Optimization of Expression and Extraction of Toxocara canis Recombinant C-Type Lectin Protein in Escherichia coli BL21 (DE3)

Toxocaiasis is an important zoonotic disease caused by the second stage larvae of Toxocara canis and Toxocara cati. Toxocariasis is the most common worm infection in several temperate countries and causes severe complications. C-type lectin is one of the larval stage products of this parasite. It is involved in immune responses, including cellular signals in vertebrate immunity, activation of innate immunity in vertebrates and non-vertebrates, and induction of homeostasis. 

The current research aimed to optimize the production of recombinant C-type lectin of Toxocara canis and investigate its antigenic properties.

Reference nucleotide sequence of lectin type C (CTL) of Toxocara canis (T. canis) was extracted from Genbank. Recombinant Plasmid, pET32a, including the desired sequence was then constructed by GENERAY. The recombinant plasmid was transformed to Escherichia coli strain BL21 (DE3). The expression of the recombinant protein was investigated using SDS-PAGE and dot blot methods and approved with human T. canis positive serum.

The findings of the present study showed that optimization and high level production of recombinant protein expression was achieved by selecting Escherichia coli (BL21 (DE3), 37 °C temperature for 4 hours after induction and 1 mM IPTG concentration. After optimization, the recombinant protein was obtained at a concentration of 1160±0.6 µg/mL. The molecular weight of the resulting recombinant protein was 42 kDa. Recombinant plasmid passage in Escherichia coli DH5α strain caused a significant increase in recombinant protein expression. The results of condition optimization evaluation, with SDS-PAGE and Dot blot methods, showed that the highest production of recombinant C type lectin protein of T. canis was obtained under optimized conditions.

Based on these results, to produce reasonable amounts of specific C-type lectin recombinant protein, further studies are needed to evaluate its immunogenicity and protection against Toxocara canis infection.