IMMUNOSUPPRESSION INDUCES TRANSCRIPTION OF MURINE CYTOMEGALOVIRUS GLYCOPROTEIN-H IN THE EYE AND AT NONOCULAR SITES

In these studies, DNA PCR was used to identify sites of murine cytomeg alovirus (MCMV) latency after inoculation of virus into the supracilia ry space of the eye. Reverse transcription (RT) PCR for an immediate e arly gene and a late gene was used to identify putative sites of virus reactivation after methylprednisolone (steroid)-induced immunosuppres sion. Ten weeks after inoculation of 5 x 10(2) PFU of MCMV, BALB/c mic e were immunosuppressed by intramuscular injection of steroid. Control mice were infected but not immunosuppressed. Two weeks after initiati on of immunosuppression, mice were sacrificed. DNA and RNA extracted f rom homogenized tissues were amplified for immediate early gene 1 (IE1 ) and late gene, glycoprotein H (gH), DNA End mRNA by PCR and RT-PCR, respectively. Replicating virus was detected in homogenized ocular and non-ocular tissues by plaque assay. In the latently infected PBS-trea ted control group, viral DNA was detected in the inoculated eye and in several non-ocular tissues; IE1 mRNA was found in most of the DNA-pos itive tissues, while gH mRNA was amplified only in a few of the MCMV D NA-positive tissues from a single mouse. After immunosuppression, vira l DNA and IE1 mRNA were detected at a higher frequency in various tiss ues of steroid-treated mice. gH mRNA was detected in a significantly h igher number of the inoculated eyes, salivary glands and other non-ocu lar tissues of steroid-treated mice. After immunosuppression, low tite rs of infectious virus were recovered from the salivary glands of ster oid-treated mice, but infectious virus was not recovered from the inoc ulated eye of either steroid-treated or nonimmunosuppressed mice. The DNA PCR results suggest that after inoculation of 5 x 10(2) PFU of MCM V into the supraciliary space of euthymic BALB/c mice, virus becomes l atent in the inoculated eye, salivary gland and other extraocular tiss ues. The RT-PCR results suggest that latent MCMV can be reactivated in multiple tissues by immunosuppression.