MF59®‐adjuvanted vaccines for seasonal and pandemic influenza prophylaxis

Abstract Influenza is a major cause of worldwide morbidity and mortality through frequent seasonal epidemics and infrequent pandemics. Morbidity and mortality rates from seasonal influenza are highest in the most frail, such as the elderly, those with underlying chronic conditions and very young children. Antigenic mismatch between strains recommended for vaccine formulation and circulating viruses can further reduce vaccine efficacy in these populations. Seasonal influenza vaccines with enhanced, cross‐reactive immunogenicity are needed to address these problems and can confer a better immune protection, particularly in seasons were antigenic mismatch occurs. A related issue for vaccine development is the growing threat of pandemic influenza caused by H5N1 avian strains. Vaccines against strains with pandemic potential offer the best approach for reducing the potential impact of a pandemic. However, current non‐adjuvanted pre‐pandemic vaccines offer suboptimal immunogenicity against H5N1. For both seasonal and pre‐pandemic vaccines, the addition of adjuvants may be the best approach for providing enhanced cross‐reactive immunogenicity. MF59^®, the first oil‐in‐water emulsion licensed as an adjuvant for human use, can enhance vaccine immune responses through multiple mechanisms. A trivalent MF59‐adjuvanted seasonal influenza vaccine (Fluad^®) has shown to induce significantly higher immune responses to influenza vaccination in the elderly, compared with non‐adjuvanted vaccines, and to provide cross‐reactive immunity against divergent influenza strains. Similar results have been generated with a MF59‐adjuvanted H5N1 pre‐pandemic vaccine, which showed higher and broader immunogenicity compared with non‐adjuvanted pre‐pandemic vaccines.     

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. Background A candidate pandemic influenza H5N1 vaccine should provide rapid and long‐lasting immunity against antigenically drifted viruses. As H5N1 viruses are poorly immunogenic, this may require a combination of immune potentiating strategies. An attractive approach is combining the intrinsic immunogenicity of virosomes with another promising adjuvant to further boost the immune response. As regulatory authorities have not yet approved a surrogate correlate of protection for H5N1 vaccines, it is important to test the protective efficacy of candidate H5N1 vaccines in a viral challenge study. Objectives This study investigated in a murine model the protective efficacy of Matrix‐M adjuvanted virosomal influenza H5N1 vaccine against highly pathogenic lethal viral challenge. Methods Mice were vaccinated intranasally (IN) or intramuscularly (IM) with 7·5 μg and 30 μg HA of inactivated A/Vietnam/1194/2004 (H5N1) (NIBRG‐14) virosomal adjuvanted vaccine formulated with or without 10 μg of Matrix‐M adjuvant and challenged IN with the highly pathogenic A/Vietnam/1194/2004 (H5N1) virus. Results and conclusions IM vaccination provided protection irrespective of dose and the presence of Matrix‐M adjuvant, whilst the IN vaccine required adjuvant to protect against the challenge. The Matrix‐M adjuvanted vaccine induced a strong and cross‐reactive serum antibody response indicative of seroprotection after both IM and IN administration. In addition, the IM vaccine induced the highest frequencies of influenza specific CD4+ and CD8+ T‐cells. The results confirm a high potential of Matrix‐M adjuvanted virosomal vaccines and support the progress of this vaccine into a phase 1 clinical trial.     

The mucosal and systemic immune responses elicited by a chitosan-adjuvanted intranasal influenza H5N1 vaccine

