Littérature scientifique sur le sujet « MF59 adjuvant prepandemic vaccination »

ABSTRACT Immunogenicity and safety of a booster dose of an MF59-adjuvanted H5N1 vaccine containing 7.5 μg A/turkey/Turkey/1/2005-like (clade 2.2) H5N1 hemagglutinin, given approximately 18 months after primary vaccination with a heterologous strain, were evaluated. The booster vaccine was well tolerated and induced a robust, cross-reactive immune response.

ABSTRACTPreparedness against an A/H5N1 influenza pandemic requires well-tolerated, effective vaccines which provide both vaccine strain-specific and heterologous, cross-clade protection. This study was conducted to assess the immunogenicity and safety profile of an MF59-adjuvanted, prepandemic influenza vaccine containing A/turkey/Turkey/01/2005 (H5N1) strain viral antigen. A total of 343 participants, 194 adults (18 to 60 years) and 149 elderly individuals (≥61 years), received two doses of the investigational vaccine given 3 weeks apart. Homologous and heterologous antibody responses were analyzed by hemagglutination inhibition (HI), single radial hemolysis (SRH), and microneutralization (MN) assays 3 weeks after administration of the first vaccine dose and 3 weeks and 6 months after the second dose. Immunogenicity was assessed according to European licensure criteria for pandemic influenza vaccines. After two vaccine doses, all three European licensure criteria were met for adult and elderly subjects against the homologous vaccine strain, A/turkey/Turkey/1/2005, when analyzed by HI and SRH assays. Cross-reactive antibody responses were observed by HI and SRH analyses against the heterologous H5N1 strains, A/Indonesia/5/2005 and A/Vietnam/1194/2004, in adult and elderly subjects. Solicited local and systemic reactions were mostly mild to moderate in severity and occurred less frequently in the elderly than in adult vaccinees. In both adult and elderly subjects, MF59-adjuvanted vaccine containing 7.5 μg of A/Turkey strain influenza virus antigen was highly immunogenic, well tolerated, and able to elicit cross-clade, heterologous antibody responses against A/Indonesia and A/Vietnam strains 6 weeks after the first vaccination.

ABSTRACTHaving previously demonstrated the feasibility of administering A/H5N1 and seasonal influenza vaccine antigens in an MF59-adjuvanted tetravalent formulation, we now report on long-term antibody persistence and responses to a booster dose of a combined seasonal-pandemic, tetravalent influenza vaccine in adults. The primary objective was the evaluation of responses to a booster dose of tetravalent influenza vaccine containing seasonal (A/H1N1, A/H3N2, and B) and avian (A/H5N1, clade 2) influenza virus strains administered to 265 healthy 18- to 40-year-old volunteers 1 year after priming with one or two clade 1 A/H5N1 doses. Secondary objectives were assessment of reactogenicity, safety, and antibody persistence 1 year after priming with a combined seasonal-pandemic, tetravalent vaccine. Responses to seasonal strains met all European licensure criteria; seroprotection rates were 94 to 100%, 100%, and 61 to 90% for A/H1N1, A/H3N2, and B strains, respectively. Anamnestic responses were observed against homologous and heterologous A/H5N1 strains whether priming with one or two A/H5N1 doses, with a monovalent A/H5N1 vaccine, or with a tetravalent vaccine. A single dose of MF59-adjuvanted A/H5N1 vaccine given alone or as part of a fixed combination with a seasonal influenza vaccine was sufficient to prime adult subjects, resulting in robust antigen-specific and cross-reactive antibody responses to heterologous booster immunization 1 year later. These data support the feasibility of incorporating prepandemic priming into seasonal influenza vaccination programs. (This study has been registered at clinicaltrials.gov under registration no. NCT00481065.)

