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Infections with extracellular trypanosomes require control by efficient innate immune mechanisms and can result in the destruction of the mammalian humoral immune system

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Abstract
Salivarian trypanosomes are extracellular parasites that affect humans, livestock, and game animals around the world. Through co-evolution with the mammalian immune system, trypanosomes have developed defense mechanisms that allow them to thrive in blood, lymphoid vessels, and tissue environments such as the brain, the fat tissue, and testes. Trypanosomes have developed ways to circumvent antibody-mediated killing and block the activation of the lytic arm of the complement pathway. Hence, this makes the innate immune control of the infection a crucial part of the host-parasite interaction, determining infection susceptibility, and parasitemia control. Indeed, trypanosomes use a combination of several independent mechanisms to avoid clearance by the humoral immune system. First, perpetuated antigenic variation of the surface coat allows to escape antibody-mediated elimination. Secondly, when antibodies bind to the coat, they are efficiently transported toward the endocytosis pathway, where they are removed from the coat proteins. Finally, trypanosomes engage in the active destruction of the mammalian humoral immune response. This provides them with a rescue solution in case antigenic variation does not confer total immunological invisibility. Both antigenic variation and B cell destruction pose significant hurdles for the development of anti-trypanosome vaccine strategies. However, developing total immune escape capacity and unlimited growth capabilities within a mammalian host is not beneficial for any parasite, as it will result in the accelerated death of the host itself. Hence, trypanosomes have acquired a system of quorum sensing that results in density-dependent population growth arrest in order to prevent overpopulating the host. The same system could possibly sense the infection-associated host tissue damage resulting from inflammatory innate immune responses, in which case the quorum sensing serves to prevent excessive immunopathology and as such also promotes host survival. In order to put these concepts together, this review summarizes current knowledge on the interaction between trypanosomes and the mammalian innate immune system, the mechanisms involved in population growth regulation, antigenic variation and the immuno-destructive effect of trypanosomes on the humoral immune system. Vaccine trials and a discussion on the role of innate immune modulation in these trials are discussed at the end.
Keywords
VARIANT SURFACE GLYCOPROTEIN, EXPERIMENTAL AFRICAN TRYPANOSOMIASIS, NECROSIS-FACTOR-ALPHA, NITRIC-OXIDE, BOVINE TRYPANOSOMIASIS, CONGOLENSE INFECTIONS, ALTERNATIVE PATHWAY, EVANSI INFECTION, BRUCEI-GAMBIENSE, CELL RESPONSES, trypanosomes, innate immunity, cytokine, antibody, immunosuppression

