Randomized, double-blind comparative trial of subunit and virosomal influenza vaccines for immunocompromised patients

BACKGROUND: To our knowledge, no study to date has compared the effects of a subunit influenza vaccine with those of a virosomal influenza vaccine on immunocompromised patients. METHODS: A prospective, double-blind, randomized study was conducted to compare the immunogenicity and reactogenicity of subunit and virosomal influenza vaccines for adult patients who had an immunosuppressive disease or who were immunocompromised as a result of treatment. RESULTS: There were 304 patients enrolled in our study: 131 with human immunodeficiency virus (HIV) infection, 47 with a chronic rheumatologic disease, 74 who underwent a renal transplant, 47 who received long-term hemodialysis, and 5 who had some other nephrologic disease. There were 151 patients who received the subunit vaccine and 153 patients who received the virosomal vaccine. A slightly higher percentage of patients from the subunit vaccine group were protected against all 3 influenza vaccine strains after being vaccinated, compared with patients from the virosomal vaccine group (41% vs. 30% of patients; P = .03). Among HIV-infected patients, the level of HIV RNA, but not the CD4 cell count, was an independent predictor of vaccine response. Among renal transplant patients, treatment with mycophenolate significantly reduced the immune response to vaccination. The 2 vaccines were comparable with regard to the frequency and severity of local and systemic reactions within 7 days after vaccination. Disease-specific scores for the activity of rheumatologic diseases did not indicate flare-ups 4-6 weeks after vaccination. CONCLUSIONS: For immunosuppressed patients, the subunit vaccine was slightly more immunogenic than the virosomal vaccine. The 2 vaccines were comparable with regard to reactogenicity. Vaccine response decreased with increasing degree of immune suppression. Among HIV-infected patients, the viral load, rather than the CD4 cell count, predicted the protective immune response to the vaccine. CLINICAL TRIALS REGISTRATION: NCT00783380 .

Adjuvant-free immunization with hemagglutinin-Fc fusion proteins as an approach to influenza vaccines

The hemagglutinins (HAs) of human H1 and H3 influenza viruses and avian H5 influenza virus were produced as recombinant fusion proteins with the human immunoglobulin Fc domain. Recombinant HA-human immunoglobulin Fc domain (HA-HuFc) proteins were secreted from baculovirus-infected insect cells as glycosylated oligomer HAs of the anticipated molecular mass, agglutinated red blood cells, were purified on protein A, and were used to immunize mice in the absence of adjuvant. Immunogenicity was demonstrated for all subtypes, with the serum samples demonstrating subtype-specific hemagglutination inhibition, epitope specificity similar to that seen with virus infection, and neutralization. HuFc-tagged HAs are potential candidates for gene-to-vaccine approaches to influenza vaccination.

Influenza symptoms and their impact on elderly adults: randomised trial of AS03-adjuvanted or non-adjuvanted inactivated trivalent seasonal influenza vaccines.

Patient-reported outcomes (PROs) are particularly relevant in influenza vaccine trials in the elderly where reduction in symptom severity could prevent illness-related functional impairment.

Immunogenicity and safety of seasonal and 2009 pandemic A/H1N1 influenza vaccines for patients with autoimmune diseases: a prospective, monocentre trial on 199 patients

The 2009 pandemic A/H1N1 influenza outbreak represented a theoretical risk for patients with autoimmune diseases (AID), especially those immunosuppressed. This study was undertaken to evaluate immunogenicity and tolerance of seasonal (SFV) and A/H1N1 flu vaccines (HFV) in AID patients.

Fusing subunit antigens to interleukin-2 and encapsulating them in liposomes improves their antigenicity but not their protective efficacy

Subunit vaccines commonly lack sufficient immunogenicity to stimulate a comprehensive protective immune response in vivo. We have investigated the potential of specific cytokines (interleukin-2) and particulate delivery systems (liposomes) to enhance antigenicity. Here we report that the IgG1 and IFN-gamma responses to a subunit antigen, consisting of a T and B-cell epitope from Influenza haemagglutinin, can be improved when it is both fused to interelukin-2 and encapsulated in liposomes. However, this vaccine formulation was not able to protect animals against a challenge with live Influenza A/PR/8/34 virus. The addition of more potent immune stimulators may be necessary to improve responses. (c) 2005 Elsevier Ltd. All rights reserved.

