MF59-adjuvanted subunit influenza vaccine: an improved interpandemic influenza vaccine for vulnerable populations

Formulation of Recombinant H1N1 Hemagglutinin in MF59 and Alum Adjuvants: A Comparison of the Vaccines Potency and Efficacy in BALB/C Mice

In this study, we reported the expression and potency of the recombinant H1N1 hemagglutinin (HA) vaccine as our in-house vaccine in a BALB/c mouse model. Recombinant H1N1 HA was produced in SF9 cell line, purified and formulated in MF59 adjuvant. Experimental mice were injected on days 0 and 14 with MF59-formulated vaccine, alum-based vaccine, and phosphate-buffered saline (PBS). Interleukin (IL)-2, IL-4, and interferon (IFN)-γ were assessed with commercial enzyme-linked immunosorbent assay (ELISA). Antibody responses and cytotoxic T lymphocyte (CTL) activity were assessed by hemagglutination inhibition and granzyme B ELISA, respectively. Moreover, the mice were challenged to show the vaccine efficacy. A considerable rise in IFN-γ and IL-4, as well as IFN-γ/IL-4 ratio, was observed in comparison with the alum-based vaccine and PBS group. Furthermore, our candidate vaccine showed superiority in humoral immune responses and CTL activity versus the alum-based vaccine and PBS group. The challenge showed that the survival rate in the vaccinated groups revealed a significant increase as compared with that in the PBS group. In conclusion, our candidate vaccine showed a robust Th1 response and CTL activity the alum-based vaccine. Moreover, a significant humoral immune response and a higher survival rate were detected in our vaccine as compared with the alum-based vaccine. It seems that the superiority of the MF59-based vaccine is due to the type of vaccine formulation in the candidate vaccine.

Overcoming immune dysfunction in the elderly: trained immunity as a novel approach

People with advanced age have a higher susceptibility to infections and exhibit increased mortality and morbidity as the ability of the immune system to combat infections decreases with age. While innate immune cells display functional defects such as decreased phagocytosis, chemotaxis and cytokine production, adaptive immune cells exhibit reduced receptor diversity, defective antibody production and a sharp decline in naive cell populations. Successful responses to vaccination in the elderly are critical to prevent common infections such as influenza and pneumonia, but vaccine efficacy decreases in older individuals compared with young adults. Trained immunity is a newly emerging concept that showed that innate immune cells possess non-specific immunological memory established through epigenetic and metabolic reprogramming upon encountering certain pathogenic stimuli. Clinical studies suggest that trained immunity can be utilized to enhance immune responses against infections and improve the efficiency of vaccinations in adults; however, how trained immunity responses are shaped with advanced age is still an open question. In this review, we provide an overview of the age-related changes in the immune system with a focus on innate immunity, discuss current vaccination strategies for the elderly, present the concept of trained immunity and propose it as a novel approach to enhance responses against infections and vaccinations in the elderly population.

Safety, Tolerability and Immunogenicity of an MF59-adjuvanted, Cell Culture-derived, A/H5N1, Subunit Influenza Virus Vaccine: Results From a Dose-finding Clinical Trial in Healthy Pediatric Subjects

BACKGROUND

A/H5N1 influenza virus has significant pandemic potential, and vaccination is the main prophylactic measure. This phase 2, randomized, observer-blind, multicenter study evaluated the safety and immunogenicity of two MF59-adjuvanted, cell culture-derived H5N1 (aH5N1c) vaccine formulations in healthy pediatric subjects 6 months to 17 years old.

METHODS

Subjects (N = 662) received 2 aH5N1c doses 3 weeks apart, containing either 7.5 μg (full dose) or 3.75 μg (half dose) hemagglutinin antigen per dose. Local reactions and adverse events (AEs) were assessed by age. Antibody responses were measured by hemagglutination inhibition assay and assessed as geometric mean titers, geometric mean ratios (GMRs) and percentages of subjects achieving titers ≥1:40 and seroconversion (NCT01776554).

