Ultrastructure of Trypanosoma cruzi and its interaction with host cells

W. de Souza1'2, T.U. de Carvalho1 and E.S. Barrias3

1Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 2Instituto Nacional de Ciencia e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil, 3Instituto nacional de Metrologia, Normalizacao e Qualidade - Inmetro, Rio de Janeiro, Brazil; Avenida Nossa Senhora das Gracas, Rio de Janeiro, Brazil

Chapter Outline

Structural organization of Trypanosoma cruzi 401 The nucleus 403

The kinetoplast-mitochondrion complex 404 The glycosome 406 The acidocalcisome 406 The contractile vacuole 408 The cytoskeleton 409 The flagellum 411 The flagellar pocket 413 The secretory pathway 414 The endocytic pathway 414 Other cytoplasmic structures 416 The cell surface 416

Fine structure of the interaction of T cruzi with host cells 416 Triggering of endocytosis 418

Lysis of the parasitophorous vacuole (PV) membrane 420 Acknowledgments 421 References 421

Structural organization of Trypanosoma cruzi

Structural features of Protozoa of the Trypanosomatidae family include structures/ organelles such as the kinetoplast, the glycosome, the paraflagellar rod, a highly specialized flagellar pocket, and a layer of subpellicular microtubules (Fig. 18.1).

American Trypanosomiasis Chagas Disease. DOI: http://dx.doi.org/10.1016/B978-0-12-801029-7.00018-6

Copyright © 2017 Elsevier Inc. All rights reserved.

Schematic representation of longitudinal section of an epimastigote showing the main structures and organelles found in T

Figure 18.1 Schematic representation of longitudinal section of an epimastigote showing the main structures and organelles found in T. cruzi. The scheme is modified from a drawing by Flavia Moreira-Leite, University of Oxford.

Source: After Docampo R, De Souza W, Miranda K, Roheloff P, Moreno S.

Acidocalcisomes—conserved from bacteria to man. Nat Rev Microbiol 2005;3:251-61.

They have the ability to change shape during their life cycle, a process described as protozoan differentiation or transformation.1,2 Among the trypanosomatids, Trypanosoma cruzi proceeds through several developmental stages in the vertebrate and invertebrate hosts, living both in the bloodstream and inside the cells of the vertebrate host (Fig. 18.2).

The infection of mammals usually occurs following an insect bite (member of Reduvidae family), when the metacyclic trypomastigote penetrates directly through the ocular mucosa or skin lesion. Another route of infection is via the ingestion of food that is contaminated with T. cruzi, especially juices from fruits, such as acal and guava, in the Amazon region and sugar cane in other regions.3,4 Once in the vertebrate host, the metacyclic trypomastigotes invade the nucleate forming a vacuole known as the parasitophorous vacuole (PV). A few hours after infection, trypo- mastigotes are gradually turned into amastigote (a stage that is rounded and with a

Life cycle of Trypanosoma cruzi

Figure 18.2 Life cycle of Trypanosoma cruzi.

short flagellum) and the PV structure are digested, allowing the amastigotes to come into direct contact with host cell organelles. In the cytoplasm, the amastigotes divide almost synchronously, with a generation time that varies according to the T. cruzi strain.5

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