Research Proposal: Homologs for chemokines and chemokine receptors encoded by herpesviruses imply virus subversion of the mammalian signaling pathway and a potential role in disease pathogenesis. Murine cytomegalovirus (MCMV) is a herpesvirus that encodes a beta chemokine homolog designated murine cytomegalovirus chemokine-1 (MCK-1). Beta chemokines function primarily as mononuclear cell chemoattractants. The monocyte-macrophage population is central to MCMV pathogenesis because macrophages are reported to support virus replication and are important in innate resistance to infection. Further, a poorly characterized mononuclear cell type disseminates MCMV. The goal of the proposed research is to identify the mononuclear cell type(s) that respond to MCK-1 and to assess whether MCK-1 has role in virus dissemination by testing the hypothesis that MCK-1 recruits host mononuclear inflammatory cells and mediates efficient virus dissemination in mice.
Specific Aim 1 will investigate the mononuclear inflammatory cell type(s) that respond to viral-encoded MCK-1 and recombinant MCK-1 (rMCK-1).
Specific Aim 2 will assess the role of viral-encoded MCK-1 in virus dissemination.
Specific Aim 1 will be accomplished by infecting mice with MCK-1 deficient or expressing viruses and analyzing the host mononuclear inflammatory response by flow cytometry and immunohistochemistry. The ability of host inflammatory cells to respond to rMCK-1 will be further evaluated in a footpad swelling assay and in a microchemotaxis assay.
Specific Aim 2 will be accomplished by adoptive transfer experiments utilizing mononuclear cell populations infected in vitro with MCK-1 deficient or expressing viruses. The impact of the host adaptive immune response on virus dissemination will be assessed in severe combined immunodeficient (SCID) mice infected with the MCK-1 deficient or expressing viruses. The impact of the host innate immune response on virus dissemination will be determined in mice depleted of tissue macrophages and natural killer cells and then infected with MCK-1 deficient or expressing viruses. The ability of mononuclear cell populations infected with the MCK-1 deficient or expressing virus to disseminate to target organs will be evaluated in an in vivo trafficking assay. In summary, these studies will define the types of mononuclear cell responding to MCK-1 as well as their role in virus dissemination.  The candidate is a veterinary immunologist completing a post doctoral fellowship in molecular virology. This proposal constitutes her post doctoral research and will provide an excellent basis for future independent research of the pathogenesis of cytomegalovirus infection.
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