Cationic liposomes as adjuvants for subunit protein vaccines:their role in the depot effect and antigen processing by APCs

Introduction: The requirement of adjuvants in subunit protein vaccination is well known yet their mechanisms of action remain elusive. Of the numerous mechanisms suggested, cationic liposomes appear to fulfil at least three: the antigen depot effect, the delivery of antigen to antigen presenting cells (APCs) and finally the danger signal. We have investigated the role of antigen depot effect with the use of dual radiolabelling whereby adjuvant and antigen presence in tissues can be quantified. In our studies a range of cationic liposomes and different antigens were studied to determine the importance of physical properties such as liposome surface charge, antigen association and inherent lipid immunogenicity. More recently we have investigated the role of liposome size with the cationic liposome formulation DDA:TDB, composed of the cationic lipid dimethyldioctadecylammonium (DDA) and the synthetic mycobacterial glycolipid trehalose 6,6’-dibehenate (TDB). Vesicle size is a frequently investigated parameter which is known to result in different routes of endocytosis. It has been postulated that targeting different routes leads to different intracellular signaling pathway activation and it is certainly true that numerous studies have shown vesicle size to have an effect on the resulting immune responses (e.g. Th1 vs. Th2). Aim: To determine the effect of cationic liposome size on the biodistribution of adjuvant and antigen, the ensuing humoral and cell-mediated immune responses and the uptake and activation of antigen by APCs including macrophages and dendritic cells. Methods: DDA:TDB liposomes were made to three different sizes (~ 0.2, 0.5 and 2 µm) followed by the addition of tuberculosis antigen Ag85B-ESAT-6 therefore resulting in surface adsorption. Liposome formulations were injected into Balb/c or C57Bl/6 mice via the intramuscular route. The biodistribution of the liposome formulations was followed using dual radiolabelling. Tissues including muscle from the site of injection and local draining lymph nodes were removed and liposome and antigen presence quantified. Mice were also immunized with the different vaccine formulations and cytokine production (from Ag85B-ESAT-6 restimulated splenocytes) and antibody presence in blood assayed. Furthermore, splenocyte proliferation after restimulating with Ag85B-ESAT-6 was measured. Finally, APCs were compared for their ability to endocytose vaccine formulations and the effect this had on the maturation status of the cell populations was compared. Flow cytometry and fluorescence labelling was used to investigate maturation marker up-regulation and efficacy of phagocytosis. Results: Our results show that for an efficient Ag85B-ESAT-6 antigen depot at the injection site, liposomes composed of DDA and TDB are required. There is no significant change in the presence of liposome or antigen at 6hrs or 24hrs p.i, nor does liposome size have an effect. Approximately 0.05% of the injected liposome dose is detected in the local draining lymph node 24hrs p.i however protein presence is low (<0.005% dose). Preliminary in vitro data shows liposome and antigen endocytosis by macrophages; further studies on this will be presented in addition to the results of the immunisation study.

A phase I randomized, double-blind, controlled trial of 2009 influenza A (H1N1) inactivated monovalent vaccines with different adjuvant systems

Methods We conducted a phase I, multicenter, randomized, double-blind, placebo-controlled, multi-arm (10) parallel study involving healthy adults to evaluate the safety and immunogenicity of influenza A (H1N1) 2009 non-adjuvanted and adjuvanted candidate vaccines. Subjects received two intramuscular injections of one of the candidate vaccines administered 21 days apart. Antibody responses were measured by means of hemagglutination-inhibition assay before and 21 days after each vaccination. The three co-primary immunogenicity end points were the proportion of seroprotection >70%, seroconversion >40%, and the factor increase in the geometric mean titer >2.5. Results A total of 266 participants were enrolled into the study. No deaths or serious adverse events were reported. The most commonly solicited local and systemic adverse events were injection-site pain and headache, respectively. Only three subjects (1.1%) reported severe injection-site pain. Four 2009 influenza A (H1N1) inactivated monovalent candidate vaccines that met the three requirements to evaluate influenza protection, after a single dose, were identified: 15 μg of hemagglutinin antigen without adjuvant; 7.5 μg of hemagglutinin antigen with aluminum hydroxide, MPL and squalene; 3.75 μg of hemagglutinin antigen with aluminum hydroxide and MPL; and 3.75 μg of hemagglutinin antigen with aluminum hydroxide and squalene. Conclusions Adjuvant systems can be safely used in influenza vaccines, including the adjuvant monophosphoryl lipid A (MPL) derived from Bordetella pertussis with squalene and aluminum hydroxide, MPL with aluminum hydroxide, and squalene and aluminum hydroxide.

