Adjuvant effect of Cliptox™ on the protective immune response induced by an inactivated vaccine against foot and mouth disease virus in mice

Zeolites as Ingredients of Medicinal Products

Development of new medicinal products for particular therapeutic treatment or for better manipulations with better quality and less side effects are possible as a result of advanced inorganic and organic materials application, among which zeolites, due to their properties and versatility, have been gaining attention. This paper is an overview of the development in the use of zeolite materials and their composites and modifications as medicinal products for several purposes such as active agents, carriers, for topical treatments, oral formulations, anticancer, the composition of theragnostic systems, vaccines, parenteral dosage forms, tissue engineering, etc. The objective of this review is to explore the main properties of zeolites and associate them with their drug interaction, mainly addressing the advances and studies related to the use of zeolites for different types of treatments due to their zeolite characteristics such as molecule storage capacity, physical and chemical stability, cation exchange capacity, and possibility of functionalization. The use of computational tools to predict the drug-zeolite interaction is also explored. As conclusion was possible to realize the possibilities and versatility of zeolite applications as being able to act in several aspects of medicinal products.

Binding and inactivation of human coronaviruses, including SARS-CoV-2, onto purified clinoptilolite-tuff

The current COVID19 pandemic is caused by a positive-sense single-stranded RNA virus, which presents high mutational rates. The development of effective therapeutics and mitigation strategies using vaccination or therapeutic antibodies faces serious challenges because of the regular emergence of immune escape variants of the virus. An efficient approach would involve the use of an agent to non-specifically limit or block viruses contacting the mucosae and therefore entering the body. Here, we investigated the ability of a micronized purified clinoptilolite-tuff to bind and neutralize different viruses from the Coronaviridae family. Using plaque assay, RT-qPCR and immunostaining, the adsorption and inactivation of the seasonal human coronavirus HCoV-229E and of 2 SARS-CoV-2 variants were demonstrated. The resulting data suggest that purified clinoptilolite-tuff could be used as an ingredient in new medical devices and/or pharmaceuticals to prevent or mitigate SARS-CoV-2 dissemination.

FMD empty capsids combined with the Immunostant Particle Adjuvant -ISPA or ISA206 induce protective immunity against foot and mouth disease virus

Foot and Mouth Disease Virus (FMDV) causes economy losses and is controlled by vaccination in many countries. Vaccine formulations based on empty capsids or Virus-Like Particles (VLPs) have the advantage of avoiding the biological hazard of using infectious FMDV, albeit are poorly immunogenic. Recently, we have described that ISPA a new Immune Stimulating Complex adjuvant, is useful to improve the response against FMD of vaccines that use inactivated virus. Now, the adjuvant effects of ISPA and ISA 206 (water/oil/water) on a VLPs-based FMD vaccine were evaluated. VLPs (strain A/Argentina/2001) were obtained in mammalian cell cultures and their elicitation of an immune response against FMDV with and without ISPA or ISA 206 was evaluated in mice as a first approach. Notably, VLPs-ISPA and VLPs-ISA 206 vaccines induced protection against viral challenge in 100 % of mice, while protection induced by VLPs alone was of 40 %. Total and neutralizing FMDV antibodies were higher in the VLPs-ISPA and VLPs-ISA 206 groups compared to the VLPs group. VLPs-ISPA induced significantly higher (p < 0.001) IgG1, IgG2a, IgG2b and IgG3 titers than the VLPs vaccine. Moreover, in comparison with non-adjuvanted VLPs, VLPs-ISPA and VLPs-ISA 206 elicited an increased virus-specific T response, including higher IFNγ+/CD8 + lymphocyte production in mice. When these vaccines were tested in calves, antibody titers reached an Expected Percentage of Protection (EPP) above 90 % in the case of the VLPs-ISPA and VLPs-ISA 206 vaccines, while, in the VLPs group, EPP reached 25 %. IFNγ levels secreted by mononuclear cells of VLP-ISPA-vaccinated cattle were significantly higher than in the VLPs group. Overall, the results demonstrate that VLPs-ISPA or VLPs-ISA 206 are promising formulations for the development of a novel FMD vaccine.

