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Brucellosis is a highly contagious bacterial zoonotic infectious disease severely affecting the public health and economic features of endemic and non-endemic countries. The present study assessed ...

Coxiella burnetii pathogen, which causes Q fever, is one of the most dangerous pathogens transmitted from the livestock to humans. The only immunization against this disease is the Q-Vax® vaccine, which is used in Australia, as it is not authorized by other countries due to its adverse side effects. Today, growing attention is being paid to the safety of subunit vaccines. Therefore, performing in silico pre-empirical studies on the functionality of recombinant proteins will be more cost-effective than empirical experiments. In this study, P1 and YbgF antigens of C. burnetii were examined and their epitopes were identified. In this case, the most accurate online tools were employed to predict the B cell, T cell and IFN-γ epitopes. Then, the best epitopes were selected based on their antigenicity potency and resistance to digestive compounds. High-ranked epitopes and Heparin-Binding Hemagglutinin as an adjuvant were used to engineer a poly-epitope fusion protein vaccine. Then, physicochemical features, secondary and tertiary structures of the engineered vaccine were evaluated. Finally, the molecular docking of the engineered vaccine and TLR4/MD2 was done. The results of the different analysis revealed that the engineered vaccine can be potentially considered as a potent candidate for fighting with C. burnetii.

Salmonella is a gram-negative bacterium belonging to the Enterobacteriaceae family. One of the major known serotypes of this bacterium is Salmonella typhi. This pathogen is the main cause of diseases in humans and livestock. It is transmitted from animals to humans through the consumption of contaminated food. At the moment, one way to prevent this illness is using the live attenuated Ty21a vaccine. To eliminate the side effects of the vaccine and improve its safety, it is important to use epitope subunit vaccines. In this study, a wide range of accurate online servers have been used to predict the epitopes of OmpA, OmpC and OmpF antigens of Salmonella typhi. The T-cell (MHCI and MHCII) and B-cell epitopes share a degree of overlap between these tools. The highest scores were chosen for the study. Further analysis of their antigenicity and resistance to digestive compounds was performed by VaxiJen Servers and Protein Digest Servers. Eventually, the resultant epitopes that had desired antigenicity (≥ 1) and showed the highest resistance to digestive compounds were selected. Using these epitopes (MHCI, MHCII and B cell) two different structures (antigenic structure and digestion-resistant structure) were designed by rigid linkers. These structures were based on the highest antigenicity ranking of epitopes and the highest resistance of epitopes to digestive compounds, respectively. Given that this pathogen is primarily transmitted through contaminated foods, oral vaccines are essential in this regard. Therefore, these structures can be considered as suitable candidates for subunit vaccines.