The Role of Telomeres in Poxvirus DNA Replication

Abstract

Poxviruses comprise a family of eukaryotic viruses which replicate exclusively in the cytoplasm of host vertebrate or invertebrate cells. The life cycle of this virus family (reviewed in Dales and Pogo 1982; Moss 1990) is initiated upon entry of the virions into the host cell. The core of the virion harbors not only the large double-stranded linear DNA genome, but also a great variety of polypeptides that are utilized during early viral transcription and for other events necessary to initiate the infective cycle. The multisubunit virus-encoded RNA polymerase, RNA capping enzyme, and poly(A) polymerase are amongst the enzymes that facilitate early gene expression in the virion core immediately upon entry into the host cell. Accurate early gene expression has also been induced in vitro. Following uncoating of the core, DNA replication takes place in specialized virus-induced structures which have been referred to as “factories”, “virosomes”, or “micro-nuclei”. Our current knowledge of the replication mechanism(s) utilized by this family of viruses is incomplete. Even though poxvirus genome structure is fairly well understood, replicative intermediate structures are ill-defined, as are the enzymes that mediate poxvirus DNA replication (reviewed in McFadden and Dales 1982; Holowczak 1982; Moss 1990).