Design, Construction and Immunogenicity Assessment of pEGFP-N1-KMP11-GP96 (Fusion) as a DNA Vaccine Candidate against Leishmania major Infection in BALB/c Mice

KMP-11 (Kinetoplastid membrane protein-Π) exists in all species of kinetoplastid family. It is fully conserved and the protein produced by this gene can induce a very high cellular immune response. We aimed to design a suitable construction for a Leishmania major DNA vaccine and evaluate the protective efficacy of it as a candidate for DNA vaccine against cutaneous leishmaniasis in BALB/c mice.

This experimental study was conducted in Tehran City, Iran, between April 20, 2015 and May 30, 2016. KMP-11 gene of L. major (MRHO/IR/75/ER, Iranian strain) and NT-GP96 of Xenopus GP96 DNA from a pBluescript-GP96 plasmid were amplified by PCR and the purified PCR products were cloned into the pJET1.2/blunt plasmid vector, then, subcloned into pEGFP-N1 plasmid as an expression vector. Finally, the KMP-11 gene was fused with GP96 and afterward the combination cloned in pEGFP-N1. All the cloned genes confirmed by enzyme digestions. Then, four groups of mice were immunized with PBS, pEGFP-N1, pEGFP-N1-KMP, and pEGFP-N1-fusion. Four weeks after immunization, all animals were challenged with L. major virulent promastigotes.

The constructed fusion potentially showed an ability to elicit Th1 responses that led to cutaneous lesion healing. Interestingly, the group received KMP11-GP96 –GFP showed the highest ratio of IFN- γ /IL-4 and IgG2a/IgG1 compare to other groups. No side effect was observed after using the fusion in the mice.

The constructed fusion could well stimulate both the cellular and humoral immune systems that led to cutaneous lesion healing in mice.