A New Cage-Like Particle Adjuvant Enhances Protection of Foot-and-Mouth Disease Vaccine

Foot-and-Mouth Disease (FMD) is an acute viral disease that causes important economy losses. Vaccines with new low-cost adjuvants that stimulate protective immune responses are needed and can be assayed in a mouse model to predict their effectiveness in cattle. Immunostimulant Particle Adjuvant (ISPA), also known as cage-like particle adjuvant, consisting of lipid boxes of dipalmitoyl-phosphatidylcholine, cholesterol, sterylamine, alpha-tocopherol, and QuilA saponin, was shown to enhance protection of a recombinant vaccine against Trypanosoma cruzi in a mouse model. Thus, in the present work, we studied the effects on the magnitude and type of immunity elicited in mice and cattle in response to a vaccine based on inactivated FMD virus (iFMDV) formulated with ISPA. It was demonstrated that iFMDV–ISPA induced protection in mice against challenge and elicited a specific antibody response in sera, characterized by a balanced Th1/Th2 profile. In cattle, the antibody titers reached corresponded to an expected percentage of protection (EPP) higher than 80%. EPP calculates the probability that livestock would be protected against a 10,000 bovine infectious doses challenge after vaccination. Moreover, in comparison with the non-adjuvanted iFMDV vaccine, iFMDV–ISPA elicited an increased specific T-cell response against the virus, including higher interferon gamma (IFNγ)+/CD8+ lymphocyte production in cattle. In this work, we report for first time that an inactivated FMDV serotype A vaccine adjuvanted with ISPA is capable of inducing protection against challenge in a murine model and of improving the specific immune responses against the virus in cattle.

Effects of dietary chitosan and nano-chitosan loaded clinoptilolite on growth and immune responses of rainbow trout (Oncorhynchus mykiss)

In this study, rainbow trout Oncorhynchus mykiss weighing 27.75 ± 0.34 g were orally subjected to eight experimental diets each in three replicates containing varying amounts of chitosan and nano-chitosan (0.05, 0.5 and 5 g kg^-1) loaded in clinoptilolite (14.28 g kg^-1) for 70 days; and the growth and immune responses were evaluated. Results showed that growth parameters in fish fed diets chit + clin2, chit + clin3, nchit + clin1, nchit + clin2 and nchit + clin3 were significantly higher than in fish fed the control diet. All feeds, except chit + clin3, and nchit + clin3, significantly increased the total protein level. Feeds containing chit + clin2, nchit + clin1, and nchit + clin2 significantly elevated serum lysozyme activity compared with the control group. All treatments, except chit + clin3, and nchit + clin3 exhibited higher serum immunoglobulin (Ig) level than control one. In contrast, diet nchit + clin1 significantly unregulated the expression of Ig M gene in fish head-kidney compared to other groups. Additionally, all feeds, except clinoptilolite, and nchit + clin3, significantly improved the serum complement activity. Diets chit + clin2, nchit + clin1, and nchit + clin2 also significantly elevated antibacterial activity against Yersinia ruckeri compared with the control diet. Expression of inducible nitric oxide synthase (iNOS) gene in fish fed diets clinoptilolite, chit + clin1, chit + clin3, nchit + clin1, nchit + clin2, and nchit + clin3 was significantly higher than the control diet. All diets, except clinoptilolite, increased IL-1β gene expression compared to the control group. Present results suggest that diets supplemented with nchit + clin, especially at 0.05 g kg^-1 nano-chitosan inclusion, could improve growth performance and immune parameters of rainbow trout.

