Brazilian contribution for a better knowledge on the biology of Toxoplasma gondii

Souza, Wanderley de; DaMatta, Renato Augusto; Attias, Márcia

doi:10.1590/s0074-02762009000200004

Cited by 6 publications

(4 citation statements)

References 25 publications

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“…Dynamin has recently been implicated in actin dynamics [24], thus, its use can alter all cell processes that involve this cytoskeleton filament, including phagocytosis. Moreover, phagocytosis also depends on the fusion of endomembrane compartments to the plasma membrane to form the phagosome, a process known as “focal exocytosis” [25].…”

Section: Discussionmentioning

confidence: 99%

Phosphatidylserine Exposure by Toxoplasma gondii Is Fundamental to Balance the Immune Response Granting Survival of the Parasite and of the Host

et al. 2011

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Phosphatidylserine (PS) exposure on the cell surface indicates apoptosis, but has also been related to evasion mechanisms of parasites, a concept known as apoptotic mimicry. Toxoplasma gondii mimics apoptotic cells by exposing PS, inducing secretion of TGF-beta1 by infected activated macrophages leading to degradation of inducible nitric oxide (NO) synthase, NO production inhibition and consequently persisting in these cells. Here PS+ and PS− subpopulation of tachyzoites were separated and the entrance mechanism, growth and NO inhibition in murine macrophages, and mice survival and pathology were analyzed. Infection index in resident macrophages was similar for both PS subpopulations but lower when compared to the total T. gondii population. Growth in resident macrophages was higher for the total T. gondii population, intermediate for the PS+ and lower for the PS− subpopulation. Production of NO by activated macrophages was inhibited after infection with the PS+ subpopulation and the total populations of tachyzoites. However, the PS− subpopulation was not able to inhibit NO production. PS+ subpopulation invaded macrophages by active penetration as indicated by tight-fitting vacuoles, but the PS− subpopulation entered macrophages by phagocytosis as suggested by loose-fitting vacuoles containing these tachyzoites. The entrance mechanism of both subpopulations was confirmed in a non-professional phagocytic cell line where only the PS+ tachyzoites were found inside these cells in tight-fitting vacuoles. Both subpopulations of T. gondii killed mice faster than the total population. Clear signs of inflammation and no tachyzoites were seen in the peritoneal cavity of mice infected with the PS− subpopulation. Moreover, mice infected with the PS+ subpopulation had no sign of inflammation and the parasite burden was intense. These results show that PS+ and PS− subpopulations of T. gondii are necessary for a successful toxoplasma infection indicating that both subpopulations are required to maintain the balance between inflammation and parasite growth.

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Section: Discussionmentioning

confidence: 99%

Phosphatidylserine Exposure by Toxoplasma gondii Is Fundamental to Balance the Immune Response Granting Survival of the Parasite and of the Host

et al. 2011

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“…As stated earlier, although most reports of ocular toxoplasmosis were from the Clínica Silveira in Erechim, the disease is probably common in the rest of the Brazilian population, and toxoplasmosis has been recognized as an important cause of uveitis in Brazil since late 1970's (Belfort et al 1978; de Abreu et al 1980, 1982; Petrilli et al 1987; Silveira et al 1987; Pinheiro et al 1990; Glasner et al 1992 b ; Schellini et al 1993; Reis et al 1998 a , b ; Sebben et al 1995; Abreu et al 1998; de Carvalho et al 1998; Jorge et al 2003; Gouveia et al 2004; Oliveira and Reis, 2004; do Carmo et al 2005; Alvarenga et al 2007; Haddad et al 2007; Nóbrega and Rosa, 2007; Lynch et al 2008; Aleixo et al 2009; de Souza and Casella, 2009; Lynch et al 2009; Melamed, 2009; Diniz et al 2011; Mattos et al 2011). Even though toxoplasmosis can affect any part of the eye, retinochoroiditis is its hallmark (Silveira et al 1989; Hayashi et al 1997; Holland et al 1999; Silveira et al 2001; Silveira, 2002; Yamamoto et al 2003; Eckert et al 2007; Oréfice et al 2007; Lynch et al 2008; Commodaro et al 2009; Melamed et al 2009; Bottós et al 2009; de Souza et al 2009; Belfort et al 2010; Arevalo et al 2010; Delair et al 2011). Ocular toxoplasmosis is the main cause of uveitis worldwide, and in Brazil it is responsible for 70% of the cases (de Amorim Garcia et al 2004).…”

Section: Toxoplasmosis In Humansmentioning

confidence: 99%

Toxoplasmosis in humans and animals in Brazil: high prevalence, high burden of disease, and epidemiology