There is a need to identify and select new promising immunodominant antigens that have the ability to provide protective immunity againstE. colicausing bovine mastitis. Recently we showed thatf17awas found to be the most prevalent and crucial virulent factor among the pathogenicE. coliisolated from bovine mastitis. Here, in this report, the recombinant F17A based subunit vaccine adjuvant with MF59 was tested for immunogenicity againstE. coliin a murine model. The vaccinated mice did not show any abnormal behavioral changes and histopathological lesions after vaccination. The specific antibody level against F17A was significantly higher in MF59-adjuvant-group, and also lasted for longer duration with a significant(P<0.01)production level of IgG1 and IgG2a. Moreover, we noted higher survival rate in mice injected with F17A-MF59-adjuvant group after challenging with the clinicalE. colistrain.Our findings of bacterial clearance test revealed that elimination rate from liver, spleen, and kidney in MF59-adjuvant-group was significantly higher than the control group. Finally, the proportion of CD4+T cells was increased, while CD8+ was decreased in MF59-adjuvant group. In conclusion, the current study reveals the capability of F17A-MF59 as a potential vaccine candidate against pathogenicE. colicausing mastitis in dairy animals.

ABSTRACT Squalene is a naturally occurring oil which has been used in the development of vaccine adjuvants, such as the oil-in-water emulsion MF59. In past years, by use of noncontrolled and nonvalidated assays, a claim was made that antisqualene antibodies were detectable in the sera of individuals with the so-called Gulf War syndrome. Using a validated enzyme-linked immunosorbent assay for the quantitation of immunoglobulin G (IgG) and IgM antibodies against squalene, we demonstrated that antisqualene antibodies are frequently detectable at very low titers in the sera of subjects who were never immunized with vaccines containing squalene. More importantly, vaccination with a subunit influenza vaccine with the MF59 adjuvant neither induced antisqualene antibodies nor enhanced preexisting antisqualene antibody titers. In conclusion, antisqualene antibodies are not increased by immunization with vaccines with the MF59 adjuvant. These data extend the safety profile of the MF59 emulsion adjuvant.

Poloxamer-188 (P188) is a nonionic triblock linear copolymer that can be used as a pharmaceutical excipient because of its amphiphilic nature. This study investigated whether P188 can act as an adjuvant to improve the immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain (RBD) subunit vaccine. BALB/c mice were vaccinated twice with the RBD antigen alone or in combination with P188 or MF59 (a commercial adjuvant for comparison purposes). The resulting humoral and cellular immunity were assessed. Results showed that P188 helped elicit higher neutralizing activity than MF59 after vaccination. P188 induced significant humoral immune response, along with type 1 T helper (Th1) and type 2 T helper (Th2) cellular immune response when compared with MF59 due to repressing p38MAPK phosphorylation. Furthermore, P188 did not result in adverse effects such as fibrosis of liver or kidney after vaccination. In conclusion, P188 is a novel adjuvant that may be used for safe and effective immune enhancement of the SARS-CoV-2 RBD antigen.

AbstractAdjuvants are substances that enhance adaptive immune responses when formulated in a vaccine. Alum and MF59 are two vaccine adjuvants licensed for human vaccination. Their mode of action has not been completely elucidated. Here we show the first ultrastructural visualization of Alum and MF59 interaction with immune cells in vitro and in vivo. We observed that Alum is engulfed by cells as inclusions of laminae that are detectable within draining lymph nodes. MF59 is instead engulfed by cells in vitro as low-electron-dense lipid-like inclusions that display a vesicle pattern, as confirmed by confocal microscopy using fluorescently labeled MF59. However, lipid-like inclusions with different high- and low-electron-dense content are detected within cells of draining lymph nodes when injecting MF59. As high-electron-dense lipid-like inclusions are also detected upon injection of Alum, our results suggest that the low-electron-dense inclusions are formed by engulfed MF59, whereas the high-electron-dense inclusions are proper lipid inclusions. Thus, we demonstrated that vaccine adjuvants are engulfed as inclusions by lymph node cells and hypothesize that adjuvant treatment may modify lipid metabolism.

