Subunit Vaccination of Mice against New World Cutaneous Leishmaniasis: Comparison of Three Proteins Expressed in Amastigotes and Six Adjuvants

Abstract

A mixture of well-defined recombinant antigens together with an adjuvant that preferentially stimulates specific gamma interferon (IFN-␥)-secreting helper type 1 CD4 ؉ T cells (Th1 cells) presents a rational option for a vaccine against leishmaniasis. The potential of this approach was investigated in murine infections with Leishmania mexicana, which are characterized by the absence of a parasite-specific Th1 response and uncontrolled parasite proliferation. A mixture of three antigens (glycoprotein 63, cysteine proteinases, and a membrane-bound acid phosphatase), which are all expressed in amastigotes, the mammalian stage of the parasite, were used for the immunization of C57BL/6 mice in combination with six adjuvants (interleukin 12 [IL-12], Detox, 4-monophosphoryl lipid A, QS-21, Mycobacterium bovis BCG, and Corynebacterium parvum). All six vaccine formulations containing the mixture of recombinant antigens were protective against challenge infections with promastigotes, the insect stage of the parasite, in that mice controlled and healed infections but developed transient and, in certain cases, accentuated disease. The most effective adjuvants were IL-12 followed by Detox. Further studies using these two adjuvants showed that a similar protective effect was observed with a mixture of the corresponding native proteins, and mice which had controlled the infection showed a preponderance of IFN-␥-secreting CD4 ؉ T cells in the lymph nodes draining the lesion. Using the recombinant proteins individually, it is shown that the relatively abundant cysteine proteinases and glycoprotein 63, but not the acid phosphatase, are able to elicit a protective response. The results are discussed in comparison to previous studies with subunit vaccines and with respect to cell biological aspects of antigen presentation in Leishmania-infected macrophages.The solid immunity observed following recovery from cutaneous leishmaniasis in humans has stimulated numerous attempts for the development of a prophylactic vaccination against this widespread (sub)tropical disease (12,16,19,35,36). Leishmania major, the etiological agent of Old World cutaneous leishmaniasis, has been the most popular species both in studies of murine infections and in human trials. In the Middle East, the deliberate infection with L. major was a common and effective practice for immunization against subsequent infections, but a fraction of the vaccinated persons produced lesions that required medical treatment. A vaccine based on killed promastigotes, the insect stage of the parasite, and Mycobacterium bovis BCG was recently shown to be ineffective in a controlled trial with several thousand volunteers in Iran (37). Mice have been used in a range of vaccination protocols against infection by L. major. Representative examples include: attenuated but live parasites (23,29,34,48,59); subunit vaccines delivered by live carriers such as BCG expressing the surface proteinase GP63 of L. major (11); vaccinia virus expressing the glycoprotein GP46/M-2 (20, 30); GP63 expr...

Leishmaniasis: Current Status of Vaccine Development

“…This study extends the data obtained with the mouse and dog models (2,72,82,83,114) and provides a basis for further human trials. However, because delayed-type hypersensitivity was not predictive of protection in this monkey model, the value of delayed-type hypersensitivity as a surrogate marker of protection in humans needs to be reassessed.…”

DNA Immunization with the Gene Encoding P4 Nuclease ofLeishmania amazonensisProtects Mice against Cutaneous Leishmaniasis

“…IL-12 plays a pivotal role in the development of a Th1 response (43) and has been used as an effective adjuvant in Leishmania vaccine studies employing both proteins (10,35,48) and DNA (1,6,25). Similar to IL-12, heat shock proteins have been reported to stimulate Th1-type responses and have remarkable immunostimulatory properties (8,21,52,64).…”

Protection against Cutaneous Leishmaniasis Induced by Recombinant Antigens in Murine and Nonhuman Primate Models of the Human Disease

“…Therefore, the development of an efficacious anti-Leishmania subunit vaccine is, in principle, feasible. In recent years, several recombinant leishmanial antigens have been identified and tested as vaccine candidates (1,18,19). However, there have been no follow-up reports on the efficacy or utility of these antigens in humans or in other animal models beyond the murine model.…”