[Human metapneumovirus: Characteristics, and therapeutic advances 10 years after its discovery]

Human metapneumovirus (hMPV), described for the first time in 2001 by the team of Pr Albert Osterhaus [1], is one of the main viral pathogens responsible for human respiratory tract infections. It may cause death in elderly and immunocompromised patients. The agent most closely related to hMPV is the human respiratory syncytial virus (hRSV), the main virus involved in bronchiolitis and pneumonia in young children and in respiratory tract infections in the elderly. hMPV is defined by two main viral groups,Aand B, and has generallya winter annual distribution in temperate countries. Because of the difficulty to culture hMPV in vitro, its diagnosis is generally achieved using RT-PCR. Like other Paramyxoviridae, hMPVhas a negative stranded RNA genome that includes eight genes coding for nine different proteins. Its genomic organization and the functions of its surface attachment and fusion glycoproteins are relatively similar to those of hRSV. Although many studies have tried to explain the viral cycle of hMPV, there are still many unanswered questions on the exact roles of the viral proteins in the attachment, fusion and replication of hMPV. There is no approved modality to combat hMPV infections for the moment. The majority of the treatments currently tested on hMPV have already demonstrated an activity againsthRSVinfections. Some innovative approaches based on RNAi nterference and on fusion inhibitors could be effective in hMPV disease. One of the biggest problems to develop an effective hMPV vaccine is the difficulty of inducing a durable immune response. Several strategies such as live attenuated viruses generated by reverse genetics or recombinant proteins have been tested in animals with encouraging results.