The human metapneumovirus (hMPV) was discovered at the dept. of Virology of Erasmus Medical Center in 2001. After the first publication on this human pathogen in the journal Nature Medicine, the research team has been responsible for the analysis of the first full genomic viral sequences and development of diagnostic tests. Studies on the prevalence, clinical impact and epidemiology have been conducted, some of these in collaboration with other research teams around the world. From these studies and those of others, it has become clear that hMPV is an important human pathogen associated with respiratory tract illnesses primarily in young children, but also in immunocompromised individuals, the elderly and the general community. The clinical symptoms associated with hMPV infection are comparable to those associated with infections by the respiratory syncytial virus. The hMPV research team was also the first to show that two serotypes of hMPV are circulating globally (serotypes A and B), each of which can be further divided in two genetic sublineages (A1, A2, B1, B2). Animal models were designed to study hMPV infection, which may aid in the development of antivirals and vaccines. Finally, the research team was responsible for the development of the first metapneumovirus reverse genetics system, which enables the production of recombinant hMPV. Continued research activities of the team include studies on the epidemiology, clinical impact and genetic and antigenic variability of hMPV. The reverse genetics techniques are being used to study basic aspects of hMPV replication and to design suitable vaccine candidates. Many of the research activities of the team are performed in collaboration with researchers around the world. Development of diagnostic tests, antivirals, and vaccines is done in close collaboration with ViroNovative B.V. and MedImmune Inc.