Abstract
Purpose :
AIDS-related cytomegalovirus retinitis remains a sight-threatening problem worldwide, and mouse models with MCMV have been established to study this eye disease. Previous work by others has shown that MCMV passaged through salivary glands (SG-MCMV) displays greater ocular and systemic virulence when compared with MCMV passaged through mouse embryonic fibroblasts grown in tissue culture (TC-MCMV). SOCS family proteins are inducible negative regulators of immune signaling, and they have been implicated in ocular diseases and viral pathogeneses. We previously have shown that ocular SOCS1 and SOCS3 expression are highly stimulated in SG-MCMV-infected eyes of mice susceptible to retinitis during retrovirus-induced immunosuppression (MAIDS), and that SG-MCMV infection of IC-21 mouse macrophages significantly stimulates SOCS1 and SOCS3 mRNA expression. Because macrophages are less susceptible to infection with SG-MCMV than with TC-MCMV, we sought to test the hypothesis that passage origin affects SOCS1 and SOCS3 expression in IC-21 cells.
Methods :
Monolayers of IC-21 mouse macrophages were inoculated with either SG-MCMV or TC-MCMV (moi = 3), or with media alone (control). All monolayers were harvested between 30 min and 28 hrs postinfection (hpi), and mRNA expression of SOCS1 and SOCS3, as well as the known SOCS inducers Type I and II interferon (IFN), were compared by real-time RT-PCR assay.
Results :
SG-MCMV, but not TC-MCMV, highly stimulated SOCS1 and SOCS3 mRNA expression between 2-6 hpi in IC-21 mouse macrophages. Infection with SG-MCMV also upregulated Type II IFN, though neither passage origin stimulated Type I IFN production within the time points investigated.
Conclusions :
Although it is well established that gene expression and replication of SG-MCMV in macrophages is significantly delayed when compared with TC-MCMV, SG-MCMV caused upregulation of SOCS1 and SOCS3 which did not take place during TC-MCMV infection. These data suggest that passage origin affects stimulation of SOCS1 and SOCS3 mRNA in IC-21 cells. Additional studies are being conducted to determine whether this phenomenon is dependent on viral input dose, time course, and/or possible genotypic or proteomic differences between SG-MCMV and TC-MCMV.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.