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Use of Artemisia annua L. in the Treatment of Diseases—An Update
Published in Tariq Aftab, M. Naeem, M. Masroor, A. Khan, Artemisia annua, 2017
M. Naeem, Tariq Aftab, Asfia Shabbir, M. Masroor, A. Khan
A study of the effects of artemisinin on Neospora caninum , a protozoal parasite infecting a wide range of mammals and causing abortion in cattle, was performed (Verdian-Rizi, 2009). Cultured host cells (Vero cells or mouse peritoneal macrophages) were infected with N. caninum tachyzoites and supplemented with concentrations of 20, 10, 1, 0.1, and 0.01 μ g/ml artemisinin. At 20 or 10 μ g/ml for 11 days, artemisinin eliminated all microscopic foci of N. caninum completely. At 1 μ g/ml for 14 days, the same result was observed. Over shorter periods, 0.1 μ g/ml artemisinin reduced the intracellular multiplication of N. caninum tachyzoites (p < 0.05).
Toxoplasma gondii
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Sarcocystis: Sarcosystis species have a similar life cycle to T. gondii. Humans are rarely infected, but they can serve as either the definitive or intermediate host, depending on the source of infection. Neospora caninum causes neurological disease in dogs, which serve as definitive hosts. This organism is a major cause of spontaneous abortion in cattle, which may become infected if they consume sporulated oocysts that are passed in an infected dog’s feces.
Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Examples in which parasites serve as indicators or sentinels of environmental problems or changes also unfortunately occur. Marine mammals ranging from sea otters to harbor seals to killer whales along the Pacific Coast of North America have been found in recent years to be infected with a variety of parasites customarily associated with humans, pets, and farm animals from terrestrial environments. These parasites exemplify what have been called pollutogens. Pollutogens are infectious agents that originate outside a particular ecosystem and are able to develop within a host found in that ecosystem. For instance, co-infections of two related apicomplexans, Toxoplasma gondii and Sarcocystis neurona, have emerged as a major cause of death in southern sea otters, Enhydra lutris nereis. The nematode Capillaria hepatica, normally associated with wild and feral rats (Rattus sp.) in which it is often transmitted by cannibalism, has also appeared in sea otters and implicated in causing mortality. Simultaneous infections with C. hepatica, T. gondii and S. neurona have been found in the otters, pointing out how polyparasitism from these pollutogens could have a devastating combined effect. Other kinds of pathogens associated with terrestrial environments such as Neospora caninum, another apicomplexan normally problematic in both cattle and its canine definitive hosts, have also appeared in marine mammals.
Structure-activity relationships of Toxoplasma gondii cytochrome bc 1 inhibitors
Published in Expert Opinion on Drug Discovery, 2022
P. Holland Alday, Aaron Nilsen, J. Stone Doggett
Cytochrome (cyt) bc1 has proven to be a tractable drug target for the majority of veterinary and human apicomplexan pathogens. In addition to T. gondii, cyt bc1 inhibitors have been found to be effective across orders of the phylum Apicomplexa: Haemosporida, Plasmodia spp.; the Piroplasmida, Babesia spp., and Theileria equii; and the Eucoccidiorida, Sarcocystis neurona, Eimeria spp., Neospora caninum, and Besnoitia besnoiti [5–10]. Cryptosporidium, the human gastrointestinal parasite, is a notable exception. It lacks a mitochondrion with genes for enzymes of oxidative phosphorylation, including cyt b and instead contains mitochondrion-related organelles [11]. On the other hand, the human gastrointestinal parasites Cyclospora cayetanensis and Cystoisospora belli encode cyt b in their mitochondrial genomes, although cyt bc1 inhibitors have not been thoroughly evaluated for these diseases.
Immunogenicity and protection efficacy of enhanced fitness recombinant Salmonella Typhi monovalent and bivalent vaccine strains against acute toxoplasmosis
Published in Pathogens and Global Health, 2021
Fei-Kean Loh, Sheila Nathan, Sek-Chuen Chow, Chee-Mun Fang
In order to improve the overall protective efficacy, different antigen combinations shall be selected. Rhoptry proteins (ROPs) have emerged as one of the most highly explored and immunogenic T. gondii antigen. As reviewed, ROP16 delivered by canine adenovirus type 2 (CAV2) has conferred the highest protection among the T. gondii DNA vaccine candidates in previous five years and is characterized by high levels of proinflammatory cytokines IFN-ɣ and IL-2 [22,50]. Apart from that, the S. Typhi bivalent strains can be potentially developed as a combination toxoplasmosis and typhoid fever vaccine to improve its commercial value. For instance, the two most established licensure combination vaccines – diphtheria, tetanus, and pertussis (DTP) vaccine and measles, mumps, and rubella (MMR) vaccine have formulated multiple antigens as a single product to facilitate fewer immunizations with broader disease coverage [61]. Hence, the selection of T. gondii antigens that are conserved with phylogenetically closely related parasites such as Neospora, may lead to vaccines developed for both parasitic diseases. Preliminary study reported that mice immunized with plasmid-expressed T. gondii MIC3 showed lower parasite burden following T. gondii and N. caninum challenge [62]. The future construction of multivalent S. Typhi strains can also include antigens from closely related intracellular pathogens which require the induction of similar immune responses.
Toxoplasma gondii infection: novel emerging therapeutic targets
Published in Expert Opinion on Therapeutic Targets, 2023
Joachim Müller, Andrew Hemphill
Toxoplasma gondii is an intracellular protozoan parasite belonging to the clade Alveolata of the super-group Diaphoretickes [1]. The life cycle comprises three stages, rapidly proliferating tachyzoites, slowly proliferating or resting bradyzoites, and sporozoites within oocysts [2]. Oocysts are excreted by felids, the definitive hosts. After ingestion by intermediate hosts, excysted sporozoites will invade intestinal epithelial cells and differentiate into tachyzoites, which are highly invasive and disseminate throughout the body within dendritic cells and other leukocytes. They will ultimately infect muscular tissue or the brain where they persist as bradyzoites, encapsulated within tissue cysts and surrounded by a cyst wall, which protects bradyzoites from physiological and immunological reactions on part of the host. The ingestion of an intermediate host or infected meat harboring T. gondii tissue cysts by a felid concludes the life cycle [3]. Thus, toxoplasmosis is a zoonosis that is orally transmitted. Another route of infection is via vertical transmission of tachyzoites from an infected mother to the fetus. According to recent estimations, approximately one-third of the world's population is infected with T. gondii, mostly via food contaminated by oocysts or bradyzoites [4] or via congenital infection [5]. In immunocompetent hosts, the infection remains, in general, without symptoms. There is, however, increasing evidence that chronic cerebral infection may cause mental disorders [6–8]. In immunocompromised hosts such as HIV-patients, cerebral toxoplasmosis is a major cause of mortality [9,10]. Vertical transmission may have severe consequences for the fetus and/or newborn [11,12], including abortion, hydrocephalus, or congenital ocular toxoplasmosis [13]. Moreover, ocular toxoplasmosis may be acquired by adults upon contact with highly virulent strains, in particular in South America [14]. Moreover, T. gondii is a major abortion-causing pathogen in farm animals, in particular in small ruminants such as goats and sheep [15,16], as well as in a variety of other mammals [17]. The closely related Neospora caninum is economically important in cattle as a major cause of abortion, stillbirth, and birth of weak calves [18].