Our laboratory studies the molecular and cellular biology of herpes simplex virus (HSV) lytic, productive infection of epithelial cells and latent infection of sensory neurons. Our research involves the mechanisms of chromatin control of viral gene expression, intranuclear targeting of the viral DNA genome and gene expression, viral regulation of host innate immune responses, and the design of genital herpes and AIDS vaccines.
HSV Lytic versus Latent Infection Decision. We have discovered that the viral latency-associated transcript promotes heterochromatin silencing of the viral genome in sensory neurons so the virus can establish a latent infection. In contrast, we have found that in epithelial cells a virion protein and an immediate early viral protein reduce heterochromatin and promote euchromatin on viral lytic gene promoters. We are studying how the long noncoding LAT RNA promotes silencing in latent infection, likely through recruitment of Polycomb repressive complexes, and how viral proteins promote euchromatin during lytic infection.
Intranuclear Targeting of the HSV Genome and Regulation of Gene Expression. We have shown that the HSV genome is initially targeted to the nuclear lamina where a transactivator complex consisting of the viral VP16 protein, the host cell factor 1 protein, and cellular Oct-1 protein bind and activate viral immediate-early gene promoters. The IE proteins activate early gene transcription and the early proteins initiate viral DNA replication at these peripheral nuclear sites. Following initiation of viral DNA replication and late gene transcription, the viral replication compartments move inward and coalesce at sites near cellular nuclear speckles to promote nuclear export of late viral mRNA. We are studying the mechanisms by which nuclear location affects viral gene expression.
Viral Activation and Inhibition of Host Innate Responses. Viruses activate and modulate host innate immune responses initiated by interaction with Toll-like receptors and cytoplasmic effectors such as RIG-I. We are studying the mechanisms by which the HSV-1 ICP0 protein sequesters interferon regulatory factor 3 away from cellular promoters and how the viral UL37 and US3 proteins inhibit host innate responses.
Replication-defective mutant viruses as a new form of viral vaccine. We have genetically engineered genital herpes strains that are mutated in essential genes for viral replication and have shown that one of these strains can serve as a genital herpes vaccine in animal models. This vaccine is being produced for clinical trials by a company. We are trying to improve the immunogenicity of the vaccine candidate by mutating viral immune evasion genes and we are studying the optimal vaccine for use in Sub-Saharan Africa, where there is an epidemic of genital herpes.
Cliffe, A.R., D.S. Garber and D. M. Knipe. 2009. Transcription of herpes simplex virus latency-associated transcript promotes the formation of facultative heterochromtain on lytic promoters. Journal of Virology 83:8182-90.
Dudek, T.E., E. Torres-Lopez, C. Crumpacker, D.M. Knipe. 2011. Evidence for differences in immunological and pathogenesis properties of herpes simplex virus 2 strains from the United States and South Africa. Journal of Infectious Diseases. 203: 1434-41. PMID: 21498376.
Chang, L., W.J. Godinez, I.-H. Kim, M. Tektonidis, P. deLanerolle, R. Eils, K. Rohr, D.M. Knipe. 2011. Herpesviral replication compartments move and coalesce at nuclear speckles to enhance viral late mRNA export. PNAS Plus 108: E136-44. PMID: 21555562