RESULTS

No vaccine-related serious AEs occurred. Incidence of solicited local reactions and systemic AEs were similar across vaccine groups. Tenderness and irritability in <6-year olds, and injection site pain, myalgia and fatigue in 6-17-year olds were the most commonly reported reactions in both full- and half-dose recipients. Frequencies of AEs were lower after the second dose than the first dose in all vaccine and age groups. Three weeks after the administration of a second dose, both full- and half-dose formulations met the Center for Biologics Evaluation Research and Review (United States) and Committee for Medicinal Products for Human Use (EU) licensure criteria for titers ≥1:40 (full dose 96% subjects; half dose 86%), seroconversion (full dose 96% subjects; half dose 86%), and GMR (full dose GMR 262; half dose 84). Antibody responses were highest in 6-35-month olds.

CONCLUSIONS

In pediatric subjects, both aH5N1c vaccine formulations were well tolerated and highly immunogenic, meeting both US and EU licensure criteria for pandemic influenza vaccines.

Innate transcriptional effects by adjuvants on the magnitude, quality, and durability of HIV envelope responses in NHPs

Adjuvants have a critical role for improving vaccine efficacy against many pathogens, including HIV. Here, using transcriptional RNA profiling and systems serology, we assessed how distinct innate pathways altered HIV-specific antibody responses in nonhuman primates (NHPs) using 8 clinically based adjuvants. NHPs were immunized with a glycoprotein 140 HIV envelope protein (Env) and insoluble aluminum salts (alum), MF59, or adjuvant nanoemulsion (ANE) coformulated with or without Toll-like receptor 4 (TLR4) and 7 agonists. These were compared with Env administered with polyinosinic-polycytidylic acid:poly-L-lysine, carboxymethylcellulose (pIC:LC) or immune-stimulating complexes. Addition of the TLR4 agonist to alum enhanced upregulation of a set of inflammatory genes, whereas the TLR7 agonist suppressed expression of alum-responsive inflammatory genes and enhanced upregulation of antiviral and interferon (IFN) genes. Moreover, coformulation of the TLR4 or 7 agonists with alum boosted Env-binding titers approximately threefold to 10-fold compared with alum alone, but remarkably did not alter gene expression or enhance antibody titers when formulated with ANE. The hierarchy of adjuvant potency was established after the second of 4 immunizations. In terms of antibody durability, antibody titers decreased ∼10-fold after the final immunization and then remained stable after 65 weeks for all adjuvants. Last, Env-specific Fc-domain glycan structures and a series of antibody effector functions were assessed by systems serology. Antiviral/IFN gene signatures correlated with Fc-receptor binding across all adjuvant groups. This study defines the potency and durability of 8 different clinically based adjuvants in NHPs and shows how specific innate pathways can alter qualitative aspects of Env antibody function.

Comparison of the safety and immunogenicity of an MF59®-adjuvanted with a non-adjuvanted seasonal influenza vaccine in elderly subjects

AIM

Adjuvanted influenza vaccines can overcome the poor antibody response of conventional non-adjuvanted vaccines in the elderly. We evaluated the immunogenicity, safety and clinical effectiveness of an MF59(®)-adjuvanted trivalent influenza vaccine (aTIV) compared with a non-adjuvanted vaccine (TIV) in subjects ≥65 years old, with or without co-morbidities.

METHODS

In 2010-2011, subjects (N=7082) were randomized to receive one dose of aTIV or TIV. Co-primary objectives were to assess lot-to-lot consistency of aTIV, non-inferiority, superiority and immunogenicity 22 days after vaccination. Clinical effectiveness, reactogenicity and serious adverse events were monitored up to Day 366.

RESULTS

The immunological equivalence of three lots of aTIV was demonstrated. aTIV was not only non-inferior to TIV but also elicited significantly higher antibody responses at Day 22 than TIV against all homologous and heterologous strains, even in subjects with co-morbidities. Superiority was not established. Reactogenicity was higher in the aTIV group, but reactions were mild to moderate and transient.

