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.

Immune Response and Partial Protection against Heterologous Foot-and-Mouth Disease Virus Induced by Dendrimer Peptides in Cattle.

Synthetic peptides mimicking protective B- and T-cell epitopes are good candidates for safer, more effective FMD vaccines. Nevertheless, previous studies of immunization with linear peptides showed that they failed to induce solid protection in cattle. Dendrimeric peptides displaying two or four copies of a peptide corresponding to the B-cell epitope VP1 [136-154] of type O FMDV (O/UKG/11/2001) linked through thioether bonds to a single copy of the T-cell epitope 3A [21-35] (termed B2T and B4T, resp.) afforded protection in vaccinated pigs. In this work, we show that dendrimeric peptides B2T and B4T can elicit specific humoral responses in cattle and confer partial protection against the challenge with a heterologous type O virus (O1/Campos/Bra/58). This protective response correlated with the induction of specific T-cells as well as with an anamnestic antibody response upon virus challenge, as shown by the detection of virus-specific antibody-secreting cells (ASC) in lymphoid tissues distal from the inoculation point.

Co-inoculation of baculovirus and FMDV vaccine in mice, elicits very early protection against foot and mouth disease virus without interfering with long lasting immunity.

Baculoviruses (Bvs) potentiate the immune response against soluble antigens. We investigated whether Bv could be used as immunoactivator in foot-and-mouth disease (FMD) vaccines using the BALB/c mouse model. Mice were vaccinated with a single dose of inactivated FMDV (iFMDV), iFMDV+Bv, Bv, or culture medium. Humoral and cellular immune responses were higher in animals immunized with iFMDV+Bv than in mice vaccinated with iFMDV alone. Animals receiving iFMDV+Bv had significantly lower viremia at 2, 4 and 7dpv, than those immunized with iFMDV alone. In order to prolong the immune response, iFMDV oil vaccine was co-inoculated with Bv. Animals receiving iFMDV oil vaccine+Bv were protected two days earlier than those receiving the iFMDV oil vaccine alone. Both formulations protected until 14dpv, the last day of the experiment. This is the first report in which Bv is used as an adjuvant in a FMDV vaccine.

Foot-and-mouth disease virus causes a decrease in spleen dendritic cells and the early release of IFN-α in the plasma of mice. Differences between infectious and inactivated virus.

Foot-and-mouth disease (FMD) is a highly contagious and acute viral disease of cloven-hoofed animals. From an economical point of view, it is the most important disease of livestock worldwide. It is known that the virus interacts with dendritic cells, both in the natural host and in mice, but the impact of this interaction on the adaptive immune response is controversial. Currently available vaccines are based on inactivated forms of the FMD virus. Little is known about the differences between infectious and inactivated virus, in terms of dendritic cell subsets involved in immune response activation. The present work, which was carried out in the murine model, shows that live virus infection induces a reduction in splenic dendritic cell subsets. In addition, lymphocyte proliferation is inhibited in the early stages of infection associated with IFN-α induction, but is restored to normal values 5 days post-infection when pro-inflammatory cytokines was produced. In contrast, the inactivated virus increases the percentage of plasmacytoid dendritic cells in the spleen and the production of IL-10, which triggers the activation of a T regulatory response.

Role of macrophages in early protective immune responses induced by two vaccines against foot and mouth disease.

Foot and Mouth Disease (FMD) is an acute disease of cloven-hoofed species. We studied the protection and early immune response induced in the murine model by vaccines formulated with inactivated virus and two different adjuvants. The presence of IMS12802PR or ISA206VG adjuvants yielded protection against viral challenge at early times post vaccination and induced FMDV-specific, but non neutralizing, antibody titers. In vivo macrophage depletion in vaccinated mice severely decreased the protection levels after virus challenge, indicating a central role of this cell population in the response elicited by the vaccines. Accordingly, opsonophagocytosis of FITC-labelled virus was augmented in 802-FMDVi and 206-FMDVi vaccinated mice. These results demonstrate the ability of the studied adjuvants to enhance the protective responses of these inactivated vaccines without the increase in seroneutralizing antibodies and the main role of opsonization and phagocytosis in the early protective immune responses against FMD infection in the murine model.

Induction of specific cytotoxic activity for bovine herpesvirus-1 by DNA immunization with different adjuvants.

It is well documented that adjuvants improve the immune response generated by traditional viral vaccines; however, less is known about their effects on the immune response elicited by DNA vaccines. In this study, we have investigated the use of adjuvants, and have analyzed the humoral and cellular specific immune responses elicited by DNA vaccines based on the BoHV-1 glycoprotein D (secreted version) in pCIneo vector with and without Montanide ISA25 (O/W), ISA206 VG (SEPPIC) and Cliptox™ (natural microparticles of clinoptilolite). The comparison of the immune response induced in mice by pCIgD formulated with or without adjuvants showed that the immunomodulators affect the total specific humoral and cellular response. The isotypes induced by these adjuvants were of the type Th1/Th2. A significant increase in the mac-3+ and F4/80+ populations of the groups receiving pCIneo with ISA25, ISA206; and an increase in CD4+ populations of the group receiving pCIneo ISA25, in comparison with the pCIneo group was observed. On the other hand, mice vaccinated with pCIgD/ISA25, pCIgD/ISA206, or pCIgD/Cliptox developed a significantly higher specific cytotoxic activity against BoHV-1 than the pCIgD and pCIneo groups. In this report we propose the use of ISA25, ISA206 or Cliptox as adjuvants in a DNA vaccine since they are able to induce not only a specific humoral immune response but also a specific cellular immune response.

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

Foot and Mouth Disease (FMD) is an acute disease caused by Foot and Mouth Disease Virus (FMDV) which causes important economy losses, this is why it is necessary to obtain a vaccine that stimulates a rapid and long-lasting protective immune response. Cliptox is a mineral microparticle that in earlier studies has shown adjuvant activity against different antigens. In this study we have examined the effects of Cliptox on the magnitude and type of immunity elicited in response to inactivated FMDV (iFMDV) vaccine. It was demonstrated that iFMDV-Cliptox stimulates a specific antibody response detected in mucosal and in sera. The different isotype profiles elicited by inoculation with this vaccine indicate a Th1/Th2 response. Also, an increase in dendritic cells and macrophages in the spleen in comparison with the iFMDV vaccine iFMDV-Cliptox was detected. The Cliptox-iFMDV formulation was non toxic by using egg embryos and yielded increased protection against challenge with FMDV in the murine model. Our results show that the incorporation of Cliptox into FMDVi vaccine induces an increase of the specific protective immune response in mice and clearly indicate that Cliptox TM exert an (important) up-regulation on DC and MPhi. Additionally, Cliptox TM adjuvant can be used in vaccines for induction of mucosal immune response.