Split-virion Influenza Vaccine Research Articles

Safety, immunogenicity and cross-reactivity of a Northern hemisphere 2013–2014 seasonal trivalent inactivated split influenza virus vaccine, Anflu®

ABSTRACTAnflu® is a seasonal trivalent inactivated split-virion influenza vaccine manufactured by Sinovac Biotech Co., Ltd. The objectives of this study were to evaluate the safety of Anflu® (2013–14 formulation: H1N1, H3N2 and BYAM) in infants and adults and its immunogenicity and cross-reactivity against mismatched influenza B lineage and avian influenza A(H7N9) viruses (hereafter BVIC and H7N9, respectively) in adults. In this phase IV open label trial, infants 6–35 months old (n=61) each received two injections with 28 days apart; adults 18–60 yrs old (n=60) and elderly >60 yrs old (n=61) each received one injection. Information of adverse events was collected through safety observation and follow-up visits. Pre- and post-immune blood samples (day 0 and 21) were collected from subjects ≥18 yrs old to detect hemagglutination inhibition antibody titers and calculate seroprotection rates (SPRs) and seroconversion rates (SCRs). The overall adverse reaction incidence was 1.6% (3/182), and no serious adverse event was reported during the study period. For subjects ≥18 yrs old, the SCRs, SPRs, and the geometric mean titers (GMTs) met the European criteria for all three strains. In addition, the point estimations of SCR, SPR and GMT for BVIC also met the European criteria. Six subjects were seroconverted against H7N9; however the serological results did not meet the European criteria. In conclusion, the results showed a satisfactory safety and immunogenicity profile of Anflu® and cross-reactivity against BVIC, but did not demonstrate cross-reactivity against H7N9 (Clinicaltrials.gov ID: NCT02269852).

Direct UV Spectrophotometry and HPLC Determination of Triton X-100 in Split Virus Influenza Vaccine.

One of the most commonly used surfactants in the production of split virus influenza vaccine is nonionic surfactant Triton X-100. After splitting of the virus is accomplished, Triton X-100 is removed from the vaccine by subsequent production steps. Because of toxicity of Triton X-100, which remains in the vaccine in residual amounts, a sufficiently sensitive method for its detection and quantification needs to be defined. Two methods for determination of Triton X-100 residuals were developed: the UV-spectrophotometry and HPLC methods. For both methods, preparation of vaccine samples and removal of proteins and virus particles were crucial: samples were treated with methanol (1:1) and then centrifuged at 25 000 × g for 30 min. After such treatment, the majority of vaccine components that interfered in the UV region were removed, and diluted samples could be directly measured. The chromatographic system included C18 column, step methanol gradient, and detection at 225 nm with a single peak of Triton X-100 at 12.6 min. Both methods were validated and gave satisfactory results for accuracy, precision, specificity, linearity, and robustness. LOQ was slightly lower for the HPLC method. Hence, it was shown that both methods are suitable for analysis of residual amounts of Triton X-100, with the advantages of the UV method being its simplicity and availability in most laboratories.

Immunogenicity and safety of a quadrivalent influenza vaccine in children and adolescents in Taiwan: A phase III open-label trial

