Modeling maternal fetal RSV F vaccine induced antibody transfer in guinea pigs

BackgroundProtection of newborns and young infants against RSV disease via maternal immunization mediated by transplacental transfer of antibodies is under evaluation in third-trimester pregnant women with the RSV recombinant F nanoparticle vaccine (RSV F vaccine). Since the hemichorial placental architecture in guinea pigs and humans is similar, the guinea pig model was employed to assess RSV F vaccine immunogenicity in pregnant sows and to compare RSV-specific maternal antibody levels in their pups.MethodsThirty (30) presumptive pregnant guinea pigs were immunized on gestational day 25 and 46 with placebo (PBS), 30 μg RSV F, or 30 μg RSV F + 400 μg aluminum phosphate. Sera at delivery/birth (sows/pups) and 15 and 30 days post-partum (pups) were analyzed for the presence of anti-F IgG, palivizumab-competitive antibody (PCA) and RSV/A microneutralization (MN).ResultsThe rates of pregnancy and stillbirth were similar between controls and vaccinees. The vaccine induced high levels of anti-F IgG, PCA and MN in sows, with the highest levels observed in adjuvanted vaccinees. Placental transfer to pups was proportional to the maternal antibody levels, with concentration effects observed for all immune measures.ConclusionsThe RSV F vaccine was safe and immunogenic in pregnant guinea pigs and supported robust transplacental antibody transfer to their pups. Relative concentration of antibodies in the pups was observed even in the presence of high levels of maternal antibody. Guinea pigs may be an important safety and immunogenicity model for preclinical assessment of candidate vaccines for maternal immunization.     

Comparative immunogenicity of hepatitis B vaccine with different dosages and schedules in healthy young adults in China

ObjectivesTo compare immunogenicity of hepatitis B vaccine between the standard 3-dose (20 μg) and 2-dose with higher-dosage (60 μg) regimens in healthy young adults and evaluate the safety profile.MethodsA randomized, parallel-group clinical trial was conducted among healthy young adults aged 18−25 years. Subjects were randomly assigned to three groups. One group was administered hepatitis B vaccine with the standard regimen of 0−1−6 month (20 μg) and other groups were immunized with regimens of 0−1 or 0−2 month (60 μg) respectively. Serum samples were collected at 1 month after a series vaccination and 12 months after the first-dose inoculation for anti-HBs antibody measurement with a Chemiluminescent Microparticle ImmunoAssay (CMIA).ResultsThe seroprotection rates in 20 μg (0−1−6 month), 60 μg (0−1 month) and 60 μg (0−2 month) groups were 100, 93.64 and 99.19% at month 7/2/3, and 100, 96.04 and 95.90% at month 12, respectively. There were no significant differences among three vaccine groups (p > 0.05). The geometric mean concentration (GMC) of anti-HBs was significantly higher in 20 μg (0−1−6 month) group than that in 60 μg (0−1 month) group at month 7/2 (1847.99 vs. 839.27 mIU/ml, p = 0.004), but was similar to that in 60 μg (0−2 month) group at month 7/3 (1847.99 vs. 1244.80 mIU/ml, p = 0.138). At month 12, the GMC in 20 μg (0−1−6 month) group was significantly higher than those of other groups (1456.63 vs. 256.30, 235.15 mIU/ml, respectively, p < 0.001). The total incidence of injection-site or systemic adverse reactions was <3%.ConclusionsA 2-dose with higher-dosage hepatitis B vaccine regimens are comparable to the standard 3-dose regimen in terms of immunogenicity except a relatively rapid decline in GMC levels which are associated with the longevity of protection. All formulations of hepatitis B vaccine were well tolerated.Clinicaltrials.gov identifierNCT02203357.     

Immunogenicity and safety of a tetravalent E. coli O-antigen bioconjugate vaccine in animal models

BackgroundExtra-intestinal pathogenic Escherichia coli (ExPEC) are major human pathogens; however, no protective vaccine is currently available. We assessed in animal models the immunogenicity and safety of a 4-valent E. coli conjugate vaccine (ExPEC-4V, serotypes O1, O2, O6 and O25 conjugated to Exotoxin A from Pseudomonas aeruginosa (EPA)) produced using a novel in vivo bioconjugation method.MethodsThree doses of ExPEC-4V (with or without aluminum hydroxide) were administered to rabbits (2 μg or 20 μg per O-antigen, subcutaneously), mice (0.2 μg or 2 μg per O-antigen, subcutaneously) and rats (0.4 μg or 4 μg per O-antigen, intramuscularly). Antibody persistence and boostability were evaluated in rats using O6-EPA monovalent conjugate (0.4 μg O-antigen/dose, intramuscularly). Toxicity was assessed in rats (16 μg total polysaccharide, intramuscularly). Serum IgG and IgM antibodies were measured by ELISA.ResultsRobust antigen-specific IgG responses were observed in all animal models, with increased responses in rabbits when administered with adjuvant. O antigen-specific antibody responses persisted up to 168 days post-priming. Booster immunization induced a rapid recall response. Toxicity of ExPEC-4V when administered to rats was considered to be at the no observed adverse effect level.ConclusionsExPEC-4V conjugate vaccine showed good immunogenicity and tolerability in animal models supporting progression to clinical evaluation.     

