<i>T. gondii</i> tachyzoites infect human retinal glial cells in preference to neurons.

<p>(A). Immediately prior to infection, dissociated human retinal cultures presented a layer of glial cells with neurons positioned above. Original magnification: 100X. (B and C). Expression of (B) neuron specific enolase (NSE) (red), as detected by rabbit polyclonal anti-human NSE antibody and Alexa Fluor 594-conjugated donkey anti-rabbit immunoglobulin (Ig)G antibody and (C) glial fibrillary acidic protein (GFAP) (red), as detected by sheep polyclonal anti-human GFAP antibody and Alexa Fluor 594-conjugated donkey anti-sheep IgG antibody. <i>T. gondii</i> tachyzoites express YFP (green). Original magnification: 630X. Negative control cultures showed no positive staining. (D). Graph showing percentage growth of tachyzoites in Y79 human retinoblastoma cells and MIO-M1 human Müller glial cells, plus positive control human foreskin fibroblasts (FF), over a 24-hour period. n = 7–8 wells/condition. Columns  =  mean. Error bars  =  standard error of mean. Representative of two independent experiments.</p

<i>T. gondii</i> tachyzoites migrate through human retina.

<p>(A). Representative photomicrographs showing <i>T. gondii</i> tachyzoites within the retina 8 hours following addition of a suspension of 1.5×10⁷ live parasites to a human posterior eyecup. Tachyzoites are identified by immunostaining for the parasite SAG-1 antigen. Fast Red with hematoxylin counter stain. Original magnification: 1000X. Arrows indicate tachyzoites. Negative control sections showed no positive staining. (B). Graph showing number of tachyzoites counted within retinas from eyecups incubated with live or heat-killed tachyzoites. Columns  =  mean. Error bars  =  standard error of mean. (C). Pie chart showing mean percentage of tachyzoites located at different retinal layers. NFL  =  nerve fiber layer; GCL  =  ganglion cell layer; IPL  =  inner plexiform layer; INL  =  inner nuclear layer; OPL  =  outer nuclear layer; ONL  =  outer nuclear layer. Data shown in (B) and (C) were generated in experiments using 3 paired human cadaver posterior eyecups.</p