After he obtained his PhD in 1994 at the Laboratory of Virology of Wageningen University with Rob Goldbach on the “Structure and expression of the Tomato spotted wilt virus (TSWV) genome, a plant-infecting bunyavirus”, he spent some time at the John Innes Centre (UK) as a post-doctoral researcher working on Geminiviruses.
After he returned he became assigned as principal investigator of the Tospovirus research group at the Laboratory of Virology. From the start of his PhD research and onwards, he aimed to unravel the molecular biology of TSWV, with a major discovery on the use of cap-snatching for the very first plant virus, to identify and characterize viral gene functions, to study the cytopathology of the virus with emphasis on particle assembly and the interplay with the host. During this time, he has supervised several post-docs, foreign (under) graduate students, and 13 PhD students that have graduated on this work. In the past 10 years the emphasis in his research slowly moved more towards virus-host interactions and during the last years has focussed on four major themes 1) The intracellular replication cycle, 2) Innate immunity (RNAi) and viral counterdefense, 3) Natural resistance genes and viral effectors, and 4) Influenza-/bunyavirus genome transcription initiation. One of the major driving forces in all his research lies in his interest in the evolutionary relation between the plant- and animal-infecting bunyaviruses, and the commonalities in cell biology and innate immunity between the animal and plant kingdom.