Post Reply - Human Meta-Pneumo Virus (HMPV)-China

Human metapneumovirus (HMPV or hMPV) is a negative-sense single-stranded RNA virus of the family Pneumoviridae^[1] and is closely related to the Avian metapneumovirus (AMPV) subgroup C. It was isolated for the first time in 2001 in the Netherlands by using the RAP-PCR (RNA arbitrarily primed PCR) technique for identification of unknown viruses growing in cultured cells.^[2] As of 2016, it was the second most common cause (after respiratory syncytial virus (RSV)) of acute respiratory tract illness in otherwise-healthy children under the age of 5 in a large US outpatient clinic.^[3]

The peak age of hospitalization for infants with HMPV occurs between 6–12 months of age, slightly older than the peak of RSV, which is around 2–3 months. The clinical features and severity of HMPV are similar to those of RSV. HMPV is also an important cause of disease in older adults.

There are no conclusive studies to date; however, it is likely that transmission occurs by contact with contaminated secretions, via droplet, aerosol, or fomite vectors. Hospital-acquired infections with human metapneumovirus have been reported.^[47] HMPV has been shown to circulate during fall and winter months with alternating predominance of a single subtype each year.^[37]

No treatment is yet known,^[48] but ribavirin has shown effectiveness in an animal model.^[49]

American pharmaceutical corporation Moderna has conducted a clinical trial for a candidate modRNA vaccine against metapneumovirus.^[50] As of October 2019, the vaccine candidate has passed through phase I, with reports that the vaccine is well-tolerated at all dose levels at two months, and provokes an immune response which boosts the production of neutralising antibodies.^[51]

Human metapneumovirus was first reported in 2001 and avian metapneumovirus in the 1970s. There are at least four lineages of human metapneumovirus—A1, A2, B1 and B2. Avian metapneumovirus has been divided into four subgroups—A, B, C and D. Bayesian estimates suggest that human metapneumovirus emerged 119–133 years ago and diverged from avian metapneumovirus around 1800.^[52]