Until recently, all seasonal influenza vaccines have been trivalent, containing strains A(H1N1), A(H3N2), and one of the two B strain lineages (Yamagata or Victoria), resulting in frequent mismatches between the circulating B strain lineage and that included in the vaccine. A quadrivalent, inactivated, split-virion influenza vaccine (IIV4) containing strains from both B lineages has been developed to address this. We performed an open-label phase III study to assess the immunogenicity and safety of the 2013–2014 Northern Hemisphere formulation of IIV4 in children and adolescents 9–17years of age in Taiwan. Participants were vaccinated with one dose of IIV4 by intramuscular or deep subcutaneous injection. Hemagglutinin inhibition (HAI) titers were measured before and 21days after vaccination. Solicited injection-site and systemic reactions were assessed for up to 7days after vaccination, and adverse events (AEs) were recorded until day 21. One hundred participants were included. Despite relatively high pre-vaccination titers, post-vaccination HAI titers increased for all four strains, with geometric mean ratios (day 21/day 0) of 2.29 for A(H1N1), 2.05 for A(H3N2), 3.33 for B/Massachusetts (Yamagata lineage), and 4.59 for B/Brisbane (Victoria lineage). Post-vaccination seroprotection rates were 99% for A(H3N2) and 100% for A(H1N1), B/Massachusetts, and B/Brisbane. Due to high pre-vaccination titers, rates of seroconversion/significant increase of HAI titer were relatively low at 24% for A(H1N1), 20% for A(H3N2), 39% for B/Massachusetts, and 48% for B/Brisbane. Injection-site pain (56%), myalgia (45%), and malaise (15%) were the most frequently reported solicited reactions, and most solicited reactions were mild or moderate. No treatment-related AEs, immediate unsolicited AEs, unsolicited non-serious injection-site AEs, grade 3 unsolicited AEs, or serious AEs were reported. In conclusion, this study showed that the 2013–2014 Northern Hemisphere formulation of the intramuscular IIV4 was immunogenic and well tolerated by children and adolescents 9–17years of age.

Investigation into alternative testing methodologies for characterization of influenza virus vaccine

The objective of this study was to explore various testing methodologies suitable for characterizing sedimented or agglomerated material. To model this, bioCSL's split influenza virus vaccine, Fluvax® was utilized. The investigation was conducted on 5 dispensed lots of commercially manufactured vaccine, formulated for the 2013 Southern Hemisphere season. Vaccine syringes were initially inspected by visual tests; the material was then aseptically pooled for characterization assessment by microscopy and several agglomeration assays. All syringes passed bioCSL's description test where any fine or large sized particles of sediment observed in the vaccine were resuspended upon shaking; inverted light microscopy verified that the sediment morphology was consistent with influenza vaccine. Electron microscopic examination of pooled vaccine material demonstrated the presence of typical influenza structures including split virus, virosomes, whole virus particles and agglomerates. An optical density turbidity assay revealed relatively high protein recoveries in the vaccine supernatant post-centrifugation treatment, thus indicative of a well-dispersed vaccine formulation. This was corroborated by particle sizing analysis using dynamic light scattering which generated reproducible volume particle size distributions of a polydisperse nature. Ultraviolet-visible absorbance profiles further confirmed the presence of some agglomerated material. Data from all methods demonstrated consistent results between all batches of vaccine. Therefore, this investigation revealed the suitability and usefulness of the various methodologies in characterizing the appearance of agglomerated vaccine material. It is suggested that such methods may be applicable and beneficial for the development of a wider spectrum of heterogeneous and agglomerated formulations to provide safe, efficacious and superior quality biopharmaceutical products.

Safety and immunogenicity of a quadrivalent intradermal influenza vaccine in adults

BackgroundAn intradermal (ID) trivalent split-virion influenza vaccine (IIV3-ID) (Fluzone® Intradermal, Sanofi Pasteur, Swiftwater, PA) has been available in the US since the 2011/2012 influenza season for adults aged 18–64 years. This study examined whether adding a second B-lineage strain affects immunogenicity and safety. MethodsThis randomized, double-blind, multicentre trial evaluated the immunogenicity and safety of an intradermal quadrivalent split-virion influenza vaccine (IIV4-ID) in adults 18–64 years of age in the US during the 2012–2013 influenza season. Participants were randomized 2:1:1 to receive a single injection of IIV4-ID, licensed IIV3-ID, or an investigational IIV3-ID containing the alternate B-lineage strain. Haemagglutination inhibition antibody titres were assessed in two-thirds of participants before vaccination and 28 days after vaccination. Results1672 participants were vaccinated with IIV4-ID, 837 with licensed IIV3-ID, and 846 with an investigational IIV3-ID. For all four vaccine strains, antibody responses to IIV4-ID were statistically non-inferior to the response to the IIV3-ID vaccines containing the matched strains. For both B strains, post-vaccination antibody responses to IIV4-ID were statistically superior to the responses to IIV3-ID lacking the corresponding B strain. Adverse events were similar for IIV4-ID and IIV3-ID. The most commonly reported solicited reactions were pain, pruritus, myalgia, headache, and malaise; and most were grade 1 or 2 and appeared and resolved within 3 days of vaccination. IIV4-ID was statistically non-inferior to the two pooled IIV3-ID vaccines for the proportions of participants with at least one grade 2 or 3 systemic reaction. ConclusionsAntibody responses to the IIV4-ID were non-inferior to IIV3-ID for the A and matched B strains and superior for the unmatched B strains. IIV4-ID was well tolerated without any safety concerns. IIV4-ID may help address an unmet need due to mismatched B strains in previous influenza vaccines.