Key Points Vaccination against influenza, with and without the adjuvant MF59, decreases the risk of inhibitor development in HA mice. Decreased FVIII immunogenicity may be attributed to antigenic competition via T-cell chemotaxis toward the site of vaccination.

ABSTRACTCD4+T cells play a central role in orchestrating adaptive immunity. To better understand the roles of CD4+T cells in the effects of adjuvants, we investigated the efficacy of a T-dependent influenza virus split vaccine with MF59 or alum in CD4 knockout (CD4KO) and wild-type (WT) mice. CD4+T cells were required for the induction of IgG antibody responses to the split vaccine and the effects of alum adjuvant. In contrast, MF59 was found to be highly effective in raising isotype-switched IgG antibodies to a T-dependent influenza virus split vaccine in CD4KO mice or CD4-depleted WT mice equivalent to those in intact WT mice, thus overcoming the deficiency of CD4+T cells in helping B cells and inducing immunity against influenza virus. Vaccination with the MF59-adjuvanted influenza virus vaccine was able to induce protective CD8+T cells and long-lived antibody-secreting cells in CD4KO mice. The effects of MF59 adjuvant in CD4KO mice might be associated with uric acid, inflammatory cytokines, and the recruitment of multiple immune cells at the injection site, but their cellularity and phenotypes were different from those in WT mice. These findings suggest a new paradigm of CD4-independent adjuvant mechanisms, providing the rationales to improve vaccine efficacy in infants, the elderly, immunocompromised patients, as well as healthy adults.IMPORTANCEMF59-adjuvanted influenza vaccines were licensed for human vaccination, but the detailed mechanisms are not fully elucidated. CD4+T cells are required to induce antibody isotype switching and long-term memory responses. In contrast, we discovered that MF59 was highly effective in inducing isotype-switched IgG antibodies and long-term protective immune responses to a T-dependent influenza vaccine independent of CD4+T cells. These findings are highly significant for the following reasons: (i) MF59 can overcome a defect of CD4+T cells in inducing protective immunity to vaccination with a T-dependent influenza virus vaccine; (ii) a CD4-independent pathway can be an alternative mechanism for certain adjuvants such as MF59; and (iii) this study has significant implications for improving vaccine efficacies in young children, the elderly, and immunocompromised populations.

Abstract Peptide vaccines are an ideal strategy to induce cross-protective T cell immunity against a broad range of influenza virus strains, but they are subimmunogenic and tend to induce regulatory T (Treg) cells. Our previous study has shown that adjuvanted peptide vaccines can suppress the development of antigen-specific Treg cells. MF59 is the first oil-in-water adjuvant approved for protein-based influenza vaccine, which enhances humoral and Th2 cellular immune responses. However, the role of MF59 in peptide-based vaccines regarding the induction of T cell immunity is unknown. We thus investigated the effects of MF59-adjuvanted peptide vaccines on antigen-specific T cell immunity against influenza virus infection. Using OT-I and OT-II TCR transgenic T cells, we found that the MF59-adjuvanted cognate OVA peptide vaccines induced a significant portion of OT-II Treg cells in primary immunization. However, MF59-adjuvanted peptide vaccine could prevent the expansion of pre-existing antigen-specific Treg cells. Of note, primary influenza virus infection induced a negligible portion of antigen-specific Treg cells, but secondary influenza virus infection drove the expansion of pre-existing Treg cells. Interestingly, swapping of the sequential immunizations with MF59-peptide vaccination and influenza virus infection resulted in very different levels of antigen-specific Treg cells, suggesting that the first immunization experience affects the development of antigen-specific Treg cells. Finally, MF59-peptide vaccines stimulated the production of IFN-γ and TNF-α of CD4 and CD8 T cells. In conclusion, MF59-peptide vaccine exhibits a unique feature in stimulation of antigen-specific T cell immunity.

