cord-factors and Leishmaniasis--Cutaneous

Heat shock proteins (HSPs) are highly conserved among different organisms. A mycobacterial HSP65 DNA vaccine was previously shown to have prophylactic and immunotherapeutic effects against Mycobacterium tuberculosis infection in mice. Here, BALB/c mice were immunized with mycobacterial DNA-hsp65 or with DNA-hsp65 and trehalose dymicolate (TDM), both carried by biodegradable microspheres (MHSP/TDM), and challenged with Leishmania (Leishmania) major. MHSP/TDM conferred protection against L. major infection, as indicated by a significant reduction of edema and parasite loads in infected tissues. Although high levels of interferon-gamma and low levels of interleukin (IL)-4 and IL-10 were detected in mice immunized with DNA-hsp65 or MHSP/TDM, only animals immunized with MHSP/TDM displayed a consistent Th1 immune response, i.e., significantly higher levels of anti-soluble Leishmania antigen (SLA) immunoglobulin G (IgG)2a and low anti-SLA IgG1 antibodies. These findings indicate that encapsulated MHSP/TDM is more immunogenic than naked hsp65 DNA, and has great potential to improve vaccine effectiveness against leishmaniasis and tuberculosis.

Topics: Animals; Antibodies, Protozoan; Bacterial Proteins; Chaperonin 60; Chaperonins; Cord Factors; Cytokines; Edema; Enzyme-Linked Immunosorbent Assay; Female; Immunoglobulin G; Leishmania major; Leishmaniasis, Cutaneous; Lower Extremity; Lymphocytes; Mice; Mice, Inbred BALB C; Microspheres; Mycobacterium tuberculosis; Protozoan Vaccines; Spleen; Vaccines, DNA

Development of an effective vaccine against Leishmania infection is a priority of tropical disease research. We have recently demonstrated protection against Leishmania major in the murine and nonhuman primate models with individual or combinations of purified leishmanial recombinant antigens delivered as plasmid DNA constructs or formulated with recombinant interleukin-12 (IL-12) as adjuvant. In the present study, we immunized BALB/c mice with a recombinant polyprotein comprising a tandem fusion of the leishmanial antigens thiol-specific antioxidant, L. major stress-inducible protein 1 (LmSTI1), and Leishmania elongation initiation factor (LeIF) delivered with adjuvants suitable for human use. Aspects of the safety, immunogenicity, and vaccine efficacy of formulations with each individual component, as well as the polyprotein referred to as Leish-111f, were assessed by using the L. major challenge model with BALB/c mice. No adverse reactions were observed when three subcutaneous injections of the Leish-111f polyprotein formulated with either MPL-squalene (SE) or Ribi 529-SE were given to BALB/c mice. A predominant Th1 immune response characterized by in vitro lymphocyte proliferation, gamma interferon production, and immunoglobulin G2A antibodies was observed with little, if any, IL-4. Moreover, Leish-111f formulated with MPL-SE conferred immunity to leishmaniasis for at least 3 months. These data demonstrate success at designing and developing a prophylactic leishmaniasis vaccine that proved effective in a preclinical model using multiple leishmanial antigens produced as a single protein delivered with a powerful Th1 adjuvant suitable for human use.

Topics: Adjuvants, Immunologic; Animals; Antigens, Protozoan; Antioxidants; Cell Wall Skeleton; Cord Factors; Disease Models, Animal; Female; Heat-Shock Proteins; Leishmania major; Leishmania mexicana; Leishmaniasis, Cutaneous; Lipid A; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Molecular Chaperones; Peptide Initiation Factors; Peroxidases; Peroxiredoxins; Polyproteins; Protozoan Proteins; Protozoan Vaccines; T-Lymphocytes; Vaccination; Vaccines, Synthetic