This is a continuation of a recently initiated program in responding to the increasing demand of more precise measurement of relevant genomic information in any viral infection. The knowledge of the presence of specific viral gene will help in identifying the infectious agent. However, to assess the stage of a disease, to evaluate the efficacy of a treatment, to determine the value of a predictor in the progression of an infection, a more precise and quantitative analysis of the specific gene would be required. These previously highly research oriented questions can now begin to be answered with the advanced technology of molecular biology such as polymerase chain reaction (PCR), sequencing and mapping of the restriction nuclease digested fragment. We would apply the technology in conjunction with our current on-going clinical research such as hepatitis B virus, hepatitis C virus and HIV infections. We will also improve the basic PCR technique to become a quantitative procedure.