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• Better performance was obtained compared to more commonly used antigens. • Dyn-1 showed excellent ability to identify asymptomatic dogs (100% sensitivity). • Overall, the ability of rDyn-1 to identify dogs with CanL was 97% (sensitivity). • rDyn-1-based ELISA assays could be advantageous over classic diagnostic tests. Visceral leishmaniasis (VL) is a fatal manifestation of an infection caused by intracellular protozoa of the Leishmania genus. In New World countries, VL is classified as a zoonotic disease with domestic dogs acting as its main reservoir. Asymptomatic dogs are as competent to transmit Leishmania to the vectors as symptomatic dogs, however current diagnostic tests are limited and present low sensitivity for this important group. The development of accurate tests is fundamental to the early diagnosis, treatment, and control of canine leishmaniasis. In this study, we investigated the use of a recombinant protein (dynamin-1-like protein, Dyn-1) from L. infantum, as a potential target antigen for leishmaniasis serodiagnosis in both symptomatic and asymptomatic dogs. The antigenic performance of the protein was evaluated by means of ELISA assays using sera from symptomatic (n = 25), asymptomatic (n = 34) and non-infected dogs (n = 36) using ELISA. In addition, sera from dogs experimentally infected with Trypanosoma cruzi (n = 49) and naturally infected with Babesia sp. (n = 8) were tested to evaluate possible cross-reactivity. A crude soluble antigen (CSA) of Leishmania was used as an antigen control and K39 and K26 were used as reference antigens because they are already widely used in commercial tests. rDyn-1-based assay showed the highest sensitivity (97%) compared to the antigens K39 (88%), K26 (86%) and crude extract (95%). The highest specificity among the tests was also obtained with the protein rDyn-1 (94%), compared with the other antigens K39 (81%), K26 (87%), and crude extract (77%). This study showed that the rDyn-1 ELISA assay was able to identify 100% of asymptomatic dogs, establishing its potential as a target for the diagnosis of canine leishmaniasis. [ABSTRACT FROM AUTHOR]

The leishmaniasis are a group of vector-borne diseases caused by a protozoan parasite from the genus Leishmania. In this study, a series of thiazolopyrimidine derivatives were designed and synthesized as novel antileishmanial agents with Lm PTR1 inhibitory activity. The final compounds were evaluated for their in vitro antipromastigote activity, Lm PTR1 and h DHFR enzyme inhibitory activities, and cytotoxicity on RAW264.7 and L929 cell lines. Based on the bioactivity results, three compounds, namely L24f , L24h and L25c , were selected for evaluation of their in vivo efficacy on CL and VL models in BALB/c mice. Among them, two promising compounds, L24h and L25c, showed in vitr o antipromastigote activity against L. tropica with the IC 50 values of 0.04 μg/ml and 6.68 μg/ml; against L. infantum with the IC 50 values of 0.042 μg/ml and 6.77 μg/ml, respectively. Moreover, the title compounds were found to have low in vitro cytotoxicity on L929 and RAW264.7 cell lines with the IC 50 14.08 μg/ml and 21.03 μg/ml, and IC 50 15.02 μg/ml and 8.75 μg/ml, respectively. Lm PTR1 enzyme inhibitory activity of these compounds was determined as 257.40 μg/ml and 59.12 μg/ml and their selectivity index (SI) over h DHFR was reported as 42.62 and 7.02, respectively. In vivo studies presented that L24h and L25c have a significant antileishmanial activity against footpad lesion development of CL and at weight measurement of VL group in comparison to the reference compound, Glucantime®. Also, docking studies were carried out with selected compounds and other potential Leishmania targets to detect the putative targets of the title compounds. Taken together, all these findings provide an important novel lead structure for the antileishmanial drug development. [Display omitted] • A series of thiazolopyrimidine derivatives were synthesized as novel antileishmanials. • L24f , L24h and L25c showed in vitro antipromastigote activity and low cytotoxicity. • L24f , L24h and L25c showed moderate Lm PTR1 inhibition and h DHFR selectivity. • L24h and L25c have shown in vivo activity on CL and VL models of BALB/c mice. [ABSTRACT FROM AUTHOR]