Please cite this paper as: Svindland et al. The mucosal and systemic immune responses elicited by a chitosan‐adjuvanted intranasal influenza H5N1 vaccine. Influenza and Other Respiratory Viruses DOI:10.1111/j.1750‐2659.2011.00271.x. Background Development of influenza vaccines that induce mucosal immunity has been highlighted by the World Health Organisation as a priority (Vaccine 2005;23:1529). Dose‐sparing strategies and an efficient mass‐vaccination regime will be paramount to reduce the morbidity and mortality of a future H5N1 pandemic. Objectives This study has investigated the immune response and the dose‐sparing potential of a chitosan‐adjuvanted intranasal H5N1 (RG‐14) subunit (SU) vaccine in a mouse model. Methods Groups of mice were intranasally immunised once or twice with a chitosan (5 mg/ml)‐adjuvanted SU vaccine [7·5, 15 or 30 μg haemagglutinin (HA)] or with a non‐adjuvanted SU vaccine (30 μg HA). For comparison, another group of mice were intranasally immunised with a whole H5N1 (RG‐14) virus (WV) vaccine (15 μg HA), and the control group consisted of unimmunised mice. Results The chitosan‐adjuvanted SU vaccine induced an immune response superior to that of the non‐adjuvanted SU vaccine. Compared with the non‐adjuvanted SU group, the chitosan‐adjuvanted SU vaccine elicited higher numbers of influenza‐specific antibody‐secreting cells (ASCs), higher concentrations of local and systemic antibodies and correspondingly an improved haemagglutination inhibition (HI) and single radial haemolysis (SRH) response against both the homologous vaccine strain and drifted H5 strains. We measured a mixed T‐helper 1/T‐helper 2 cytokine response in the chitosan‐adjuvanted SU groups, and these groups had an increased percentage of virus‐specific CD4⁺ T cells producing two Thelper 1 (Th1) cytokines simultaneously compared with the non‐adjuvanted SU group. Overall, the WV vaccine induced higher antibody concentrations in sera and an HI and SRH response similar to that of the chitosan‐adjuvanted SU vaccine. Furthermore, the WV vaccine formulation showed a stronger bias towards a T‐helper 1 profile than the SU vaccine and elicited the highest frequencies of CD4⁺ Th1 cells simultaneously secreting three different cytokines (INFγ⁺, IL2⁺ and INFα⁺). As expected, two immunisations gave a better immune response than one in all groups. The control group had very low or not detectable results in the performed immunoassays. Conclusion The cross‐clade serum reactivity, improved B‐ and T‐cell responses and dose‐sparing potential of chitosan show that a chitosan‐adjuvanted intranasal influenza vaccine is a promising candidate vaccine for further preclinical development.     

A phase II,open-label,multicentre study to evaluate the immunogenicity and safety of an adjuvanted prepandemic (H5N1) influenza vaccine in healthy Japanese adults

Background  

Promising clinical data and significant antigen-sparing have been demonstrated for a pandemic H5N1 influenza split-virion vaccine adjuvanted with AS03_A, an α-tocopherol-containing oil-in-water emulsion-based Adjuvant System. Although studies using this formulation have been reported, there have been no data for Japanese populations. This study therefore aimed to assess the immunogenicity and tolerability of a prepandemic (H5N1) influenza vaccine adjuvanted with AS03_A in Japanese adults.     

Safety and immunogenicity of Sinovac’s prototype pandemic influenza H5N1 vaccines: a review on clinical trials

Abstract  Sinovac Biotech started to develop prototype pandemic influenza H5N1 vaccines in March 2004. On 2 April 2008, Sinovac’s inactivated, aluminium‐adjuvanted, whole‐virion prototype pandemic influenza A (H5N1) vaccine (PanFlu™) was granted production licensure by the China regulatory authority State Food and Drug Administration. The whole‐virion H5N1 vaccine was manufactured in embryonated hens’ eggs using the reassortant strain NIBRG‐14 (A/Vietnam/1194/2004‐A/PR/8/34) as vaccine virus. It showed good safety, immunogenicity and cross‐reactivity in immunologically naïve adults. In primed adults, the vaccine induced a strong booster response. Plasma from a vaccinated individual showed a beneficial effect following passive immunotherapy of an H5N1 human infection case. This article reviews the process, status and results of clinical evaluation of Sinovac’s whole‐ and split‐virion H5N1 vaccines by focusing on the whole‐virion vaccine.     

