The focus of my laboratory research is the molecular mechanisms of pathogenesis associated with cytomegalovirus infection. Human cytomegalovirus (HCMV) is a member of the herpesvirus family and a pathogen of growing medical importance. While infection is widespread and generally asymptomatic in healthy individuals, HCMV causes serious problems in AIDS patients, transplant patients and neonates. HCMV infection is also associated with virally induced birth defects. A prominent feature of HCMV replication in the host is a prolonged period of persistent replication followed by the establishment of a latent infection lasting the lifetime of the host. The latent infection may be reactivated to periods of acute viral replication which are sometimes associated with disease, depending upon the health and immune status of the individual. Understanding the mechanisms that regulate persistent and latent infection in the host is crucial to the development of new anti-viral therapies.
I have characterized an unusual and large, non-coding RNA expressed during HCMV infection. Known as the 5 kb RNA, it is a stable intron produced from the splicing of a large precursor RNA during lytic infection. The 5 kb RNA is dispensable for viral replication in culture and its function is unknown. The genomic locus from which the 5 kb RNA of HCMV is expressed is conserved across cytomegaloviruses from all species examined, suggesting that the RNA has an important function in vivo. I have identified the mouse cytomegalovirus (MCMV) ortholog of the 5 kb RNA, a 7.2 kb RNA that has many features in common with the 5 kb RNA of HCMV, including size, sequence composition and intronic origin. Like the 5 kb RNA of HCMV, the 7.2 kb RNA of MCMV is not required for replication in cultured cells. However, in vivo studies suggest that the RNA plays an important role in persistent replication in the host. Recombinant MCMV that does not express the 7.2 kb RNA fails to establish a persistent infection in the salivary gland of the mouse. The persistent phase of replication in the host is likely to be important in the development of the immune response, pathogenesis and latency, although the mechanisms are unclear. Studies of the function of the 7.2 kb RNA are likely to help us learn more about these aspects of cytomegalovirus pathogenesis in the host. My immediate experimental focus is on identifying cellular partners and pathways that intersect with intron RNA function during infection to shed light on its role in persistence in the host.
The cloning of cytomegaloviruses as bacterial artificial chromosome constructs has greatly enhanced our ability to use molecular genetics to study all aspects of viral replication. My laboratory extensively uses this technology in combination with an excellent in vivo model of cytomegalovirus pathogenesis to study the function of viral non-coding RNAs as well as other genes of indeterminate function.