Abstract
Abstract: :
Purpose: Several lines of evidence suggest that retinal pigment epithelial cells (RPE) might serve as a reservoir for virus infection during human cytomegalovirus (HCMV) retinitis. We and others (Detrick et al, 1996) have shown previously that primary cultures of RPE are semipermissive for HCMV replication. Moreover, infectious virus can be rescued from infected monolayers of primary RPE cells (Howell et al, 1993) when cocultivated with human embryonic lung (HEL) fibroblasts that are permissive for HCMV replication. Since establishment of primary RPE cultures is tedious, we hypothesized that an established cell line of human RPE cells (ARPE-19) would also be semipermissive for HCMV infection and would allow rescue of virus by HEL cocultivation. Methods: Monolayers of ARPE-19 cells or HEL cells were inoculated with HCMV (Towne) at a dose of 0.01 PFU/cell and followed for up to 20 days for the appearance of virus-induced cytopathic effect (CPE). Rescue experiments were performed by either direct cocultivation of trypsinized ARPE-19 cells at 20 days postinoculation onto monolayers of uninfected HEL cells, or by cocultivation of ARPE-19 cells at 20 days postinfection with uninfected HEL cells separated by a clear polyester membrane in Costar transwell plates. HCMV-infected cells were identified by immunohistochemical staining using a polyclonal antibody to HCMV. Results: Whereas CPE developed rapidly in monolayers of HEL cells, monolayers of ARPE-19 cells failed to produce plaques of cytopathology at 20 days postinoculation. Nevertheless, small foci of HCMV infection were detected in these ARPE-19-inoculated cells by immunohistochemical staining. Unlike primary RPE cells, however, infectious virus could not be rescued from ARPE-19 cells at 20 days postinoculation when cocultivated with uninfected HEL cells. Direct treatment of monolayers of ARPE-19 cells at 20 days postinoculation with a number of cytokines (bFGF, TNF-alpha, TGF-beta, and PDGF) also failed to rescue virus. Conclusions: Like primary RPE cells, ARPE-19 cells were semipermissive for HCMV replication. Unlike primary RPE cells, infectious virus could not be rescued from HCMV-infected ARPE-19 cells when placed in an environment containing cells permissive for productive HCMV infection. This difference might be a useful tool as we explore transcriptional signals used by HCMV during RPE infection. CR: None Support: NIH grant EY10568 & an unrestricted grant from RPB
Keywords: 567 retinal pigment epithelium • 382 cytomegalovirus • 434 immunohistochemistry