Parasitoids and Polydnaviruses

Polydnaviruses as Symbionts and Gene Delivery Systems

Textbooks define viruses as infectious agents with nucleic acid genomes (RNA or DNA), which replicate inside living host cells to produce particles (virions) that can transfer the genome to other cells [1,2]. The Polydnaviridae was recognized as a family of viruses in 1995, and is currently divided into two genera named the Bracovirus and Ichnovirus [3]. Polydnavirus (PDV) virions consist of en...

Virus or not? Phylogenetics of polydnaviruses and their wasp carriers.

Our current, still limited, understanding of the comparative biology and evolution of polydnaviruses (PDVs) is reviewed, especially in the context of the possible origins of these parasitoid viruses and of their coevolution with carrier wasps. A hypothetical scenario of evolution of PDVs from ascovirus (or ascovirus-like) ancestors is presented, with examples of apparent extant transitional for...

Parasitoids

Are there many of them about? Just a few! Current estimates suggest there may be between one half and two million species; they are found in virtually every terrestrial habitat, and in a few freshwater ones. They include the smallest known insects — the tiny eggparasitising mymarids — as well as giant ichneumon-flies with egg-laying apparatuses (ovipositors) up to several inches long. Pass a sw...

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

Mutualistic Polydnaviruses Share Essential Replication Gene Functions with Pathogenic Ancestors

Viruses are usually thought to form parasitic associations with hosts, but all members of the family Polydnaviridae are obligate mutualists of insects called parasitoid wasps. Phylogenetic data founded on sequence comparisons of viral genes indicate that polydnaviruses in the genus Bracovirus (BV) are closely related to pathogenic nudiviruses and baculoviruses. However, pronounced differences i...