Design of a multi-epitope-based vaccine candidate against Bovine Genital Campylobacteriosis using a reverse vaccinology approach.

BACKGROUND: Bovine Genital Campylobacteriosis (BGC), a worldwide distributed venereal disease caused by Campylobacter fetus subsp. venerealis (Cfv), has a relevant negative economic impact in cattle herds. The control of BGC is hampered by the inexistence of globally available effective vaccines. The present in silico study aimed to develop a multi-epitope vaccine candidate against Cfv through reverse vaccinology. RESULTS: The analysis of Cfv strain NCTC 10354 proteome allowed the identification of 9 proteins suitable for vaccine development. From these, an outer membrane protein, OmpA, and a flagellar protein, FliK, were selected for prediction of B-cell and T-cell epitopes. The top-ranked epitopes conservancy was assessed in 31 Cfv strains. The selected epitopes were integrated to form a multi-epitope fragment of 241 amino acids, which included 2 epitopes from OmpA and 13 epitopes from FliK linked by GPGPG linkers and connected to the cholera toxin subunit B by an EAAAK linker. The vaccine candidate was predicted to be antigenic, non-toxic, non-allergenic, and soluble upon overexpression. The protein structure was predicted and optimized, and the sequence was successfully cloned in silico into a plasmid vector. Additionally, immunological simulations demonstrated the vaccine candidate's ability to stimulate an immune response. CONCLUSIONS: This study developed a novel vaccine candidate suitable for further in vitro and in vivo experimental validation, which may become a useful tool for the control of BGC.

Loss of Notch signalling induced by Dll4 causes arterial calibre reduction by increasing endothelial cell response to angiogenic stimuli.

BACKGROUND: In the vascular system, Notch receptors and ligands are expressed mainly on arteries, with Delta-like 4 (Dll4) being the only ligand known to be expressed early during the development of arterial endothelial cells and capillaries. Dll4 null embryos die very early in development with severely reduced arterial calibre and lumen and loss of arterial cell identity. RESULTS: The current detailed analysis of these mutants shows that the arterial defect precedes the initiation of blood flow and that the arterial Dll4-/- endothelial cells proliferate and migrate more actively. Dll4-/- mutants reveal a defective basement membrane around the forming aorta and increased endothelial cell migration from the dorsal aorta to peripheral regions, which constitute the main causes of arterial lumen reduction in these embryos. The increased proliferation and migration of Dll4-/- endothelial cells was found to coincide with increased expression of the receptors VEGFR-2 and Robo4 and with downregulation of the TGF-beta accessory receptor Endoglin. CONCLUSION: Together, these results strongly suggest that Notch signalling can increase arterial stability and calibre by decreasing the response of arterial endothelial cells to local gradients of pro-angiogenic factors like VEGF.