Polydnavirus

Polydnaviruses are a unique family of large, double-stranded DNA viruses that are obligate endosymbionts of parasitic wasps. These viruses infect only the female reproductive tract of their wasp hosts and are transmitted to the host's eggs. During oviposition, the wasp injects the polydnavirus along with its eggs into a host insect. The virus then infects the host insect's cells, altering its physiology and immune system to create a more favorable environment for the wasp larvae to develop. Polydnaviruses are characterized by their extremely large and complex genomes, which are packaged into multiple nucleocapsids within a single virion. They are known to encode a wide array of genes, many of which are involved in manipulating the host's immune response, preventing premature encapsulation of the wasp eggs, and suppressing host defenses. There are two main genera within the family: Campoletovirus and Bracovirus, which infect different groups of parasitic wasps. Polydnaviruses do not replicate within the host insect; rather, their replication occurs within the wasp germline. Their intricate relationship with their wasp hosts and their ability to profoundly influence host biology make them a fascinating subject of study in virology and evolutionary biology.