Potency, Efficacy and Durability of DNA/DNA, DNA/Protein and Protein/Protein Based Vaccination Using gp63 Against Leishmania donovani in BALB/c Mice

Abstract

BackgroundVisceral leishmaniasis (VL) caused by an intracellular protozoan parasite Leishmania, is fatal in the absence of treatment. At present there are no effective vaccines against any form of leishmaniasis. Here, we evaluate the potency, efficacy and durability of DNA/DNA, DNA-prime/Protein-boost, and Protein/Protein based vaccination against VL in a susceptible murine model.Methods and FindingsTo compare the potency, efficacy, and durability of DNA, protein and heterologous prime-boost (HPB) vaccination against Leishmania donovani, major surface glycoprotein gp63 was cloned into mammalian expression vector pcDNA3.1 for DNA based vaccines. We demonstrated that gp63 DNA based vaccination induced immune responses and conferred protection against challenge infection. However, vaccination with HPB approach showed comparatively enhanced cellular and humoral responses than other regimens and elicited early mixed Th1/Th2 responses before infection. Moreover, challenge with parasites induced polarized Th1 responses with enhanced IFN-γ, IL-12, nitric oxide, IgG2a/IgG1 ratio and reduced IL-4 and IL-10 responses compared to other vaccination strategies. Although, vaccination with gp63 DNA either alone or mixed with CpG- ODN or heterologously prime-boosting with CpG- ODN showed comparable levels of protection at short-term protection study, DNA-prime/Protein-boost in presence of CpG significantly reduced hepatic and splenic parasite load by 107 fold and 1010 fold respectively, in long-term study. The extent of protection, obtained in this study has till now not been achieved in long-term protection through HPB approach in susceptible BALB/c model against VL. Interestingly, the HPB regimen also showed marked reduction in the footpad swelling of BALB/c mice against Leishmania major infection.Conclusion/SignificanceHPB approach based on gp63 in association with CpG, resulted in robust cellular and humoral responses correlating with durable protection against L. donovani challenge till twelve weeks post-vaccination. These results emphasize the potential of DNA-prime/Protein-boost vaccination over DNA/DNA and Protein/Protein based vaccination in maintaining long-term immunity against intracellular pathogen like Leishmania.

Molecular cloning and expression analysis of peptidase genes in the fish-pathogenic scuticociliate Miamiensis avidus

“…This protein is the most abundant cell surface protein during the promastigote stage of the parasite and is attached to the membrane by a glycosylphosphatidylinositol anchor [37-40]. The protective effects of gp63 immunization have been recently demonstrated using various vaccine formulations by many researchers [41,42]. In fish pathogenic haemoflagellates Cryptobia spp., metallopeptidase activity was only found in the pathogenic strain of C. salmositica , its activity decreased significantly with long-term in vitro culture, and the purified metallopeptidases could lyse fish red blood cells [43-45].…”

Immunocytochemistry of Proteases in the Study of Leishmania Physiology and Host-Parasite Interaction

“…This protease proved to be essential in the development and survival of parasite into sandfly gut, because it degrades hemoglobin and other proteins in the blood meals, thereby providing nutrients needed for the growth of promastigotes and protects promastigotes from degradation by the midgut digestive enzymes (Hajmová et al, 2004). Besides all the functions of Gp63 in Leishmania-hosts interactions, the native protein, recombinant or specific peptides from this cleavage was able to elicit a protective immunity to many species of Leishmania infection in a variety of animal models (Handman, et al, 1990;Abdelhak et al, 1995;Bhowmick et al, 2008;Mazumder et al, 2011). The immunogenicity and antigenicity of gp63 is very well known.…”

Molecular Cloning of Leishmania major gp63 Gene in BALB/c Mouse CT26 Cell Line

“…One of the characterised immunogenic proteins in all Leishmania species is Leishmania gp63 or leishmanolysin [16]. It has been shown that vaccination based on gp63 DNA or recombinant gp63 protein is potential to induce T cell stimulation against Leishmania in human producing high levels of INF-γ from effector T cells [27,28]. Our previous studies also proved the immunogenicity of peptides predicted for either class I or II derived from this protein [29,30].…”