Expression of enhancing-activity-free neutralizing antibody against dengue type 1 virus in plasmid-inoculated mice

BackgroundMost candidate dengue vaccines currently under development induce neutralizing antibodies, which are considered important for immunoprotection. However, the concomitant induction of infection-enhancing antibodies is an unavoidable concern. In contrast, a neutralizing antibody developed for passive immunotherapy has been engineered to eliminate its enhancing activity. Therefore, a strategy for the long-term expression of enhancing-activity-free neutralizing antibodies may resolve this concern.MethodsA mouse monoclonal antibody, 7F4, of the IgG3 subclass and with no detectable enhancing activity, was selected as the model neutralizing antibody to evaluate the potential of this strategy. Equal amounts of commercial vector (pFUSE)-based plasmids containing 7F4 heavy (H)- or light (L)-chain variable region genes were mixed and used for the cotransfection of 293T cells and co-delivery into ICR and BALB/c mice. The recombinant plasmids were designed to express IgG2b or IgG3 subclass antibodies (p7F4G2b or p7F4G3, respectively).Results293T cells transfected with 2 μg of p7F4G2b or p7F4G3 produced approximately 15,000 or 800 ng/ml IgG in the culture fluids, respectively. The dose is expressed as the total amount of H- and L-chain plasmids. Neutralizing antibody was detected dose-dependently in ICR mice inoculated with 50–200 μg of p7F4G2b. A 1:2 dilution of sera from ICR and BALB/c mice inoculated with 100 μg of p7F4G3 showed average plaque reduction levels of >70% on day 3 and >90% on days 5–9. BALB/c mice maintained detectable neutralizing antibody for at least 3 months. The neutralizing antibody expressed by p7F4G3 in mice showed no enhancing activity.DiscussionAlthough the expression of neutralizing antibodies from immunoglobulin genes is a type of passive immunization, its durability can be utilized as a dengue vaccine strategy. This “proof-of-concept” study using a mouse model demonstrates that the enhancing-activity-free characteristic of this strategy augurs well for dengue vaccine development, although further improvement is required.     

The doses of 10 μg should replace the doses of 5 μg in newborn hepatitis B vaccination in China: A cost-effectiveness analysis

ObjectiveTo identify whether Chinese current series of three 5 μg doses for newborn hepatitis B vaccination should be replaced by the series of three 10 μg doses.MethodsA cost-effectiveness analysis was conducted from the societal perspective based on the constructed decision tree-Markov model. Model parameters were estimated from published literatures, government documents and our surveys. The expected cost and effectiveness were compared between the 3-dose 5 μg series (the 5 μg strategy) and the 3-dose 10 μg series (the 10 μg strategy), and the incremental cost-effectiveness ratio (ICER, additional cost per quality-adjusted life-years gained) was calculated. Threshold values of the efficacy difference of the two series for the ICER = 0, 1 and 3 times per capita gross domestic product were analyzed under different scenarios to understand whether the 10 μg strategy should replace the 5 μg strategy according to the recommendation of World Health Organization.ResultsThe 10 μg strategy would be cost-saving compared with the 5 μg strategy under the base-case scenario. Under keeping all the other parameters at the base-case values or further adjusting any one of them to the value most unfavorable to the 10 μg strategy, as long as the efficacy of 3-dose 10 μg series was slightly higher than that of 3-dose 5 μg series, the 10 μg strategy would be cost-effective, highly cost-effective, or even cost-saving. Even under the most pessimistic scenario, i.e. all the other parameters, but the discount rate, at the values most unfavorable to the 10 μg strategy, the 10 μg strategy would be cost-effective if the efficacy difference reached higher than 1.23 percentage point.ConclusionFor newborn hepatitis B vaccination in China, the 10 μg strategy should be cost-effective, even more possibly highly cost-effective or cost-saving compared with the current 5 μg strategy. The doses of 10 μg should be considered to replace the doses of 5 μg in newborn hepatitis B vaccination in China.     

