A Simple and Effective Method to Concentrate Hepatitis C Virus: Aqueous Two-Phase System Allows Highly Efficient Enrichment of Enveloped Viruses

To investigate the proliferation cycle of a virus, virus-host interaction, and pathogenesis of a virus, virion particles must be concentrated from the media of virus cell culture or the sera of virus-infected patients. Ultracentrifugation of the culture media is a standard method for concentrating virion particles. However, this method is time-consuming and requires special equipment (ultracentrifuge). Moreover, a large number of infectious viruses are lost during enrichment. We developed a new method of hepatitis C virus (HCV) concentration to overcome the issues associated with traditional methods of virus concentration. We used an aqueous two-phase system (ATPS) to concentrate the virus. HCV, which causes various liver diseases, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma, was used as a model virus to test the efficacy and reliability of the ATPS. The efficiency of HCV concentration by the ATPS was approximately three times higher than that by ultracentrifugation. Moreover, the infectivity of the concentrated HCV, which is a labile virus, remained the same after concentration of the virus by the ATPS. Considering the simplicity and effectiveness of the ATPS, it is the method of choice for concentrating viruses.