Annual influenza A infections affect 5-15% of the population, causing an estimate half million deaths per year worldwide, with the majority of the severe diseases in infants, elderly and immunocompromised individuals. Influenza viruses infect the epithelium of the upper and lower respiratory tracts, typically resulting in an abrupt onset of illness, that usually includes fever, myalgias, upper respiratory tract congestion and pharyngytis. These symptoms persist for approximately one week; pneumonia is a frequent manifestation of more severe infection, while myocarditis, encephalitis and other extra respiratory tract disease occur more ralely. Influenza viruses belongs to Orthomixoviridae family, are enveloped negative single stranded RNA virus able to infect a wide range of avian and mammalian species. The genome of influenza A virus is composed of eight segments that encode for at least ten proteins. Influenza A viruses are subdivided further into subtypes based on their two surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), and currently, 16 known types of HA and 9 known types of NA have been isolated from aquatic birds, the natural reservoir for all influenza viruses. Haemagglutinin (HA) and neuraminidase (NA) are the primary targets of influenza vaccines but also the viral surface glycoproteins that accumulate the highest number of mutations. Haemagglutinin, the most abundant surface glycoprotein, directs binding and viral entry into host cells whereas neuraminidase, the second most abundant surface glycoprotein, cleaves sialic acid and plays important roles in viral entry and release. Influenza vaccination is the most effective method for preventing influenza virus infection and its potentially severe complications. Natural infection and vaccination elicit long lasting protective responses, nevertheless influenza vaccines are modified yearly due to the high propensity of the virus to mutate. Minor mutations, antigenic drift, occur continuously due to the low fidelity of the RNA polymerase and support the need for yearly changes in vaccine strains. Major modifications in the virus, antigenic shift, arise from viral re-assortments, occur more rarely, but represent a major challenge for public health since they can give rise to novel viruses for which the human population has little or no immunity. The latter scenario creates the risk of a pandemic infection similar to the Spanish flu pandemic (1918-1920) resulting in more than 40 million deaths worldwide and to the Asian flu (1957) and the Hong Kong Flu (1968) resulting in 1-4 million deaths. Occasionally, avian influenza A virus cross the species barrier into human and a pandemic may arise if such viruses have the ability to spread efficiently from human to human. In 1997, the increase in outbreaks of highly pathogenic avian influenza (HPAI) in poultry and the occasional transmission of these viruses to humans has caused great concern for the emergence of a new influenza A virus pandemics. Since then HPAI H5N1 viruses have continued to circulate in Asia and 400 human cases have been reported with a fatal outcome of 60%. Protection from avian H5N1 influenza virus could be achieved by vaccines capable of eliciting sustained and broadly cross-reactive immune responses. All clinical studies so far have shown the need for two doses of adjuvanted pre-pandemic flu vaccines to achieve potentially protective neutralizing antibody titers against avian H5N1 Vietnam. Two doses of avian influenza vaccines formulated with a strong adjuvant such as MF59 are required to induce potentially protective titers of neutralizing antibodies broadly reactive to drifted H5 strains. In addition all clinical studies have shown in influenza a limited efficacy of alum compared to oil in water emulsions, such as MF59, an adjuvant with excellent safety record licensed from more than a decade for seasonal flu vaccines in Europe. Those studies also showed that years after priming even if antibodies become undetectable the immune-response can be efficiently boosted in subjects that received a successful priming regimen. Such considerations support a prime boost strategy based on 1 or 2 immunizations for “pre pandemic vaccination” followed by a “booster dose” at the start of the pandemic outbreak. A drawback to this strategy is the lack of early markers capable of predicting the proportion of the population that develops a memory response after pre pandemic vaccination, information currently deduced only post hoc based on the response to the booster dose. To identify an early marker of effective pre pandemic priming we analyzed both the antibody and cell mediated responses in a prime boost clinical trial. We conducted a phase II study wherein healthy adults received 2 doses of a subunit H5N1 A/Vietnam/1194/2004 vaccine as “pre pandemic vaccination”, followed at 6 months by a 3rd booster dose. The vaccine was either plain (Non Adj 15) or adjuvanted with MF59 (MF59 H5N1), an oil/water proprietary adjuvant used in seasonal flu vaccines since 1997. We found that one dose of MF59 H5N1 vaccine is sufficient to expand CD4+ T lymphocytes with a Th1-prone effector/memory phenotype; whereas 2 doses are required to expand the pool of H5N1 memory B cells and to elicit high titers of neutralizing antibodies. Strikingly, a 3 fold increase in total H5 specific CD4+ T cells after the 1st dose predicts the rise of MN antibodies to titers ≥80 after booster immunization and their persistence at 6 months with 75% and 85% accuracy, respectively. We suggest that, if confirmed on a larger number of subjects, CD4+ T cell priming can be used as early measure of vaccine efficacy and can help screen different pre-pandemic vaccine formulations for their ability to induce immune-memory.