Immunogenicity and safety of an E. coli-produced bivalent human papillomavirus (type 16 and 18) vaccine: A randomized controlled phase 2 clinical trial

BackgroundThis study aimed to investigate the dosage, immunogenicity and safety profile of a novel human papillomavirus (HPV) types 16 and 18 bivalent vaccine produced by E. coli.MethodsThis randomized, double-blinded, controlled phase 2 trial enrolled women aged 18–25 years in China. Totally 1600 eligible participants were randomized to receive 90 μg, 60 μg, or 30 μg of the recombinant HPV 16/18 bivalent vaccine or the control hepatitis B vaccine on a 0, 1 and 6 month schedule. The designated doses are the combined micrograms of HPV16 and 18 VLPs with dose ratio of 2:1. The immunogenicity of the vaccines was assessed by measuring anti-HPV 16 and 18 neutralizing antibodies and total IgG antibodies. Safety of the vaccine was assessed.ResultsAll but one of the seronegative participants who received 3 doses of the HPV vaccines seroconverted at month 7 for anti-HPV 16/18 neutralizing antibodies and IgG antibodies. For HPV 16, the geometric mean titers (GMTs) of the neutralizing antibodies were similar between the 60 μg (GMT = 10,548) and 90 μg (GMT = 12,505) HPV vaccine groups and were significantly higher than those in the 30 μg (GMT = 7596) group. For HPV 18, the GMTs of the neutralizing antibodies were similar among the 3 groups. The HPV vaccine was well tolerated. No vaccine-associated serious adverse events were identified.ConclusionThe prokaryotic-expressed HPV vaccine is safe and immunogenic in women aged 18–25 years. The 60 μg dosage formulation was selected for further investigation for efficacy.Clinical trials registration: NCT01356823.     

Specific memory B cell response and participation of CD4+ central and effector memory T cells in mice immunized with liposome encapsulated recombinant NE protein based Hepatitis E vaccine candidate

BackgroundLiposome encapsulated neutralizing epitope protein of Hepatitis E virus (HEV), rNEp, our Hepatitis E vaccine candidate, was shown to be immunogenic and safe in pregnant and non-pregnant mice and yielded sterilizing immunity in rhesus monkeys.MethodsThe current study in Balb/c mice assessed the levels and persistence of anti-HEV IgG antibodies by ELISA, frequencies of B, memory B, T and memory T cells by flow cytometry and HEV-specific IgG secreting memory B cells by ELISPOT till 420 days post immunization (PI) with 5 μg rNEp encapsulated in liposome based adjuvant (2 doses, 4 weeks apart). Mice immunized with a lower dose (1 μg) were assessed only for anamnestic response post booster dose.ResultsVaccine candidate immunized mice (5 μg dose) elicited strong anti-HEV IgG response that was estimated to persist for lifetime. At day 120 PI, frequency of memory B cells was higher in immunized mice than those receiving adjuvant alone. Anti-HEV IgG titers were lower in mice immunized with 1 μg dose. A booster dose yielded a heightened antibody response in mice with both high (>800 GMT, 5 μg) and low (⩽100 GMT, 1 μg) anti-HEV IgG titers. At day 6th post booster dose, HEV-specific antibody secreting plasma cells (ASCs) were detected in 100% and 50% of mice with high and low anti-HEV IgG titers, respectively, whereas the frequencies of CD4⁺ central and effector memory T cells were high in mice with high anti-HEV IgG titers only.ConclusionsTaken together, the vaccine candidate effectively generates persistent and anamnestic antibody response, elicits participation of CD4⁺ memory T cells and triggers memory B cells to differentiate into ASCs upon boosting. This approach of assessing the immunogenicity of vaccine candidate could be useful to explore the longevity of HEV-specific memory response in future HEV vaccine trials in human.     

A phase 1a,first-in-human,randomized study of a respiratory syncytial virus F protein vaccine with and without a toll-like receptor-4 agonist and stable emulsion adjuvant

BackgroundRespiratory syncytial virus (RSV) causes significant illness in older adults resulting in substantial health and economic impact. A successful vaccine would reduce morbidity in this growing segment of the population.MethodsIn this double-blind phase 1 study, subjects 60 years of age and older were enrolled by cohort and randomized to receive vaccines containing escalating doses (20, 50, or 80 μg) of soluble RSV fusion protein (sF) alone or adjuvanted with 2.5 μg of glucopyranosyl lipid A, a toll-like receptor-4 agonist, in 2% stable emulsion (GLA-SE). Each cohort included 20 vaccine and 4 placebo recipients. Immune responses were evaluated using assays for RSV microneutralizing, anti-F IgG, and palivizumab competitive antibodies and for F-specific interferon (IFN)-γ enzyme-linked immunospot (ELISPOT) responses.ResultsThe inclusion of adjuvant increased local reactogenicity, with the majority of subjects who received sF and adjuvant reporting low-grade injection site pain or tenderness. At all doses, the safety profile was acceptable for further development. Immune responses were antigen dose-dependent, and the inclusion of adjuvant increased both humoral and cellular immune responses, with responses statistically higher than for placebo recipients in all 4 assays. At the highest dosage level with adjuvant, half of the subjects had a ≥3-fold rise from day 0 in RSV neutralizing antibody titers, and all had a ≥3-fold rise in antibody levels by anti-F IgG and palivizumab competitive antibody assays on day 29. For the day 8 IFNγ ELISPOT assay, 74% of subjects in the highest dosing cohort had a ≥3-fold rise from baseline.ConclusionsThe safety and immunogenicity results from this study support inclusion of the GLA-SE adjuvant in this RSV vaccine for older adults and also support assessment of the efficacy of the vaccine in a larger clinical trial. Clinicaltrials.gov NCT02115815.     

