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1.
Autophagy Rep ; 2(1)2023.
Article in English | MEDLINE | ID: mdl-37064813

ABSTRACT

Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.

2.
Vaccine ; 32(11): 1287-95, 2014 Mar 05.
Article in English | MEDLINE | ID: mdl-24406392

ABSTRACT

BACKGROUND: The incidence of zoonotic canine visceral leishmaniasis (CVL) would decrease if dogs were effectively vaccinated; however, additional data on the efficacy of canine vaccines are required for their approved preventative use. PURPOSE: To prospectively evaluate vaccination outcomes using two products commercially available in Brazil, with respect to adverse reactions (reactogenicity), humoral response, disease signs, parasitism, and parasite infectiousness in naturally exposed pet dogs in an endemic area of visceral leishmaniasis (VL). METHODS: From 2010 to 2012, healthy dogs were vaccinated with Leishmune(®) (50 animals) or Leish-Tec(®) (50 animals). Each dog was examined to identify clinical signs during peri- and post-vaccination procedures every 2 months for 11 months to identify the presence of parasites or parasite DNA in splenic samples using culturing or PCR, respectively. Levels of anti-Leishmania IgG, IgG1, and IgG2 were quantified in sera by ELISA and infectiousness was assessed by xenodiagnosis. RESULTS: Adverse effects occurred in 2.2% (1/45) and 13.0% (6/46) of the animals in the Leishmune(®) and Leish-Tec(®) groups, respectively. IgG levels peaked on the 21st day following the first dose of Leishmune(®) and on the 21st day after the second dose of Leish-Tec(®). The final seropositivity rate for IgG was 32.5% (13/40) and 30.9% (13/42) in the Leishmune(®) and Leish-Tec(®) groups, respectively. The Leishmune(®) group presented higher levels of IgG1 and IgG2 compared to the Leish-Tec(®) group (p<0.001), and ELISA reactivity in both vaccinated groups was significantly lower (p<0.001) than in infected positive control dogs. Parasitism was observed in 12.2% (5/41) of the Leishmune(®) group, and 7.9% (3/38) of the Leish-Tec(®) group, with xenodiagnostic transmission rates of Leishmania to Lutzomyia longipalpis of 5.1% (2/39), and 5.4% (2/37), respectively. CONCLUSIONS: No significant differences were observed in dogs vaccinated with Leishmune(®) or Leish-Tec(®), with respect to LVC clinical aspects, parasitism, IgG seropositivity, or dog infectiousness. The Leishmune(®)-vaccinated animals presented higher levels of IgG, IgG1, and IgG2. The animals vaccinated with Leish-Tec(®) exhibited adverse reactions with greater frequency and severity.


Subject(s)
Dog Diseases/prevention & control , Leishmaniasis Vaccines/therapeutic use , Leishmaniasis, Visceral/prevention & control , Xenodiagnosis , Animals , Antibodies, Protozoan/blood , Brazil , Dog Diseases/parasitology , Dogs , Female , Immunity, Humoral , Immunoglobulin G/blood , Leishmaniasis Vaccines/adverse effects , Leishmaniasis, Visceral/diagnosis , Leishmaniasis, Visceral/veterinary , Male , Prospective Studies , Vaccination/veterinary
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