Vaccines are the most effective agents to control infections [1]. In addition to the pathogen antigens, vaccines contain adjuvants that are used to enhance the specific immune responses. Despite their effectiveness and their wide use, the mechanism of action of many adjuvants is poorly characterized [2]. Therefore, adjuvant research is crucial to better understand how they work and to exploit their full potential in vaccinology [3]. Release of endogenous danger signals has been linked to adjuvanticity, however the role of extracellular ATP during vaccination has never been explored. Extracellular ATP can work as "danger signal" and, as such is a strong modulator of immune responses [4-6]. Here, we tested whether ATP release is involved in the immune boosting effect of four common adjuvants: aluminium hydroxide, calcium phosphate (CaPi), incomplete Freund’s adjuvant (IFA) and the squalene-based oil in water emulsion MF59. Experiments were performed ex vivo in excised mice muscles (tibialis anterior and quadriceps) and in vivo in live mice injected with the reporter system luciferase-luciferin that reports on ATP changes. We found that intramuscular injection in general is always associated to a weak transient release of ATP. In contrast, a greatly enhanced ATP release was found upon injection of MF59 but not by all other adjuvants tested. Therefore, we wanted to dissect whether and how ATP release would contribute to the activity of MF59. The strong adjuvanticity of MF59 [7-8] has been ascribed to its capability to induce an immunocompetent environment in the muscle, characterized by a rapid and transient influx of a large number of immune cells participating in antigen uptake and transport to draining lymph nodes [9-11]. We found that the local injection of apyrase, an ATP-hydrolyzing enzyme, reduced the immune cells recruitment induced by MF59 but not by alum or IFA. These findings indicated that the ability of MF59 to induce migration of different immune cells into the injected muscle is partly due to induced ATP release. Moreover, co-injection of apyrase and MF59 at the muscle injection site reduces the number of antigen positive cells in the draining lymph nodes in a cell type-specific manner. Indeed, co-injection of apyrase negatively impacts the number of antigen positive B cells induced by MF59, suggesting that B cells could be a key component in ATP-mediated signaling during vaccination. Strong innate immune responses lead to enhanced adaptive immune responses [12]. Accordingly, we compared the impact of MF59-induced ATP release on T cells responses and antibody titers. Groups of mice were immunized with an experimental trivalent influenza vaccine (TIV) either as plain antigens or together with MF59 with or without apyrase. Apyrase strongly inhibited influenza specific T cell responses, total IgG and hemagglutination inhibition titers in response to an MF59-adjuvanted trivalent influenza vaccine. These data demonstrate that a transient ATP release is required for innate and adaptive immune responses induced by MF59 and link for the first time extracellular ATP to an enhanced response to vaccination.