A phase 1, placebo-controlled,randomized study of the safety,tolerability, and immunogenicity of a Clostridium difficile vaccine administered with or without aluminum hydroxide in healthy adults

IntroductionClostridium difficile is a significant cause of morbidity and mortality in hospitals, nursing homes, and long-term care facilities. The bacteria can produce 3 toxins, of which the C. difficile toxin A and C. difficile toxin B are the principal virulence factors for C. difficile-associated disease.MethodsA phase 1, first-in-human, placebo-controlled, dose-escalation study was performed to assess the safety and immunogenicity of an investigational vaccine candidate consisting of genetically and chemically detoxified, purified toxins A and B. The toxoids, either alone or in combination with aluminum hydroxide (Al(OH)₃), were administered to healthy adults 50–85 years of age at antigen dose levels of 50, 100, or 200 μg in a 3-dose regimen administered at 0, 1, and 6 months.ResultsOverall, the C. difficile vaccine formulations and doses administered were generally well tolerated. Local reactions and systemic events were predominantly mild to moderate, were more common in the 50–64-year age cohort, and comprised mostly injection site pain, headache, and fatigue.In subjects who received the vaccine formulations, both the toxin A- and toxin B-specific neutralizing antibody geometric mean concentrations increased substantially at 1 month after Dose 2 and after Dose 3 compared to baseline. In the 50–64-year age cohort, geometric mean fold rises (GMFRs) in toxin A-specific neutralizing antibodies from baseline at Month 7 ranged from 59.19 to 149.23 in the vaccine groups compared to 2.47 in the control group. For toxin-B specific neutralizing antibodies, the GMFRs from baseline at Month 7 ranged from 116.67 to 2503.75 in the vaccine groups compared to 2.48 in the control group. In the 65–85-year age cohort, GMFRs in toxin A-specific neutralizing antibodies from baseline at Month 7 ranged from 42.73 to 254.77 in the vaccine groups compared to 2.03 in the control group. For toxin-B specific neutralizing antibodies, the GMFRs from baseline at Month 7 ranged from 136.12 to 4922.80 in the vaccine groups compared to 1.58 in the control group. Potent antitoxin neutralizing responses were still evident in immunized subjects in both age groups at Month 12. Although there was no clear dose-level response pattern, the data suggest that both the antitoxin A- and B-specific neutralizing responses were trending higher in the toxoid-only groups compared to the toxoid + Al(OH)₃ groups. Furthermore, the magnitude of the immune response was similar in the 2 age cohorts.ConclusionThe vaccine formulations studied in this phase 1 study were immunogenic and well tolerated. The results presented support further development of the C. difficile vaccine candidate in a larger population of subjects to determine the optimal dose and immunization schedule.Clinical trial registryNCT01706367.     

Immunogenicity and safety of the new intradermal influenza vaccine in adults and elderly: A randomized phase 1/2 clinical trial

BackgroundRecent clinical evidence indicates that an intradermal (ID) delivery of vaccines confers superior immunogenicity as compared to a standard intramusclular or subcutaneous (SC) delivery.MethodsIn this exploratory study, 600 healthy adults were randomized to 6 study groups with subgroups of young adults (20–64 years old) and older adults (65 years and older). The subjects were either injected by a novel ID injection system with a single dose of 6, 9, or 15 μg HA or two doses (21 days apart) of 15 μg HA per strain or injected by an SC injection method with a single or two doses (21 days apart) of 15 μg HA per strain. Immunogenicity was assessed using hemagglutination inhibition (HAI) titer and microneutralization titer on Days 0, 10, 21, and 42. Solicited and unsolicited adverse events were recorded for 7 and 21 days post-vaccination, respectively.ResultsIn both young adults and older adults groups, the geometric titer (GMT) ratios of HAI in the ID 15 μg HA group were higher than those in the SC 15 μg HA group on both Day 10 and Day 21, while those in the ID 6 and ID 9 μg HA groups were comparable with those in the SC 15 μg HA group. The kinetics of GMTs of HAI suggested that the ID vaccine has the potential to induce the prompt immune response, which is rather hampered in older adults as seen in the SC vaccine groups. The injection-site AEs were generally mild and transient, and did not occur in a dose or dosage-dependent manner.ConclusionsThe results of this study clearly suggest that the immunologic profile of the ID vaccine is better than that of the SC vaccine, while the safety profile of the ID vaccine is similar to that of the SC vaccine. In this exploratory study with almost 100 subjects per each group, single or two-dose administration of the ID vaccine containing 15 μg HA was suggested to be an appropriate regimen in order to prevent influenza and to reduce the associated disease burden.Trial registrationJAPIC Clinical Trials Information (JapicCTI-132096).     

