After virus binding to cellular membranes, a fusion step, which is generally poorly understood, results in the release of the virion core into the cytoplasm of the cell [39] . The released core, which contains the endogenous RNA polymerase and transcription factors, initiates the first wave of early viral gene transcription by synthesizing viral mRNA under the control of early viral promoters. This is followed by the uncoating stage, the release of viral DNA into the cytoplasm where it serves as a precursor for viral DNA replication as well as the source of intermediate and late viral gene transcription. As a late viral gene product accumulates, the virus undergoes assembly and morphogenesis of infectious virus particles. During morphogenesis, APVs induce the formation of inclusion bodies in the cytoplasm of infected cells (Figure 2A and 2B). The inclusions, which may also be termed viral factories, viroplasms, or viral replication complexes, are generally believed to be the sites of active viral replication and particle assembly within infected cells [17] . One model for the function of viral inclusion bodies is that they act to concentrate and sequester proteins, nucleic acids, and other small molecules essential for viral processes.