West Nile virus infection induces interferon signalling in human retinal pigment epithelial cells.
OBJECTIVE
In addition to neuroinvasive disease, West Nile virus (WNV) infection is frequently associated with self-limiting chorioretinitis and vitritis. However, the mechanisms of ophthalmic WNV infection are rarely investigated, in part because of the lack of reliable in vitro models. The authors therefore established the first model of ocular WNV infection and investigated interaction of WNV with IFN signal-transduction mechanisms.


METHODS
Human retinal pigment epithelial (RPE) cells were infected with WNV strain NY385-99 at a multiplicity of infection of 5. Virus replication was evaluated by virus titers at different times after infection. The susceptibility of RPE cells to WNV infection was confirmed by transmission electron microscopy. IFN-beta expression was assessed by quantitative real-time PCR and by measurements of antiviral activity in cell culture supernatants. IFN signaling was evaluated by phosphorylation of transducer and activator of transcription 1 and 2 (STAT1/2) proteins, with immunoblot analysis.


RESULTS
RPE cells appeared to be highly sensitive to WNV infection. Maximum viral titers were found 24 hours after infection, followed by a continuous decline during the course of infection. WNV infection of RPE cells was followed by increased IFN-beta expression associated with IFN signaling and subsequent inhibition of WNV replication.


CONCLUSIONS
In this study, the first cell culture model of ophthalmic WNV infection was developed and characterized in RPE cells, and the molecular mechanisms of WNV infection were studied. The data suggest that WNV induces a general antiviral state in RPE cells. This general antiviral state correlates with WNV-induced IFN signaling in retinal cells.
Cinatl
Jindrich
J
Institute for Medical Virology, Johann Wolfgang Goethe-University Hospital, Frankfurt, Germany. cinatl@em.uni-frankfurt.de
Michaelis
Martin
M
Fleckenstein
Corinna
C
Bauer
Gabriele
G
Kabicková
Hanka
H
Scholz
Martin
M
Rabenau
Holger F
HF
Doerr
Hans Wilhelm
HW
D000818:Animals; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002522:Chlorocebus aethiops; D006801:Humans; D016899:Interferon-beta / Q000096:biosynthesis* / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D010766:Phosphorylation; D010857:Pigment Epithelium of Eye / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000378:metabolism; D050795:STAT2 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014709:Vero Cells; D014779:Virus Replication / Q000502:physiology; D014902:West Nile virus / Q000502:physiology* / Q000648:ultrastructure
D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D016899:Interferon-beta