A phase 1, open-label,randomized study to compare the immunogenicity and safety of different administration routes and doses of virosomal influenza vaccine in elderly

BackgroundInfluenza remains a significant problem in elderly despite widespread vaccination coverage. This randomized, phase-I study in elderly compared different strategies of improving vaccine immunogenicity.MethodsA total of 370 healthy participants (⩾65 years) were randomized equally 1:1:1:1:1:1 to six influenza vaccine treatments (approximately 60–63 participants per treatment arm) at day 1 that consisted of three investigational virosomal vaccine formulations at doses of 7.5, 15, and 45 μg HA antigen/strain administered intradermally (ID) by MicronJet600™ microneedle device (NanoPass Technologies) or intramuscularly (IM), and three comparator registered seasonal vaccines; Inflexal V™ (Janssen) and MF59 adjuvanted Fluad™ (Novartis) administered IM and Intanza™ (Sanofi Pasteur) administered ID via Soluvia™ prefilled microinjection system (BD). Serological evaluations were performed at days 22 and 90 and safety followed-up for 6 months.ResultsIntradermal delivery of virosomal vaccine using MicronJet600™ resulted in significantly higher immunogenicity than the equivalent dose of virosomal Inflexal V™ administered intramuscularly across most of the parameters and strains, as well as in some of the readouts and strains as compared with the 45 μg dose of virosomal vaccine formulation. Of 370 participants, 300 (81.1%) reported ⩾1 adverse event (AE); more participants reported solicited local AEs (72.2%) than solicited systemic AEs (12.2%).ConclusionsIntradermal delivery significantly improved influenza vaccine immunogenicity compared with intramuscular delivery. Triple dose (45 μg) virosomal vaccine did not demonstrate any benefit on vaccine’s immunogenicity over 15 μg commercial presentation. All treatments were generally safe and well-tolerated.     

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in healthy adults: A phase I/II,observer-blind,randomized, controlled trial

BackgroundH7 influenza strains have pandemic potential. AS03-adjuvanted H7N1 A/mallard/Netherlands/12/2000 split-virion vaccine formulations were evaluated as model H7-subtype vaccine and tested after H7N9 emerged in China, and caused severe human disease with high mortality.MethodsIn this phase I/II, observer-blind, randomized trial in US and Canada, 420 healthy adults (21–64 years) were randomized to receive 1 of 4 H7N1 vaccine formulations (3.75 or 7.5 μg hemagglutinin adjuvanted with either AS03_A or AS03_B), 15 μg unadjuvanted H7N1 hemagglutinin, or saline placebo, given as 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays, at day 42 (21 days post-dose 2), month 6, and month 12 (HI only) for the per-protocol cohorts (398, 379 and 368 participants, respectively). Safety is reported up to month 12.ResultsBeneficial AS03 adjuvant effect was demonstrated. Committee for Medical Products for Human Use, and Center for Biologics Evaluation and Research (CBER) criteria were met for all adjuvanted formulations at day 42 (H7N1 HI assay); seroprotection (SPR) and seroconversion rates (SCR) were 88.5–94.8%, mean geometric increase (MGI) 19.2–34.9, and geometric mean titers (GMT) 98.3–180.7. Unadjuvanted H7N1 vaccine did not meet CBER criteria. In adjuvanted groups, antibody titers decreased over time; month 12 SPRs and GMTs were low (2.0–18.8% and 8.1–12.2). MN antibodies showed similar kinetics, with titers persisting at higher range than HI at month 6. All adjuvanted groups showed cross-reactivity against H7N9, with HI responses similar to H7N1.The most frequent solicited symptom in adjuvanted groups was injection site pain (71.2–86.7%); grade 3 solicited symptoms were infrequent. Nine participants reported 17 serious adverse events; none were considered causally related to vaccination.ConclusionsAdjuvanted H7N1 vaccine formulations had an acceptable safety profile and induced an antibody response after 2 doses with cross-reactivity to H7N9.ClinicalTrials.gov: NCT01934127     

Safety and immunogenicity of an inactivated cell culture-derived H7N9 influenza vaccine in healthy adults: A phase I/II,prospective, randomized,open-label trial

