40）,3组应答率差异无统计学意义（χ^2=1．920,P=0．383）;T2和T7时,3组复种后应答率分别为67．5％（27／40）、47．5％（19／40）、40．0％（16／40）和77．5％（31／40）、55．0％（22／40）、50．0％（20／40）,进口40μg组应答率高于其余两组（χ^2为4．014～6．545之间,P均〈0．05）。T2和T7时,进口40μg组应答率差异无统计学意义（χ^2=1．003,P=0.317）。各组患者复种后均未出现严重副反应。结论对乙肝疫苗无（低）应答者增加疫苗剂量加强免疫是有效的措施,抗-HBs应答率随疫苗剂量增加而提高。进口40μg组加强2针即可,加强3针未能较加强2针明显提高抗-HBs应答率。     

Strategies for improving the efficacy of a H6 subtype avian influenza DNA vaccine in chickens

A low-pathogenicity avian influenza H6N2 virus was used to investigate approaches to improve DNA vaccine efficacy. The viral hemagglutinin (HA) gene or its chicken biased HA gene, incorporating a Kozak sequence, was cloned into a pCAGGS vector to produce the pCAG-HAk and pCAG-optiHAk constructs. Following two intramuscular injections, the seroconversion rate in vaccinated chickens with 10, 100 or 300 μg pCAG-HAk were 87.5%, 75% and 75%, respectively. The profile of H6 hemagglutination inhibition (HI) antibodies induced by different doses of pCAG-HAk during the 8-week study period was similar. The HI titer rose significantly in the three different dose groups following the booster and reached a plateau 2-3 weeks post-booster. In a single dose vaccination group with 100 μg pCAG-HAk, a maximum seroconversion rate reached 53.3% at 5 weeks post-vaccination. The earliest time of seroconversion appeared two weeks after DNA immunization. Following two electroporation (EP) vaccinations with 100 μg pCAG-HAk, all birds seroconverted and the HI antibody titers were significantly higher than those using intramuscular immunization, suggesting that EP was more efficient than intramuscular delivery of the DNA vaccines. In comparison, chickens immunized with 10 or 100 μg pCAG-optiHAk showed 37.5% and 87.5% seroconversion rates, respectively, at 3 weeks following the booster. The pCAG-HAk was not significantly different from the pCAG-optiHAk in either the seroconversion rate or H6 HI titer, suggesting that the codon-optimized HA DNA vaccine did not achieve significantly better immunogenicity than the pCAG-HAk vaccine.     

Safety and persistence of immunological response 6 months after intramuscular vaccination with an AS03-adjuvanted H1N1 2009 influenza vaccine: an open-label, randomized trial in Japanese children aged 6 months to 17 years

This study evaluated the long-term persistence of immune response and safety of two doses of an A/California/7/2009 H1N1 pandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based Adjuvant System) in Japanese children (NCT01001169). Sixty healthy subjects aged 6 mo-17 y were enrolled (1:1) into two study groups to receive 21 d apart, two doses of 1.9 μg haemagglutinin [HA]+AS03B (5.93 mg α-tocopherol) vaccine (6 mo-9 y) and 3.75 μg HA+AS03A (11.86 mg α-tocopherol) vaccine (10-17 y), respectively. Immunogenicity data (by haemagglutination inhibition [HI] and microneutralisation assays) to six months after the first vaccine dose are reported here. It was observed that following Dose 2, the HI immune response against the vaccine homologous strain induced by the two different dosages of the AS03-adjuvanted vaccine met and exceeded the US and European regulatory guidance criteria for pandemic influenza vaccines (seroprotection rate[SPR]/seroconversion rate[SCR]: 100%/100%; geometric mean fold rise GMFR: 146.8/57.1). Further, the immune response persisted for at least six months after the first vaccine dose wherein these regulatory criteria were still met (SPR: 100%/100%; SCR: 96.4%/89.7%; GMFR: 25.3/23.5). The neutralising antibody response was comparable to the HI immune response at Day 42 (vaccine response rate [VRR]: 100%/100%) and at Day 182 (VRR: 96.4%/82.8%). Overall, both vaccine dosages had a clinically acceptable safety profile. Thus, two doses of a 1.9 μg or 3.75 μg HA AS03-adjuvanted H1N1 2009 pandemic influenza vaccine in children aged 6 mo-17 y induced strong immune responses against the vaccine homologous strain that persisted for at least six months after the first vaccine dose.     

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.     