Zanamivir versus trivalent split virus influenza vaccine: a pilot randomized trial.

BackgroundHealthcare workers may be exposed to people with respiratory viral infections more often than other working adults. Understanding the risk and the effectiveness of different preventive measures is of great importance.ObjectivesTo estimate adherence to prophylactic antiviral medication for a full influenza season, to the compare efficacy of antiviral prophylaxis to that of the seasonal influenza vaccine and to identify exposures that increase risk of acute respiratory illnesses (ARI) in healthy adults.MethodsParticipants were randomized 1:2 to receive the 2008–2009 influenza vaccine or daily prophylaxis with 10 mg of zanamivir during the season. Web-based questionnaires collected information on demographics, symptoms, exposures, medication use and side effects.ResultsSixty-four healthy adults were recruited in November 2008. Three of 40 active participants discontinued zanamivir due to side effects; the remaining 37 took >85% of scheduled doses for a median of 121 days. Symptomatic, laboratory-confirmed influenza was detected in one person randomized to zanamivir (2·5%) and 2/20 (10%) who received the vaccine (P = 0·25). Forty-seven participants reported 109 episodes of ARI. Factors associated with an ARI were exposure to a spouse (OR 7·2), child (OR 2·4) or patient (OR 2·0) with symptoms of an ARI in the previous 7 days.ConclusionsBreakthrough influenza infection occurred in both vaccinated participants and those receiving antiviral prophylaxis. Most adults were willing and able to comply with season-long prophylaxis. Report of recent exposure to family members and patients with an ARI increased the risk of developing an ARI in healthy adults.

Different arms of the adaptive immune system induced by a combination vaccine work in concert to provide enhanced clearance of influenza.

Current split influenza virus vaccines that induce strain-specific neutralising antibodies provide some degree of protection against influenza infection but there is a clear need to improve their effectiveness. The constant antigenic drift of influenza viruses means that vaccines are often not an exact match to the circulating strain and so levels of relevant antibodies may not be sufficiently high to afford protection. In the situation where the emergent influenza virus is completely novel, as is the case with pandemic strains, existing vaccines may provide no benefit. In this study we tested the concept of a combination vaccine consisting of sub-optimal doses of split influenza virus vaccine mixed with a cross-protective T-cell inducing lipopeptide containing the TLR2 ligand Pam2Cys. Mice immunised with combination vaccines showed superior levels of lung viral clearance after challenge compared to either split virus or lipopeptide alone, mediated through activation of enhanced humoral and/or additional cellular responses. The mechanism of action of these vaccines was dependent on the route of administration, with intranasal administration being superior to subcutaneous and intramuscular routes, potentially through the induction of memory CD8+ T cells in the lungs. This immunisation strategy not only provides a mechanism for minimising the dose of split virus antigen but also, through the induction of cross-protective CD8+ T cells, proves a breadth of immunity to provide potential benefit upon encounter with serologically diverse influenza isolates.