BackgroundWe conducted a phase I/II clinical trial to evaluate the safety and immunogenicity of a Madin-Darby canine kidney (MDCK) cell-grown inactivated H7N9 influenza vaccine for pandemic preparedness purposes.MethodsBetween April 7, 2015 and May 27, 2016, healthy adults aged 20–60 years were enrolled sequentially in phase I (n = 40) and phase II (n = 160) from three hospitals in Taiwan and randomized to receive 2 doses of whole-virus H7N9 vaccine (15 or 30 μg hemagglutinin antigen (HA) with or without an aluminum hydroxide adjuvant) at 21-day intervals. Safety up to 180 days and changes in hemagglutinin inhibition (HI) titers at 21 days after each vaccination were determined.ResultsOf the 200 randomized subjects, 193 (96.5%) received 2 doses of the study vaccine and were included in the intention-to-treat analysis for safety, and 190 (95%) were included in the per-protocol analysis for immunogenicity. Most adverse events were mild and transient; no death or vaccine-related serious adverse events were reported. Overall, higher immune responses were observed in the groups administered with 30 μg HA formulation than in the other two groups administered with 15 μg HA formulation. The highest immune response was observed in subjects who received 2 doses of the adjuvanted vaccine containing 30 μg HA with HI titer, seroprotection rate, seroconversion rate, and seroconversion factor of 36.2, 64.6%, 64.6% and 5.7, respectively.ConclusionsOur study demonstrated that the H7N9 influenza vaccine containing 30 µg HA with aluminum hydroxide adjuvant was immunogenic and safe in adults aged 20–60 years.CLINICALTRIALS.GOV identifier: NCT02436928.     

Immunogenicity and safety of a high-dose hepatitis B vaccine among patients receiving methadone maintenance treatment: A randomized,double-blinded,parallel-controlled trial

Background and aimsTo explore whether the immunization with high-dose (60 μg) hepatitis B vaccines in patients receiving methadone maintenance treatment (MMT) could yield a superior protection against hepatitis B infection than did the standard dose (20 μg).MethodsWe conducted a randomized, double-blinded, parallel-controlled trial in MMT patients. Patients with serologically negative hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) were randomized in a ratio of 1:1 to receive three intramuscular injections of 20 μg or 60 μg recombinant hepatitis B vaccine at months 0, 1, and 6. Serum HBsAg and anti-HBs were measured at months 7 and 12 post-vaccination to assess the immunogenicity.ResultsA total of 196 MMT patients were randomized and 195 received at least one injection (98 and 97 in 20 and 60 μg vaccine groups, respectively). The 60 μg vaccine group showed a seroconversion of anti-HBs of 87.3%, high-level response rate of 56.3%, and GMC of 742.9 mIU/mL at month 7. While these results were numerically higher than the 20 μg group, a statistical difference was not found. HIV infection and concomitant drug abuse were negatively associated with the robust immune responses. 7.7% of MMT patients receiving at least one dose of vaccine reported solicited adverse reactions within 7 days after vaccination, 2.6% reported unsolicited adverse reactions within 28 days after vaccination. None of the MMT patients reported serious adverse events or became HBsAg positive during the follow-up.ConclusionsThe three-dose regimen of 60 μg recombinant hepatitis B vaccine at months 0, 1, and 6 can yield a similar immunogenicity among MMT patients as compared to the 20 μg vaccine.ClinicalTrials.gov identifier: NCT02991599     

Hepatitis B vaccination uptake and correlates of serologic response among HIV-infected and uninfected men who have sex with men (MSM) in Bangkok,Thailand

BackgroundVaccination against hepatitis B virus (HBV) is recommended for all HBV-susceptible men who have sex with men (MSM). There is limited information on correlates of immunity to HBV vaccination in this group. We present serologic response rates to hepatitis B vaccine and identify factors associated with impaired response among HIV-uninfected and HIV-infected Thai MSM.MethodologyHBV-susceptible volunteers were offered hepatitis B vaccination at months zero, one, and six. We measured baseline (pre-vaccination) total serum IgG and IgG subclasses (all participants), baseline CD4 count, and plasma HIV-1 viral load (PVL) (HIV+ participants). HBV serologies were retested at 12 months. Serologic responses were compared between all groups in men receiving three vaccine doses.Results511/651 HIV-negative and 64/84 HIV-positive participants completed the three-dose series. Response rates in HIV-uninfected and -infected participants were 90.1% vs. 50.0% (p < 0.0001). Median pre-vaccination IgG was higher among non-responders than responders overall (1238.9.0 vs. 1057.0 mg/dL, p = 0.003) and among HIV-infected participants (1534.0 vs. 1244.5 mg/dL, p = 0.005), but not significantly among HIV-uninfected participants (1105.5 vs. 1054.3 mg/dL, p = 0.96). Pre-vaccination IgG1 and IgG3 levels were higher among HIV-positive than HIV-negative participants (median 866.0 vs. 520.3, and 105.8 vs. 83.1 mg/dL, respectively, p < 0.0001). Among HIV-infected participants, median CD4 count in non-responders was 378 cells/μL vs. 431 cells/μL in responders (p = 0.20). Median PVL in non-responders was 64,800 copies/mL vs. 15500 copies/mL in responders (p = 0.04). Participants with pre-vaccination plasma IgG >1550 mg/dL and PVL >10,000 copies/mL were almost always non-responsive (p < 0.01).ConclusionsHIV infection was associated with poor vaccine responses. High plasma viral load, elevated pre-vaccination total serum IgG and elevated pre-vaccination IgG1 are associated with poorer response to vaccination among HIV-infected MSM. In this group, the combination of high PVL and pre-vaccination total IgG is highly predictive of vaccine failure.     

