Immunogenicity in dogs of three recombinant antigens (TSA, LeiF and LmSTI1) potential vaccine for canine visceral leishmaniasis.
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2005
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Control of canine visceral leishmaniasis (VL) remains a difficult and serious problem
mostly because there is no reliable and effective vaccine available to prevent this disease. A mixture
of three recombinant leishmanial antigens (TSA, LeIF and LmSTI1) encoded by three genes highly
conserved in the Leishmania genus have been shown to induce excellent protection against infection
in both murine and simian models of cutaneous leishmaniasis. A human clinical trial with these
antigens is currently underway. Because of the high degree of conservation, these antigens might be
useful vaccine candidates for VL as well. In the present study, using the dog model of the visceral
disease, we evaluated the immunogenicity of these three antigens formulated with two different
adjuvants, MPL-SE® and AdjuPrime®. The results were compared with a whole parasite vaccine
formulated with BCG as the adjuvant. In order to investigate if sensitization with the recombinant
antigens would result in recognition of the corresponding native parasite antigens upon infection,
the animals were exposed for four weeks after the termination of the immunization protocol with
the recombinant antigens to a low number of L. chagasi promastigotes, an etiological agent of VL.
Immune response was evaluated by quantitative ELISA in the animal sera before and after exposure to the viable parasites. Both antigen specific IgG1 and IgG2 antibody levels were measured.
Immunization of dogs with the recombinant antigens formulated in either MPL-SE® or AdjuPrime®
resulted in high antibody levels particularly to LmSTI1. In addition, this immunization although to
low levels, resulted in the development of antibody response to the whole parasite lysate. Importantly,
experimental exposure with low numbers of culture forms of L. chagasi promastigotes caused a clear
boost in the immune response to both the recombinant antigens and the corresponding native
molecules. The boost response was predominantly of the IgG2 isotype in animals primed with the
recombinant antigens plus MPL-SE®. In contrast, animals primed with the recombinant antigens
formulated in AdjuPrime® as well as animals vaccinated with crude antigen preparation responded
with mixed IgG1/IgG2 isotypes. These results point to the possible use of this antigen cocktail
formulated with the adjuvant MPL-SE® in efficacy field trials against canine VL.
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Leishmania chagasi, Vaccine
Citação
FUHIWARA, R. T. et al. Immunogenicity in dogs of three recombinant antigens (TSA, LeiF and LmSTI1) potential vaccine for canine visceral leishmaniasis. Veterinary Research, v. 36, p.827-838, 2005. Disponível em: <http://www.vetres.org/articles/vetres/abs/2005/05/v4085/v4085.html>. Acesso em: 10 out. 2016.