Prediction of an Epitope-based Computational Vaccine Strategy for Gaining Concurrent Immunization Against the Venom Proteins of Australian Box Jellyfish

Cloning and Expression of N-CFTX-1 Antigen from Chironex fleckeri in Escherichia coli and Determination of Immunogenicity in Mice

Background:

Most jellyfish species are poisonous. Human victims of jellyfish sting each year are 120 million. Chironex fleckeri is a venomous box jellyfish that inflicts painful and potentially fatal stings to humans. The CfTX-1 is one of the antigenic proteins of venom that is suggested to stimulate the immune system for treatment and vaccine. This study aimed to clone and express the CfTX-1 antigen in E. coli and then to determine the synthesis of related antibody in the mice.

Methods:

The study was performed in the Persian Gulf and Oman Sea Ecology Research Center, Bandar Abbas, Iran in autumn 2016. The synthetic CfTX-1 gene in PUC57 plasmid was purchased from Nedaye Fan Company. The 723 bp fragment of N-CfTX-1 was amplified by PCR, PUC57 plasmid containing CfTX-1 with BamHI SalI restriction enzyme sites were subcloned in pET28a [+] expression vector and transformed into E. coli BL21 (DE3). The CfTX-1 gene expression was induced by IPTG. Then antibody produced from the mice serum were isolated and confirmed by ELISA. After protein purification, resulted antigen was injected to mice in 4 repeats and then evaluated the rate of antibody in mice serum. Mice were challenged by the Carybdea alata.

Results:

The 726 bp of N-CfTX-1 were cloned in a vector of expression pET28a [+] and confirmed by PCR, sequencing and enzymatic analysis. Moreover, the recombinant protein was confirmed by SDS-PAGE and Western blotting. Then the antibody was isolated from mice serum and confirmed by ELISA test. The results showed that immunized mice tolerated 50x LD50¹ of jellyfish venom.

Conclusion:

The CfTX-1 recombinant protein was able to protect the BALB/c mice against jellyfish venom. The produced protein can be used as a candidate for vaccine against jellyfish venom.

The pathology of Chironex fleckeri venom and known biological mechanisms

The large box jellyfish Chironex fleckeri is found in northern Australian waters. A sting from this cubozoan species can kill within minutes. From clinical and animal studies, symptoms comprise severe pain, welts, scarring, hypotension, vasospasms, cardiac irregularities and cardiac arrest. At present, there is no cure and opioids are used to manage pain. Antivenom is available but controversy exists over its effectiveness. Experimental and combination therapies performed in vitro and in vivo have shown varied efficacy. These inconsistent results are likely a consequence of the different methods used to extract venom. Recent omics analysis has shed light on the systems of C. fleckeri venom action, including new toxin classes that use pore formation, cell membrane collapse and ion channel modulation. This review covers what is known on C. fleckeri pathomechanisms and highlights current gaps in knowledge. A more complete understanding of the mechanisms of C. fleckeri venom-induced pathology may lead to novel treatments and possibly, the discovery of novel cell pathways, novel drug scaffolds and novel drug targets for human disease.

Metadherin peptides containing CD4(+) and CD8(+) T cell epitopes as a therapeutic vaccine candidate against cancer

The concept of peptide-based vaccines against cancer has made noteworthy progress. Metadherin (MTDH) overexpression and its role in the development of diverse cancers make it an attractive target for cancer immunotherapy. In the current study, six different T cell epitope prediction tools were run to identify MTDH peptides with multiple immunogenic regions. Further, molecular docking was performed to assess HLA-peptide binding interactions. Nine and eleven peptides fragments containing multiple CD8 (+) and CD4 (+) T-cell epitopes, ranging from 9 to 20 amino acids, respectively, were obtained using a consensus immunoinformatics approach. The three peptides that were finally identified as having overlapping CD4 (+) and CD8 (+) T- cell epitopes are ARLREMLSVGLGFLRTELG, FLLGYGWAAACAGAR, YIDDEWSGLNGLSSADP. These peptides were found to not only have multiple T cell epitopes but also to have binding affinity with wide HLA molecules. A molecular docking study revealed that the predicted immunogenic peptides (with single or multiple T cell epitopes) of MTDH have comparable binding energies with naturally bound peptides for both HLA classes I and II. Thus, these peptides have the potential to induce immune responses that could be considered for developing synthetic peptide vaccines against multiple cancers.