Immune response in infants after universal high-dose hepatitis B vaccination: A community-based study in Beijing,China

BackgroundVaccination of infants beginning at birth is recommended to prevent Hepatitis B virus (HBV) infection in China. Compared to 5 μg/dose vaccine administered in other regions in China, a three-dose HB recombinant yeast vaccine at 10 μg/dose has been administered for infants within 24 h after birth, 1 month and 6 months of age in Beijing since 2006. In a community-based retrospective cohort study, factors influencing immunologic vaccine response were evaluated.MethodsA total of 3670 infants who completed a 3-dose 10 μg recombinant HB vaccine regimen and born to hepatitis B antigen negative mothers were included. The effect on anti-HBs titers of maternal nutrient status, infants’ birth condition, growth factors, timeliness of vaccination, dosing interval and the interval until post-vaccination serologic testing (PVST) were evaluated.ResultsA total of 3666 infants with no markers of HBV infection were included in analysis. The mean anti-HB titers were 1767.17 mIU/ml. Only 16.9% of the infants completed their PVST within 30–59 days after the final dose of vaccination. Multivariate linear regression analysis showed that delay in PVST (β = −0.097, p < 0.0001) and maternal folic acid supplementation (β = 0.067, p = 0.002) were associated with log-transformed anti-HB titers. Also a trend toward significant association was observed between the calcium supplementation of infants and log-transformed anti-HBs titers (β = 0.062, p = 0.057). Longer interval between dose 2 and dose 3 was not observed to increase the anti-HB titers after cofactors adjustment.ConclusionsOur findings illustrate the importance of timing of PVST to avoid unnecessary revaccination. Multi-center large cohort studies should verify the effect and magnitude of folate and calcium supplementation on HB vaccine response.     

Safety and immunogenicity of an MF59®-adjuvanted A/H1N1 pandemic influenza vaccine in children from three to seventeen years of age

ObjectivesThis study was designed to identify the optimal dose of an MF59^®-adjuvanted, monovalent, A/H1N1 influenza vaccine in healthy paediatric subjects.MethodsSubjects aged 3–8 years (n = 194) and 9–17 years (n = 160) were randomized to receive two primary doses of A/H1N1 vaccine containing either 3.75 μg antigen with half a standard dose of MF59 adjuvant, 7.5 μg antigen with a full dose of MF59, or (children 3–8 years only), a non-adjuvanted 15 μg formulation. A booster dose of MF59-adjuvanted seasonal influenza vaccine including homologous A/H1N1 strain was given one year after priming. Immunogenicity was assessed by haemagglutination inhibition (HI) and microneutralization assays. Vaccine safety was assessed throughout the study (up to 18 months).ResultsA single priming dose of either MF59-adjuvanted formulation was sufficient to meet the European licensure criteria for pandemic influenza vaccines (HI titres ≥1:40 > 70%; seroconversion > 40%; and GMR > 2.5). Two non-adjuvanted vaccine doses were required to meet the same licensure criteria. After first and second doses, percentage of subjects with HI titres ≥1:40 were between 97% and 100% in the adjuvanted vaccine groups compared with 68% and 91% in the non-adjuvanted group, respectively. Postvaccination seroconversion rates ranged from 91% to 98% in adjuvanted groups and were 68% (first dose) and 98% (second dose) in the non-adjuvanted group. HI titres ≥1:330 after primary doses were achieved in 69% to 90% in adjuvanted groups compared with 41% in the non-adjuvanted group. Long-term antibody persistence after priming and a robust antibody response to booster immunization were observed in all vaccination groups. All A/H1N1 vaccine formulations were generally well tolerated. No vaccine-related serious adverse events occurred, and no subjects were withdrawn from the study due to an adverse event.ConclusionsAn MF59-adjuvanted influenza vaccine containing 3.75 μg of A/H1N1 antigen was well tolerated and sufficiently immunogenic to meet all the European licensure criteria after a single dose in healthy children 3–17 years old.     

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in adults 65 years of age and older: A phase II,observer-blind,randomized, controlled trial