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MLA
Magez, Stefan, et al. “Infections with Extracellular Trypanosomes Require Control by Efficient Innate Immune Mechanisms and Can Result in the Destruction of the Mammalian Humoral Immune System.” FRONTIERS IN IMMUNOLOGY, vol. 11, 2020, doi:10.3389/fimmu.2020.00382.
APA
Magez, S., Pinto Torres, J. E., Obishakin, E. T., & Radwanska, M. (2020). Infections with extracellular trypanosomes require control by efficient innate immune mechanisms and can result in the destruction of the mammalian humoral immune system. FRONTIERS IN IMMUNOLOGY, 11. https://doi.org/10.3389/fimmu.2020.00382
Chicago author-date
Magez, Stefan, Joar Esteban Pinto Torres, Emmanuel Tumininu Obishakin, and Magdalena Radwanska. 2020. “Infections with Extracellular Trypanosomes Require Control by Efficient Innate Immune Mechanisms and Can Result in the Destruction of the Mammalian Humoral Immune System.” FRONTIERS IN IMMUNOLOGY 11. https://doi.org/10.3389/fimmu.2020.00382.
Chicago author-date (all authors)
Magez, Stefan, Joar Esteban Pinto Torres, Emmanuel Tumininu Obishakin, and Magdalena Radwanska. 2020. “Infections with Extracellular Trypanosomes Require Control by Efficient Innate Immune Mechanisms and Can Result in the Destruction of the Mammalian Humoral Immune System.” FRONTIERS IN IMMUNOLOGY 11. doi:10.3389/fimmu.2020.00382.
Vancouver
1.
Magez S, Pinto Torres JE, Obishakin ET, Radwanska M. Infections with extracellular trypanosomes require control by efficient innate immune mechanisms and can result in the destruction of the mammalian humoral immune system. FRONTIERS IN IMMUNOLOGY. 2020;11.
IEEE
[1]
S. Magez, J. E. Pinto Torres, E. T. Obishakin, and M. Radwanska, “Infections with extracellular trypanosomes require control by efficient innate immune mechanisms and can result in the destruction of the mammalian humoral immune system,” FRONTIERS IN IMMUNOLOGY, vol. 11, 2020.
@article{8654453,
  abstract     = {{Salivarian trypanosomes are extracellular parasites that affect humans, livestock, and game animals around the world. Through co-evolution with the mammalian immune system, trypanosomes have developed defense mechanisms that allow them to thrive in blood, lymphoid vessels, and tissue environments such as the brain, the fat tissue, and testes. Trypanosomes have developed ways to circumvent antibody-mediated killing and block the activation of the lytic arm of the complement pathway. Hence, this makes the innate immune control of the infection a crucial part of the host-parasite interaction, determining infection susceptibility, and parasitemia control. Indeed, trypanosomes use a combination of several independent mechanisms to avoid clearance by the humoral immune system. First, perpetuated antigenic variation of the surface coat allows to escape antibody-mediated elimination. Secondly, when antibodies bind to the coat, they are efficiently transported toward the endocytosis pathway, where they are removed from the coat proteins. Finally, trypanosomes engage in the active destruction of the mammalian humoral immune response. This provides them with a rescue solution in case antigenic variation does not confer total immunological invisibility. Both antigenic variation and B cell destruction pose significant hurdles for the development of anti-trypanosome vaccine strategies. However, developing total immune escape capacity and unlimited growth capabilities within a mammalian host is not beneficial for any parasite, as it will result in the accelerated death of the host itself. Hence, trypanosomes have acquired a system of quorum sensing that results in density-dependent population growth arrest in order to prevent overpopulating the host. The same system could possibly sense the infection-associated host tissue damage resulting from inflammatory innate immune responses, in which case the quorum sensing serves to prevent excessive immunopathology and as such also promotes host survival. In order to put these concepts together, this review summarizes current knowledge on the interaction between trypanosomes and the mammalian innate immune system, the mechanisms involved in population growth regulation, antigenic variation and the immuno-destructive effect of trypanosomes on the humoral immune system. Vaccine trials and a discussion on the role of innate immune modulation in these trials are discussed at the end.}},
  articleno    = {{382}},
  author       = {{Magez, Stefan and Pinto Torres, Joar Esteban and Obishakin, Emmanuel Tumininu and Radwanska, Magdalena}},
  issn         = {{1664-3224}},
  journal      = {{FRONTIERS IN IMMUNOLOGY}},
  keywords     = {{VARIANT SURFACE GLYCOPROTEIN,EXPERIMENTAL AFRICAN TRYPANOSOMIASIS,NECROSIS-FACTOR-ALPHA,NITRIC-OXIDE,BOVINE TRYPANOSOMIASIS,CONGOLENSE INFECTIONS,ALTERNATIVE PATHWAY,EVANSI INFECTION,BRUCEI-GAMBIENSE,CELL RESPONSES,trypanosomes,innate immunity,cytokine,antibody,immunosuppression}},
  language     = {{eng}},
  pages        = {{19}},
  title        = {{Infections with extracellular trypanosomes require control by efficient innate immune mechanisms and can result in the destruction of the mammalian humoral immune system}},
  url          = {{http://dx.doi.org/10.3389/fimmu.2020.00382}},
  volume       = {{11}},
  year         = {{2020}},
}

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