Abstract
Purpose:
Previous results in our laboratory showed that during MCMV retinitis, uninfected retinal cells become apoptotic while infected cells do not. The purpose of this study was to determine if MCMV lacking m38.5 or m41.1 prevent viral infected cells from BAX and BAK mediated apoptosis.
Methods:
Immunosuppressed female Balb/c mice were injected via the supraciliary route with m38.5 and m41.1 mutant murine cytomegaloviruses (MCMV) and K181 parent MCMV virus. Eyes were collected at days 4 and 7 post infection (p.i.) and sectioned for immunohistochemistry or homogenized for plaque assay. Double staining for MCMV Early Antigen (EA) and TUNEL were performed. Virus titers were performed by plaque assay on monolayers of mouse embryo fibroblast (MEF) cells and in-vitro studies were performed using an organotypic retinal culture model.
Results:
Staining for MCMV EA showed more cells to be positive in the m38.5 and m41.1 mutant viruses than in the K181 parent virus. Late stage apoptosis activity was observed by TUNEL staining and in both m38.5 and m41.1 mutant viruses more DNA fragmentation was seen than in the K181 virus. Virus titers were lower in the injected eyes of the m38.5 and m41.1 mutants compared to the K181 virus after day 7 p.i.. Likewise, in retinal cultures at both days 4 and 7 p.i., less virus was recovered from cultures infected with mutant viruses than from cultures infected with the parent virus.
Conclusions:
Our results indicate that MCMV lacking m38.5 or m41.1 has a reduced capacity to prevent viral infected cells, of immunosuppressed mice, from undergoing BAX and BAK mediated apoptosis. In altering the apoptotic process of the viral infected cells, further spread of the virus to the uninfected cells may be reduced and further retinal damage potentially eliminated.
Keywords: 492 cytomegalovirus •
426 apoptosis/cell death •
702 retinitis