Infliximab is a chimeric monoclonal antibody biologic. Humanized antibodies are distinct from chimeric antibodies. Chimeric and humanized antibodies have generally replaced them in therapeutic antibody applications. Antibodies may also referred to as murine, chimeric, humanized or human. It is possible to produce a humanized antibody without creating a chimeric intermediate. Partly chimeric and partly humanized antibodies used "-xizu-". Four major antibody types that have been developed are murine, chimeric, humanised and human. Chimeric antibody names contain a "-xi-" stem. These fragments are then ligated together to generate chimeric genes. The expression of this "chimeric" or "humanised" DNA through cell culture yielded part-mouse, part-human antibodies. This usually requires replacing the proteins causing virus-cell interactions with chimeric proteins. These gene fragments are mixed and ligated in an appropriate order to form chimeric libraries. This method generates chimeric genes directly from metagenomic samples. Subsequent offspring of the chimeric mouse will then have the gene knock-in. This is done by generating chimeric mice, and exposing the mice HCV infection.