HIV

As a novel approach to cure HIV we are targeting latently infected cells with the aim to purge all viral reservoirs and effectively cure infected individuals. Our objective is to inactivate the integrated HIV provirus in latently infected cell populations in order to prevent reactivation from latency. To do this we are engineering rare-cutting endonucleases that can introduce DNA double strand breaks (DSBs) at unique essential sequences within the integrated HIV provirus. Upon cleavage mutations can be introduced during misrepair of these DSBs upon non-homologous end joining (NHEJ) and the introduced mutations either prevent expression of a functional target gene or disrupt the function of HIV regulatory elements. This approach of ‘targeted mutagenesis’ will enable us to inactivate HIV in latently infected cells such as central memory T cells and we are developing HIV specific ZFNs, TALENs and homing endonucleases towards this end.

HBV

As with HIV, HBV infected patients taking antiviral medications push the virus into a form of latency and for HBV this is due to persistence of HBV covalently closed circular DNA (cccDNA) within infected hepatocytes. Without replication suppression by antivirals cccDNA is able to initiate replication and viremia can reoccur. We are targeting HBV cccDNA for inactivation by introducing mutations in essential HBV genes. Although cccDNA may not be eliminated, the inactivation of essential genes in cccDNA will prevent reactivation of HBV and persistent infection. We have developed HBV specific ZFNs, TALENs and homing endonucleases with the aim to prevent HBV reactivation from latency within the liver. We are testing these enzymes in a number of in vitro and in vivo models.

HSV

HSV infected patients taking antivirals can effectively eliminate infections at sites of active replication, however, HSV can establish latency in sensory neurons making infected individuals susceptible to lifelong reactivations. HSV latency is established when sensory neurons become infected since the HSV genome is able persist in an episomal state within neuronal cell bodies throughout the life of a patient. By targeting HSV genomes within infected neurons for disruption we aim to prevent reactivation of latent HSV infections and effectively cure them. Using engineered homing endonucleases that target essential HSV genes we have been able to prevent HSV reactivation from latency in vitro. We have also developed ZFNs targeting essential HSV genes that can inhibit HSV replication in vitro. Our aim is to use these enzymes to prevent HSV reactivation from latency in vivo.