Inhibition of Human Cytomegalovirus Entry into Host Cells through A Pleiotropic Small Molecule

Elste, James; Kaltenbach, Dominik; Patel, Vraj R.; Nguyen, Max T.; Sharthiya, Harsh; Tandon, Ritesh; Mehta, Satish K.; Volin, Michael V.; Fornaro, Michele; Tiwari, Vaibhav; Desai, Umesh R.

We monitored IE gene expression using AD169, a widely characterized HCMV strain [65] , using a cell-ELISA assay (Figure 4 ). Control mock-treatment (PBS) experiments with HCMV strain AD169 showed robust expression of both IE 1 and 2 genes within one hour of incubation with host cells. Pre-treatment of AD169 strain with SPGG followed by incubation with either HFF-1 or SK-N-MC cells showed significant reductions in expression of both IE1 and IE2. A clear dose-dependent decrease in IE 1 and 2 expression was evident, which gave IC 50 s of 3.1 µM (HFF-1) and 5.6 µM (SK-N-MC) ( Figure 4A ,B). As with puncta formation, the best results were observed at 100 µM SPGG. Thus, the results show that SPGG-mediated interference in viral entry negatively impacts the expression of viral genes, which probably contribute to reducing the viral infectivity. Our study is first to report a unique heparin mimetic, which has been previously been reported as a broad spectrum antimicrobial activity, as an inhibitor of HCMV. Earlier, we have demonstrated that SPGG inhibits HSV [50, 51] and Chlamydia infection [66] . Since HSV and Chlamydia are known to exploit heparan sulfate during early stages of host pathogen interactions [66, 67] , SPGG's lowering of HCMV early gene expression is not too surprising considering that the viral entry is blocked in the first place. A more important point of this result is the possibility that SPGG could be utilizing multiple mechanisms for its antiviral effects.