We study molecular processes that lead to the replication of RNA viruses. We developed an heterologous system in which to biochemically dissect mechanisms of virus synthesis. Microinjection of poliovirus RNA into Xenopus laevis oocytes initiates a complete and authentic replication cycle which yields a high level of infectious viruses, but only if poliovirus RNA is co-injected with factors present in HeLa cells. Two additional mammalian cell factors are required for viral replication in oocytes, one involved in initiation of translation, and the other in RNA synthesis. Thus, microinjection in oocytes can be used to identify and further analyze the function of viral and cellular factors and to biochemically dissect the mechanism of initiation of poliovirus translation and RNA synthesis. Recently, we discovered that the virus overlaps translation and replication cis-acting signals as a strategy to control the use of the RNA template for viral processes that require a concerted action like translation and RNA replication.
We also study the mechanism of immunity to RNA viruses with the hope of developing safe and efficacious vaccines. Protective immunity against many infectious diseases and effective immunotherapies for cancer may require priming of both humoral and cellular immune responses. Recombinant viruses represent a particularly promising approach because they can replicate in a variety of host cell types and induce both humoral and cell-mediated immune responses. We have engineered poliovirus to express antigens derived from influenza virus, rotavirus, Vibrio cholerae, HBV, SIV, and HIV. Mice and monkeys infected with recombinant viruses raised antibody response against the foreign proteins. Importantly, vaccination of mice with recombinant poliovirus elicits an antigen specific CTL response that protects 100% of the immunized animals from challenge with a highly aggressive melanoma cell line. Thus, poliovirus vectors may provide an effective system to induce both humoral and cellular immune responses systemically and also at local mucosal sites. |
Biomedical Sciences (BMS) Graduate Program
