New Insights into Protozoa Parasites: Essential Processes and Drug Targets

Dear Colleagues,

Protozoa are a polyphyletic group of unicellular eukaryotes, including free-living or parasitic organisms. Among 50,000 described species, the great majority comprehends free-living cells that colonize almost all kinds of habitats, mainly feeding on organic matter. However, some species are parasites, producing disease in their hosts. In nature, protozoa parasites can be found in different hosts, such as plants, insects and other arthropods, as well as in all kind of vertebrate animals, including mammals. Since most of these diseases present anthropozoonotic potential, completely eliminating them is almost impossible, especially in wild environments. Serious and regular surveillance actions are essential if we are to avoid increases in the number of cases. Among the most important protozoa diseases for humans are Chagas disease, sleeping sickness, and leishmaniasis, caused by trypanosomatids; malaria and toxoplasmosis, caused by apicomplexa; and giardiasis, trichomoniasis, and amebiasis, caused by anaerobic protozoa. Together, these diseases affect almost all populations across the world, posing risks of infection related to geographic areas and economic and social issues, among other features. The clinical drugs used to combat these diseases are unsatisfactory, showing limited efficacy and high toxicity in many cases. The parasites’ interactions with their hosts are very complex, based on the balance between pathogens’ virulence and the host immune response. The comprehension of crucial molecular, cellular, and biochemical mechanisms, identifying their checkpoints for the success of the infection, seems to be a very reasonable approach for the development of alternative anti-protozoan drugs in the near future. In this context, the involvement of oxidative stress in protozoan infections has been demonstrated, at times aiding in cell signaling and regulation, while, at other times, causing parasites’ death. The role of antioxidant enzymes as virulence factors highlights the significance of these molecular processes, as well as the adaptive strategies employed by protozoa parasites to survive in oxidative conditions within the host, impacting the success of the infection. Conversely, autophagy serves as a physiological mechanism in eukaryotes to maintain homeostasis by degrading nonfunctional cellular components, thus minimizing the accumulation of damaged organelles and macromolecules. The participation of the autophagic pathway in protozoa has been described, particularly in relation to chemotherapy, where it can counteract the effects of drugs. The scope of this Special Issue includes distinct aspects of the protozoa–host interactions, describing cellular, molecular, and biochemical processes that relate to survival mechanisms, antioxidant defenses, and redox metabolism. We will accept reviews or original contributions.

Dr. Rubem F. S. Menna-Barreto
Dr. Ana Cristina Souza Bombaça
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pathogens is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• protozoa
• parasites
• trypanosomatids
• apicomplexan parasites
• anaerobic protozoa
• chemotherapy
• drug targets
• protozoa–host interactions
• autophagy
• oxidative stress