et al. 2012

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SUMMARYInfections by the protozoan parasiteToxoplasma gondiiare widely prevalent in humans and animals in Brazil. The burden of clinical toxoplasmosis in humans is considered to be very high. The high prevalence and encouragement of the Brazilian Government provides a unique opportunity for international groups to study the epidemiology and control of toxoplasmosis in Brazil. Many early papers on toxoplasmosis in Brazil were published in Portuguese and often not available to scientists in English-speaking countries. In the present paper we review prevalence, clinical spectrum, molecular epidemiology, and control ofT. gondiiin humans and animals in Brazil. This knowledge should be useful to biologists, public health workers, veterinarians, and physicians. Brazil has a very high rate ofT. gondiiinfection in humans. Up to 50% of elementary school children and 50–80% of women of child-bearing age have antibodies toT. gondii. The risks for uninfected women to acquire toxoplasmosis during pregnancy and fetal transmission are high because the environment is highly contaminated with oocysts. The burden of toxoplasmosis in congenitally infected children is also very high. From limited data on screening of infants forT. gondiiIgM at birth, 5–23 children are born infected per 10 000 live births in Brazil. Based on an estimate of 1 infected child per 1000 births, 2649 children with congenital toxoplasmosis are likely to be born annually in Brazil. Most of these infected children are likely to develop symptoms or signs of clinical toxoplasmosis. Among the congenitally infected children whose clinical data are described in this review, several died soon after birth, 35% had neurological disease including hydrocephalus, microcephaly and mental retardation, 80% had ocular lesions, and in one report 40% of children had hearing loss. The severity of clinical toxoplasmosis in Brazilian children may be associated with the genetic characteristics ofT. gondiiisolates prevailing in animals and humans in Brazil.

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“…O superior mede 160 nm de diâmetro, enquanto o inferior, 200 nm. Abaixo destes, encontra-se um anel polar posterior, onde está o centro organizador de microtúbulos (revisto em Souza, DaMatta & Attias, 2009), de onde partem 22 microtúbulos subpeliculares, compostos de 13 protofilamentos cada um. A natureza molecular destes três anéis ainda é desconhecida.…”

Section: Citoesqueletounclassified

“…Os parasitas resultantes das sucessivas divisões celulares permanecem ligados a um único corpo residual, o que lhes dá um aspecto de roseta dentro do vacúolo parasitóforo. No egresso, estas rosetas se desfazem e os parasitas individualizados abandonam e terminam por lisar a célula hospedeira (Souza, DaMatta & Attias, 2009) As organelas secretórias, como róptrias, micronemas e grânulos densos se formam de novo durante o processo de brotamento e antes que o núcleo se divida. Uma proteína chamada DrpB (proteína B relacionada à dinamina) está diretamente envolvida na formação de vesículas que participam da via de secreção regulada, que endereça às organelas apicais.…”

Section: Acidocalcissomos E Corpos Lipídicosunclassified

Toxoplasmose & Toxoplasma gondii

Souza¹,

Belfort²

2014

Self Cite

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por Jacobs e Lund, a imunofluorescência indireta, por Kelen e colaboradores, e a fixação do complemento, por Nicolau e Revelo e por Warren e Sabin. Frenkel, em 1948, inseriu no contexto de prova de reconhecimento da parasitose o teste da sensibilidade cutânea à toxoplasmose.Com o uso de exames sorológicos, ficou demonstrada a presença de anticorpos contra T. gondii em grande número de habitantes de diferentes áreas geográficas, bem como em numerosas espécies de animais. De tal forma está disseminada a infecção por T. gondii, que pode ser considerada inteiramente válida a afirmativa feita por Jacobs de que "vivemos num mar de infecção toxoplásmica".Quarta etapa (identificação do hospedeiro definitivo) -nesta fase sucedeu a descoberta do hospedeiro definitivo do T. gondii, ou seja, o gato, permitindo melhor conhecimento da epidemiologia da toxoplasmose. Outros felídeos, convém destacar, também atuam como hospedeiro definitivo.Os estudos que levaram à identificação do hospedeiro definitivo tiveram início com a detecção, por Hutchison, de uma forma infectante e resistente do toxoplasma em fezes de gato. Posteriormente, graças aos trabalhos de vários pesquisadores -como Hutchison, na Dinamarca; Frenkel, Jacobs, Dubey e Miller, nos Estados Unidos; e Piekarski e Wite, na Alemanha -, ficou demonstrado o ciclo sexuado de T. gondii no intestino desse felídeo.Por fim, ouso apontar sugestões quiçá valiosas que, se concretizadas, conduzirão ao prosseguimento do processo de aquisição de mais alguns subsídios para abordarmos construtivamente singularidades atinentes à toxoplasmose. Ei-las: programar sorologicamente conhecer mulheres ainda não infectadas, possibilitando recomendações de caráter preventivo; procurar drogas efetivas para tratamento com esquemas de curta duração e sem toxicidade; produzir drogas que atinjam os cistos, com o objetivo de suprimir a parasitose e evitar recaídas ou reativações; pesquisar para saber se cepas influem quanto às feições clínico-patológicas; investigar a provável transmissão de T. gondii por transfusão de sangue; e por fim, a consecução de um fabuloso sonho, ou seja, a obtenção de vacina preventiva bem respaldada cientificamente, sendo conveniente lembrar que se encontram em curso, com este objetivo, esforços diversificados. Esta é minha simplória colaboração. Wanderley e Rubens: não esmoreçam e persistam contribuindo com brilho para a medicina brasileira.

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Brazilian contribution for a better knowledge on the biology of Toxoplasma gondii

Cited by 6 publications

References 25 publications

Phosphatidylserine Exposure by Toxoplasma gondii Is Fundamental to Balance the Immune Response Granting Survival of the Parasite and of the Host

Phosphatidylserine Exposure by Toxoplasma gondii Is Fundamental to Balance the Immune Response Granting Survival of the Parasite and of the Host

Toxoplasmosis in humans and animals in Brazil: high prevalence, high burden of disease, and epidemiology

Toxoplasmose & Toxoplasma gondii

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