BIOLOGY OF CYTOMEGALOVIRUS INFECTION

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This is a continuation of a project which investigates the pathogenesis of human cytomegalovirus (HCMV) infection after bone marrow transplantation (BMT). In the initial 8 years of this project, persistent HCMV infection has been documented and a model of asymptomatic lung infection has been described. The question of how the virus and host interact during periods of persistent infection remains unexplained, and it is possible that structural and non-structural virus-encoded proteins play a role in altering host function and leading to disease. In this regard, this project has cloned and partially expressed the matrix proteins, pp28, pp65, pp71, and pp150, of Towne strain HCMV. In this proposal, the regulation and biologic function of these proteins will be investigated in an effort to further understand the pathogenesis of HCMV-associated disease after BMT. This project will complete the DNA sequencing of pp28 and pp150 from Towne strain HCMV and will characterize the 5'-untranslated structural elements of pp28, pp65, pp71, and pp150 important in transcriptional regulation. In addition, the functional effects of matrix proteins on virus transcription will be studied with emphasis on whether they mediate virion-associated transactivation. The purported kinase activity of pp65 will be characterized using recombinant pp65, and, using deletion mutational analyses, the kinase subdomains and potential phosphorylation sites of the protein will be mapped. To characterize potential effects of matrix proteins on cellular transcription, HCMV-induced fibronectin (FN)-specific mRNA transcription repression will be studied. This model system will be used to determine if HCMV-encoded sequences directly mediate virus-induced transrepression of cellular mRNA. In addition, it is proposed to utilize the repository of wild HCMV isolates, collected to date, in order to determine whether virus sequence domains, found to be important for specific functions in laboratory strains, exist in nature.