Effect of Isolated Proteins from Crotalus Durissus Terrificus Venom on Leishmania (Leishmania) Amazonensis-Infected Macrophages

Viperidae snakes infected by mammalian-associated trypanosomatids and a free-living kinetoplastid

Trypanosomatids have achieved significant evolutionary success in parasitizing various groups, yet reptiles remain relatively unexplored. The utilization of advanced molecular tools has revealed an increased richness of trypanosomatids in vertebrate hosts. The aim of this study was to identify the trypanosomatid species infecting Bothrops moojeni and Crotalus durissus kept in captivity from 2000 to 2022. Blood samples were obtained from 106 snakes: 73C. durissus and 33 B. moojeni. Whole blood was collected for hemoculture, blood smears and centrifugated to obtain the blood clot that had its DNA extracted and submitted to Nested PCR (18S rDNA gene) to detect Trypanosomatidae. Positive samples were quantified and submitted to both conventional (Sanger) and next generation sequencing (NGS). Cloning of the amplified PCR product was performed for only one individual of C. durissus. To exclude the possibility of local vector transmission, attempts to capture sandflies were conducted using six CDC-LT type light traps. Molecular diagnosis revealed that 34% of the snakes presented trypanosomatid DNA, 47.94% in C. durissus and 3.9% in B. moojeni. The cloning process generated four colonies identified as a new MOTU named Trypanosomatidae sp. CROT. The presence of DNA of five trypanosomatids (Trypanosoma cruzi TcII/VI, Trypanosoma sp. DID, Trypanosoma cascavelli, Trypanosomatidae sp. CROT, Leishmania infantum and Leishmania sp.) and one free-living kinetoplastid (Neobodo sp.) was revealed through NGS and confirmed by phylogenetic analysis. The haplotypic network divided the T. cascavelli sequences into two groups, 1) marsupials and snakes and 2) exclusive to marsupials. Therefore, the diversity of Kinetoplastea is still underestimated. Snakes have the ability to maintain infection with T. cruzi and L. infantum for up to 20 years and the DNA finding of Neobodo sp. in the blood of a C. durissus suggests that this genus can infect vertebrates.

Unlocking the potential of snake venom-based molecules against the malaria, Chagas disease, and leishmaniasis triad

Malaria, leishmaniasis and Chagas disease are vector-borne protozoal infections with a disproportionately high impact on the most fragile societies in the world, and despite malaria-focused research gained momentum in the past two decades, both trypanosomiases and leishmaniases remain neglected tropical diseases. Affordable effective drugs remain the mainstay of tackling this burden, but toxicicty, inneficiency against later stage disease, and drug resistance issues are serious shortcomings. One strategy to overcome these hurdles is to get new therapeutics or inspiration in nature. Indeed, snake venoms have been recognized as valuable sources of biomacromolecules, like peptides and proteins, with antiprotozoal activity. This review highlights major snake venom components active against at least one of the three aforementioned diseases, which include phospholipases A2, metalloproteases, L-amino acid oxidases, lectins, and oligopeptides. The relevance of this repertoire of biomacromolecules and the bottlenecks in their clinical translation are discussed considering approaches that should increase the success rate in this arduous task. Overall, this review underlines how venom-derived biomacromolecules could lead to pioneering antiprotozoal treatments and how the drug landscape for neglected diseases may be revolutionized by a closer look at venoms. Further investigations on poorly studied venoms is needed and could add new therapeutics to the pipeline.

Biological and Medical Aspects Related to South American Rattlesnake Crotalus durissus (Linnaeus, 1758): A View from Colombia