Antibody responses against influenza A(H1N1)pdm09 virus after sequential vaccination with pandemic and seasonal influenza vaccines in Finnish healthcare professionals

Background Influenza A(H1N1)pdm09 virus has been circulating in human population for three epidemic seasons. During this time, monovalent pandemic and trivalent seasonal influenza vaccination against this virus have been offered to Finnish healthcare professionals. It is, however, unclear how well vaccine‐induced antibodies recognize different strains of influenza A(H1N1)pdm09 circulating in the population and whether the booster vaccination with seasonal influenza vaccine would broaden the antibody cross‐reactivity. Objectives Influenza vaccine‐induced humoral immunity against several isolates of influenza A(H1N1)pdm09 virus was analyzed in healthcare professionals. Age‐dependent responses were also analyzed. Methods Influenza viruses were selected to represent viruses that circulated in Finland during two consecutive influenza epidemic seasons 2009–2010 and 2010–2011. Serum samples from vaccinated volunteers, age 20–64 years, were collected before and after vaccination with AS03‐adjuvanted pandemic and non‐adjuvanted trivalent seasonal influenza vaccine that was given 1 year later. Results Single dose of pandemic vaccine induced a good albeit variable antibody response. On day 21 after vaccination, depending on the virus strain, 14–75% of vaccinated had reached antibody titers (≥1:40) considered seroprotective. The booster vaccination 1 year later with a seasonal vaccine elevated the seroprotection rate to 57–98%. After primary immunization, younger individuals (20–48 years) had significantly higher antibody titers against all tested viruses than older persons (49–64 years) but this difference disappeared after the seasonal booster vaccination. Conclusions Even a few amino acid changes in influenza A HA may compromise the vaccine‐induced antibody recognition. Older adults (49 years and older) may benefit more from repeated influenza vaccinations.     

A new MF59-adjuvanted influenza vaccine enhances the immune response in the elderly with chronic diseases: results from an immunogenicity meta-analysis

BACKGROUND: The elderly are at a higher risk of morbidity and mortality associated with influenza infection than younger adults, but get less protection from conventional vaccination. OBJECTIVE: We conducted a meta-analysis of all available data from clinical trials in the elderly on a recently introduced MF59-adjuvanted influenza vaccine to determine its immunogenicity and safety in subjects with underlying chronic disease who are at highest risk of influenza infection. METHODS: Data on immunogenicity and safety from 3600 subjects immunized with either the MF59-adjuvanted or conventional comparator influenza vaccine in 13 clinical trials were analyzed by disease history. Geometric mean haemagglutination inhibition titres (GMTs) and differences between the vaccine groups were compared using two-way analysis of variance. Differences between vaccine groups in the percentages with post-immunization reactions were assessed using chi-squared test and Fischer's exact test. RESULTS: At 28 days the adjuvanted:comparator GMT ratio for the A/H3N2 antigen was 1.18 in healthy elderly subjects and 1.43 in elderly subjects with chronic disease (p = 0.004). The respective GMT ratios were 1.17 versus 1.37 for the B antigen (p = 0.065) and 1.10 versus 1.17 for the A/H1N1 antigen (p = 0.41). Although post-immunization reactions were more common in the group receiving the adjuvanted vaccine, these were predominantly mild and transient, and none were serious. CONCLUSIONS: The MF59-adjuvanted influenza vaccine is more immunogenic in elderly subjects than conventional non-adjuvanted influenza vaccines and especially so in those with chronic disease. Therefore, since its safety profile is clinically acceptable, this adjuvanted vaccine represents an excellent option for influenza immunization of elderly subjects at highest risk of complications.     

Development of a new candidate H5N1 avian influenza virus for pre‐pandemic vaccine production

