Deterioration of visual function as examined by electroretinograms in Toxoplasma gondii-infected IFN-gamma-knockout mice.
OBJECTIVE
To investigate by ERG the effects of Toxoplasma gondii infection on the visual function of interferon gamma knockout (GKO) mice, as a model of immunocompromised hosts.


METHODS
Susceptible wild-type (WT) C57BL/6 and GKO C57BL/6 mice were infected with five cysts of the avirulent T. gondii perorally. ERGs were recorded before and after the infection. The eyes of WT and GKO mice were enucleated and prepared for histologic studies 4 weeks and 12 days after infection, respectively.


RESULTS
The a- and b-waves of ERGs did not change significantly up to 1 month after infection in WT mice, but those of GKO mice were significantly reduced 11 days after infection. Histopathology revealed focal retinitis and vasculitis in WT mice 4 weeks after infection. Mild inflammation and sludging of blood in the retina and choroid were found in GKO mice 12 days after infection, just before death. Cysts were found in the inner nuclear layer, with little disturbance of the surrounding retinal architecture in both WT and GKO mice.


CONCLUSIONS
ERG clearly showed deterioration of visual function in GKO but not in WT mice after T. gondii infection. ERG is a sensitive and reliable method for observing activity in mice severely affected with experimental toxoplasmic retinochoroiditis.
Norose
Kazumi
K
Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba, Japan.
Aosai
Fumie
F
Mizota
Atsushi
A
Yamamoto
Shuichi
S
Mun
Hye-Seong
HS
Yano
Akihiko
A
D000818:Animals; D002825:Chorioretinitis / Q000503:physiopathology*; D004596:Electroretinography / Q000379:methods*; D005260:Female; D007371:Interferon-gamma / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015203:Reproducibility of Results; D012160:Retina / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D014124:Toxoplasmosis, Animal / Q000503:physiopathology*; D014126:Toxoplasmosis, Ocular / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology*
D007371:Interferon-gamma