In Colombia, South America, there is a subspecies of the South American rattlesnake Crotalus durissus, C. d. cumanensis, a snake of the Viperidae family, whose presence has been reduced due to the destruction of its habitat. It is an enigmatic snake from the group of pit vipers, venomous, with large articulated front fangs, special designs on its body, and a characteristic rattle on its tail. Unlike in Brazil, the occurrence of human envenomation by C. durisus in Colombia is very rare and contributes to less than 1% of envenomation caused by snakes. Its venom is a complex cocktail of proteins with different biological effects, which evolved with the purpose of paralyzing the prey, killing it, and starting its digestive process, as well as having defense functions. When its venom is injected into humans as the result of a bite, the victim presents with both local tissue damage and with systemic involvement, including a diverse degree of neurotoxic, myotoxic, nephrotoxic, and coagulopathic effects, among others. Its biological effects are being studied for use in human health, including the possible development of analgesic, muscle relaxant, anti-inflammatory, immunosuppressive, anti-infection, and antineoplastic drugs. Several groups of researchers in Brazil are very active in their contributions in this regard. In this work, a review is made of the most relevant biological and medical aspects related to the South American rattlesnake and of what may be of importance for a better understanding of the snake C. d. cumanensis, present in Colombia and Venezuela.

Comparative Study of the Effect of Snake Venoms on the Growth of Ciliates Tetrahymena pyriformis: Identification of Venoms with High Antiprotozoal Activity

To search for compounds with antiprotozoal activity, effects of snake venoms on the ciliates Tetrahymena pyriformis was studied. T. pyriformis from subkingdom of Protozoa, including the protozoal pathogens, was used as a model organism to select the venoms that are the most active against parasitic protozoans. Various concentrations of venoms were added to the cells, and the cells that survived after 24 h were counted. Among the six snake species from the Viperidae family, the venom of the viper Vipera berus, which completely killed the cells at 49 μg/mL, was the most active. Among four species from the Elapidae family, the previously studied cobra venoms containing cytotoxins with strong antiprotozoal activity as well as the venom of krait Bungarus multicinctus (10 μg/mL) were the most active. The venoms of the pit vipers and Nikolsky's viper did not show any activity at 12.5 mg/mL. Thus, the venoms of V. berus and B. multicinctus are promising for the isolation of new antiprotozoal compounds.

Cruzioseptins, antibacterial peptides from Cruziohyla calcarifer skin, as promising leishmanicidal agents

Screenings of natural products have significantly contributed to the discovery of novel leishmanicidal agents. In this study, three known cruzioseptins-antibacterial peptides from Cruziohyla calcarifer skin-were synthesized and evaluated against promastigotes and amastigotes stages of Leishmania (L.) amazonensis and L. (V.) braziliensis. EC50 ranged from 9.17 to 74.82 μM, being cruzioseptin-1 the most active and selective compound, with selectivity index > 10 for both promastigotes and amastigotes of L. (V.) braziliensis. In vitro infections incubated with cruzioseptins at 50 μM showed up to ∼86% reduction in the amastigote number. Cruzioseptins were able to destabilize the parasite's cell membrane, allowing the incorporation of a DNA-fluorescent dye. Our data also demonstrated that hydrophobicity and charge appear to be advantageous features for enhancing parasiticidal activity. Antimicrobial cruzioseptins are suitable candidates and alternative molecules that deserve further in vivo investigation focusing on the development of novel antileishmanial therapies.

Peptides to Tackle Leishmaniasis: Current Status and Future Directions

Peptide-based drugs are an attractive class of therapeutic agents, recently recognized by the pharmaceutical industry. These molecules are currently being used in the development of innovative therapies for diverse health conditions, including tropical diseases such as leishmaniasis. Despite its socioeconomic influence on public health, leishmaniasis remains long-neglected and categorized as a poverty-related disease, with limited treatment options. Peptides with antileishmanial effects encountered to date are a structurally heterogeneous group, which can be found in different natural sources—amphibians, reptiles, insects, bacteria, marine organisms, mammals, plants, and others—or inspired by natural toxins or proteins. This review details the biochemical and structural characteristics of over one hundred peptides and their potential use as molecular frameworks for the design of antileishmanial drug leads. Additionally, we detail the main chemical modifications or substitutions of amino acid residues carried out in the peptide sequence, and their implications in the development of antileishmanial candidates for clinical trials. Our bibliographic research highlights that the action of leishmanicidal peptides has been evaluated mainly using in vitro assays, with a special emphasis on the promastigote stage. In light of these findings, and considering the advances in the successful application of peptides in leishmaniasis chemotherapy, possible approaches and future directions are discussed here.