Abdullah S. Madhun

A phase I clinical trial of a PER.C6 cell grown influenza H7 virus vaccine.

Avian influenza H7 viruses have transmitted from poultry to man causing human illness and fatality, highlighting the need for pandemic preparedness against this subtype. We have developed and tested the first cell-based human vaccine against H7 avian influenza virus in a phase I clinical trial. Sixty healthy volunteers were intramuscularly vaccinated with two doses of split H7N1 virus vaccine containing 12 microg or 24 microg haemagglutinin alone or with aluminium hydroxide adjuvant (300 microg or 600 microg, respectively). The vaccine was well tolerated in all subjects and no serious adverse events occurred. The vaccine elicited low haemagglutination inhibition and microneutralisation titres, although the addition of aluminium adjuvant augmented the antibody response. We found a higher number of antibody secreting cells and an association with IL-2 production in subjects with antibody response. In conclusion, our study shows that producing effective H7 pandemic vaccines is as challenging as has been observed for H5 vaccines.

Evaluation of a virosomal H5N1 vaccine formulated with Matrix M™ adjuvant in a phase I clinical trial

The avian influenza H5 virus epizootic continues to cause zoonosis with human fatalities, highlighting the continued need for pandemic preparedness against this subtype. This study evaluated the tolerability and immunogenicity of a Matrix M™ adjuvanted virosomal H5N1 vaccine in a phase I clinical trial. Sixty healthy adults were vaccinated intramuscularly with two doses of influenza H5N1 (NIBRG-14) virosomal vaccine alone (30 μg haemagglutinin (HA)) or 1.5, 7.5 or 30 μg HA formulated with 50 μg Matrix M™ adjuvant. The antibody response was analysed by haemagglutination inhibition (HI), microneutralisation (MN) and single radial haemolysis (SRH) assays. The vaccine was well tolerated in all groups but injection site pain was more frequently observed in the Matrix M™ adjuvanted groups. The vaccine elicited homologous and heterologous H5N1-specific antibody responses and the Matrix M™ adjuvanted formulations met all the EU regulatory criteria. In conclusion, Matrix M™ adjuvant was well tolerated and augmented the antibody response allowing considerable dose sparing down to 1.5 μg HA.

An adjuvanted pandemic influenza H1N1 vaccine provides early and long term protection in health care workers

Mass vaccination was the most effective prophylaxis for protecting the population during the influenza H1N1 pandemic. We have evaluated the tolerability, immunogenicity and kinetics of the antibody response to a monovalent oil-in-water (AS03) adjuvanted human pandemic split influenza A/California/7/2009 H1N1 (3.75 μg haemagglutinin) vaccine in health care workers. Vaccination elicited a rapid and early protective level of haemagglutination inhibition antibody from 6 to 7 days post vaccination, and by 14 to 21 days post vaccination, up to 98% of vaccinees had protective antibody titres which persisted for at least 3 months in 84-92% of subjects. A rapid induction of protective antibody is important in reducing community spread of pandemic influenza and in helping maintain the integrity of the health care system during the pandemic.

T-Helper 1 Cells Elicited by H5N1 Vaccination Predict Seroprotection

BACKGROUND Vaccination is the best measure to protect the population against a potential influenza H5N1 pandemic, but 2 doses of vaccine are needed to elicit protective immune responses. An immunological marker for H5N1 vaccine effectiveness is needed for early identification of the best vaccine candidate. METHODS We conducted a phase I clinical trial of a virosomal H5N1 vaccine adjuvanted with Matrix M. Sixty adult volunteers were vaccinated intramuscularly with 2 doses of either 30 μg hemagglutinin (HA) alone or with 1.5, 7.5, or 30 μg HA and Matrix M adjuvant (50 μg). The humoral response was measured by the hemagglutination inhibition (HI), microneutralization (MN), and single radial hemolysis (SRH) assays, and the CD4(+) T-helper 1 (Th1)-cell response was measured by intracellular staining for the cytokines interleukin 2, interferon γ, and tumor necrosis factor α. RESULTS The adjuvanted vaccine effectively induced CD4(+) Th1-cell responses, and the frequency of influenza-specific Th1 cells after the first vaccine dose predicted subsequent HI, MN, and SRH seroprotective responses after the second vaccination. CONCLUSIONS These results support early identification of Th1-cell responses as a predictive biomarker for an efficient vaccine response, which could have great implications for early identification of persons with low or no response to vaccine when evaluating future pandemic influenza vaccines.

Intramuscular Matrix-M-adjuvanted virosomal H5N1 vaccine induces high frequencies of multifunctional Th1 CD4+ cells and strong antibody responses in mice.

Ideally, a candidate pandemic influenza vaccine should elicit rapid and strong cell-mediated and humoral immune responses, which are long-lasting and exhibit broad cross-reactivity against drifted strains. The present study investigated the detailed humoral and cellular immune responses in mice vaccinated intranasally or intramuscularly with inactivated influenza H5N1 (NIBRG-14) virosomal vaccine alone or formulated with Matrix-M adjuvant. The intramuscular Matrix-M-adjuvanted vaccine induced a strong immediate and long-term humoral immune response with high cross-reactivity against drifted H5N1 viruses and showed a dose-sparing potential. Additionally, the vaccine induced a balanced Th1/Th2 cytokine profile and most importantly high frequencies of multifunctional Th1 CD4(+) cells. Our results highlight that Matrix-M adjuvant is a promising parenteral adjuvant for formulating pandemic candidate vaccines.

