Murine cytomegalovirus infection markedly reduces serum MCP-1 levels in MCP-1 transgenic mice

Monocyte chemoattractant protein-1 (MCP-1) is a pro-inflammatory chemokine believed to play a major role in atherogenesis. Injured endothelial cells express MCP-1, which attracts monocytes to the blood vessel wall and leads to the formation of atheromas. Cytomegalovirus infection may also play a role in atherogenesis and accelerates inflammation in tissues that overexpress MCP-1. To examine the relationship of cytomegalovirus infection and MCP-1, we infected MCP-1 transgenic mice with murine cytomegalovirus (MCMV) and collected serum 6 days post-infection to evaluate TH1-related cytokine levels by ELISA. Serum levels of IL-10, IL-12 and IFN-γ were increased in MCP-1 transgenic mice on day 6 following MCMV infection, while levels of IL-1β and TNF-α were undetectable. However, MCP-1 serum levels were reduced >50% in MCP-1 transgenic mice following MCMV infection compared to uninfected transgenic mice. This effect was not as dramatic when an M33 null MCMV was administered to MCP-1 transgenic mice. The mechanism by which MCMV lowers serum MCP-1 levels is unknown, but this effect may enhance the survival of the virus and thus allow CMV to contribute to the chronic inflammation of atherogenesis.