Figure 1 Cotesia melanoscela bracovirus (left) and Campoletis sonorensis ichnovirus virions (right). The bars represent 200 nm.
Figure 2 Encapsidated DNA genomes from a member of the genus Ichnovirus (Campoletis sonorensis ichnovirus, CsIV); left panel, two lanes with two different amounts of DNA); and a Bracovirus (Cotesia marginiventris bracovirus, CmaBV; right panel, two lanes with two different amounts of DNA). Genomes were electrophoresed on 1% agarose gels and visualized with ethidium bromide. The different amounts of DNA illustrate the non-equimolarity of individual genomic segments.
Figure 3 Polydnavirus replication and transmission cycles. The replication and transmission of polydnaviruses and the life cycle of an endoparasitic wasp are illustrated. Viral DNA is transmitted as proviral DNA in wasp cells (thin arrows) and as circular episomal DNAs within virions (thick arrows). In replicative wasp cells and in infected lepidopteran cells, viral DNA is present in an unpackaged closed circular form. In non-replicative cells (i.e. all wasp cells except female pupal/adult calyx cells) the virus does not replicate and exists predominantly in the proviral form. Polydnaviruses are vertically transmitted in only the proviral DNA form.
Figure 4 (Left) Sectional diagram and (right) negative contrast electron micrograph of particles of Protapanteles paleacritae bracovirus (PpBV). The bar represents 200 nm.
(Courtesy of D. Stoltz.)
Figure 5 Bracovirus genome organization and replication. The Microplitis demolitor bracovirus (MdBV) genome is shown on left with selected viral segments identified. The right panel shows a representative bracovirus segment, MdBV segment K, in the proviral (top) and episomal form (bottom). Proviral segments may be found in tandem arrays with adjacent viral segments (AVS) flanking the integration site of proviral segments. MdBV segments encode genes but are predominantly non-coding sequence.
Figure 6 (Left) Sectional diagram and (right) negative contrast electron micrograph of particles of Hyposoter exiguae ichnovirus (HeIV). The bar represents 200 nm.
Figure 7 Undigested Campoletis sonorensis ichnovirus (CsIV) genome (left panel) with unique segment labels on right and nested segment labels on left. Colors indicate genes known to be associated with each segment. On left all segments encode cys-motif genes. Segments indicated in red are derived from larger segments (nested). Labels on right in this panel indicate unique segments that encode rep genes (black) and “non-rep” genes (e.g. P has similarity to NF-κβ genes). Right panel illustrates unique (top) and nested segments (bottom) in their proviral (integrated-linear) and episomal forms (circular).
Figure 8 Bracovirus and ichnovirus phylogenetic tree illustrating that all members of the Polydnaviridae are associated with parasitoid wasps in the superfamily Ichneumonoidea. Subfamilies of the Braconidae that carry bracoviruses and subfamilies of the Ichneumonidae that carry ichnoviruses are shown. Parentheses indicate the approximate number of wasp species in each subfamily.