The human metapneumovirus: Biology, epidemiological features, and clinical characteristics of infection

In 2001 a hitherto unknown, and important human virus pathogen, human metapneumovirus (hMPV) was identified. This virus was classified as the single human member of the Metapneumovirus genus of the family Paramyxoviridae. hMPV is related to avian metapneumoviruses and respiratory syncytial virus (RSV). Similar to the latter, hMPV is the aetiological agent of a large number of acute respiratory tract illnesses in both children and adults. In infected humans, hMPV causes mild-to-severe respiratory tract diseases, including bronchitis, bronchiolitis, and pneumonia. Infections caused by hMPV have been linked to an increased risk of asthma exacerbations and, according to some preliminary data, may also contribute to the development of acute neurological conditions. Laboratory diagnosis of hMPV infection is based on virus isolation in cell cultures and/or detection of viral RNA by PCR. Reported animal models of hMPV infection, including mice, cotton rats, hamsters, and primates, appear to be extremely useful for investigation of many characteristics of hMPV infection, including pathogenesis and antiviral immunity. Most recent studies based on the use of the reverse genetic technique reported the development of several experimental hMPV vaccine prototypes. These vaccines candidates were able to induce neutralizing serum antibodies and conferred protection of hamsters or non-human primates against subsequent challenge with wild-type hMPV.