TESTING INFECTIVITY OF HCV ISOLATED FROM CELL CULTURE IN CHIMPANZEES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Hepatitis C virus infections in man become chronic in approximately 85% percent of individuals exposed. At present there are an estimated 2.7 million chronically infected people in the United States and an estimated 200 million worldwide. There is no vaccine and therapy for chronic HCV infections is limited a combination of interferon and ribavirin, but treatment is successful in less than half the patients. There currently exist poor cell culture systems for the virus which have not proved to be reproducible between labs and the only animal model for the virus is the chimpanzee. Recently we succeeded in producing infectious hepatitis C virus in cell culture (termed HCVcc). The goal of this chimpanzee experiment is to test the infectivity of these particles in vivo. For most HCV isolates, adaptive mutations are required for efficient RNA replication in cell culture. Although only a limited number of these adaptive changes have been tested in vivo, they appear to be deleterious for replication in chimpanzees and have only rarely been detected in sequences of natural HCV isolates. Testing this isolate or cell culture infectious chimeras in chimpanzees is potentially of great importance to the HCV field. Until this point, HCV produced in vivo (from chimpanzees or humans) is non-infectious or poorly infectious in cell culture. Conversely, HCV RNAs adapted to replicate in cell culture are compromised in their ability to replicate in vivo. Having an isolate that can replicate both in cell culture and in vivo would be a very powerful tool for characterizing HCV replication, entry and pathogenesis. This will enable us to compare the behavior of true HCV particles produced in the liver to HCVcc produced in cell culture. The will be particularly important for studies of virus entry and neutralization and also reduce the need for future chimpanzee experiments. 10^6 cell culture infectious units of two different cell culture adapted viruses will be inoculated i.v. into two different animals. (Total volume ~1-2mL). The inoculum will consist of concentrated cell culture supernatant. Animals will be bled weekly and monitored for HCV viremia. If no infection is indicated after 8 weeks the animals will be challenged with a known infectious isolate (HCVH77 monoclonal virus) to demonstrate infectivity.