Antibody and cell-mediated immune response to whole virion and split virion influenza vaccine in patients with inflammatory bowel disease on maintenance immunosuppressive and biological therapy

Objective. Influenza vaccination is recommended for inflammatory bowel disease (IBD) patients on immunosuppressive therapy. The objective was to evaluate the antibody and cell-mediated immune response to the split and whole virion influenza vaccine in patients with IBD treated with anti-TNF-α and immunosuppressive therapy. Patients and methods.One hundred and fifty-six immunocompromised IBD patients were vaccinated. Fifty-three patients (control group) refused vaccination. Split virion vaccine and whole virion vaccine were used. Serum samples were obtained for pre- and postimmunization antibody titers to influenza vaccine (A/California/7/2009 [H1N1], A/Victoria/361/2011 [H3N2], B/Wisconsin/1/2010–like B/Hubei-Wujiagang/158/2009). Cell-mediated response was evaluated using an interferon (INF)-γ, interleukine (IL)-2 and tumor necrosis factor (TNF)-α ELISA. Results. Postimmunization titers of both influenza subtypes increased significantly after the administration of split virion vaccines compared to the controls and to those who received whole virion vaccine. The antibody titers of Influenza B also increased significantly in patients immunized with split vaccine and treated with anti-TNF-α therapy. After influenza vaccination, the level of serum IL-2 significantly decreased. No serious side effects developed occurred after influenza vaccination, and the influenza-like symptoms did not differ significantly between vaccinated versus control patients. The relapse of the disease was observed in only 10% of the patients and was more common in vaccinated than in control subjects. Conclusion. Split virion vaccines seem to be more effective than whole virion vaccines. Measuring the antibody responses is worthwhile in patients treated with immunosuppressants to determine the efficacy of influenza vaccination.

The Split Virus Influenza Vaccine rapidly activates immune cells through Fcγ receptors

Seasonal influenza vaccination is one of the most common medical procedures and yet the extent to which it activates the immune system beyond inducing antibody production is not well understood. In the United States, the most prevalent formulations of the vaccine consist of degraded or “split” viral particles distributed without any adjuvants. Based on previous reports we sought to determine whether the split influenza vaccine activates innate immune receptors—specifically Toll-like receptors. High-dimensional proteomic profiling of human whole-blood using Cytometry by Time-of-Flight (CyTOF) was used to compare signaling pathway activation and cytokine production between the split influenza vaccine and a prototypical TLR response ex vivo. This analysis revealed that the split vaccine rapidly and potently activates multiple immune cell types but yields a proteomic signature quite distinct from TLR activation. Importantly, vaccine induced activity was dependent upon the presence of human sera indicating that a serum factor was necessary for vaccine-dependent immune activation. We found this serum factor to be human antibodies specific for influenza proteins and therefore immediate immune activation by the split vaccine is immune-complex dependent. These studies demonstrate that influenza virus “splitting” inactivates any potential adjuvants endogenous to influenza, such as RNA, but in previously exposed individuals can elicit a potent immune response by facilitating the rapid formation of immune complexes.

Colocalization of Cell Death with Antigen Deposition in Skin Enhances Vaccine Immunogenicity

Vaccines delivered to the skin by microneedles – with and without adjuvants – have increased immunogenicity with lower doses than standard vaccine delivery techniques such as intramuscular (i.m.) or intradermal (i.d.) injection. However, the mechanisms behind this skin-mediated ‘adjuvant’ effect are not clear. Here, we show that the dynamic application of a microprojection array (the Nanopatch) to skin generates localized transient stresses invoking cell death around each projection. Nanopatch application caused significantly higher levels (~65-fold) of cell death in murine ear skin than i.d. injection using a hypodermic needle. Measured skin cell death is associated with modeled stresses ~1–10 MPa. Nanopatch-immunized groups also yielded consistently higher anti-IgG endpoint titers (up to 50-fold higher) than i.d. groups after delivery of a split virion influenza vaccine. Importantly, co-localization of cell death with nearby live skin cells and delivered antigen was necessary for immunogenicity enhancement. These results suggest a correlation between cell death caused by the Nanopatch with increased immunogenicity. We propose that the localized cell death serves as a ‘physical immune enhancer’ for the adjacent viable skin cells, which also receive antigen from the projections. This natural immune enhancer effect has the potential to mitigate or replace chemical-based adjuvants in vaccines.

