Reproduction of the original virus. This process can be viewed as occurring in stages, in which the first stage consists of the adsorption of the virus to the host cell, followed by penetration of the virus (or its nucleic acid) into the cell, the taking over of the cell’s biomachinery and harnessing of it to replicate viral nucleic acid along with the synthesis of other virus constituents, the correct assembly of the nucleic acids and other constituents into a functional virus, followed finally by release of the virus from the confines of the cell.