Computational design of a novel multi-epitope vaccine against Coxiella burnetii.

Query fever is a zoonotic disease caused by Coxiella burnetii. There is no universal method for the prevention of this disease. Recombinant vaccine is a potent strategy that can be utilized for this purpose. The current study was conducted to develop a multi-epitope vaccine against Coxiella burnetii. Hence, OmpA, Tuf2, GroEL, Mip and sucB antigens were used for the prediction of epitopes. Then, a multi-epitope vaccine was developed based on a molecular adjuvant and fragments that contained the best MHCI, B cell, MHCII and IFN-γ epitopes. The features of the developed vaccine including physicochemical parameters, antigenicity and protein structures were assessed. Also, interaction between the developed vaccine and TLR4/MD2 receptor along with molecular dynamics of the ligand-receptor complex were investigated. Finally, the codon adaptation and cloning were conducted for the developed vaccine. According to the results, molecular weight, instability index, antigenicity and random coil percentage of the developed vaccine were 54.4 kDa, 32.84, 1.1936 and 34.92%, respectively. Besides, residues distribution in core region of the refined model was 85%. The results demonstrated that the developed vaccine could dock to its receptor with the lowest energy of -976.7 as well as RMSD value of the complex was between 0.15 and 0.22 nm. Also, the results showed that CIA index of the codon adapted sequence was 0.95. Finally, cloning results revealed that nucleotide sequence of the developed vaccine could be successfully cloned into pET-21a (+). Based on these results, it seems that the developed vaccine can be a suitable candidate to prevent Coxiella burnetii.

Comparative study of antimicrobial activity between some medicine plants and recombinant Lactoferrin peptide against some pathogens of cultivated button mushroom.

The adverse effects of chemical pesticides on human health and environment cannot be ignored, hence it seems that novel alternative compounds should be applied to control plant pathogens. Among various alternative sources, natural compounds such as plant essential oils, plant extracts and recombinant antimicrobial peptides are of significance. The aim of the present study was to investigate antimicrobial activity of plants essential oils and plant extracts of six medicinal plants (Lippia citriodora, Ferula gummosa, Bunium persicum, Mentha piperita, Plantago major and Salvadora persica) along with a chimera peptide of camel lactoferrin, which is the most important antimicrobial component of camel milk, against Pseudomonas tolaasii and Trichoderma harzianum as pathogens of white button mushroom. The antibacterial activity test was conducted under in vitro conditions through disc diffusion method. The results showed that chimera camel lactoferrin peptide, with the highest amount of inhibitory zone (14.63 mm in 20 µg/mL concentration), has a significant difference in antibacterial activity compared to other treatments. Ferula gummosa conferred no antibacterial activity. Also, the results of antifungal effects indicated that plant essential oils and extracts have more antifungal activity than recombinant peptide. Generally, L. citriodora, B. persicum, M. piperita treatments could completely prevent growth of fungal in in vitro conditions. Therefore, using the mentioned plants can be a good replacement for reducing the chemical pesticides against pathogenic agents of button mushroom, without any adverse effects on environment and human health.

In vivo immunogenicity assessment and vaccine efficacy evaluation of a chimeric tandem repeat of epitopic region of OMP31 antigen fused to interleukin 2 (IL-2) against Brucella melitensis in BALB/c mice.

BACKGROUND: Designing a potent recombinant vaccine, using the appropriate subunits with the greatest effect on stimulating the immune system, especially in the case of intracellular pathogens such as gram negative Brucella Melitensis bacteria, is of great importance. In this study, three repeats of 27 amino acids of the immunogenic epitope derived from OMP31 antigen (3E) from the Brucella melitensis, in a protective manner against Brucellosis have been used. To fortify the delivery system of recombinant antigens, IL-2 cytokine as a molecular adjuvant was fused to recombinant constructs. Recombinant proteins were evaluated for immunological studies in a mouse model (BALB/c). RESULTS: The results showed that all recombinant proteins could stimulate the immune system to produce Th1 cytokines and antibodies in compare to the negative control treatments. 3E-IL2 and then OMP31-IL2 proteins stimulated higher levels of IFN-γ and IL-2 compared to the other treatments (p < 0.05). Also, the results indicated that experimental treatments produced a higher level of IgG2a isotype than IgG1 isotype. In addition, the findings of the experiment showed that the presence of chemical adjuvant (IFA) along with molecular adjuvant can play a significant role in stimulating the immune system. After determining the potency of recombinant structures, their efficacy in stimulating the immune system were also evaluated. B. melitensis M16 strain was used to challenge 30 days after last immunization. The microbial load of the splenocyte in the treatments receiving chimeric proteins were significantly lower. Also, Wright serological test confirmed that these treatments had the lowest agglutination rate, as well as the positive treatment, while in the negative treatments in excess of blood serum dilutions, agglutination rate were more than 2 + . CONCLUSIONS: 3E-IL2 treatment showed the best performance compared to other recombinant proteins and could be considered as the suitable candidate for further research on the production of recombinant vaccine against Brucella.

Determination of immunodominant scaffolds of Com1 and OmpH antigens of Coxiella burnetii.

Today, there is an increasing emphasis on recombinant vaccines to eliminate the side effects of conventional vaccines such as whole-cell bacteria. Query fever is an emerging disease that causes irreparable complications for both humans and domestic animals. The cause of this disease is Coxiella burnetii, a gram-negative intracellular bacteria. In order to determine the most immunodominant epitopes of Com1 and OmpH antigens of C. burnetii, the most reliable bioinformatics tools with high rates of citation in predicting B cell and T cell epitopes were used. Finally, by comparing the results of all servers, the best overlapped epitopes with the highest antigenicity among different servers were selected. In this regard, epitopes in 18-27and 67-82 amino acids residues were introduced for MHCI and MHCII of T cell, respectively, whereas epitope in 16-25 amino acids residues was introduced for B cell of OmpH antigen. The epitopes in the range of 193-202, 100-108 and 215-223 amino acid residues were preferred for MHCI class of T cell, MHCII class of T cell and B cell of Com1 antigen, respectively. For each antigen, some empirical common epitopic regions were introduced, which included both T and B cells epitopes, 53-65 and 102-111 amino acid residues of OmpH antigen as well as 38-54 range of the amino acid of Com1 antigen. All the predicted epitopes were selected based on their high antigenicity scores and number of non-digestive enzymes. To optimize the application of reported epitopes, various orders of epitopes were arranged in three categories of B cell, T cell and common T and B cells epitopes for each antigen. Then, the best immunodominant scaffolds for each antigen were proposed in these categories. The results demonstrated that the scaffold arranged based on B cell epitopes had the highest antigenicity in both antigens.