Development of a Novel Multi-Epitope Vaccine Candidate against Streptococcus Iniae Infection in Fish: An Immunoinformatics Study.

Streptococcus Iniae infection is recognized as a disease with substantial economic losses, infecting a wide range of fish species. The limitations of current vaccines and strategies have led to the identification of new methods to control this disease. Multi-epitope vaccines which employ various immunogenic proteins can be promising. The current research project aimed to design an efficient multi-epitope vaccine against Streptococcus Iniae infection in fish. To this end, six immunogenic proteins of Streptococcus Iniae, including FBA, ENO, Sip11, GAPDH, MtsB, and SCPI proteins, were applied for epitope prediction. The best B cell, T cell, and IFNγ epitopes of the immunogenic proteins, as well as interleukin-8, were used to construct a multi-epitope vaccine. Thereafter, different parameters of the designed vaccine, including physicochemical features, antigenicity, secondary structure, and tertiary structure, were evaluated. Moreover, the interaction of the interleukin-8 domain of the designed vaccine and its receptor was investigated by molecular docking strategy. Finally, nucleotide sequence of the vaccine was adapted to express in Escherichia coli. The results of the present study pointed out that the designed vaccine was a stable vaccine with molecular weight and antigenicity score of 45 kDa and 0.936, respectively. Furthermore, the structure analysis results revealed that the designed vaccine contained 23.49% alpha helix, with 90.5% residues in favored region. Finally, it was demonstrated that the interleukin-8 domain of the designed vaccine could be successfully docked to its receptor with the lowest energy of -1020.9. Based on the obtained results, it seems that the designed vaccine can be an efficient candidate to prevent Streptococcus Iniae infection in fish.

Cloning and Expression of Com1 and OmpH Genes of Coxiella burnetii in Periplasmic Compartment of Escherichia coli with the Aim of Recombinant Subunit Vaccine Production.

Coxiella burnetiiis an obligate and gram-negative bacteria causing query fever (Q fever) disease, despite the importance of Q fever, there is no universal vaccine against this disease. Therefore, application of the recombinant subunit vaccines which use Com1 and OmpH as immunogenic proteins can be useful in this regard. To perform the current project, Com1 and OmpH genes were amplified by polymerase chain reaction (PCR) method, then, the PCR products were purified by DNA precipitation technique. In order to clone, first, both genes along with the pET-22b(+) vector were digested by NcoI and XhoI enzymes and then, Com1 and OmpH genes were ligated in linear vectors by T4 DNA ligase. The recombinant vectors were transformed in BL21 (DE3) strain of Escherichia coli and expression was induced by 1 mM Isopropyl β-D-1-thiogalactopyranoside. Expression of Com1 and OmpH was investigated using 12% Sodium dodecyl sulfate polyacrylamide gel electrophoresis. Finally, both proteins were purified by Ni-NTA columns and consequently confirmed by western blotting. The results of assessing 1% agarose gel showed that PCR amplification, DNA precipitation, and digestion of both genes were successfully performed.Theresults of colony PCRs and sequencing revealed that Com1 and OmpH were correctly cloned in pET-22b(+) vector. Finally, the results of expression, purification, and western blotting of both proteins showed thatBL21 (DE3) strain of Escherichia colicould be able to express Com1 and OmpH proteins. Based on the collected data, it seems that Escherichia coli as an affordable and simple host can be applied to express Com1 and OmpH genes. It should be mentioned that products of the present project can be examined as recombinant subunit vaccines against Q fever.