CONCLUSIONS

aTIV elicited a significantly higher antibody response than TIV, especially against A/H3N2 strains, although superiority by pre-defined criteria was not formally met. The study demonstrates potential immunological benefits of MF59-adjuvanted influenza vaccines for the elderly. This trial was registered with www.clinicaltrials.gov (NCT01162122).

Hemozoin is a potent adjuvant for hemagglutinin split vaccine without pyrogenicity in ferrets

BACKGROUND

Synthetic hemozoin (sHZ, also known as β-hematin) from monomeric heme is a particle adjuvant which activates antigen-presenting cells (APCs), such as dendritic cells and macrophages, and enhances humoral immune responses to several antigens, including ovalbumin, human serum albumin, and serine repeat antigen 36 of Plasmodium falciparum. In the present study, we evaluated the adjuvanticity and pyrogenicity of sHZ as an adjuvant for seasonal trivalent hemagglutinin split vaccine (SV) for humans using the experimental ferret model.

METHOD

Ferrets were twice immunized with trivalent SV, SV with sHZ (SV/sHZ) or Fluad, composed of trivalent SV with MF59. Serum hemagglutination inhibition (HI) titers against three viral hemagglutinin (HA) antigens were measured at every week after the immunization. The pyrogenicity of SV/sHZ was examined by monitoring the body temperature of the immunized ferrets. To evaluate the protective efficacy of SV/sHZ, the immunized ferrets were challenged with influenza virus B infection, followed by measurement of viral titers in the nasal cavity and body temperature.

RESULTS

sHZ enhanced HI titers against three viral HA antigens in a dose-dependent manner, to an extent comparable to that of Fluad. The highest dose of sHZ (800 μg) immunized with SV conferred sterile protection against infection with heterologous Influenza B virus, without causing any pyrogenic reaction such as high fever.

CONCLUSION

In the present study, sHZ enhanced the protective efficacy of SV against influenza infection without inducing pyrogenic reaction, suggesting sHZ to be a promising adjuvant candidate for human SV.

Recall responses to tetanus and diphtheria vaccination are frequently insufficient in elderly persons

Demographic changes and a more active life-style in older age have contributed to an increasing public awareness of the need for lifelong vaccination. Currently many older persons have been vaccinated against selected pathogens during childhood but lack regular booster immunizations. The impact of regular vaccinations when started late in life was analyzed in an open, explorative trial by evaluating the immune response against tetanus and diphtheria in healthy older individuals. 252 persons aged above 60 years received a booster vaccination against tetanus, diphtheria, pertussis and polio and a subcohort (n=87) was recruited to receive a second booster vaccination against tetanus, diphtheria and pertussis 5 years later. The percentage of unprotected individuals at the time of enrollment differed substantially for tetanus (12%) and diphtheria (65%). Despite protective antibody concentrations 4 weeks after the first vaccination in almost all vaccinees, antibodies had again dropped below protective levels in 10% (tetanus) and 45% (diphtheria) of the cohort after 5 years. Protection was restored in almost all vaccinees after the second vaccination. No correlation between tetanus- and diphtheria-specific responses was observed, and antibody concentrations were not associated with age-related changes in the T cell repertoire, inflammatory parameters, or CMV-seropositivity suggesting that there was no general biological “non-responder type.” Post-vaccination antibody concentrations depended on pre-existing plasma cells and B cell memory as indicated by a strong positive relationship between post-vaccination antibodies and pre-vaccination antibodies as well as antibody-secreting cells. In contrast, antigen-specific T cell responses were not or only weakly associated with antibody concentrations. In conclusion, our findings demonstrate that single shot vaccinations against tetanus and/or diphtheria do not lead to long-lasting immunity in many elderly persons despite administration at relatively short intervals. Sufficient antigen-specific B cell memory B generated by adequate priming and consecutive booster vaccinations and/or exposure is a prerequisite for long-term protection.