Novel G3/DT adjuvant promotes the induction of protective T cells responses after vaccination with a seasonal trivalent inactivated split-virion influenza vaccine

Vaccines used against seasonal influenza are poorly effective against influenza A viruses of novel subtypes that may have pandemic potential. Furthermore, pre(pandemic) influenza vaccines are poorly immunogenic, which can be overcome by the use of adjuvants. A limited number of adjuvants has been approved for use in humans, however there is a need for alternative safe and effective adjuvants that can enhance the immunogenicity of influenza vaccines and that promote the induction of broad-protective T cell responses. Here we evaluated a novel nanoparticle, G3, as an adjuvant for a seasonal trivalent inactivated influenza vaccine in a mouse model. The G3 adjuvant was formulated with or without steviol glycosides (DT, for diterpenoid). The use of both formulations enhanced the virus-specific antibody response to all three vaccine strains considerably. The adjuvants were well tolerated without any signs of discomfort. To assess the protective potential of the vaccine-induced immune responses, an antigenically distinct influenza virus strain, A/Puerto Rico/8/34 (A/PR/8/34), was used for challenge infection. The vaccine-induced antibodies did not cross-react with strain A/PR/8/34 in HI and VN assays. However, mice immunized with the G3/DT-adjuvanted vaccine were partially protected against A/PR/8/34 infection, which correlated with the induction of anamnestic virus-specific CD8+ T cell responses that were not observed with the use of G3 without DT. Both formulations induced maturation of human dendritic cells and promoted antigen presentation to a similar extent. In conclusion, G3/DT is a promising adjuvant formulation that not only potentiates the antibody response induced by influenza vaccines, but also induces T cell immunity which could afford broader protection against antigenically distinct influenza viruses.

Superior in vitro stimulation of human CD8+ T-cells by whole virus versus split virus influenza vaccines.

Pandemic and seasonal influenza viruses cause considerable morbidity and mortality in the general human population. Protection from severe disease may result from vaccines that activate antigen-presenting DC for effective stimulation of influenza-specific memory T cells. Special attention is paid to vaccine-induced CD8+ T-cell responses, because they are mainly directed against conserved internal influenza proteins thereby presumably mediating cross-protection against circulating seasonal as well as emerging pandemic virus strains. Our study showed that influenza whole virus vaccines of major seasonal A and B strains activated DC more efficiently than those of pandemic swine-origin H1N1 and pandemic-like avian H5N1 strains. In contrast, influenza split virus vaccines had a low ability to activate DC, regardless which strain was investigated. We also observed that whole virus vaccines stimulated virus-specific CD8+ memory T cells much stronger compared to split virus counterparts, whereas both vaccine formats activated CD4+ Th cell responses similarly. Moreover, our data showed that whole virus vaccine material is delivered into the cytosolic pathway of DC for effective activation of virus-specific CD8+ T cells. We conclude that vaccines against seasonal and pandemic (-like) influenza strains that aim to stimulate cross-reacting CD8+ T cells should include whole virus rather than split virus formulations.

