Seminars in respiratory and critical care medicine
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Human metapneumovirus (hMPV) is a newly discovered paramyxovirus associated with upper and lower respiratory tract infections most commonly in young children, elderly subjects, and immunocompromised patients. hMPV can cause severe infections such as bronchiolitis and pneumonia and is responsible for 5 to 10% of hospitalizations of children suffering from acute respiratory tract infections. Such infections are indistinguishable from those caused by human respiratory syncytial virus. The first hMPV infection occurs during early childhood but reinfections are common throughout life, especially in older subjects. ⋯ Promising experimental models have been developed to better understand hMPV pathogenesis and to evaluate the potential effect of different therapeutic modalities. No commercial treatments are yet available for hMPV, although ribavirin has shown activity both in vitro and in animal models. Live attenuated vaccines produced by reverse genetics have also shown good efficacy in animals.
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Viral respiratory infections continue to cause significant morbidity and mortality in infants and young children as well as in at-risk adults and the elderly. Although many viral pathogens are capable of causing acute respiratory disease, vaccine development has to focus on a limited number of pathogens (i.e., agents that commonly cause serious lower respiratory disease). Inactivated and, more recently, live attenuated influenza virus vaccines are the mainstay of interpandemic influenza prevention, but vaccines are not available yet for other important viruses such as respiratory syncytial virus, metapneumovirus, the parainfluenza viruses, and avian influenza viruses with pandemic potential. Reverse genetics systems that allow rational vaccine development are now widely used, and considerable progress has been made in preclinical and clinical development of novel respiratory virus vaccines.