This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this link to a friend Similar articles in this journal Similar articles in PubMed Add article to my folders Download to citation manager Request Permissions Google Scholar Articles by Zamora, D O Articles by Smith, J R PubMed PubMed Citation Articles by Zamora, D O Articles by Smith, J R

Invasion of human retinal vascular endothelial cells by Toxoplasma gondii tachyzoites

¹ Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
² Department of Cell and Developmental Biology, Oregon Health and Science University, Portland, Oregon, USA
³ Department of Medicine, Oregon Health and Science University, Portland, Oregon, USA

Correspondence to:
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}ohsu.edu

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 (p0.002, 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.

Competing interests: None.