Visceral infection by Porocephalus spp. (Pentastomida) in Neotropical wild mammals

Larval stages of pentastomids were collected from different organs of small mammals from the Peruvian Amazon. These parasitized mammals included: a western Amazonian oryzomys (Hylaeamys perenensis), an elegant oryzomys (Euryoryzomys nitidus), a lowland paca (Cuniculus paca), two kinkajous (Potos flavus), two silvery woolly monkeys (Lagothrix poeppigii) and a brown-mantled tamarin (Leontocebus fuscicollis). Pentastomids were found in the mesentery and parenchyma of the liver and lungs of these animals. All pentastomids were morphologically identified as nymphs of Porocephalus spp. Only the nymphs collected from select animals (the western Amazonian oryzomys, the elegant oryzomys and the brown-mantled tamarin) were analysed molecularly. Molecular analysis was performed amplifying the mitochondrial cytochrome c oxidase subunit I gene from select nymphs collected from the western Amazonian oryzomys, the elegant oryzomys and the brown-mantled tamarin. The nucleotide sequences exhibited 95.8–97.7% similarity between them. Also, these sequences showed an identity of 95.8–97.9% to Porocephalus crotali (GenBank accession numbers MG559647–MG559655). Molecular analysis indicated the presence of at least two Porocephalus species. These findings represent the first record of Porocephalus in these mammals, thus adding new intermediate hosts for this pentastomid genus. This work represents the first molecular data of Porocephalus in a Neotropical climate.

Whole-mouse in vivo bioluminescence imaging applied to drug screening against Leishmania infantum: a reliable method to evaluate efficacy and optimize treatment regimens

ABSTRACTLeishmaniasis is an important vector-borne neglected tropical disease caused by Leishmania parasites. Current anti-Leishmania chemotherapy is unsatisfactory, justifying the continued search for alternative treatment options. Herein, we propose the use of a minimally invasive bioluminescence-based murine model for preliminary in vivo screening of compounds against visceral infection by Leishmania infantum. We demonstrate that luciferase-expressing axenic amastigotes, unlike promastigotes, are highly infectious to BALB/c mice and generate a robust bioluminescent signal in the main target organs, such as the liver and spleen. Finally, we validate the use of this technique to evaluate in vivo treatment efficacy using reference drugs amphotericin B and miltefosine.

Diagnosis of leishmaniasis

Leishmaniasis is a clinically heterogeneous syndrome caused by intracellular protozoan parasites of the genus Leishmania. The clinical spectrum of leishmaniasis encompasses subclinical ( not apparent), localized (skin lesion), and disseminated (cutaneous, mucocutaneous, and visceral) infection. This spectrum of manifestations depends on the immune status of the host, on the parasite, and on immunoinflammatory responses. Visceral leishmaniasis causes high morbidity and mortality in the developing world. Reliable laboratory methods become mandatory for accurate diagnosis, especially in immunocompromised patients such as those infected with HIV. In this article, we review the current state of the diagnostic tools for leishmaniasis, especially the serological test.

Efficacy of Orally Administered 2-Substituted Quinolines in Experimental Murine Cutaneous and Visceral Leishmaniases

ABSTRACT We report in this study the in vivo efficacy of nine 2-substituted quinolines on the Leishmania amazonensis cutaneous infection murine model and on the Leishmania infantum and Leishmania donovani visceral infection murine models. In the case of the L. amazonensis model, quinolines were administered orally at 25 mg/kg twice daily for 15 days. Quinolines 1, 2, 3, and 7 reduced by 80 to 90% the parasite burdens in the lesion, whereas N-methylglucamine antimoniate (Glucantime), administered by subcutaneous injections at 100 mg [28 mg Sb(V)] per kg of body weight daily, reduced the parasite burdens by 98%. In visceral leishmaniasis due to L. infantum, mice treated orally at 25 mg/kg daily for 10 days with quinolines 1, 4, 5, and 6 showed a significant reduction of parasite burdens in the liver and spleen. These quinolines were significantly more effective than meglumine antimoniate to reduce the parasite burden in both the liver and spleen. Also, the oral in vivo activity of three quinolines (quinolines 4, 5, and 2-n-propylquinoline) were determined against L. donovani (LV 9) at 12.5 and 25 mg/kg for 10 days. Their activity was compared with that of miltefosine at 7.5 mg/kg. Miltefosine, 2-n-propylquinoline, and quinoline 5 at 12.5 mg/kg significantly reduced the parasite burdens in the liver by 72, 66, and 61%, respectively. From the present study, quinoline 5 is the most promising compound against both cutaneous and visceral leishmaniasis. The double antileishmanial and antiviral activities of these compounds suggest that this series could be a potential treatment for coinfection of Leishmania-human immunodeficiency virus.

Modulation of T-Cell Costimulation as Immunotherapy or Immunochemotherapy in Experimental Visceral Leishmaniasis

ABSTRACT CD40 ligand (CD40L)-deficient C57BL/6 mice failed to control intracellular Leishmania donovani visceral infection, indicating that acquired resistance involves CD40-CD40L signaling and costimulation. Conversely, in wild-type C57BL/6 and BALB/c mice with established visceral infection, injection of agonist anti-CD40 monoclonal antibody (MAb) induced killing of ∼60% of parasites within liver macrophages, stimulated gamma interferon (IFN-γ) secretion, and enhanced mononuclear cell recruitment and tissue granuloma formation. Comparable parasite killing was also induced by MAb blockade (inhibition) of cytotoxic T lymphocyte antigen-4 (CTLA-4) which downregulates separate CD28-B7 T-cell costimulation. Optimal killing triggered by both anti-CD40 and anti-CTLA-4 required endogenous IFN-γ and involved interleukin 12. CD40L−/− mice also failed to respond to antileishmanial chemotherapy (antimony), while in normal animals, anti-CD40 and anti-CTLA-4 synergistically enhanced antimony-associated killing. CD40L-CD40 signaling regulates outcome and response to treatment of experimental visceral leishmaniasis, and MAb targeting of T-cell costimulatory pathways (CD40L-CD40 and CD28-B7) yields macrophage activation and immunotherapeutic and immunochemotherapeutic activity.

Immunoenhancement Combined with Amphotericin B as Treatment for Experimental Visceral Leishmaniasis

ABSTRACT To determine if stimulation of Th1-cell-associated immune responses, mediated by interleukin 12 (IL-12) and gamma interferon (IFN-γ), enhance the antileishmanial effect of amphotericin B (AMB), Leishmania donovani-infected BALB/c mice were first treated with (i) exogenous IL-12 to induce IFN-γ, (ii) agonist anti-CD40 monoclonal antibody (MAb) to maintain IL-12 and induce IFN-γ, or (iii) anti-IL-10 receptor (IL-10R) MAb to blockade suppression of IL-12 and IFN-γ. In animals with established visceral infection, low-dose AMB alone (two injections of 1 mg/kg of body weight; total dose, 2 mg/kg) killed 15 to 29% of liver parasites; by themselves, the immunointerventions induced 16 to 33% killing. When the interventions were combined, the leishmanicidal activities increased 3.4-fold (anti-CD40), 6.3-fold (anti-IL-10R), and 9-fold (IL-12) compared with the activities of AMB plus the control preparations; and overall killing (76 to 84%) approximated the 84 to 92% killing effect of 7.5-fold more AMB alone (three injections of 5 mg/kg; total dose, 15 mg/kg). These results suggest that strengthening the host Th1-cell response may be a strategy for the development of AMB-sparing regimens in visceral leishmaniasis.