Measurement of myometrial blood flow in rabbits by washout of Xenon-133 after atraumatic local labelling

In vivo experiments were performed on the uterine tissue of non-pregnant estradiol treated rabbit anesthetized with sodium pentobarbitone. The average blood flow calculated from the washout of Xenon-133 after atraumatic labelling from the uterine surface was 25.4 ml-min^-1-(100 g)^-1 (range 7.4–66.6), and after local injection of the tracer in isotonic saline directly into the myometrium 24.4 ml-min^-1-(100 g)^-1(range 8.7–45.3). During the experiments a monoexponential washout curve was found for the whole washout process both after atraumatic labelling and when the injected volume was 5μl. No trauma of injection was observed using this injection volume. The results support the applicability of a monocompartmental model for the washout of inert gas from the myometrium. Thus myometrial blood flow can be calculated from the Xenon-133 washout rate at any time interval during the washout process.     

Single dose inactivated hepatitis A vaccine: Rationale and clinical assessment of the safety and immunogenicity

In comparison with the classical immunisation schedules (0-1-6 or 0-1-12 months) for hepatitis A, a 0- and 12- or a 0- and 6-month schedule would have important advantages by reducing the number of injections and discomfort and increasing scheduling convenience and patient compliance. It would be convenient if a single dose with enough antigen could protect both rapidly and for at least 12 months, when the booster dose would be given. Several clinical trials have been carried out with an inactivated hepatitis A vaccine containing 1,440 ELU. (1 ml), according to a 0–12 and a 0–6 vaccination schedule. This hepatitis A vaccine is safe and well tolerated. It offers a rapid seroresponse: 14 days after a single dose the seroconversion is 88% (95% C.I.: 84.6–90.9). The 0–12 schedule study showed good persistence of hepatitis A virus (HAV) antibodies with a seroconversion rate of almost 95% at month 12. Booster doses given at 6 or 12 months result in a substantial rise in antibody levels; according to these antibody litres, the 1,440 EL. U. vaccine can be expected to confer comparable duration of protection as the 720 EL. U. vaccine, i.e., 10–20 years. Preliminary data show that tinning of the booster may not be critical for the antibody response. In conclusion, the 1,440 EL. U. hepatitis A vaccine is safe, offers rapid seroconversion, and is highly immunogenic. The persistence of HAV antibodies until month 12 allows a certain flexibility in the administration of the booster: month 6 or 12, and a 0–12 or 0–6 schedule can increase the vaccination compliance. copy; 1994 Wiiey-Liss, inc.     

鱼藤酮损伤大鼠黑质至行为学及黑质多巴胺能神经元损伤

目的 探讨不同剂量鱼藤酮损伤大鼠黑质后行为学和酪氨酸羟化酶免疫活性细胞的变化.方法 采用大鼠黑质立体定位注射不同剂量鱼藤酮的方法,观察大鼠行为学变化,应用免疫组化染色检测黑质酪氨酸羟化酶(TH)免疫活性细胞的变化.结果 给鱼藤酮21d后,2.5μg/μl组大鼠行为测试记分2-4分为主,占91.3%,TH免疫活性细胞百分...     

Safety and efficacy of Salmonella gallinarum 9R vaccine in young laying chickens.

Salmonella enterica subsp. enterica serovar Gallinarum (S. gallinarum) is the agent of fowl typhoid, and the 9R vaccine is a commercially available, live vaccine for the prevention of fowl typhoid. The aim of this study was to assess the safety and efficacy of the 9R vaccine in young chickens. The mean weights of 5-week-old chickens vaccinated with one and 10 doses at 2 weeks old were 450.3+/-33.83 g and 446.8+/-35.68 g, respectively, which were statistically lower (P<0.05) than the mean weight (475.5+/-44.17 g) of the control group. Using the same procedure, the mean weights of chickens vaccinated with one and 10 doses at the age of 4 and 6 weeks were 721.3+/-64.03 g and 723.7+/-63.92 g, and 1114.2+/-92.21 g and 1078.27+/-68.93 g, respectively. Compared with the mean weights (725.7+/-49.50 g and 1104.3+/-92.34 g, respectively) of the control groups, there was no difference in terms of statistical significance (P < 0.05). In addition, all vaccinated birds showed no clinical signs and survived the time course of the experiment. When all chickens were challenged with the wild-type S. gallinarum 21 days after one-dose vaccination, the mortalities between the vaccinated group and the control group were 0% to 5% and 95% to 100%, respectively. In addition, the control group demonstrated a 95% to 100% re-isolation rate of the challenge strain in internal organs and the caecum, while in the vaccinated group only a 1% to 60% re-isolation rate was observed. In this study, we showed that adjusting the minimum vaccination age of the 9R vaccine to 4 weeks is acceptable considering the safety and efficacy of the vaccine.     