A cell-based H7N1 split influenza virion vaccine confers protection in mouse and ferret challenge models

Background  In recent years, several avian influenza subtypes (H5, H7 and H9) have transmitted directly from birds to man, posing a pandemic threat.

Matrix-M adjuvanted virosomal H5N1 vaccine confers protection against lethal viral challenge in a murine model

Please cite this paper as: Pedersen et al. (2011) Matrix‐M adjuvanted virosomal H5N1 vaccine confers protection against lethal viral challenge in a murine model. Influenza and Other Respiratory Viruses 5(6), 426–437.

Two Doses of Parenterally Administered Split Influenza Virus Vaccine Elicited High Serum IgG Concentrations which Effectively Limited Viral Shedding upon Challenge in Mice

We have previously found that whole influenza virus vaccine induced a more rapid and stronger humoral response, particularly after the first dose of vaccine, than split virus vaccine in mice. In this study, we have evaluated the protective efficacy of whole and split influenza virus vaccines in mice using a nonlethal upper respiratory tract challenge model. We have also investigated the immunological correlates associated with no or very little viral shedding after viral challenge. Vaccination resulted in reduced viral shedding and shortened the duration of infection by at least 2 days. After one dose of vaccine, whole virus vaccine generally resulted in less viral shedding than split virus vaccine. In contrast, two doses of split virus vaccine, particularly the highest vaccine strengths of 15 and 30 µg HA, most effectively limited viral replication and these mice had high concentrations of prechallenge influenza‐specific serum IgG. The vaccine formulation influenced the IgG2a/IgG1 ratio, and this IgG subclass profile was maintained upon challenge to some extent, although it did not influence the level of viral shedding. The concentration of postvaccination serum IgG showed an inverse relationship with the level of viral shedding after viral challenge. Therefore, serum IgG is an important factor in limiting viral replication in the upper respiratory tract upon challenge of an antigenically similar virus.

Quality and Kinetics of the Antibody Response in Mice after Three Different Low-Dose Influenza Virus Vaccination Strategies

ABSTRACT The threat of a new influenza pandemic has led to renewed interest in dose-sparing vaccination strategies such as intradermal immunization and the use of adjuvanted vaccines. In this study we compared the quality and kinetics of the serum antibody response elicited in mice after one or two immunizations with a split influenza A (H3N2) virus, using three different low-dose vaccination strategies. The mice were divided into four groups, receiving either a low-dose vaccine (3 μg hemagglutinin [HA]) intradermally or intramuscularly with or without aluminum adjuvant or the normal human vaccine dose (15 μg HA) intramuscularly. Sera were collected weekly after vaccination and tested in the hemagglutination inhibition, virus neutralization, and enzyme-linked immunosorbent assays. The antibody responses induced after intradermal or intramuscular low-dose vaccinations were similar and lower than those observed after the human vaccine dose. However, low-dose adjuvanted vaccine elicited a serum antibody response comparable to that elicited by the human dose, although the second immunization did not result in any increase in cross-reactive hemagglutination inhibition antibodies, and the peak serum antibody response was observed 1 week later than in the other vaccination groups. Our murine data suggest that the low-dose intradermal route does not show any obvious advantage over the low-dose intramuscular route in inducing a serum antibody response and that none of the low-dose vaccination strategies is as effective as intramuscular vaccination with the normal human dose. However, the low-dose aluminum-adjuvanted vaccine could present a feasible alternative in case of limited vaccine supply.

Impact of Influenza Vaccine Formulation with a Detailed Analysis of the Cytokine Response

Vaccination provides the most effective method of limiting the impact of influenza. Inactivated influenza vaccines are available in three formulations and more information needs to be generated on how antigen presented in different vaccine formulations influences the subsequent immune response. In the present study, we have investigated the effect of two different influenza vaccine formulations on the resulting antibody and cytokine responses and compared these responses with influenza infection. Mice were vaccinated intramuscularly with one or two doses of whole or split virus vaccine or alternatively intranasally infected with influenza virus. Lymphocytes were isolated from spleen cells and stimulated in vitro for 24 or 72 h for analysis of cytokine profile at the gene expression and at the protein level. Additionally, whole blood was collected and the serum antibody response investigated by haemagglutination inhibition (HI) and enzyme‐linked immunosorbent assay (ELISA). We found that one dose of whole virus vaccine induced higher antibody and cytokine responses and thus was more immunogenic in unprimed mice than split virus vaccine. Whole virus vaccine induced a strong IFN‐γ (type 1) immune response after one dose of vaccine and a more mixed cytokine response after the second dose. Split virus vaccine induced a type 2 response, particularly after two vaccine doses. Our results show that two doses of vaccine (both vaccine formulation) were more effective in induction of Th2 type of cytokines and thus indicate that both the formulation and also the number of vaccine doses substantially influences the magnitude and quality of the immune response.