Multipartite viruses have one of the most puzzling genetic organizations found in living organisms. These viruses have several genome segments, each containing only a part of the genetic information, and each individually encapsidated into a separate virus particle. While countless studies on molecular and cellular mechanisms of the infection cycle of multipartite viruses are available, just as for other virus types, very seldom is their lifestyle questioned at the viral system level. No convincing advantage of multipartitism has been definitely identified, yet the maintenance of genomic integrity appears problematic and how such a “split” viral system can be functional remains unclear.

This seminar will review the discoveries we have made on this question over the years, highlighting some properties of multipartite viruses that do not match current paradigms in Virology. I will insist on the life cycle steps of our multipartite virus model where unforeseen viral behaviors have been observed and on how these behaviors have the potential to enlarge/enrich the way we conceive a virus.