Background Highly pathogenic H5N1 avian influenza viruses currently circulating in birds have caused hundreds of human infections, and pose a significant pandemic threat. Vaccines are a major component of the public health preparedness for this likely event. The rapid evolution of H5N1 viruses has resulted in the emergence of multiple clades with distinct antigenic characteristics that require clade‐specific vaccines. A variant H5N1 virus termed clade 2.3.4 emerged in 2005 and has caused multiple fatal infections. Vaccine candidates that match the antigenic properties of variant viruses are necessary because inactivated influenza vaccines elicit strain‐specific protection. Objective To address the need for a suitable seed for manufacturing a clade 2.3.4 vaccine, we developed a new H5N1 pre‐pandemic candidate vaccine by reverse genetics and evaluated its safety and replication in vitro and in vivo. Methods A reassortant virus termed, Anhui/PR8, was produced by reverse genetics in compliance with WHO pandemic vaccine development guidelines and contains six genes from A/Puerto Rico/8/34 as well as the neuraminidase and hemagglutinin (HA) genomic segments from the A/Anhui/01/2005 virus. The multi‐basic cleavage site of HA was removed to reduce virulence. Results The reassortant Anhui/PR8 grows well in eggs and is avirulent to chicken and ferrets but retains the antigenicity of the parental A/Anhui/01/2005 virus. Conclusion These results indicate that the Anhui/PR8 reassortant lost a major virulent determinant and it is suitable for its use in vaccine manufacturing and as a reference vaccine virus against the H5N1 clade 2.3.4 viruses circulating in eastern China, Vietnam, Thailand, and Laos.     

An assessment of prime‐boost vaccination schedules with AS03A‐adjuvanted prepandemic H5N1 vaccines: a randomized study in European adults

Please cite this paper as: Gillard et al. (2012) An assessment of prime‐boost vaccination schedules with AS03_A‐adjuvanted prepandemic H5N1 vaccines: a randomized study in European adults. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00349.x. Background Long‐term persistence of immune response and safety of an H5N1 prepandemic influenza vaccine adjuvanted with AS03 (an α‐tocopherol oil‐in‐water emulsion‐based adjuvant system) was evaluated using various prime‐boost schedules that mimicked potential pandemic scenarios (NCT00430521). Methods Five hundred and twelve healthy adults aged 18–60 years received primary vaccination with one or two doses (0, 21 days schedule) of the A/Vietnam/1194/2004 H5N1 vaccine followed by a booster dose (A/Vietnam/1194/2004 or A/Indonesia/05/2005 strain) six or twelve months later across eight randomized groups. Immunogenicity results by hemagglutination inhibition [HI] assay, microneutralization assay, and the cell‐mediated immune response (CMI) are reported here for the four groups boosted at Month 12. Results A one‐dose‐adjuvanted primary administration followed 12 months later by a single‐adjuvanted booster dose containing a heterologous vaccine strain met or exceeded all US and European criteria for both strains. Increasing the interval between the first and second dose (from 21 days to 12 months) resulted in stronger cross‐reactive immune responses against the A/Indonesia/05/2005 strain. The HI antibody response against the two strains persisted for 6 months after the booster dose irrespective of the booster vaccine’s strain. The neutralizing antibody responses and the CMI observed in the study population paralleled the HI immune response. Overall, the vaccine had a clinically acceptable safety profile. Conclusion The H5N1 vaccine in this study allowed for flexibility in the time interval between primary and booster vaccination and the use of a heterologous strain without impacting the strength of the humoral and cellular immune response to both vaccine strains.     

Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study

Please cite this paper as: McVernon et al. (2010) Absence of cross‐reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months–9 years: a prospective study. Influenza and Other Respiratory Viruses 5(1), 7–11. Background Early outbreaks of the pandemic influenza A (H1N1) 2009 virus predominantly involved young children, who fuelled transmission through spread in homes and schools. Seroprevalence studies conducted on stored serum collections indicated low levels of antibody to the novel strain in this age group, leading many to recommend priority immunisation of paediatric populations. Objectives In a prospective study, we sought evidence of cross‐reactive antibodies to the pandemic virus in children who were naïve to seasonal influenza vaccines, at baseline and following two doses of the 2009 Southern Hemisphere trivalent influenza vaccine (TIV). Patients/Methods Twenty children were recruited, with a median age of 4 years (interquartile range 3–5 years); all received two age appropriate doses of TIV. Paired sera were collected pre‐ and post‐vaccination for the assessment of vaccine immunogenicity, using haemagglutination inhibition and microneutralisation assays against vaccine‐related viruses and influenza A (H1N1) 2009. Results Robust responses to H3N2 were observed regardless of age or pre‐vaccination titre, with 100% seroconversion. Fewer seroconverted to the seasonal H1N1 component. Only two children were weakly seropositive (HI titre 40) to the pandemic H1N1 strain at study entry, and none showed evidence of seroconversion by HI assay following TIV administration. Conclusions Administration of 2009 Southern Hemisphere TIV did little to elicit cross‐reactive antibodies to the pandemic H1N1 virus in children, in keeping with assay results on stored sera from studies of previous seasonal vaccines. Our findings support the recommendations for influenza A (H1N1) 2009 vaccination of children in preparation for the 2010 winter season.     

