Polydnaviruses: From discovery to current insights

•Polydnaviruses were recognized as a virus family in 1991.•Here we review the polydnavirus literature in largely historical order.•The early literature established key features of polydnavirus biology.•Studies in the 1990s and early 2000s generated functional and phylogenetic insights.•Studies in the mid-2000s raised issues about the origins of polydnaviruses.•Recent studies provide key data on origins, genome structure, and function.

The International Committee on Taxonomy of Viruses (ICTV) recognized the Polydnaviridae in 1991 as a virus family associated with insects called parasitoid wasps. Polydnaviruses (PDVs) have historically received limited attention but advances in recent years have elevated interest because their unusual biology sheds interesting light on the question of what viruses are and how they function. Here, we present a succinct history of the PDV literature. We begin with the findings that first led ICTV to recognize the Polydnaviridae. We then discuss what subsequent studies revealed and how these findings have shaped views of PDV evolution.