Biocompatible cationic solid lipid nanoparticles as adjuvants effectively improve humoral and T cell immune response of foot and mouth disease vaccines

In this work, we explored the potential of cationic solid lipid nanoparticles (cSLN) as efficient adjuvants for inactivated foot and mouth disease virus (iFMDV) vaccine. The cSLN were prepared by O/W emulsion method with Compritol 888 ATO as lipid matrix, and were modified by cationic lipid Didodecyldimethylammonium bromide (DDAB). The content of cationic lipid was optimized to produce cSLN with appropriate particle size, surface morphology, zeta potential, and polydispersity. Loading iFMDV onto cSLN by electrostatic attraction did not destruct iFMDV particle structure as measured by high performance size exclusion chromatography (HPSEC). Differential scanning fluorimetry (DSF) showed the transition temperature, T_m, related to iFMDV dissociation increased for 1.2 °C after loading on cSLN, indicating an enhanced stability of this unstable antigen. The cSLN loaded iFMDV enhanced in vitro antigen uptake and activation of bone-marrow-derived dendritic cells (BMDCs) with augmented expression of CD86, CD40, and MHC I. In animal trials, BALB/c mice were immunized with free iFMDV, antigen adjuvanted with the cSLN, and antigen adjuvanted with Montanide ISA 206 emulsion. Specific antibody titers showed cSLN could stimulate similar FMDV-specific IgG and IgG subclasses antibody level compared with the widely used ISA 206. In addition, cSLN significantly enhanced memory immune response including effector-memory T cells and central-memory T cells compared to free iFMDV antigen and antigen adjuvanted with ISA 206. Taken together the enhanced humoral and T cell immune responses and the antigen structure friendly properties, cSLN can be a potential adjuvant for iFMDV vaccines.

Immunogenic evaluation of FMD virus immuno-dominant epitopes coupled with IL-2/FcIgG in BALB/c mice

Previous studies on vaccine development against foot-and-mouth disease (FMD) virus reported that application of the inactivated vaccines for FMD virus is not completely effective. Novel vaccinations based on immune-dominant epitopes showed they induced immune responses. In addition, for better and safer immunization, access to of efficient adjuvants against FMD virus seems to be critical. In this study, we produced epitope recombinant vaccines from the VP1 protein of the FMD virus for serotype O of Iran that conjugated with Fc Immunoglobulin (FcIgG) and Interleukin-2 (IL-2). Multiple-epitope constructs included Polytope, Polytope-IL2-FcIgG, Polytope-IL2, Polytope-FcIgG that cloned and expressed in E. coli BL21 (DE3). To evaluate whether these epitope recombinant vaccines induce immune responses, BALB/c mice were injected with the epitope recombinant vaccines and their immune responses were compared with a negative control group. The humoral and cellular immune responses were measured by ELISA. The results showed there were significant differences between the negative control group and other immunized mice with recombinant epitope proteins (p < 0.05). The results of total IgG, IgG1, IgG2a levels and secretion of IFN-γ, IL-4 and IL-10 revealed that immune responses were enhanced when the epitope recombinant vaccine of FMD virus coupled with IL-2 and FcIgG. Observations indicated that the epitope recombinant plasmid of the VP1 protein co-expressed with IL-2 and FcIgG was effective in inducing an enhanced immune response. Therefore, IL-2 and FcIgG could be recommended as a potential adjuvant for epitope recombinant vaccine of the VP1 protein from FMD virus.

Adjuvanticity of a CTLA-4 3' UTR complementary oligonucleotide for emulsion formulated recombinant subunit and inactivated vaccines

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is recognized as a critical inhibitory regulator of T-cell proliferation and activation, opposing the action of CD28-mediated co-stimulation. Interfering or blocking CTLA-4 can result in continuous T-cell activation required for the full immune response to pathogenic microbes and vaccines. To test if nucleic acid-based CTLA-4 inhibitors could be developed into a novel adjuvant, we designed two oligonucleotides, CMD-1 and CMD-2, with the sequences complementary to the conserve regions identical between human and mouse CTLA-4 mRNA 3' untranslated region (3' UTR), and tested their in vitro effects on CTLA-4 production and their adjuvanticity for vaccines in mice. We found that CMD-1 inhibited the antigen-induced CTLA-4 up-regulation on the CD4⁺ T cells by interfering its mRNA expression, maintained higher levels of CD80 and CD86 on the CD11c⁺ cells and promoted the recalled proliferation of the CD4⁺ T cells and CD19⁺ B cells, and that the CMD-1 enhanced the antibody response against recombinant PCV2b capsid protein or inactivated foot-and-mouth disease virus in both ICR and BALB/c mice. These data suggest that the CMD-1 could be used as a novel vaccine adjuvant capable of inhibiting inhibitory signals rather than inducing stimulatory signals of immune cells.

