Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 50 2 2021 02 01 376 383 EN Hossein JAFARI Department of Biology, Faculty of Basic Sciences, Imam Hossein Comprehensive University, Tehran, Iran Saeid TAMADONI JAHROMI Persian Gulf and Oman Sea Ecology Research Center, Iranian Fisheries Sciences Research Institute, Agricultural Research Education and Extension Organization (AREEO), Bandar Abbas, Iran Jamil ZARGAN Department of Biology, Faculty of Basic Sciences, Imam Hossein Comprehensive University, Tehran, Iran Ehsan ZAMANI Department of Biology, Faculty of Basic Sciences, Imam Hossein Comprehensive University, Tehran, Iran Reza RANJBAR Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran Hossein HONARI Department of Biology, Faculty of Basic Sciences, Imam Hossein Comprehensive University, Tehran, Iran 2018 09 30 2019 04 30 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 LD50[1] 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. https://ijph.tums.ac.ir/index.php/ijph/article/view/14854 https://ijph.tums.ac.ir/index.php/ijph/article/download/14854/7138