Analysis of genome integrity of influenza virus in formaldehyde-inactivated split vaccines

Although inactivated split-virus influenza vaccines are widely used to render protection against the viral infection, information regarding the effects of the vaccine preparation on the integrity of the viral genomes is currently very limited. In the present study, to gain insight into the physical and genetic alterations of RNA viral genomes in the course of the vaccine preparation, we analyzed the influenza virus A H1N1 hemagglutinin (HA) genome segment in a conventional split-virus influenza vaccine inactivated by formaldehyde, which encodes the major surface protein of the virus. The vaccine solutions were treated with proteinase K prior to RNA purification, and viral genomic RNA was successfully retrieved up to almost eightfold higher than samples without the treatment. Despite the high yield, no full-length bands of the influenza viral genomes were identifiable upon electrophoresis due to severe degradation. Interestingly, however, we were able to amplify a variety of genomic regions including a fragment covering the full-length HA gene using cDNA. Furthermore, sequencing of a series of the fragments for confirmation revealed that the rate of base alteration of the gene in the vaccine was approximately 0.1 %, which is comparable to the spontaneous error rate occurring during PCR. We next constructed a GST expression vector carrying the full-length HA fragment cloned from the vaccine and confirmed that the correct size of the expected GST-fused HA protein was expressed. Taken together, these results demonstrate that a full-length HA RNA genome fragment with comparatively intact sequence information may exist in the inactivated split-virus vaccine. Therefore, these experimental findings on the properties of the HA RNA in the influenza vaccine, may contribute to cautious use of the vaccine in a variety of research areas and protocols.

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

BackgroundPatient-reported outcomes (PROs) are particularly relevant in influenza vaccine trials in the elderly where reduction in symptom severity could prevent illness-related functional impairment.ObjectivesTo evaluate PROs in people aged ≥65 years receiving two different vaccines.MethodsThis was a phase III, randomised, observer-blind study (NCT00753272) of the AS03-adjuvanted inactivated trivalent split-virion influenza vaccine (AS03-TIV) versus non-adjuvanted vaccine (TIV). Using the FluiiQ questionnaire, symptom (systemic, respiratory, total) and life impact (activities, emotions, relationships) scores were computed as exploratory endpoints, with minimal important difference (MID) in influenza severity between vaccines considered post-hoc as >7%. Vaccine efficacy of AS03-TIV relative to TIV in severe influenza (hospitalisation, complication, most severe one-third of episodes based on the area under the curve for systemic symptom score) was calculated post-hoc. The main analyses (descriptive) were conducted in the according-to-protocol cohort (n = 280 AS03-TIV, n = 315 TIV) for influenza confirmed by culture or reverse transcriptase polymerase chain reaction.ResultsMean systemic symptom, total symptom and impact on activities scores were lower with AS03-TIV versus TIV. Mean respiratory symptom, impact on emotions and impact on relationships scores were similar. Influenza tended to be less severe with AS03-TIV, but the MID was reached only for impact on activities (mean 9·0%). Relative vaccine efficacy in severe influenza was 29·38% (95% CI: 7·60–46·02).ConclusionsAS03-TIV had advantages over TIV in impact on systemic symptoms and activities as measured by the FluiiQ in elderly people. Higher efficacy of AS03-TIV relative to TIV was shown for prevention of severe illness.

P557 Antibody and cell-mediated immune response to whole virion and split virion influenza vaccine in patients with inflammatory bowel disease on maintenance immunosuppressive and biological therapy

Objective. Influenza vaccination is recommended for inflammatory bowel disease (IBD) patients on immunosuppressive therapy. The objective was to evaluate the antibody and cell-mediated immune respo...

Effectiveness and safety of seasonal influenza vaccination in children with underlying respiratory diseases and allergy.

Influenza causes acute respiratory infections and various complications. Children in the high-risk group have higher complication and hospitalization rates than high-risk elderly individuals. Influenza prevention in children is important, as they can be a source infection spread in their communities. Influenza vaccination is strongly recommended for high-risk children with chronic underlying circulatory and respiratory disease, immature infants, and children receiving long-term immunosuppressant treatment or aspirin. However, vaccination rates in these children are low because of concerns regarding the exacerbation of underlying diseases and vaccine efficacy. To address these concerns, many clinical studies on children with underlying respiratory diseases have been conducted since the 1970s. Most of these reported no differences in immunogenicity or adverse reactions between healthy children and those with underlying respiratory diseases and no adverse effects of the influenza vaccine on the disease course. Further to these studies, the inactivated split-virus influenza vaccine is recommended for children with underlying respiratory disease, in many countries. However, the live-attenuated influenza vaccine (LAIV) is not recommended for children younger than 5 years with asthma or recurrent wheezing. Influenza vaccination is contraindicated in patients with severe allergies to egg, chicken, or feathers, because egg-cultivated influenza vaccines may contain ovalbumin. There has been no recent report of serious adverse events after influenza vaccination in children with egg allergy. However, many experts recommend the trivalent influenza vaccine for patients with severe egg allergy, with close observation for 30 minutes after vaccination. LAIV is still not recommended for patients with asthma or egg allergy.

