Figure 1. Ad lytic cycle.

Ad attachment to the host cell is initiated by the fiber protein interacting with the cellular CAR receptor or CD46, followed by interaction between the Ad penton base and cellular integrin (1). Ad enters the cell through the endocytic pathway and the viral particle is partially degraded inside the endosome before being released into the cytosol (2). At the nuclear-pore complex, the viral particle is disassembled (3). The Ad DNA-core protein VII complex is transported through the nuclear-pore complex and VII proteins are released from viral genome by early gene transcription (4). E1A is the first viral protein expressed (5) during Ad infection and induces the expression of other early genes that facilitate viral replication and counteract cellular responses to infection (6). After replication occurs (7), the major late promoter is activated to produce late proteins, which are required for the formation of empty procapsids (8). Following encapsidation of the viral genome (9), a viral encoded protease proteolyzes multiple viral proteins inside the virus particle to generate a mature virion that is released from the infected cell (10).