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Leishmaniasis represents a group of parasitic diseases caused by a protozoan of the genus Leishmania and is widely distributed in tropical and subtropical regions. Leishmaniasis is one of the major tropical neglected diseases, with 1.5 to 2 million new cases occurring annually. Diagnosis remains a challenge despite advances in parasitological, serological, and molecular methods. Dogs are an important host for the parasite and develop both visceral and cutaneous lesions. Our goal was to contribute to the diagnosis of canine cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) using the recombinant cysteine proteinase B (F-CPB) from Leishmania braziliensis and its N- and C-terminal domains (N-CPB and C-CPB) as antigens in an enzyme-linked immunosorbent assay (ELISA). Sera from dogs from Northwest Argentina diagnosed with CL were tested by ELISA against a supernatant of L. braziliensis lysate, the F-CPB protein, and its domains. We found values of sensitivity (Se) of 90.7%, 94.4%, and 94.3% and specificity (Sp) of 95.5%, 90.9%, and 91.3% for F-CPB and its N- and C-terminal domains, respectively. In sera from dogs diagnosed with VL from Northeast Argentina, we found Se of 93.3%, 73.3%, and 66.7% and Sp of 92.3%, 76.9%, and 88.5% for F-CPB and its N- and C-terminal domains, respectively. These results support CPB as a relevant antigen for canine leishmaniasis diagnosis in its different clinical presentations. More interestingly, the amino acid sequence of CPB showed high percentages of identity in several Leishmania species, suggesting that the CPB from L. braziliensis qualifies as a good antigen for the diagnosis of leishmaniasis caused by different species., (Copyright © 2019 American Society for Microbiology.)

In this work we immunized mice with DNA encoding full-length Tc52 or its amino- or carboxy-terminal (N- and C-term, respectively) domain carried by attenuated Salmonella as a DNA delivery system. As expected, Salmonella-mediated DNA delivery resulted in low antibody titers and a predominantly Th1 response, as shown by the ratio of IgG2a/IgG1-specific antibodies. Despite modest expression of Tc52 in trypomastigotes, the antibodies elicited by vaccination were able to mediate lysis of the trypomastigotes in the presence of complement and inhibit their invasion of mammal cells in vitro. The strongest functional activity was observed with sera from mice immunized with Salmonella carrying the N-term domain (SN-term), followed by Tc52 (STc52), and the C-term domain (SC-term). All immunized groups developed strong cellular responses, with predominant activation of Th1 cells. However, mice immunized with SN-term showed higher levels of interleukin-10 (IL-10), counterbalancing the inflammatory reaction, and also strong activation of Tc52-specific gamma interferon-positive (IFN-γ(+)) CD8(+) T cells. In agreement with this, although all prototypes conferred protection against infection, immunization with SN-term promoted greater protection than that with SC-term for all parameters tested and slightly better protection than that with STc52, especially in the acute stage of infection. We conclude that the N-terminal domain of Tc52 is the section of the protein that confers maximal protection against infection and propose it as a promising candidate for vaccine development., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)