The Hen's Egg Test on Chorioallantoic Membrane: An Alternative Assay for the Assessment of the Irritating Effect of Vaccine Adjuvants

Local reactions are the most frequent adverse event associated with vaccines. Adjuvants are major constituents of many vaccines and they are frequently involved in these reactions, associated with their irritating effect and the stimulation of local inflammation. The hen's egg test on chorioallantoic membrane (HET-CAM) is an alternative toxicological method widely used to determine ocular irritation potential, but very few studies have demonstrated the utility of this method for assessing the irritant properties of vaccine adjuvants. In this work, known/experimental adjuvants were evaluated by both HET-CAM and an in vivo local toxicity study in mice to compare irritation scores to determine whether there was a correlation (Pearson test). Based on these data (r = 0.9034; P < 0.0001), the HET-CAM assay can be used as an alternate method for the prediction of the local toxicity potential of adjuvant candidates to be used in vaccines.

Foot-and-mouth disease: overview of motives of disease spread and efficacy of available vaccines

Control and prevention of foot and mouth disease (FMD) by vaccination remains unsatisfactory in endemic countries. Indeed, consistent and new FMD epidemics in previously disease-free countries have precipitated the need for a worldwide control strategy. Outbreaks in vaccinated animals require that a new and safe vaccine be developed against foot and mouth virus (FMDV). FMDV can be eradicated worldwide based on previous scientific information about its spread using existing and modern control strategies.

Laboratory animal models to study foot-and-mouth disease: a review with emphasis on natural and vaccine-induced immunity

Laboratory animal models have provided valuable insight into foot-and-mouth disease virus (FMDV) pathogenesis in epidemiologically important target species. While not perfect, these models have delivered an accelerated time frame to characterize the immune responses in natural hosts and a platform to evaluate therapeutics and vaccine candidates at a reduced cost. Further expansion of these models in mice has allowed access to genetic mutations not available for target species, providing a powerful and versatile experimental system to interrogate the immune response to FMDV and to target more expensive studies in natural hosts. The purpose of this review is to describe commonly used FMDV infection models in laboratory animals and to cite examples of when these models have failed or successfully provided insight relevant for target species, with an emphasis on natural and vaccine-induced immunity.

Dietary germanium biotite supplementation enhances the induction of antibody responses to foot-and-mouth disease virus vaccine in pigs

We evaluated the potential ability of germanium biotite (GB) to stimulate the production of antibodies specific for foot-and-mouth disease virus (FMDV). To this aim, we measured the total FMDV-specific antibody responses and IgM production after vaccination against FMD both experimentally and in the field. GB supplementation with FMDV vaccination stimulated the production of anti-FMDV antibodies, and effectively increased IFN-γ and TNF-α levels. These results suggest that GB may be a novel alternative feed supplement that can serve as a boosting agent and an immunostimulator for increasing the efficacy of FMDV vaccination in pigs.

Resiquimod and polyinosinic-polycytidylic acid formulation with aluminum hydroxide as an adjuvant for foot-and-mouth disease vaccine

Background

Toll-like receptor (TLR) agonists reportedly have potent antiviral and antitumor activities and may be a new kind of adjuvant for enhancing immune efficacy. Resiquimod (R848) is an imidazoquinoline compound with potent antiviral activity and functions through the TLR7/TLR8 MyD88-dependent signaling pathway. Polyinosinic-polycytidylic acid [poly(I:C)] is a synthetic analog of double-stranded RNA that induces the production of pro-inflammatory cytokines by the activation of NF-κB through TLR3. This study investigated the potential of R848 and poly(I:C) as an adjuvant 146S foot-and-mouth disease virus (FMDV) vaccine formulated with aluminum hydroxide (Al(OH)₃).