BackgroundH7 influenza strains can cause severe and often fatal human infections, especially in the elderly. This phase II, observer-blind, randomized trial (www.ClinicalTrials.gov: NCT01949090) assessed the immunogenicity and safety of a novel AS03-adjuvanted H7N1 vaccine that may serve as a model H7-subtype vaccine.Methods360 adults ≥65 years of age in stable health received either 1 of 4 adjuvanted A/mallard/Netherlands/12/2000 split virion vaccine formulations (3.75 μg or 7.5 μg hemagglutinin adjuvanted with either AS03_A or AS03_B) or saline placebo, given as a 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays for the per-protocol cohort, comprising 332 participants at 21 days post-each dose, 332 at month 6, and 309 at month 12 (HI assay only). Safety was assessed up to month 12 for all participants who had received ≥1 dose (360 participants).ResultsFor H7N1 HI antibody assessment at day 42 (21 days post-dose 2), seroprotection rates (SPR) in the vaccinated groups were 69.6%–88.7%, seroconversion rates (SCR) 69.6%–88.5%, mean geometric increase (MGI) 11.0–18.9, and HI geometric mean titers (GMTs) 55.0–104.8. These parameters declined by month 6 and month 12. Microneutralization GMTs were 46.2–74.7 in the vaccinated groups at day 42, while vaccine response rate (VRR; proportion with ≥4-fold increase in MN titer) was 46.4%–81.5%. For the cross-reactive H7N9 strain, at day 42, HI GMT were 64.3–201.3, SPR 78.6%–96.3%, SCR 79.3%–96.3%, and MGI 14.1–37.7; MN GMTs were 44.0–85.6, and VRR 46.4–85.2%.The most frequent solicited symptom was injection site pain (41.7%–65.0% of vaccine recipients). In total, 40 participants reported 67 serious adverse events; none were considered causally related to vaccination.ConclusionsIn adults aged ≥65 years, the adjuvanted H7N1 vaccine was immunogenic after 2 doses, and had an acceptable safety profile.www.ClinicalTrials.gov: NCT01949090.     

Preclinical and clinical development of a dengue recombinant subunit vaccine

This review focuses on a dengue virus (DENV) vaccine candidate based on a recombinant subunit approach which targets the DENV envelope glycoprotein (E). Truncated versions of E consisting of the N-terminal portion of E (DEN-80E) have been expressed recombinantly in the Drosophila S2 expression system and shown to have native-like conformation. Preclinical studies demonstrate that formulations containing tetravalent DEN-80E adjuvanted with ISCOMATRIX™ adjuvant induce high titer virus neutralizing antibodies and IFN-γ producing T cells in flavivirus-naïve non-human primates. The preclinical data further suggest that administration of such formulations on a 0, 1, 6 month schedule may result in higher maximum virus neutralizing antibody titers and better durability of those titers compared to administration on a 0, 1, 2 month schedule. In addition, the virus neutralizing antibody titers induced by adjuvanted tetravalent DEN-80E compare favorably to the titers induced by a tetravalent live virus comparator. Furthermore, DEN-80E was demonstrated to be able to boost virus neutralizing antibody titers in macaques that have had a prior DENV exposure. A monovalent version of the vaccine candidate, DEN1-80E, was formulated with Alhydrogel™ and studied in a proof-of-principle Phase I clinical trial by Hawaii Biotech, Inc. (NCT00936429). The clinical trial results demonstrate that both the 10 μg and 50 μg formulations of DEN1-80E with 1.25 mg of elemental aluminum were immunogenic when administered in a 3-injection series (0, 1, 2 months) to healthy, flavivirus-naïve adults. The vaccine formulations induced DENV-1 neutralizing antibodies in the majority of subjects, although the titers in most subjects were modest and waned over time. Both the 10 μg DEN1-80E and the 50 μg DEN1-80E formulations with Alhydrogel™ were generally well tolerated.     

Safety,immunogenicity and dose response of VLA84, a new vaccine candidate against Clostridium difficile,in healthy volunteers

BackgroundClostridium difficile infection (CDI) is the leading cause of antibiotic-associated diarrhoea and colitis and the most common pathogen of health care-associated infections. In the US, CDI causes approximately half a million infections and close to 30,000 deaths. Despite antibiotic treatment of C. difficile associated diarrhoea, the disease is complicated by its recurrence in up to 30% of patients.MethodsAn open-label, partially randomized, dose-escalation Phase I trial was performed in two parts. Sixty volunteers aged ≥18 to <65 years were randomized into five treatment groups to receive three immunizations (Day 0, 7, 21) of VLA84 (20 μg with Alum, 75 μg with or without Alum, 200 μg with or without Alum). Eighty-one volunteers aged ≥65 were randomized into four treatment groups (75 μg with or without Alum, 200 μg with or without Alum) and received four immunizations (Day 0, 7, 28 and 56). All subjects were followed for safety and immunogenicity for six months.ResultsVLA84 was safe and well tolerated. Fifty-one adult volunteers (85%) and 50 elderly (62%) experienced at least one solicited or unsolicited adverse event (AE). Forty-eight adult volunteers (80%) and 40 elderly (49%) experienced related AEs which were mostly mild or moderate. No related serious adverse event and no death occurred. The vaccine induced high antibody titres against Toxin A and Toxin B in both study populations.ConclusionVLA84 was safe, well tolerated and highly immunogenic in adult volunteers aged ≥18 to <65 years and elderly volunteers aged ≥65 years.This study is registered at ClinicalTrials.gov under registration number NCT01296386.