A Leishmania-specific hypothetical protein expressed in both promastigote and amastigote stages of Leishmania infantum employed for the serodiagnosis of,and as a vaccine candidate against,visceral leishmaniasis

Background: lihyv is an antigenic hypothetical protein present in both promastigote and amastigote stages of leishmania infantum,which was recently identified by an immunoproteomic approach. a recombinant version of this protein (rlihyv) was evaluated as a diagnostic marker for canine vl (cvl). in addition,the prophylactic efficacy of the rlihyv protein,and two of its cd8+ t cell epitopes,has been analyzed in a murine model of visceral leishmaniasis (vl). methods: initially,the rlihyv protein was evaluated by an elisa technique for the serodiagnosis of cvl. secondly,vaccines composed of the recombinant protein and both chemically synthesized peptides,combined with saponin as an adjuvant; were administered subcutaneously into balb/c mice. the cellular and humoral responses generated by vaccination were evaluated. in addition,the parasite burden and immune response were studied 10 weeks after l. infantum infection. results: the rlihyv protein was recognized by antibodies of vl dogs. no cross-reactivity was obtained with sera from dogs vaccinated with a brazilian commercial vaccine,with sera from animals infected with trypanosoma cruzi,babesia canis and ehrlichia canis,or those from non-infected animals living in an endemic area for leishmaniasis. after challenge with l. infantum,spleen cells of balb/c mice vaccinated with rlihyv/saponin stimulated with parasite antigens showed a higher production of ifn-γ,il-12 and gm-csf,than the same cells obtained from mice vaccinated with the individual peptides,or mice from control (inoculated with saline or saponin) groups. this th1-type cellular response observed in rlihyv/saponin vaccinated mice was accompanied by the induction of parasite-specific igg2a isotype antibodies. animals immunized with rlihyv/saponin showed significant reductions in the parasite burden in the liver,spleen,bone marrow and in the lymph nodes draining the paws relative to control mice. conclusions: the present study showed for the first time that the l. infantum lihyv protein could be considered as a vaccine candidate against l. infantum infection,as well as a diagnostic marker for cvl. © 2015 martins et al.