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Description:
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ANTIGEN IDENTIFICATION AND GENE DISCOVERY FOR LEISHMANIA VACCINE DEVELOPMENT
Publication No . _ _ _ _ _ _ _ _ _ _ _ _ _
Kimberly S . Campbell , Ph .D .
The University of Texas Graduate School of Biomedical Sciences at Galveston , 2003
Supervisor : Lynn Soong
Leishmania parasites are important human pathogens , with over twenty different species causing disease in millions of people . Currently , there is no effective vaccine against leishmaniasis . The solid immunity observed following recovery from cutaneous leishmaniasis in humans implies prevention of leishmaniasis through vaccination is feasible . The purpose of this dissertation is to identify potential targets for DNA vaccination capable of preventing cutaneous leishmaniasis . Given the complex nature of the parasite , we hypothesize that a multi -valent Leishmania DNA vaccine would provide long -term protection against multiple Leishmania species . DNA vaccination is a relatively new technology that offers advantages over conventional vaccines : they can elicit cellular responses , they are low in cost , ensure proper folding of the protein , produce the antigen over a long period of time , have the potential for long -lasting immunity , and can be used on immunocompromised individuals . Initially , we chose the P4 antigen for our DNA vaccine study since it was previously shown to protect mice in native protein form . Murine IL -12 and Leishmania heat shock protein 70 (HSP70 ) were chosen as adjuvants for their ability to stimulate a Th1 response , which is essential for protection against Leishmania infection in mouse models . We found that co -injection with plasmids encoding the L . amazonensis P4 gene and the IL -12 gene was able to protect susceptible mice against L . amazonensis but not against L . major . Conversely , we found that the P4 /HSP70 vaccine was able to protect mice against L . major but only delayed lesion development in L . amazonensis -infected mice . To identify additional antigen targets , we screened an L . amazonensis cDNA expression library and identified a novel antigen , which we named LAWD (Leishmania antigenic WD protein ) . Recombinant LAWD stimulated CD4+ T cells from infected mice to produce high levels
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of a Th1 cytokine , suggesting its potential for DNA vaccination . The LAWD gene , when co -administered with the IL -12 gene , was able to significantly delay lesion development and reduced parasite burdens in susceptible mice challenged with L . amazonensis . Results presented here demonstrate that DNA vaccination is an effective way to protect mice against L . amazonensis and has the potential to cross -protect against evolutionarily diverse Leishmania |