Safety and immunogenicity of a novel Staphylococcus aureus vaccine: results from the first study of the vaccine dose range in humans

Merck V710 is a novel vaccine containing the conserved Staphylococcus aureus iron surface determinant B shown to be protective in animal models. A phase I, multicenter, double-blind study of the dose range was conducted to assess the immunogenicity and safety of an adjuvanted liquid formulation of V710. A total of 124 adults (18 to 55 years of age) were randomized 1:1:1:1 to receive one 0.5-ml intramuscular injection of V710 (5 μg, 30 μg, or 90 μg) or saline placebo. A positive immune response was defined as at least a 2-fold increase in IsdB-specific IgG levels from baseline levels. Local and systemic adverse events were assessed for 5 and 14 days, respectively, following vaccination. Positive immune responses were detected in 12 (67%) of the 18 subjects in the groups receiving 30 and 90 μg V710 tested at day 10. At day 14, a significantly greater proportion of subjects manifested a positive immune response with higher geometric mean concentrations in the V710 30-μg (86%; geometric mean concentration of 116 μg/ml) and 90-μg (87%; geometric mean concentration of 131 μg/ml) dose groups than in the V710 5-μg (29%; geometric mean concentration of 51 μg/ml) or placebo (4%; geometric mean concentration of 23 μg/ml) groups. Immune responses were durable through day 84. Subjects <40 and ≥40 years of age had comparable immune responses. The most common adverse events were injection-site pain, nausea, fatigue, and headache, usually of mild intensity. No immediate reactions or serious adverse events were reported. In this first study of V710 in humans, a single 30-μg or 90-μg dose was more immunogenic than the 5-μg dose or placebo. Immune responses were evident by 10 to 14 days after vaccination in most responders.     

The safety and immunogenicity of a cell-derived adjuvanted H5N1 vaccine – A phase I randomized clinical trial

BackgroundDevelopment of an efficacious egg-free mock-up H5N1 vaccine is key to our preparedness against pandemic avian flu.MethodsThis is a single-center, randomized, observer-blinded phase I clinical trial evaluating the safety and immunogenicity of an alum-adjuvanted Madin–Darby canine kidney (MDCK)-derived inactivated whole-virion H5N1 influenza vaccine in healthy adults. Hemagglutination inhibition (HAI) and neutralizing antibody titers were measured using horse and turkey red blood cells (RBCs).ResultsThirty-six adult subjects were randomized to receive two doses of 0.5 mL of the MDCK-derived H5N1 alum-adjuvanted vaccine containing 7.5, 15, or 30 μg of hemagglutinin (HA) 21 days apart. The candidate vaccine was well tolerated and safe across the three dosing groups. The most frequent adverse event was injection site pain (46.5%). Both HAI and neutralizing antibody titers increased after each vaccination in all three dosing groups. The best HAI responses, namely a seroconversion rate of 91.7% and a geometric mean ratio of 9.51 were achieved with the HA dose of 30 μg assayed using horse RBCs at day 42. HAI titers against H5N1 avian influenza virus was significantly higher when measured using horse RBCs compared with turkey RBCs.ConclusionsThis Phase I trial showed the MDCK-derived H5N1 candidate vaccine is safe and immunogenic. The source of RBCs has a significant impact on the measurement of HAI titers (ClinicalTrials.gov number: NCT01675284.).     

Immunogenicity of influenza A/USSR (H1N1) subunit vaccine in unprimed young adults

Purified subunit vaccines (HANAflu) containing 20 /xg of hemagglutinin of influenza A/USSR/90/77 (H1N1) alone or with 1–5% whole virus were compared to commercially available vaccines for reactogenicity and immunogenicity in unprimed young adults. Reactions to all vaccines were minimal. Sera from volunteers who received two intramuscular doses of vaccine or placebo were tested by hemagglutination-inhibition and neutralization tests. HANAflu with 1 m?g (5%) whole virus added was not different in immunogenicity from commercial vaccine. Both commercial vaccine and HANAflu with 1 m?g whole virus added gave higher seroconversion rates and more neutralization titers ≥ 4 log₂ than HANAflu alone and HANAflu + 0.2 m?g (1%) whole virus. Thus, the HANAflu subunit vaccine alone was less immunogenic than commercial vaccine in unprimed persons. However, addition of 1 m?g (5%) whole virus, but not 0.2 m?g (1%), eliminated this difference. There may be a role for addition of small amounts of whole virus to subunit influenza vaccines to overcome lower immunogenicity in unprimed populations.