Lars R. Haaheim

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.

Systemic and Mucosal Immune Responses in Young Children and Adults after Parenteral Influenza Vaccination

The effect of natural mucosal priming on systemic and mucosal immune responses was investigated in young children after parenteral influenza vaccination. Eighteen young children and 8 adults were vaccinated with trivalent influenza vaccine at various time intervals before tonsillectomy. The influenza-specific IgG, IgA, and IgM immune responses were examined in tonsillar lymphocytes and frequent samples of peripheral blood and oral fluid. Young children were divided into primed and unprimed groups on the basis of presence of prevaccination serum antibodies. In peripheral blood, adults and primed children had significantly higher IgG and IgA antibody responses than did unprimed children. Irrespective of priming, children elicited weaker IgA responses than adults in both tonsils and oral fluid. While natural priming was essential to elicit strong systemic response in young children after parenteral influenza vaccination, it did not influence the local responses, which were significantly lower in both primed and unprimed children than in adults.

Cross-reaction but no avidity change of the serum antibody response after influenza vaccination

Pre- and post-vaccination sera from 19 volunteers were analysed by the haemagglutination inhibition (HI) test, virus neutralization (VN) assay and avidity enzyme-linked immunosorbent assay (ELISA). The sera were tested against the three strains in a commercial inactivated influenza vaccine; A/Beijing/353/89(H3N2); A/Taiwan/1/86 (H1N1) and B/Yamagata/16/88. Additionally, a range of earlier strains and one newer isolate were assayed for HI- and VN-antibodies. Large variations in the pre-vaccination HI titres were observed for the viruses tested. However, 8-9 days after vaccination HI titres increased to above the assumed protective level (HI > or = 40) in most subjects. Although a limited number of patients were analysed at each sampling point, the time-profile we observed in this study is consistent with data we have obtained in earlier trials (Cox, R.J. et al., Vaccine 1994, 12,993-999). The VN titres, on the other hand, were low against all influenza strains before and up to 6 days, but increased rapidly 8-9 days after vaccination. A recent H3N2 isolate, A/Beijing/32/92 (H3N2), which had drifted further away from the vaccine strain, reacted to low titres or were negative in both the HI and VN assays. No change in the serum avidity to the influenza surface antigens was detected after vaccination, whereas sera from subjects naturally infected with influenza showed an increase in avidity to the infecting virus strain. The increase in serum avidity observed in the infected subjects is probably due to the increased and prolonged antigenic stimulus provided by the replicating virus.

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.

The effect of age and natural priming on the IgG and IgA subclass responses after parenteral influenza vaccination.

This study investigated the effect of natural priming and age on serum IgG and IgA subclass responses after parenteral trivalent influenza vaccination. Sera from 18 young children and 8 adults were collected at various times after vaccination. An ELISA was performed to quantify the concentrations of antibody subclasses. The children were divided into primed and unprimed groups based on the presence of prevaccination serum antibodies. In both children and adults, IgG1 and IgA1 were the predominant IgG and IgA subclasses detected after vaccination. No IgG2 responses were detected in sera of unprimed children, and the proportion of the IgG2 response was lower in primed children than in adults. This suggests that the IgG2 immune response in young children is dependent on previous priming and may mature later than the other IgG subclasses after parenteral influenza vaccination.

Non-Lethal Viral Challenge of Influenza Haemagglutinin and Nucleoprotein DNA Vaccinated Mice Results in Reduced Viral Replication

Influenza DNA vaccines have been widely studied in experimental animal models and protection documented after lethal viral challenge. In this study, we have investigated the humoral response after a non‐lethal viral challenge of mice vaccinated with plasmids encoding the influenza haemagglutinin (HA) or nucleoprotein (NP) genes. BALB/c mice were immunized intramuscularly with three doses (100 µg) of HA, NP or backbone plasmid at 3‐week intervals, or alternatively infected intranasally, before being challenged with homologous virus 13 weeks later. Mice were then sacrificed at weekly intervals and the antibody‐secreting cell response was examined systemically (spleen and bone marrow) and in the respiratory tract (nasal associated lymphoid tissue (NALT) and lungs). Sera were collected after each dose of vaccine and at sacrifice and analyzed by ELISA, haemagglutination inhibition and virus neutralization assays. We found that previous viral infection apparently elicits sterilizing immunity. Vaccination with HA or NP DNA significantly reduced viral replication in the nasal cavity after viral challenge, however, increases in serum antibody titres were observed after challenge. Prior to challenge, specific antibody‐secreting cells were observed in the systemic compartment after HA or NP DNA vaccination but were also found in the NALT after viral challenge. In conclusion, intramuscular DNA vaccination resulted in immunological memory in the systemic compartment, which was rapidly reactivated upon viral challenge.

A Monoclonal Antibody Inhibiting Human Placental Fcγ-Receptor Activity

Fc γ receptor (FcR) from human placenta was solubilized using EDTA and 2-mercaptoethanol and purified by affinity chromatography on human IgG-coated Sepharose 4B. BALB/C mice were im

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.

Autoantibodies to myelin basic protein are not present in the serum and CSF of MS patients

Myelin basic protein (MBP) is one of the main constituents of the CNS myelin sheaths, and an autoimmune response directed against MBP may be crucial in the demyelination process in patients with multiple sclerosis (MS). In this study sera and cerebrospinal fluid (CSF) from 25 MS patients, 25 patients with other neurological diseases and 16 healthy controls were examined for antibodies against MBP by using radio immunoblot, western blot, radio immunoassay and enzyme‐linked immunosorbant assay. No evidence for the presence of antibodies to MBP was found in sera or CSFs in either the MS patients, or in the control groups tested.

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.