Mitigating an undesirable immune response of inherent susceptibility to cutaneous leishmaniosis in a mouse model: the role of the pathoantigenic HISA70 DNA vaccine

Gustavo Domínguez-Bernal,José A Orden,Pilar Horcajo,Ricardo De La Fuente,Aldara Herrero-Gil,Javier Carrión,Lara Ordóñez-Gutiérrez

doi:10.1186/1297-9716-43-59

Abstract

Leishmania major is the major cause of cutaneous leishmaniosis (CL) outside of the Americas. In the present study we have cloned six Leishmania genes (H2A, H2B, H3, H4, A2 and HSP70) into the eukaryotic expression vector pCMVβ-m2a, resulting in pCMV-HISA70m2A, which encodes all six pathoantigenic proteins as a single polyprotein. This expression plasmid has been evaluated as a novel vaccine candidate in the BALB/c mouse model of CL. The DNA vaccine shifted the immune response normally induced by L. major infection away from a Th2-specific pathway to one of basal susceptibility. Immunization with pCMV-HISA70m2A dramatically reduced footpad lesions and lymph node parasite burdens relative to infected control mice. Complete absence of visceral parasite burden was observed in all 12 immunized animals but not in any of the 24 control mice. Moreover, vaccinated mice produced large amounts of IFN-γ, IL-17 and NO at 7 weeks post-infection (pi), and they showed lower arginase activity at the site of infection, lower IL-4 production and a weaker humoral immune response than infected control mice. Taken together, these results demonstrate the ability of the HISA70 vaccine to shift the murine immune response to L. major infection away from an undesirable, Th2-specific pathway to a less susceptible-like pathway involving Th1 and Th17 cytokine profiles.

Highlights

The leishmaniases are a group of diseases caused by infection by several species of the intracellular protozoan parasites of the genus Leishmania, which are transmitted by the bite of an infected female phlebotomine sandfly
HISA70 protein can be expressed in CHO-K1 cells Expression of recombinant proteins by host mammalian cells transfected with plasmid DNA is an essential requirement for stimulating the host immune system
Expression of HISA70 in CHO-K1 cells transfected with pCMV-HISA70m2A was detected using an antibody against L. infantum H2A (Figure 1B)

Summary

Introduction

The leishmaniases are a group of diseases caused by infection by several species of the intracellular protozoan parasites of the genus Leishmania, which are transmitted by the bite of an infected female phlebotomine sandfly. Clinical manifestations are divided into three broad categories, ranging from localized skin ulcers at the site of the sandfly bite (CL), to disfigurements (mucocutaneous leishmaniosis, MCL) and a potentially fatal disease of the viscera (visceral leishmaniosis, VL). These vectorborne diseases are a global public health problem, affecting an estimated 12 million people around the world. 1.5 million new cases of CL and 0.5 million new cases of VL are reported in humans each year [1] Despite their great importance, the leishmaniases are among the most neglected tropical diseases (NTD) in the developing world [2]. Despite considerable progress, no vaccines are available to control any form of human leishmaniosis [7,8]

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Results