Preclinical evaluation of Vaxfectin®-adjuvanted Vero cell-derived seasonal split and pandemic whole virus influenza vaccines

Increasing the potency and supply of seasonal and pandemic influenza vaccines remains an important unmet medical need which may be effectively accomplished with adjuvanted egg- or cell culture-derived vaccines. Vaxfectin®, a cationic lipid-based adjuvant with a favorable safety profile in phase 1 plasmid DNA vaccines trials, was tested in combination with seasonal split, trivalent and pandemic whole virus, monovalent influenza vaccines produced in Vero cell cultures. Comparison of hemagglutination inhibition (HI) antibody titers in Vaxfectin®-adjuvanted to nonadjuvanted vaccinated mice and guinea pigs revealed 3- to 20-fold increases in antibody titers against each of the trivalent influenza virus vaccine strains and 2- to 8-fold increases in antibody titers against the monovalent H5N1 influenza virus vaccine strain. With the vaccine doses tested, comparable antibody responses were induced with formulations that were freshly prepared or refrigerated at conventional 2–8°C storage conditions for up to 6 mo. Comparison of T-cell frequencies measured by interferon-gamma ELISPOT assay between groups revealed increases of between 2- to 10-fold for each of the adjuvanted trivalent strains and up to 22-fold higher with monovalent H5N1 strain. Both trivalent and monovalent vaccines were easy to formulate with Vaxfectin® by simple mixing. These preclinical data support further testing of Vaxfectin®-adjuvanted Vero cell culture vaccines toward clinical studies designed to assess safety and immunogenicity of these vaccines in humans.

Immunogenicity and Safety of an Inactivated Trivalent Split Influenza Virus Vaccine in Young Children with Recurrent Wheezing

Influenza virus vaccination is recommended for children, but so far, active vaccination has not been achieved because most parents lack knowledge of vaccine safety and many doctors are reluctant to administer vaccine due to concerns that steroids might alter immunogenicity. The aim of this study was to compare the immunogenicity and safety of inactivated trivalent split influenza virus vaccine between children with recurrent wheezing and healthy children of the same age group. Sixty-eight healthy children and 62 children with recurrent wheezing took part in this study. Seroconversion rates, seroprotection rates, geometric mean titers (GMTs), and geometric mean titer ratios (GMTRs) were measured by a hemagglutination inhibition assay for the assessment of immunogenicity. Solicited and unsolicited local and systemic adverse events were measured for the assessment of safety. Regarding immunogenicity, the seroconversion and seroprotection rates showed no difference overall between healthy children and children with recurrent wheezing. Also, no difference was observed between steroid-treated and nontreated groups with recurrent wheezing. Generally, the GMTs after vaccination were higher in the one-dose vaccination groups for healthy children and children with recurrent wheezing, but the GMTRs revealed different results according to strain in the two groups. Regarding safety, solicited local and systemic adverse events showed no differences between healthy children and children with recurrent wheezing. This study demonstrates that inactivated split influenza virus vaccine is able to induce protective immune responses in healthy children, as observed in previous studies, as well as in children with recurrent wheezing who require frequent steroid treatment.