Towards the knowledge-based design of universal influenza epitope ensemble vaccines

Motivation: Influenza A viral heterogeneity remains a significant threat due to unpredictable antigenic drift in seasonal influenza and antigenic shifts caused by the emergence of novel subtypes. Annual review of multivalent influenza vaccines targets strains of influenza A and B likely to be predominant in future influenza seasons. This does not induce broad, cross protective immunity against emergent subtypes. Better strategies are needed to prevent future pandemics. Cross-protection can be achieved by activating CD8+ and CD4+ T cells against highly-conserved regions of the influenza genome. We combine available experimental data with informatics-based immunological predictions to help design vaccines potentially able to induce cross-protective T-cells against multiple influenza subtypes. Results: To exemplify our approach we designed two epitope ensemble vaccines comprising highly-conserved and experimentally-verified immunogenic influenza A epitopes as putative non-seasonal influenza vaccines; one specifically targets the US population and the other is a universal vaccine. The USA-specific vaccine comprised 6 CD8+ T cell epitopes (GILGFVFTL, FMYSDFHFI, GMDPRMCSL, SVKEKDMTK, FYIQMCTEL, DTVNRTHQY) and 3 CD4+ epitopes (KGILGFVFTLTVPSE, EYIMKGVYINTALLN, ILGFVFTLTVPSERG). The universal vaccine comprised 8 CD8+ epitopes: (FMYSDFHFI, GILGFVFTL, ILRGSVAHK, FYIQMCTEL, ILKGKFQTA, YYLEKANKI, VSDGGPNLY, YSHGTGTGY) and the same 3 CD4+ epitopes. Our USA-specific vaccine has a population protection coverage (portion of the population potentially responsive to one or more component epitopes of the vaccine, PPC) of over 96% and 95% coverage of observed influenza subtypes. The universal vaccine has a PPC value of over 97% and 88% coverage of observed subtypes.

Towards the Knowledge-based Design of Universal Influenza Epitope Ensemble Vaccines

Motivation: Influenza A viral heterogeneity remains a significant threat due to unpredictable antigenic drift in seasonal influenza and antigenic shifts caused by the emergence of novel subtypes. Annual review of multivalent influenza vaccines targets strains of influenza A and B likely to be predominant in future influenza seasons. This does not induce broad, cross protective immunity against emergent subtypes. Better strategies are needed to prevent future pandemics. Cross-protection can be achieved by activating CD8+ and CD4+ T cells against highly-conserved regions of the influenza genome. We combine available experimental data with informatics-based immunological predictions to help design vaccines potentially able to induce cross-protective T-cells against multiple influenza subtypes. Results: To exemplify our approach we designed two epitope ensemble vaccines comprising highlyconserved and experimentally-verified immunogenic influenza A epitopes as putative non-seasonal influenza vaccines; one specifically targets the US population and the other is a universal vaccine. The USA-specific vaccine comprised 6 CD8+ T cell epitopes (GILGFVFTL, FMYSDFHFI, GMDPRMCSL, SVKEKDMTK, FYIQMCTEL, DTVNRTHQY) and 3 CD4+ epitopes (KGILGFVFTLTVPSE, EYIMKGVYINTALLN, ILGFVFTLTVPSERG). The universal vaccine comprised 8 CD8+ epitopes: (FMYSDFHFI, GILGFVFTL, ILRGSVAHK, FYIQMCTEL, ILKGKFQTA, YYLEKANKI, VSDGGPNLY, YSHGTGTGY) and the same 3 CD4+ epitopes. Our USA-specific vaccine has a population protection coverage (portion of the population potentially responsive to one or more component epitopes of the vaccine, PPC) of over 96% and 95% coverage of observed influenza subtypes. The universal vaccine has a PPC value of over 97% and 88% coverage of observed subtypes.

Cochrane review summary for cancer nursing : influenza vaccination in children having chemotherapy for cancer

Background: Children having chemotherapy for cancer are prone to developing influenza infections. Influenza virus infection may lead to hospitalization/prolonged hospitalization, interruption of treatment, and other severe adverse outcomes such as death. Although clinical guidelines recommend children who are being treated for cancer be vaccinated against influenza, evidence supporting this recommendation is unclear.--------- Objectives: The objectives of this review were to (1) assess the efficacy of influenza vaccination in stimulating immunologic response in children with cancer receiving chemotherapy, compared with other control groups; (2) assess the efficacy of influenza vaccination in preventing influenza infection; and (3) establish any adverse effects associated with influenza vaccines in children with cancer.

Setting up a platform for plant-based influenza virus vaccine production in South Africa