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. Objectives We have investigated the immunogenicity and protective efficacy of a cell based candidate pandemic influenza H7 vaccine in pre‐clinical animal models. Methods Mice and ferrets were immunised with two doses of the split virus vaccine (12–24 μg haemagglutinin) with or without aluminium hydroxide adjuvant and challenged 3 weeks after second dose with the highly pathogenic A/chicken/Italy/13474/99 (H7N1) virus. The H7N1‐specific serum antibody response was also measured. After challenge, viral shedding, weight loss, disease signs and death (only mice) were recorded. Results Low‐to‐modest serum antibody titres were detected after vaccination. Nevertheless, the vaccine induced significant protection from disease after challenge with the wild‐type virus. In the murine lethal challenge model, vaccination effectively prevented death and, furthermore, formulation with adjuvant reduced excessive weight loss and viral shedding. In ferrets, vaccination reduced viral shedding and protected against systemic spread of the virus. Conclusions We have extended to the H7 subtype the finding that protective efficacy may not be directly correlated with the pre‐challenge levels of serum antibodies, a finding which could be of great importance in assessing the potential effectiveness of pandemic influenza vaccines.     

Immunogenicity and Safety of Varying Dosages of a Monovalent 2009 H1N1 Influenza Vaccine Given With and Without AS03 Adjuvant System in Healthy Adults and Older Persons

Background.?Adjuvanted vaccines have the potential to improve influenza pandemic response. AS03 adjuvant has been shown to enhance the immune response to inactivated influenza vaccines. Methods.?This trial was designed to evaluate the immunogenicity and safety of an inactivated 2009 H1N1 influenza vaccine at varying dosages of hemagglutinin with and without extemporaneously mixed AS03 adjuvant system in adults ≥18 years of age. Adults were randomized to receive 2 doses of 1 of 5 vaccine formulations (3.75?μg, 7.5?μg, or 15?μg with AS03 or 7.5?μg or 15?μg without adjuvant). Results.?The study population included 544 persons <65 years of age and 245 persons ≥65 years of age. Local adverse events tended to be more frequent in the adjuvanted vaccine groups, but severe reactions were uncommon. In both age groups, hemagglutination inhibition antibody geometric mean titers after dose one were higher in the adjuvanted groups, compared with the 15?μg unadjuvanted group, and this difference was statistically significant for the comparison of the 15?μg adjuvanted group with the 15?μg unadjuvanted group. Conclusions.?AS03 adjuvant system improves the immune response to inactivated 2009 H1N1 influenza vaccine in both younger and older adults and is generally well tolerated. ClinicalTrials.gov NCT00963157.     

Genetic analysis of H3N2 influenza A viruses isolated in 2006–2007 in Nairobi,Kenya