Expression of hBD-2 induced by 23-valent pneumococcal polysaccharide vaccine, Haemophilus influenzae type b vaccine and split influenza virus vaccine

Human β-defensin-2 (hBD-2) is an antimicrobial peptide with high activity and broad spectrum activity. hBD-2 expression may be highly elevated by microorganisms and inflammation. We reported that the majority of common vaccines used, including 23-valent pneumococcal polysaccharide vaccine, Haemophilus influenzae type b vaccine and split influenza virus vaccine, could induce the expression of hBD-2 in epithelial cells. Among them, the 23-valent pneumococcal polysaccharide vaccine was effective at a lower concentration (0.5 µg/ml), while Haemophilus influenzae type b vaccine and split influenza virus vaccine were effective at the concentration of 1 µg/ml. However, bacteriostatic experiments revealed that the split influenza virus vaccine was capable of inducing the highest antimicrobial activity. The medium of the 23-valent pneumococcal polysaccharide vaccine treatment group had a higher antimicrobial activity than the medium of the Haemophilus influenzae type b vaccine treatment group. The transcriptional regulator of hBD-2, that is, the NF-κB subunit, had a high level of activity, while the normal epithelial cells showed barely detectable activity, indicating that these vaccines have potential for clinical application.

Intanza® 15 mcg intradermal influenza vaccine elicits cross-reactive antibody responses against heterologous A(H3N2) influenza viruses

The aim of the present study was to explore the ability of Intanza® 15μg, the intradermal (ID) trivalent inactivated split-virion influenza vaccine containing 15μg hemagglutinin per strain, to enhance the antibody responses against heterologous circulating H3N2 strains in adults 60 years and older. During the 2006–2007 influenza season, subjects aged 60 years or older were randomly assigned to receive one dose of ID or an intramuscular (IM, Vaxigrip®) influenza vaccine, which contained the reassortant A/Wisconsin/67/05(H3N2) strain as the H3N2 component. Antibody responses were assessed against the homologous vaccine strain, against the A/Brisbane/10/07(H3N2) reassortant strain and against four heterologous H3N2 field isolates (A/Genoa/62/05(H3N2), A/Genoa/3/07(H3N2), A/Genoa/2/07(H3N2), A/Genoa/3/06(H3N2)). The viruses tested belonged to three different clades that were closely related antigenically to A/California/7/04(H3N2), A/Nepal/921/06(H3N2) and A/Brisbane/10/07(H3N2). Antibody responses to these viruses were measured in 25 subjects per group using both haemagglutination inhibition (HI) and neutralization (NT) assays.At least one Committee for Medicinal Products for Human Use (CHMP) immunogenicity criteria for vaccine approval in the elderly was reached by both vaccines against all the viruses used in the study. All three CHMP criteria were reached against A/California/7/04(H3N2)-like, A/Nepal/921/06(H3N2)-like and A/Brisbane/10/07(H3N2)-like viruses by Intanza® 15μg ID vaccine, while IM vaccination did not meet seroprotection criteria against circulating A/Nepal/921/06(H3N2)-like and A/Brisbane/10/07(H3N2)-like viruses or seroconversion criteria against A/Brisbane/10/07(H3N2)-like viruses.Post-vaccination HI titer, seroconversion, and seroprotection rates were higher against all viruses in subjects who received Intanza® 15μg. The superiority of the seroprotection rate against the A/Nepal/921/06(H3N2)-like strain attained statistical significance despite the small sample size.Upon Beyer correction for pre-vaccination status, post-immunization HI titers against A/California/7/04(H3N2)-like and A/Brisbane/10/07(H3N2)-like strains and NT post-immunization titers against A/Wisconsin/67/05(H3N2), A/California/7/04(H3N2)-like, A/Brisbane/10/07(H3N2)-like strains were significantly higher in subjects immunized with Intanza® 15μg than in individuals receiving IM vaccine.This study, although limited in the size of study population, demonstrated the broader immune response elicited by an ID influenza vaccine vs. a standard IM influenza vaccine against heterologous viruses including field isolates.