Reexamining Chronic Toxoplasma gondii Infection: Surprising Activity for a “Dormant” Parasite

Anthony P. Sinai, Elizabeth A. Watts, Animesh Dhara, Robert D. Murphy, Matthew S. Gentry, Abhijit Patwardhan

Research output: Contribution to journalReview articlepeer-review

45 Scopus citations

Abstract

Purpose of Review: Despite over a third of the world’s population being chronically infected with Toxoplasma gondii, little is known about this largely asymptomatic phase of infection. This stage is mediated in vivo by bradyzoites within tissue cysts. The absence of overt symptoms has been attributed to the dormancy of bradyzoites. In this review, we reexamine the conventional view of chronic toxoplasmosis in light of emerging evidence challenging both the nature of dormancy and the consequences of infection in the CNS. Recent Findings: New and emerging data reveal a previously unrecognized level of physiological and replicative capacity of bradyzoites within tissue cysts. These findings have emerged in the context of a reexamination of the chronic infection in the brain that correlates with changes in neuronal architecture, neurochemistry, and behavior that suggest that the chronic infection is not without consequence. Summary: The emerging data driven by the development of new approaches to study the progression of chronic toxoplasma infection reveals significant physiological and replicative capacity for what has been viewed as a dormant state. The emergence of bradyzoite and tissue cyst biology from what was viewed as a physiological “black box” offers exciting new areas for investigation with direct implications on the approaches to drug development targeting this drug-refractory state. In addition, new insights from studies on the neurobiology on chronic infection reveal a complex and dynamic interplay between the parasite, brain microenvironment, and the immune response that results in the detente that promotes the life-long persistence of the parasite in the host.

Original languageEnglish
Pages (from-to)175-185
Number of pages11
JournalCurrent Clinical Microbiology Reports
Volume3
Issue number4
DOIs
StatePublished - Dec 1 2016

Bibliographical note

Publisher Copyright:
© 2016, Springer International Publishing AG.

Keywords

  • Bradyzoite
  • CNS infection
  • Glycosylation
  • Tissue cyst
  • Toxoplasma

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

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