Background Minimal influenza surveillance has been carried out in sub‐Saharan Africa to provide information on circulating influenza subtypes for the purpose of vaccine production and monitoring trends in virus spread and mutations. Objective The aim of this study was to investigate a surveillance program in Kenya to isolate and characterize influenza viruses. Results In the 2006–2007 influenza season, nine influenza A viruses were isolated. All were of H3N2 subtype with key amino acid (aa) changes indicating that they were more closely related to recent World Health Organization recommended vaccine strains than to older vaccine strains, and mirroring the evolution of circulating influenza A globally. Hemagglutination inhibition data showed that the 2006 Kenya isolates had titers identical to the 2005–2006 H3N2 vaccine strain but two‐ to threefold lower titers to the 2006–2007 vaccine strain, suggesting that the isolates were antigenic variants of the 2006–2007 vaccine strains. Analysis of aa substitutions of hemagglutinin‐1 (HA1) protein of the 2006 Kenyan viruses revealed unique genetic variations with several aa substitutions located at immunodominant epitopes of the HA1 protein. These mutations included the V112I change at site E, the K 173 E substitution at site D and N 278 K change at site C, mutations that may result in conformational change on the HA molecule to expose novel epitopes thus abrogating binding of pre‐existing antibodies at these sites. Conclusion Characterization of these important genetic variations in influenza A viruses isolated from Kenya highlights the importance of continuing surveillance and characterization of emerging influenza drift variants in sub‐Saharan Africa.     

Comparative immunogenicity and cross-clade protective efficacy of mammalian cell-grown inactivated and live attenuated H5N1 reassortant vaccines in ferrets

Continued H5N1 virus infection in humans highlights the need for vaccine strategies that provide cross-clade protection against this rapidly evolving virus. We report a comparative evaluation in ferrets of the immunogenicity and cross-protective efficacy of isogenic mammalian cell-grown, live attenuated influenza vaccine (LAIV) and adjuvanted, whole-virus, inactivated influenza vaccine (IIV), produced from a clade 1 H5N1 6:2 reassortant vaccine candidate (caVN1203-Len17rg) based on the cold-adapted A/Leningrad/134/17/57 (H2N2) master donor virus. Two doses of LAIV or IIV provided complete protection against lethal homologous H5N1 virus challenge and a reduction in virus shedding and disease severity after heterologous clade 2.2.1 H5N1 virus challenge and increased virus-specific serum and nasal wash antibody levels. Although both vaccines demonstrated cross-protective efficacy, LAIV induced higher levels of nasal wash IgA and reduction of heterologous virus shedding, compared with IIV. Thus, enhanced respiratory tract antibody responses elicited by LAIV were associated with improved cross-clade protection.     

Protective efficacy of crude virus‐like particle vaccine against HPAI H5N1 in chickens and its application on DIVA strategy

Background Currently, Asian lineage highly pathogenic avian influenza (HPAI) H5N1 has become widespread across continents. These viruses are persistently circulating among poultry populations in endemic regions, causing huge economic losses, and raising concerns about an H5N1 pandemic. To control HPAI H5N1, effective vaccines for poultry are urgently needed. Objective In this study, we developed HPAI virus‐like particle (VLP) vaccine as a candidate poultry vaccine and evaluated its protective efficacy and possible application for differentiating infected from vaccinated animals (DIVA). Methods Specific pathogen‐free chickens received a single injection of HPAI H5N1 VLP vaccine generated using baculovirus expression vector system. Immunogenicity of VLP vaccines was determined using hemagglutination inhibition (HI), neuraminidase inhibition (NI), and ELISA test. Challenge study was performed to evaluate efficacy of VLP vaccines. Results and Conclusions A single immunization with HPAI H5N1 VLP vaccine induced high levels of HI and NI antibodies and protected chickens from a lethal challenge of wild‐type HPAI H5N1 virus. Viral excretion from the vaccinated and challenged group was strongly reduced compared with a mock‐vaccinated control group. Furthermore, we were able to differentiate VLP‐vaccinated chickens from vaccinated and then infected chickens with a commercial ELISA test kit, which offers a promising strategy for the application of DIVA concept.     

Efficacy and safety of vaccination against pandemic 2009 influenza A (H1N1) virus among patients with rheumatic diseases

Objective

To assess the efficacy and safety of vaccination against pandemic H1N1 virus in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) compared with healthy controls.

Methods

The study population comprised 41 RA patients, 21 SLE patients, 17 PsA patients, 15 AS patients, and 25 healthy controls. All were vaccinated using the Novartis MF59‐adjuvanted H1N1v monovalent influenza vaccine. The immunogenicity of the vaccine was assessed on day 1 and again 4 weeks later by hemagglutination inhibition assay. Geometric mean titers and seroconversion rates were calculated for each group. The safety of the vaccine was evaluated using the 28‐joint Disease Activity Score (DAS28) for RA and PsA, the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI).