Results

Antibody titers to FMDV and CD8⁺ T cells were markedly enhanced in mice immunized to 146S FMDV + Al(OH)₃ + R848 + poly(I:C) compared with mice immunized to FMDV + ISA206. IFN-γ secretion substantially increased compared with IL-4 secretion by splenic T cells stimulated with FMDV antigens in vitro, suggesting that R848, poly(I:C), and with Al(OH)₃ together biased the immune response toward a Th1-type direction.

Conclusions

These results indicated that the R848 and poly(I:C) together with Al(OH)₃ enhanced humoral and cellular immune responses to immunization with 146S FMDV antigens. Thus, this new vaccine formulation can be used for FMDV prevention.

An approach to local immunotoxicity induced by adjuvanted vaccines

The occurrence of injection site reactions following immunization is the most frequently reported toxicity manifestation of vaccines; however, the different types of local reactions and the different mechanisms involved are still unclear. Here, the current advances in adjuvants and the role that adjuvants play in local reactions are reviewed. The role of adjuvants in the formation of the loco-regional complex (LRC), which consists of the injection site, draining lymphatic vessels and regional lymph nodes, is also discussed. Finally, strategies and recommendations for the rational design of adjuvanted vaccines are discussed, with a particular interest in the reduction of local inflammation.

Delivery of synthetic RNA can enhance the immunogenicity of vaccines against foot-and-mouth disease virus (FMDV) in mice

We have recently described the antiviral effect in mice of in vitro-transcribed RNAs mimicking structural domains in the non-coding regions of the foot-and-mouth disease virus (FMDV) genome RNA. These small, synthetic and non-infectious RNA molecules (ncRNAs) are potent type-I interferon (IFN) inducers in vivo. In this work, the immunomodulatory effect of the ncRNA corresponding to the internal ribosome entry site (IRES) on immunization with two different FMD vaccine formulations, both based on inactivated virus, including or not a commercial adjuvant, was analyzed in the mice model. The effect of the time interval between RNA inoculation and immunization was also studied. RNA delivery consistently increased the titers of specific anti-FMDV antibodies, including neutralizing antibodies, elicited after vaccination. Moreover, at day 2 after immunization, significant differences in mean antibody titers could be detected between the groups of mice receiving either vaccine co-administered with the RNA and the control group, unlike those immunized with the vaccine alone. When vaccinated mice were challenged with FMDV, the mean values of viral load were lower in the groups receiving the RNA together with the vaccine. Our results show the enhancing effect of the IRES RNA on the immune response elicited after vaccination and suggest the potential of this molecule as an adjuvant for new FMD vaccine design.

Requirements for improved vaccines against foot-and-mouth disease epidemics

Inactivated foot-and-mouth disease (FMD) vaccines are currently used worldwide. With the emergence of various FMD virus serotypes and subtypes, vaccines must become more suitable for field-based uses under the current circumstances in terms of the fast and proper selection of vaccine strains, an extended vaccine development period for new viruses, protecting against the risk of virus leakage during vaccine manufacture, counteracting the delayed onset of immune response, counteracting shorter durations of immunity, and the accurate serological differentiation of infected and vaccinated animals and multiple vaccination. The quality of vaccines should then be improved to effectively control FMD outbreaks and minimize the problems that can arise among livestock after vaccinations. Vaccine improvement should be based on using attenuated virus strains with high levels of safety. Moreover, when vaccines are urgently required for newly spread field strains, the seed viruses for new vaccines should be developed for only a short period. Improved vaccines should offer superior immunization to all susceptible animals including cattle and swine. In addition, they should have highly protective effects without persistent infection. In this way, if vaccines are developed using new methods such as reverse genetics or vector vaccine technology, in which live viruses can be easily made by replacing specific protective antigens, even a single vaccination is likely to generate highly protective effects with an extended duration of immunity, and the safety and stability of the vaccines will be assured. We therefore reviewed the current FMD vaccines and their adjuvants, and evaluated if they provide superior immunization to all susceptible animals including cattle and swine.