Background During a global influenza pandemic, the vaccine requirements of developing countries can surpass their supply capabilities, if these exist at all, compelling them to rely on developed countries for stocks that may not be available in time. There is thus a need for developing countries in general to produce their own pandemic and possibly seasonal influenza vaccines. Here we describe the development of a plant-based platform for producing influenza vaccines locally, in South Africa. Plant-produced influenza vaccine candidates are quicker to develop and potentially cheaper than egg-produced influenza vaccines, and their production can be rapidly upscaled. In this study, we investigated the feasibility of producing a vaccine to the highly pathogenic avian influenza A subtype H5N1 virus, the most generally virulent influenza virus identified to date. Two variants of the haemagglutinin (HA) surface glycoprotein gene were synthesised for optimum expression in plants: these were the full-length HA gene (H5) and a truncated form lacking the transmembrane domain (H5tr). The genes were cloned into a panel of Agrobacterium tumefaciens binary plant expression vectors in order to test HA accumulation in different cell compartments. The constructs were transiently expressed in tobacco by means of agroinfiltration. Stable transgenic tobacco plants were also generated to provide seed for stable storage of the material as a pre-pandemic strategy. Results For both transient and transgenic expression systems the highest accumulation of full-length H5 protein occurred in the apoplastic spaces, while the highest accumulation of H5tr was in the endoplasmic reticulum. The H5 proteins were produced at relatively high concentrations in both systems. Following partial purification, haemagglutination and haemagglutination inhibition tests indicated that the conformation of the plant-produced HA variants was correct and the proteins were functional. The immunisation of chickens and mice with the candidate vaccines elicited HA-specific antibody responses. Conclusions We managed, after synthesis of two versions of a single gene, to produce by transient and transgenic expression in plants, two variants of a highly pathogenic avian influenza virus HA protein which could have vaccine potential. This is a proof of principle of the potential of plant-produced influenza vaccines as a feasible pandemic response strategy for South Africa and other developing countries.

Rapid-response vaccines - does DNA offer a solution?

In responding to future influenza pandemics and other infectious agents, plasmid DNA overcomes many of the limitations of conventional vaccine production approaches.

Clinical factors associated with the humoral immune response to influenza vaccination in chronic obstructive pulmonary disease

Background and objective Individuals with chronic obstructive pulmonary disease (COPD) are at a high risk of developing significant complications from infection with the influenza virus. It is therefore vital to ensure that prophylaxis with the influenza vaccine is effective in COPD. The aim of this study was to assess the immunogenicity of the 2010 trivalent influenza vaccine in persons with COPD compared to healthy subjects without lung disease, and to examine clinical factors associated with the serological response to the vaccine. Methods In this observational study, 34 subjects (20 COPD, 14 healthy) received the 2010 influenza vaccine. Antibody titers at baseline and 28 days post-vaccination were measured using the hemagglutination inhibition assay (HAI) assay. Primary endpoints included seroconversion (≥4-fold increase in antibody titers from baseline) and the fold increase in antibody titer after vaccination. Results Persons with COPD mounted a significantly lower humoral immune response to the influenza vaccine compared to healthy participants. Seroconversion occurred in 90% of healthy participants, but only in 43% of COPD patients (P=0.036). Increasing age and previous influenza vaccination were associated with lower antibody responses. Antibody titers did not vary significantly with cigarette smoking, presence of other comorbid diseases, or COPD severity. Conclusion The humoral immune response to the 2010 influenza vaccine was lower in persons with COPD compared to non-COPD controls. The antibody response also declined with increasing age and in those with a history of prior vaccination.

Influenza hemagglutinin stem-fragment immunogen elicits broadly neutralizing antibodies and confers heterologous protection

Influenza hemagglutinin (HA) is the primary target of the humoral response during infection/vaccination. Current influenza vaccines typically fail to elicit/boost broadly neutralizing antibodies (bnAbs), thereby limiting their efficacy. Although several bnAbs bind to the conserved stem domain of HA, focusing the immune response to this conserved stem in the presence of the immunodominant, variable head domain of HA is challenging. We report the design of a thermotolerant, disulfide-free, and trimeric HA stem-fragment immunogen which mimics the native, prefusion conformation of HA and binds conformation specific bnAbs with high affinity. The immunogen elicited bnAbs that neutralized highly divergent group 1 (H1 and H5 subtypes) and 2 (H3 subtype) influenza virus strains in vitro. Stem immunogens designed from unmatched, highly drifted influenza strains conferred robust protection against a lethal heterologous A/Puerto Rico/8/34 virus challenge in vivo. Soluble, bacterial expression of such designed immunogens allows for rapid scale-up during pandemic outbreaks.

Immunogen design for HIV-1 and influenza

Vaccines provide the most cost effective defense against pathogens. Although vaccines have been designed for a number of viral diseases, a vaccine against HIV-1 still remains elusive. In contrast while there are excellent influenza vaccines, these need to be changed every few years because of antigenic drift and shift The recent discovery of a large number of broadly neutralizing antibodies (bNAbs) and structural characterization of the conserved epitopes targeted by them presents an opportunity for structure based HIV-1 and influenza A vaccine design. We discuss strategies to design immunogens either targeting a particular antigenic region or focusing on native structure stabilization. This article is part of a Special Issue entitled: Recent advances in molecular engineering of antibody. (C) 2014 Elsevier B.V. All rights reserved.