Results

The proportion of baseline protective levels of antibodies against H1N1 was similar in all but the AS group, in which it was lower. The geometric mean titers increased significantly in all 5 groups. A substantial proportion of patients and controls responded to the vaccine. The healthy controls demonstrated a better response than each of the other groups: 84% versus 56% for RA, 67% for SLE, 59% for PsA, and 53% for AS. Multivariate logistic regression analysis identified RA and PsA as parameters of significantly lower response. The DAS28, BASDAI, and SLEDAI remained unchanged after vaccination.

Conclusion

Vaccination against pandemic H1N1 using an adjuvanted H1N1v monovalent influenza is safe and induced an appropriate response in patients with RA, SLE, PsA, and AS.     

Pandemic influenza 1918 H1N1 and 1968 H3N2 DNA vaccines induce cross-reactive immunity in ferrets against infection with viruses drifted for decades

Please cite this paper as: Bragstad et al. (2010) Pandemic influenza 1918 H1N1 and 1968 H3N2 DNA vaccines induce cross‐reactive immunity in ferrets against infection with viruses drifted for decades. Influenza and Other Respiratory Viruses 5(1), 13–23. Background Alternative influenza vaccines and vaccine production forms are needed as the conventional protein vaccines do not induce broad cross‐reactivity against drifted strains. Furthermore, fast vaccine production is especially important in a pandemic situation, and broader vaccine reactivity would diminish the need for frequent change in the vaccine formulations. Objective In this study, we compared the ability of pandemic influenza DNA vaccines to induce immunity against distantly related strains within a subtype with the immunity induced by conventional trivalent protein vaccines against homologous virus challenge. Methods Ferrets were immunised by particle‐mediated epidermal delivery (gene gun) with DNA vaccines based on the haemagglutinin (HA) and neuraminidase (NA) and/or the matrix (M) and nucleoprotein genes of the 1918 H1N1 Spanish influenza pandemic virus or the 1968 H3N2 Hong Kong influenza pandemic virus. The animals were challenged with contemporary H1N1 or H3N2 viruses. Results We demonstrated that DNA vaccines encoding proteins of the original 1918 H1N1 pandemic virus induced protective cross‐reactive immune responses in ferrets against infection with a 1947 H1N1 virus and a recent 1999 H1N1 virus. Similarly, a DNA vaccine, based on the HA and NA of the 1968 H3N2 pandemic virus, induced cross‐reactive immune responses against a recent 2005 H3N2 virus challenge. Conclusions DNA vaccines based on pandemic or recent seasonal influenza genes induced cross‐reactive immunity against contemporary virus challenge as good as or superior to contemporary conventional trivalent protein vaccines. This suggests a unique ability of influenza DNA to induce cross‐protective immunity against both contemporary and long‐time drifted viruses.     

Protective effect of single-dose adjuvanted pandemic influenza vaccine in children

Please cite this paper as: Van Buynder et al. (2010) Protective effect of single-dose adjuvanted pandemic influenza vaccine in children. Influenza and Other Respiratory Viruses 4(4), 171–178. Background During the first wave of A/California/7/2009(H1N1) influenza, high rates of hospitalization in children under 5 years were seen in many countries. Subsequent policies for vaccinating children varied in both type of vaccine and number of doses. In Canada, children 36 months to <10 years received a single dose of 0·25 ml of the GSK adjuvanted vaccine (Arepanrix™) equivalent to 1·9 μg HA. Children 6 months to 35 months received two doses as did those 36–119 months with chronic medical conditions. Method We conducted a community-based case–control vaccine effectiveness (VE) review of children under 10 years with influenza like illness who were tested for H1N1 infection at the central provincial laboratory. Laboratory-confirmed influenza was the primary outcome, and vaccination status the primary exposure to assess VE after a single 0·25-ml dose. Results If vaccination was designated to be effective after 14 days, no vaccinated child had laboratory-confirmed influenza compared to 38% of controls. The VE of 100% was statistically significant for children <10 years of age and <5 years considered separately. If vaccination was considered effective after 10 days, VE dropped to 96% overall but was statistically significant and over 90% in all age subgroups, including those under 36 months. Conclusions A single 0·25-ml dose of the GSK adjuvanted vaccine (Arepanrix™) protects children against laboratory-confirmed pandemic influenza potentially avoiding any increased reactogenicity associated with second doses. Adjuvanted vaccines offer hope for improved seasonal vaccines in the future.     