DNA vaccine that targets hemagglutinin to MHC class II molecules rapidly induces antibody-mediated protection against influenza

New influenza A viruses with pandemic potential periodically emerge due to viral genomic reassortment. In the face of pandemic threats, production of conventional egg-based vaccines is time consuming and of limited capacity. We have developed in this study a novel DNA vaccine in which viral hemagglutinin (HA) is bivalently targeted to MHC class II (MHC II) molecules on APCs. Following DNA vaccination, transfected cells secreted vaccine proteins that bound MHC II on APCs and initiated adaptive immune responses. A single DNA immunization induced within 8 d protective levels of strain-specific Abs and also cross-reactive T cells. During the Mexican flu pandemic, a targeted DNA vaccine (HA from A/California/07/2009) was generated within 3 wk after the HA sequences were published online. These results suggest that MHC II-targeted DNA vaccines could play a role in situations of pandemic threats. The vaccine principle should be extendable to other infectious diseases.

A randomized clinical trial to identify the optimal antigen and MF59(®) adjuvant dose of a monovalent A/H1N1 pandemic influenza vaccine in healthy adult and elderly subjects

BACKGROUND

Vaccines against pandemic A/H1N1 influenza are required to protect the entire population. This dose range study aimed to identify priming antigen and adjuvant doses resulting in optimal levels of antibody-mediated protection after primary and one-year booster immunizations.

METHODS

This randomised trial enrolled 410 healthy adult (18-60 years) and 251 healthy elderly (>60 years) participants. Subjects received vaccine containing either 3.75 μg or 7.5 μg antigen, adjuvanted with half the standard dose, or a standard dose of MF59(®) (Novartis Vaccines) adjuvant, respectively. An additional adult cohort received non-adjuvanted vaccine containing 15 μg antigen. Two doses of investigational vaccine were administered three weeks apart, followed by a single booster dose of adjuvanted seasonal influenza vaccine one year after priming. Immunogenicity was assessed by haemagglutination inhibition and microneutralization assays pre- and post-immunization, the safety profile of each vaccine was also evaluated.

RESULTS

All of the vaccine formulations investigated were highly immunogenic and well tolerated in both adult and elderly subjects. The 7.5 μg formulation induced the highest antibody titres after primary and booster immunizations, and resulted in better long-term antibody persistence, in both age groups. Assessment according to European licensure criteria for influenza vaccines concluded that single adjuvanted priming doses containing 3.75 μg and 7.5 μg antigen were optimal for the adult and elderly populations, respectively.

CONCLUSIONS

These data demonstrate that one priming dose of MF59-adjuvanted A/H1N1 vaccine provided healthy adult (3.75 μg or 7.5 μg formulations) and healthy elderly (7.5 μg formulation) individuals with adequate levels of seroprotection. Booster administration after two priming doses of either vaccine formulation resulted in the rapid development of seroprotective antibody titres.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT00971906).

Effectiveness of a MF-59™-adjuvanted pandemic influenza vaccine to prevent 2009 A/H1N1 influenza-related hospitalisation; a matched case-control study

Background

During the 2009 influenza A/H1N1 pandemic, adjuvanted influenza vaccines were used for the first time on a large scale. Results on the effectiveness of the vaccines in preventing 2009 influenza A/H1N1-related hospitalisation are scanty and varying.

Methods

We conducted a matched case-control study in individuals with an indication for vaccination due to underlying medical conditions and/or age ≥ 60 years in the Netherlands. Cases were patients hospitalised with laboratory-confirmed 2009 A/H1N1 influenza infection between November 16, 2009 and January 15, 2010. Controls were matched to cases on age, sex and type of underlying medical condition(s) and drawn from an extensive general practitioner network. Conditional logistic regression was used to estimate the vaccine effectiveness (VE = 1 - OR). Different sensitivity analyses were used to assess confounding by severity of underlying medical condition(s) and the effect of different assumptions for missing dates of vaccination.

