Immunogenic potential and neutralizing ability of a heterologous version of the most abundant three-finger toxin from the coral snake Micrurus mipartitus

Background: Micrurus mipartitus is a coral snake of public health concern in Colombia. Its venom is mainly composed of three-finger toxins (3FTxs), Mipartoxin-1 being the most abundant protein partially responsible for its lethal effect. In this work, we present the production of Mipartoxin-1 in a recombinant form and evaluate its immunogenic potential. Methods: A genetic construct HisrMipartoxin-1 was cloned into the pET28a vector and heterologous expression was obtained in E. coli BL21 (DE3). The recombinant HisrMipartoxin-1 protein was extracted from inclusion bodies, refolded in vitro, and isolated by affinity and RP-HPLC chromatography. The lethal effect of HisrMipartoxin-1 was tested, and antibodies against HisrMipartoxin-1 were produced by immunization in rabbits. The antibody titers were monitored by an ELISA test. The neutralizing ability of the antibodies, against the lethal effect of native toxins and M. mipartitus venom, was also assessed. Results: HisrMipartoxin-1 was detected on SDS-PAGE, with a molecular mass of around 11 kDa. The retention time was 16.0 minutes. HisrMipartoxin-1 did not exhibit lethality in mice; however, antibodies against HisrMipartoxin-1 recognized the native toxin, the whole venom of M. mipartitus, and a 3FTx from another species within the Micrurus genus. Furthermore, antibodies against HisrMipartoxin-1 completely neutralized the lethal effect of native Mipartoxin-1 in mice but not M. mipartitus whole venom. Conclusion: These findings indicate that HisrMipartoxin-1 might be used as an immunogen to develop anticoral antivenoms or complement them. This work is the first report of the heterologous expression of 3FTx from M. mipartitus.