Sexual Development in Non-Human Parasitic Apicomplexa: Just Biology or Targets for Control?

Published on Oct 1, 2021in Animal3.24
· DOI :10.3390/ANI11102891
Teresa Cruz-Bustos1
Estimated H-index: 1
Anna Sophia Feix1
Estimated H-index: 1
+ 1 AuthorsAnja Joachim35
Estimated H-index: 35
The phylum Apicomplexa is a major group of protozoan parasites including gregarines, coccidia, haemogregarines, haemosporidia and piroplasms, with more than 6000 named species. Three of these subgroups, the coccidia, hemosporidia, and piroplasms, contain parasites that cause important diseases of humans and animals worldwide. All of them have complex life cycles involving a switch between asexual and sexual reproduction, which is key to their development. Fertilization (i.e., fusion of female and male cells) results in the formation of a zygote that undergoes meiosis, forming a new generation of asexual stages. In eukaryotes, sexual reproduction is the predominant mode of recombination and segregation of DNA. Sex is well documented in many protist groups, and together with meiosis, is frequently linked with transmission to new hosts. Apicomplexan sexual stages constitute a bottleneck in the life cycle of these parasites, as they are obligatory for the development of new transmissible stages. Consequently, the sexual stages represent attractive targets for vaccination. Detailed understanding of apicomplexan sexual biology will pave the way for the design and implementation of effective transmission-blocking strategies for parasite control. This article reviews the current knowledge on the sexual development of Apicomplexa and the progress in transmission-blocking vaccines for their control, their advantages and limitations and outstanding questions for the future.
#1Anna Sophia Feix (University of Veterinary Medicine Vienna)H-Index: 1
#2Teresa Cruz-Bustos (University of Veterinary Medicine Vienna)H-Index: 1
Last. Anja Joachim (University of Veterinary Medicine Vienna)H-Index: 35
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#1Petra Schneider (Edin.: University of Edinburgh)H-Index: 25
#2Sarah E. Reece (Edin.: University of Edinburgh)H-Index: 36
Malaria parasites exhibit a complex lifecycle, requiring extensive asexual replication in the liver and blood of the vertebrate host, and in the haemocoel of the insect vector. Yet, they must also undergo a single round of sexual reproduction, which occurs in the vector's midgut upon uptake of a blood meal. Sexual reproduction is obligate for infection of the vector and thus, is essential for onwards transmission to new hosts. Sex in malaria parasites involves several bottlenecks in parasite num...
#1Chandra Ramakrishnan (UZH: University of Zurich)H-Index: 15
#2Nicholas C. Smith (ANU: Australian National University)H-Index: 42
Abstract The Coccidia is the largest group of parasites within the Apicomplexa, a phylum of unicellular, obligate parasites characterized by the possession of an apical complex of organelles and structures in the asexual stages of their life cycles, as well as by a sexual reproductive phase that occurs enterically in host animals. Coccidian sexual reproduction involves morphologically distinct microgametes and macrogametes that combine to form a diploid zygote and, ultimately, following meiosis ...
Preliminary results suggest the vaccine is up to 77% effective in young children, but researchers await larger studies. Preliminary results suggest the vaccine is up to 77% effective in young children, but researchers await larger studies.
Abstract Much of the vast evolutionary landscape occupied by Eukaryotes is dominated by protists. Though parasitism has arisen in many lineages, there are three main groups of parasitic protists of relevance to human and livestock health: the Apicomplexa, including the malaria parasite Plasmodium and coccidian pathogens of livestock such as Eimeria; the excavate flagellates, encompassing a diverse range of protist pathogens including trypanosomes, Leishmania, Giardia and Trichomonas; and the Amo...
#1Camila H. Coelho (NIH: National Institutes of Health)H-Index: 6
#2Wai Kwan Tang (NIH: National Institutes of Health)H-Index: 2
Last. Vu Nguyen (NIH: National Institutes of Health)H-Index: 10
view all 29 authors...
Malaria elimination requires tools that interrupt parasite transmission. Here, we characterize B cell receptor responses among Malian adults vaccinated against the first domain of the cysteine-rich 230 kDa gamete surface protein Pfs230, a key protein in sexual stage development of P. falciparum parasites. Among nine Pfs230 human monoclonal antibodies (mAbs) that we generated, one potently blocks transmission to mosquitoes in a complement-dependent manner and reacts to the gamete surface; the oth...
#1Jyotsna ChawlaH-Index: 1
#2Jenna OberstallerH-Index: 11
Last. John AdamsH-Index: 72
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Mosquito transmission of the deadly malaria parasite Plasmodium falciparum is mediated by mature sexual forms (gametocytes). Circulating in the vertebrate host, relatively few intraerythrocytic gametocytes are picked up during a bloodmeal to continue sexual development in the mosquito vector. Human-to-vector transmission thus represents an infection bottleneck in the parasite’s life cycle for therapeutic interventions to prevent malaria. Even though recent progress has been made in the identific...
#1Saleh Al-QuraishyH-Index: 30
#2Fathy Abdel-GhaffarH-Index: 25
Last. Rewaida Abdel-GaberH-Index: 11
view all 4 authors...
Apicomplexa is a phylum that includes all parasitic protozoa sharing unique ultrastructural features. Haemogregarines are sophisticated apicomplexan blood parasites with an obligatory heteroxenous life cycle and haplohomophasic alternation of generations. Haemogregarines are common blood parasites of fish, amphibians, lizards, snakes, turtles, tortoises, crocodilians, birds, and mammals. Haemogregarine ultrastructure has been so far examined only for stages from the vertebrate host. PCR-based as...
Toxoplasma gondii and Eimeria spp. are widely prevalent Coccidian parasites that undergo sexual reproduction during their life cycle. T. gondii can infect any warm-blooded animal in its asexual cycle; however, its sexual cycle is restricted to felines. Eimeria spp. are usually restricted to one host species, and their whole life cycle is completed within this same host. The literature reviewed in this article comprises the recent findings regarding the unique biology of the sexual development of...
#1Ramiro Tomasina (Pasteur Institute)H-Index: 1
#2Maria E. Francia (Pasteur Institute)H-Index: 11
Toxoplasma gondii is a widely prevalent protozoan parasite member of the phylum Apicomplexa. It causes disease in humans with clinical outcomes ranging from an asymptomatic manifestation to eye disease to reproductive failure and neurological symptoms. In farm animals, and particularly in sheep, toxoplasmosis costs the industry millions by profoundly affecting their reproductive potential. As do all the parasites in the phylum, T. gondii parasites go through sexual and asexual replication in the...
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