Apyrase Protein (PsSP42) Expression in DNA Construct Transfected COS-7 Cells

Area of Science:

• Molecular Biology
• Vaccinology
• Parasitology

Background:

• DNA vaccines show promise for treating intracellular parasites like Leishmania by inducing both humoral and cellular immunity.
• Challenges in delivering large DNA vaccine constructs can hinder protein expression and overall immune efficacy.
• Evaluating the expression of specific antigens, such as the P. sergenti salivary protein (PsSP42), is a critical preliminary step for DNA vaccine development.

Purpose of the Study:

• To assess the in vitro expression of the P. sergenti salivary protein (PsSP42) using two distinct plasmid vectors.
• To compare the efficacy of a small, antibiotic-free plasmid (NTC9385R) against a conventional plasmid (VR1020) for PsSP42 expression.
• To validate the expression of PsSP42 prior to its use in preclinical DNA vaccine studies against Leishmania.

Main Methods:

• Recombinant expression of PsSP42 was performed using two plasmids: NTC9385R and VR1020.
• COS-7 cells were transfected with the plasmids via electroporation and Polyethylenimine (PEI)-mediated transfection.
• Protein expression was confirmed using Western blotting after enrichment from cell supernatants with Ni-NTA beads.

Main Results:

• Both VR1020-PsSP42 and NTC-PsSP42 constructs successfully expressed the PsSP42 protein in COS-7 cells.
• The expressed PsSP42 protein, approximately 39.6 kDa, was detected in the cell supernatants irrespective of the transfection method used.
• Similar protein expression levels were observed between the two plasmid types in vitro.

Conclusions:

• The NTC9385R and VR1020 plasmids yield comparable in vitro expression of the PsSP42 protein.
• Transfection method (PEI or electroporation) did not significantly impact PsSP42 expression levels.
• Preclinical assessment of DNA vaccine construct expression is essential for optimizing efficacy in vivo.