Results

149 cases and 28,238 matched controls were included. It was estimated that 22% of the cases and 28% of the controls received vaccination more than 7 days before the date of onset of symptoms in cases. A significant number of breakthrough infections were observed. The VE was estimated at 19% (95%CI -28-49). After restricting the analysis to cases with controls suffering from severe underlying medical conditions, the VE was 49% (95%CI 16-69).

Conclusions

The number of breakthrough infections, resulting in modest VE estimates, suggests that the MF-59™ adjuvanted vaccine may have had only a limited impact on preventing 2009 influenza A/H1N1-related hospitalisation in this setting. As the main aim of influenza vaccination programmes is to reduce severe influenza-related morbidity and mortality from influenza in persons at high risk of complications, a more effective vaccine, or additional preventive measures, are needed.

Cost-effectiveness of adjuvanted versus nonadjuvanted influenza vaccine in adult hemodialysis patients

BACKGROUND

Currently more than 340,000 individuals are receiving long-term hemodialysis (HD) therapy for end-stage renal disease and therefore are particularly vulnerable to influenza, prone to more severe influenza outcomes, and less likely to achieve seroprotection from standard influenza vaccines. Influenza vaccine adjuvants, chemical or biologic compounds added to a vaccine to boost the elicited immunologic response, may help overcome this problem.

STUDY DESIGN

Economic stochastic decision analytic simulation model.

SETTING & PARTICIPANTS

US adult HD population.

MODEL, PERSPECTIVE, & TIMEFRAME

The model simulated the decision to use either an adjuvanted or nonadjuvanted vaccine, assumed the societal perspective, and represented a single influenza season, or 1 year.

INTERVENTION

Adjuvanted influenza vaccine at different adjuvant costs and efficacies. Sensitivity analyses explored the impact of varying influenza clinical attack rate, influenza hospitalization rate, and influenza-related mortality.

OUTCOMES

Incremental cost-effectiveness ratio of adjuvanted influenza vaccine (vs nonadjuvanted) with effectiveness measured in quality-adjusted life-years.

RESULTS

Adjuvanted influenza vaccine would be cost-effective (incremental cost-effectiveness ratio <$50,000/quality-adjusted life-year) at a $1 adjuvant cost (on top of the standard vaccine cost) when adjuvant efficacy (in overcoming the difference between influenza vaccine response in HD patients and healthy adults) ≥60% and economically dominant (provides both cost savings and health benefits) when the $1 adjuvant's efficacy is 100%. A $2 adjuvant would be cost-effective if adjuvant efficacy was 100%.

LIMITATIONS

All models are simplifications of real life and cannot capture all possible factors and outcomes.

CONCLUSIONS

Adjuvanted influenza vaccine with adjuvant cost ≤$2 could be a cost-effective strategy in a standard influenza season depending on the potency of the adjuvant.

Immunogenicity and safety of MF59-adjuvanted H5N1 influenza vaccine from infancy to adolescence

OBJECTIVE

This study evaluated the immunogenicity, safety, and tolerability of a MF59-adjuvanted H5N1 vaccine in a population 6 months through 17 years of age.

METHODS

Healthy subjects 6 to <36 months, 3 to <9 months, and 9 to <18 years of age were assigned randomly to receive 2 doses of either a MF59-adjuvanted H5N1 vaccine (7.5 μg/dose) or a MF59-adjuvanted trivalent seasonal influenza control vaccine (15 μg/dose for each antigen). Immunogenicity against the A/Vietnam/1194/2004-like vaccine strain was measured before and 3 weeks after the 2-dose primary series, through hemagglutination inhibition (HI), single radial hemolysis (SRH), and microneutralization. Local and systemic reactions were recorded.

RESULTS

A total of 335 subjects received the H5N1 vaccine, and 137 subjects received the seasonal vaccine. Rates of seroprotection (HI titer of ≥40) against the H5N1 vaccine antigen were 97% for children 6 to 36 months and 3 to 9 years of age and 89% for older children. All subjects seroconverted in the SRH assay. Microneutralization titers of ≥40 were achieved by 99% of subjects, and ≥98% of subjects, respectively. Local reactions, particularly injection site pain in older children, were common, generally mild to moderate in nature, and transient and resolved spontaneously. Up to 5% of participants. There were no vaccine-related serious adverse events in either group.