Safety and immunogenicity of live attenuated influenza reassortant H5 vaccine (phase I–II clinical trials)

Objective Our studies aimed to evaluate in clinical trials the safety and immunogenicity of an H5 live influenza vaccine candidate obtained using classical reassortment techniques from a low pathogenicity avian influenza (LPAI) A/Duck/Potsdam/1402‐6/86(H5N2) virus and the cold‐adapted (ca) donor strain A/Leningrad/134/17/57(H2N2). Methods During Phase I–II clinical trials, volunteers received intranasally two doses of reassortant influenza vaccine strain A/17/Duck/Potsdam/86/92 (H5N2) 21 days apart. Clinical examination of all vaccinees was conducted 7 days post‐vaccination. Serum antibody responses were measured by hemagglutination‐inhibition and microneutralization and local antibodies were estimated using an enzyme‐linked immunosorbent assay test. Results The vaccine was safe and of low reactogenicity with no febrile reactions. After revaccination 47·1–54·8% of subjects showed ≥fourfold seroconversions of Hamagglutination inhibition (HAI) antibodies to the hemagglutinin (HA) antigen of the A/17/Duck/Potsdam/86/92 (H5N2) virus and 29·4–30·8% were seroconverted to the HA antigen of the reverse genetics reassortant A/Indonesia/05/2005 × PR8 IBCDC‐RG (H5N1). Virus‐neutralizing antibody levels in sera of volunteers were similar to those shown in HAI test. The virus‐specific nasal IgA antibody response after two vaccine doses demonstrated significant increases of ≥fourfold rise SIgA antibodies (65%) geometrical mean titers (16·0) and a rise in SIgA antibodies (2·8) compared with one dose. Conclusion The live attenuated influenza vaccine candidate prepared using the LPAI A(H5N2) strain was well tolerated and elicited serum and local immune responses. There was evident cross‐reactivity to the A(H5N1) strain in the HAI test.     

Live attenuated H5N1 vaccine with H9N2 internal genes protects chickens from infections by both Highly Pathogenic H5N1 and H9N2 Influenza Viruses

Please cite this paper as: Nang et al. (2013) Live attenuated H5N1 vaccine with H9N2 internal genes protects chickens from infections by both Highly Pathogenic H5N1 and H9N2 Influenza Viruses. Influenza and Other Respiratory Viruses 7(2) 120–131. Background The highly pathogenic H5N1 and H9N2 influenza viruses are endemic in many countries around the world and have caused considerable economic loss to the poultry industry. Objectives We aimed to study whether a live attenuated H5N1 vaccine comprising internal genes from a cold‐adapted H9N2 influenza virus could protect chickens from infection by both H5N1 and H9N2 viruses. Methods We developed a cold‐adapted H9N2 vaccine virus expressing hemagglutinin and neuraminidase derived from the highly pathogenic H5N1 influenza virus using reverse genetics. Results and Conclusions Chickens immunized with the vaccine were protected from lethal infections with homologous and heterologous H5N1 or H9N2 influenza viruses. Specific antibody against H5N1 virus was detected up to 11 weeks after vaccination (the endpoint of this study). In vaccinated chickens, IgA and IgG antibody subtypes were induced in lung and intestinal tissue, and CD4+ and CD8+ T lymphocytes expressing interferon‐gamma were induced in the splenocytes. These data suggest that a live attenuated H5N1 vaccine with cold‐adapted H9N2 internal genes can protect chickens from infection with H5N1 and H9N2 influenza viruses by eliciting humoral and cellular immunity.