The Roller laboratory studies mechanisms of herpesvirus assembly, exit and spread from infected cells.
One goal of research in our laboratory is to understand in detail the process of herpesvirus capsid envelopment at the inner nuclear membrane (INM) with the purpose of using this information for development of antiviral therapies and to advance understanding of the structure and function of the nuclear envelope (NE). This long-term goal can be broken down into the following steps: (i) Identification of the viral and cellular proteins that mediate and regulate envelopment; (ii) Identification of the functions of each of those proteins in envelopment; (iii) Identification of interactions between viral and cellular factors that are critical for envelopment functions; (iv) Characterization of the structures of the essential proteins; (v) Development of assays for therapeutics based on interactions that are essential for envelopment.
We and others have identified essential factors for envelopment and defined functions for some of the critical viral factors. Specifically we have identified specific roles for three viral proteins, pUL34, pUL31 and pUS3 in assembly of a nuclear envelopment complex at the nuclear membrane, in reorganization of the nuclear lamina, and in curvature of the nuclear membrane around the viral capsid. In the process, we have designed and optimized powerful reagents and approaches for study of herpesvirus envelopment. Our goal is to exploit those advantages to further define the functions of the herpesvirus envelopment apparatus, and to begin exploiting the knowledge gained for development of therapeutics based on interference with envelopment interactions.
Herpesviruses cause life-long infections and can cause recurrent disease and shedding in infected people. Recurrence of symptoms and spread of the virus to new hosts requires the ability to spread from the site of latent infection to cells at the periphery and among the cells on the mucosal surface. Amazingly, spread of the virus in recurrent infection occurs in the face of an adaptive immune response, including an antibody response that should neutralize virus released from the cell. The disease-causing properties of these viruses therefore depend on the mechanisms used for spread from cell to cell that protect the virus from exposure to effectors of the immune response.
Spread of the human herpesviruses within the host requires trafficking of newly assembled virus particles from their assembly site at the Golgi to exposed cell surfaces for release to extracellular medium or to cell junctions for cell-to-cell spread (CCS). Neither trafficking pathway is well understood. In part this is because no viral gene functions have been identified that are required for spread trafficking in most cell types. We have discovered that two viral gene products, pUL34 and pUL51, play critical roles in efficient virus release and/or CCS. Both proteins are apparently multifunctional. pUL34 is required for nuclear egress of herpesvirus capsids, and pUL51 has been shown to be required for efficient cytoplasmic assembly of the virus. We have discovered, however, that both proteins play critical roles in release and CCS that can be genetically uncoupled from their roles in virion assembly. Our goal is to understand how these proteins interact with other viral proteins and with cellular membrane trafficking pathways to direct virus particles for spread to an adjacent cell.