RESUMEN
Certain strains of fowl adenovirus serotype 4 (FAdV-4) of the family Adenoviridae are recognized to be the causative agents of Hydropericardium Syndrome (HPS) in broiler chicken. Despite the significantly spiking mortality in broilers due to HPS, not much effort has been made to design an effective vaccine against FAdV-4. The combination of immuno- and bioinformatics tools for immunogenic epitope prediction is the most recent concept of vaccine design. It reduces the time and effort required for hunting a potent vaccine candidate and is economical. Previously, we have reported the penton base protein of FAdV-4 to be a candidate for subunit vaccine against HPS. In the present study, we have computationally pre-screened promising B- and T-cell epitopes of the penton base. Multiple methods were employed for linear B-cell epitope identification; BepiPred and five other methods based on physicochemical properties of the amino acids. The penton base was homology modeled by means of Modeller 9.17 and after refinement of the model (by GalaxyRefine web server) ElliPro web tool was used to predict the discontinuous epitopes. NetMHCcons 1.1 and NetMHCIIpan 3.1 servers were used for the likelihood of peptide binding to Major Histocompatibility Complex (MHC) class I & II molecules respectively for T-cell epitope forecast. As a result, we identified the peptide stretch of 1-225⯠as the most promiscuous B- and T-cell epitope region in penton base Full Length (FL) protein sequence. Escherichia coli based expression vectors were generated containing cloned peptide stretch 1-225 (penton base1-225) and penton base FL gene sequence. The recombinant penton base1-225 and penton base FL proteins were expressed and purified using Escherichia coli-based expression system. Purification yield of penton base1-225 was 3-fold higher compared to penton base FL. These proteins were injected in chickens to determine their competence in protection against HPS. The results showed equal protection level of the two proteins and the commercial inactivated vaccine against FAdV-4 infection. The results suggest the peptide stretch 1-225 of penton base as a valuable candidate for developing an epitope-driven vaccine to combat HPS.
Asunto(s)
Infecciones por Adenoviridae/veterinaria , Vacunas contra el Adenovirus/inmunología , Aviadenovirus/inmunología , Proteínas de la Cápside/inmunología , Epítopos/inmunología , Pericardio/patología , Enfermedades de las Aves de Corral/virología , Infecciones por Adenoviridae/inmunología , Infecciones por Adenoviridae/prevención & control , Vacunas contra el Adenovirus/administración & dosificación , Vacunas contra el Adenovirus/genética , Animales , Aviadenovirus/genética , Proteínas de la Cápside/genética , Pollos/inmunología , Simulación por Computador , Mapeo Epitopo/métodos , Epítopos/genética , Epítopos de Linfocito B/inmunología , Epítopos de Linfocito T/inmunología , Modelos Moleculares , Pericardio/virología , Enfermedades de las Aves de Corral/inmunología , Enfermedades de las Aves de Corral/prevención & control , Serogrupo , Síndrome , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/genética , Vacunas Sintéticas/inmunologíaRESUMEN
We exploit the features of a virus-like particle, adenoviral dodecahedron (Ad Dd), for engineering a multivalent vaccination platform carrying influenza epitopes for cell-mediated immunity. The delivery platform, Ad Dd, is a proteinaceous, polyvalent, and biodegradable nanoparticle endowed with remarkable endocytosis activity that can be engineered to carry 60 copies of a peptide. Influenza M1 is the most abundant influenza internal protein with the conserved primary structure. Two different M1 immunodominant epitopes were separately inserted in Dd external positions without destroying the particles' dodecahedric structure. Both kinds of DdFluM1 obtained through expression in baculovirus system were properly presented by human dendritic cells triggering efficient activation of antigen-specific T cells responses. Importantly, the candidate vaccine was able to induce cellular immunity in vivo in chickens. These results warrant further investigation of Dd as a platform for candidate vaccine, able to stimulate cellular immune responses.