I vaccini rappresentano senza dubbio l’arma più efficace per combattere e tenere sotto controllo le infezioni [1]. In aggiunta agli antigeni del patogeno, i vaccini contengono adiuvanti utilizzati per potenziare le risposte immunitarie specifiche verso determinati antigeni. Nonostante la loro efficacia e il loro largo uso, il meccanismo di azione di molti adiuvanti è ancora scarsamente caratterizzato [2]. Pertanto, far luce sui meccanismi d’azione degli adiuvanti vaccinali è fondamentale per sviluppare prodotti nuovi, più efficienti e sicuri, e poter così sfruttare appieno il potenziale della vaccinologia [3]. Dopo la vaccinazione, è stato osservato al sito di iniezione il rilascio locale di molecole endogene con la capacità di segnalare “danno” al sistema immunitario, note come allarmine. Per esempio, un rilascio locale di acido urico e DNA è stato osservato nel modello murino dopo vaccinazione con alum, il più diffuso tra gli adiuvanti approvati per uso sull’uomo. Tuttavia, finora non è mai stato esplorato un potenziale ruolo dell’ATP durante la vaccinazione. L’ATP, tra le sue tante funzioni, quando rilasciato nell’ambiente extracellulare in concentrazioni opportune può fungere da allarmina e, come tale è un forte modulatore delle risposte immunitarie [4-6]. Pertanto, in questo lavoro abbiamo indagato se un rilascio di ATP è coinvolto nel meccanismo d’azione di quattro comuni adiuvanti vaccinali: idrossido di alluminio (alum), calcio fosfato (CaPi), adiuvante incompleto di Freund (IFA) e MF59. Sono stati condotti esperimenti ex vivo su muscoli murini isolati (tibiale anteriore e quadricipite) e in vivo in topi immunizzati intramuscolo con l’adiuvante da testare e il sistema reporter luciferina-luciferasi in grado di segnalare il livello di ATP al sito d’iniezione. Abbiamo osservato che l'iniezione intramuscolare è sempre associata a un debole e transitorio rilascio di ATP. Il rilascio basale di ATP è notevolmente potenziato dall’iniezione di MF59 ma non dagli altri adiuvanti testati. Pertanto, abbiamo esplorato se e come il rapido e transitorio rilascio di ATP indotto da MF59 al sito d’iniezione potesse contribuire al suo meccanismo d’azione. Il forte potere adiuvante di MF59 [7, 8] è stato attribuito alla sua capacità di istituire un ambiente immunocompetente al sito di iniezione nel muscolo, caratterizzato da un rapido e transitorio afflusso di un gran numero di cellule immunitarie che captano e assorbono l’antigene e lo trasportano ai linfonodi drenanti [9-11]. Abbiamo qui dimostrato, che la co-iniezione di apirasi, un enzima in grado di idrolizzare l’ATP, riduce fortemente l’afflusso di cellule immunitarie indotto da MF59 ma non quello indotto da alum o IFA. Questi risultati indicano che l’abilità di MF59 di indurre un forte afflusso di cellule immunitarie al sito di iniezione è in parte dovuta alla sua intrinseca capacità di rilasciare ATP. Inoltre, abbiamo osservato che la co-iniezione di apirasi e MF59 riduce il numero di cellule antigene-positive che dal muscolo raggiungono i linfonodi drenanti. Tale riduzione si è rivelata tipo cellulare-specifica, infatti il trattamento con apirasi impatta negativamente il numero di cellule B antigene-positive indotto da MF59 nei linfonodi drenanti, suggerendo che le cellule B potrebbero essere un elemento chiave nei “pathways” mediati da ATP durante la vaccinazione. Efficienti risposte immunitarie di tipo innato si traducono spesso in forti risposte adattative [12]. Pertanto, abbiamo analizzato un eventuale ruolo dell’ATP rilasciato da MF59 sull’attivazione delle cellule T e la produzione di titoli anticorpali antigene-specifici. Di conseguenza, gruppi di topi sono stati immunizzati con un vaccino influenzale trivalente, iniettato come tale o adiuvato con MF59 con o senza apirasi. L’apirasi ha fortemente ridotto la proliferazione delle cellule T vaccino-specifiche e i relativi titoli anticorpali. Questi dati dimostrano che un locale e transitorio rilascio di ATP a livello del sito d’iniezione è necessario per lo sviluppo di risposte immunitarie innate e adattative indotte da MF59 e associano per la prima volta un rilascio extracellulare di ATP a un potenziamento delle risposte immunitarie indotte dalla vaccinazione.