CONCLUSIONS

In this pediatric population, MF59-adjuvanted H5N1 vaccine was highly immunogenic, had a good safety profile, reactogenicity comparable with that of an adjuvanted seasonal influenza control vaccine.

MF59®-adjuvanted seasonalinfluenza vaccine

Correlated with increasing chronologic age, immunosenescence impairs the response to influenza vaccines. MF59®-adjuvanted influenza vaccine (Fluad®, Novartis, Basel, Switzerland) elicits a stronger and broader immune response against well-matched and drifted influenza strains compared with conventional vaccines. MF5-adjuvanted influenza vaccine reduces the rate of hospitalization for pneumonia, cardiovascular disease and cerebrovascular disease, even in seasons with an imperfect match between the vaccine and circulating strains, in vaccinated compared with unvaccinated older adults.

Influenza control in the 21st century: Optimizing protection of older adults

Older adults (> or =65 years of age) are particularly vulnerable to influenza illness. This is due to a waning immune system that reduces their ability to respond to infection, which leads to more severe cases of disease. The majority ( approximately 90%) of influenza-related deaths occur in older adults and, in addition, catastrophic disability resulting from influenza-related hospitalization represents a significant burden in this vulnerable population. Current influenza vaccines provide benefits for older adults against influenza; however, vaccine effectiveness is lower than in younger adults. In addition, antigenic drift is also a concern, as it can impact on vaccine effectiveness due to a mismatch between the vaccine virus strain and the circulating virus strain. As such, vaccines that offer higher and broader protection against both homologous and heterologous virus strains are desirable. Approaches currently available in some countries to meet this medical need in older adults may include the use of adjuvanted vaccines. Future strategies under evaluation include the use of high-dose vaccines; novel or enhanced adjuvantation of current vaccines; use of live attenuated vaccines in combination with current vaccines; DNA vaccines; recombinant vaccines; as well as the use of different modes of delivery and alternative antigens. However, to truly evaluate the benefits that these solutions offer, further efficacy and effectiveness studies, and better correlates of protection, including a precise measurement of the T cell responses that are markers for protection, are needed. While it is clear that vaccines with greater immunogenicity are required for older adults, and that adjuvanted vaccines may offer a short-term solution, further research is required to exploit the many other new technologies.

Current status and progress of prepandemic and pandemic influenza vaccine development

H5N1 viruses are widely considered to be a probable cause of the next influenza pandemic. Influenza vaccines are considered to form the main prophylactic measure against pandemic influenza. The world's population is expected to have no pre-existing immunity against the pandemic virus strain and will need two vaccine doses to acquire protective immunity. A pandemic outbreak will spread much faster than it will take for pandemic vaccines to be produced and distributed. Therefore, increasing efforts are being made to develop prepandemic vaccines that can induce broad cross-protective responses and that can be administered as soon as a pandemic is declared or even before, in order to successfully prime the immune system and allow for a rapid and protective antibody response with one dose of the pandemic vaccine. Several vaccine manufacturers have developed candidate pandemic and prepandemic vaccines, predominantly based on reverse-genetics reference strains and have improved the immunogenicity by formulating these vaccines with different adjuvants. Clinical studies with inactivated split-virion or whole-virion vaccines based on H5N1 indicate that two immunizations appear necessary to elicit the level of immunity required to meet licensure criteria. A detailed overview is given of the most successful candidate vaccines developed by seven vaccine manufacturers.

The failure of HIV vaccines: a new autovaccine may overcome some problems

The hypothesis of an autovaccine for HIV is borne out by: (1) the present lack of a valid vaccine; (2) by a remarkable improvement of the HAART, which however does not prevent HIV mutagenicity and a consequent valid immunological response and (3) the persistence of a hidden infection ready to thrive again. The preparation of the autovaccine is described as well as the administration schedule but only a clinical study will define its validity.