Article Text

Download PDFPDF
Invasion of human retinal vascular endothelial cells by Toxoplasma gondii tachyzoites
  1. D O Zamora1,
  2. J T Rosenbaum1,2,3,
  3. J R Smith1,2
  1. 1
    Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
  2. 2
    Department of Cell and Developmental Biology, Oregon Health and Science University, Portland, Oregon, USA
  3. 3
    Department of Medicine, Oregon Health and Science University, Portland, Oregon, USA
  1. Dr J R Smith, Oregon Health and Science University, L467AD, Biomedical Research Building, 3181 S.W. Sam Jackson Park Rd, Portland, OR 97239, USA; smithjus{at}


Background: Toxoplasma gondii infection is a leading cause of posterior uveitis. Human retinal endothelial cells (HREC) are more susceptible to infection with T gondii tachyzoites than other subpopulations of endothelial cells. It is hypothesised that this phenomenon reflects differences in invasion efficiency.

Methods: YFP-expressing RH strain T gondii tachyzoites were added to confluent HREC or human dermal endothelial cells (HDEC) (MOI = 50:1). Tachyzoite invasion after 1 h was determined by microplate reading of fluorescence intensity or parasite counts obtained using image analysis software. Selected cultures were incubated for three subsequent days, at which time fluorescence intensity indicated intracellular tachyzoite proliferation.

Results: HREC-tachyzoite cultures were more fluorescent than HDEC-tachyzoite cultures after 1 h (p = 0.020, paired t test, 3 experiments). Parasite counts also indicated that more tachyzoites invaded HREC than HDEC (p = 0.042, paired t test, 5 experiments). At 3 days, fluorescence intensity remained higher in HREC-tachyzoite cultures (p⩽0.002, t test, 3 experiments).

Conclusion: In culture, T gondii tachyzoites invade HREC with greater efficiency than they invade HDEC. This observation suggests that the relative susceptibility of HREC to infection may reflect a high efficiency of tachyzoite invasion which may be relevant to understanding how T gondii infects human retina.

Statistics from


  • Funding: This project was supported by NEI grants EY014909 and EY10572 and by Research to Prevent Blindness (Career Development Award to JRS, Senior Scholar Award to JTR and an unrestricted grant to Casey Eye Institute).

  • Competing interests: None.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.