Foot-and-Mouth Disease Virus (FMDV) causes an acute disease with important economy losses worldwide. Currently available vaccines are based on inactivated FMDV and oil-adjuvants. The use of Virus-Like Particles (VLPs) for subunit vaccines has been reported to be promising since it avoids the biological hazard of using virus in vaccine production while conserving conformational viral epitopes. However, a more efficient and cost-effective adjuvant than those currently used is needed. Immunostimulant-Particle Adjuvant (ISPA) is an Immune Stimulating Complex (ISCOM) - type adjuvant formulated with dipalmitoyl-phosphatidylcholine, cholesterol, stearylamine, alpha tocopherol and QuilA. In the present work, we have evaluated the immune response against FMDV using VLPs and ISPA as adjuvant. VLPs (serotype A/Arg/01) were obtained by transient gene expression in mammalian cell cultures, and a previously developed murine model, able to predict the ability of a vaccine to induce protection in cattle, was used for vaccination experiments in a first approach. The VLPs-ISPA vaccine induced protection in mice against challenge and elicited a specific antibody response in sera. In a second approach, the VLPs-ISPA vaccine was tested in calves. Interestingly one vaccine dose was enough to induce total α-FMDV antibodies , as measured by ELISA, as well as neutralizing Abs. Antibody titers reached an Expected Percentage of Protection higher than 90%. The EPP index calculates the probability that livestock will be protected against a challenge of 10.000 bovine infectious doses after vaccination. Moreover, IFN-γ levels secreted in vitro by mononuclear cells of VLP-ISPA vaccinated animals were significantly higher (p <0.05) than in the non-adjuvanted VLPs group. Overall, the results demonstrate that VLPs and ISPA are a promising combination for the development of a novel FMD vaccine, since no infectious FMDV is used and a protective immune response can be induced in calves, comparable to that achieved with the commercial FMDV vaccine.
New technologies in the field of vaccinology arise as necessity for treatment and control of many diseases. Currently modified live virus and inactivated vaccines used for Bovine Herpesvirus-1 (BoHV-1) have several disadvantages. Previous works for preventive treatment of BoHV-1 with DNA based vaccines have demonstrated the capability to induce humoral and cellular immune response. Nevertheless, it is well known that “naked” DNA induces low immunogenic response. Thus, loading of antigen encoding DNA sequences in liposomal formulations targeting dendritic cell receptors could be a promising strategy to better activate these antigen presenting cells (APC). In this work, DNA based vaccine encoding the truncated version of gD glycoprotein (pCIgD) of BoHV-1 was investigated alone and upon encapsulation on liposomal formulation coated with MANα1-2MAN-PEG-DOPE and LPS from Brucella ovis (pCIgD-Man-L) in mice and cattle assay. Results showed that the use of pCIgD-Man-L was capable to enhance the immune response in both animal models. Significant levels of humoral immunity were achieved when total antibody titers and isotypes were detected in sera and mucosa. For cellular immunity, specific viral lymphoproliferation was detected in the animals inoculated with pCIgD-Man-L. In addition, positively modulation of CD40 molecules on the surface of bovine dendritic cells (DCs) was observed when cells were stimulated and activated with vaccine formulations. When challenge assay was performed, bovines inoculated with pCIgD and liposome decorated with MANα1-2MAN-PEG-DOPE elicited better protection and diminished viral excretion. The results demonstrate the targeting of the MANα1-2MAN coated liposomes toward dendritic cells and their ability to boost the immunogenicity according to an adjuvant effect that results in long-lasting immunity. Liposome decorated with MANα1-2MAN-PEG-DOPE were for the first time tested as DNA based vaccine in cattle as preventive treatment of BoHV-1. These results open up new perspectives for the design of vaccine for the control of bovine rhinotracheitis.