Human metapneumovirus (HMPV) is a negative-sense RNA virus that primarily causes respiratory illnesses, particularly in children and older adults. It was first isolated in 2001 and has been linked to significant respiratory infections, with outbreaks observed and a seasonal pattern of prevalence. Diagnosis mainly relies on RT-PCR technology, and no specific treatment is currently available, though ribavirin shows promise in models.

1. Human metapneumovirus
(HMPV or hMPV)
Dr Jyoti Prasad Pattanayak
MBBS, PGDMCH, PGDHM, DCND
Senior Resident
IMS & SUM Hospital 3, Ganjam, Odisha
Dr Jyoti Prasad Pattanayak 1

2. Human metapneumovirus (HMPV or
hMPV) is a negative-sense single-
stranded RNA virus of the family
Pneumoviridae and is closely related
to the Avian metapneumovirus
(AMPV) subgroup C.
Dr Jyoti Prasad Pattanayak 2

3. Discovery
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.
Dr Jyoti Prasad Pattanayak 3

4. 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.
Dr Jyoti Prasad Pattanayak 4

5. The clinical features and severity
of HMPV are similar to those of
RSV. HMPV is also an important
cause of disease in older adults.
A notable outbreak of HMPV has
been observed through the end
of 2024 in China.
Dr Jyoti Prasad Pattanayak 5

6. HMPV was responsible for 12% of cases
of acute respiratory tract illness in
otherwise-healthy children in a US
outpatient clinic and 15% and 8% of
cases (respectively) of community-
acquired pneumonia requiring
hospitalization in children under and
over the age of 5 in the United States.
Dr Jyoti Prasad Pattanayak 6

7. The virus is distributed
worldwide and, in temperate
regions, has a seasonal
distribution generally following
that of RSV and influenza virus
during late winter and spring.
Dr Jyoti Prasad Pattanayak 7

8. Human metapneumovirus may cause
mild upper respiratory tract infection (the
common cold). However, premature
infants, immuno-compromised persons,
and older adults >65 years are at risk for
severe disease and hospitalization.
Numerous outbreaks of HMPV have been
reported in long-term care facilities for
children and adults, causing fatalities.
Dr Jyoti Prasad Pattanayak 8

9. hMPV is estimated to have a 3–6 day
incubation period and is often most
active during the later winter and
spring seasons in temperate
climates, overlapping with the RSV
and influenza seasons and possibly
allowing for repeated infection.
Dr Jyoti Prasad Pattanayak 9

10. Reproduction
The first step of the hMPV replication cycle
is attachment to the host cell, specifically
the epithelial cells of the respiratory tract,
using the G protein. This G protein contains
a hydrophobic region that acts as an
uncleaved signal peptide and a membrane
anchor to facilitate its binding; however,
because recombinant viruses that lack the
G protein have still been able to replicate in
vitro and in vivo, it seems that attachment
via the G protein is not required for rest of
the replication cycle.
Dr Jyoti Prasad Pattanayak 10

11. HMPV infects airway epithelial cells in the
nose and lung. HMPV is thought to attach to
the target cell via the glycoprotein (G)
protein interactions with heparan sulfate
and other glycosaminoglycans.
HMPV then induces the response of
chemokines and cytokines such as IL-6,
IFN-alpha, TNF-alpha, IL-2, and macrophage
inflammatory proteins, which in turn leads
to peribronchiolar and perivascular
infiltration and inflammation.
Dr Jyoti Prasad Pattanayak 11

12. Detection
The identification of HMPV has
predominantly relied on reverse-
transcriptase polymerase chain
reaction (RT-PCR) technology to
amplify directly from RNA extracted
from respiratory specimens.
Dr Jyoti Prasad Pattanayak 12

13. Alternate Methods
Alternative more cost-effective approaches to the
detection of HMPV by nucleic acid-based approaches
have been employed and these include:
•detection of hMPV antigens in nasopharyngeal
secretions by immunofluorescent-antibody test
•the use of immunofluorescence staining with
monoclonal antibodies to detect HMPV in
nasopharyngeal secretions and shell vial cultures
•immunofluorescence assays for detection of hMPV-
specific antibodies
•the use of polyclonal antibodies and direct isolation in
cultured cells.
Dr Jyoti Prasad Pattanayak 13

14. Researchers have found that hMPV
is mostly localized and can differ
significantly from community to
community, allowing for the
possibility of the strain in one
location one year to be most similar
to the strain in a different location
the next year.
Dr Jyoti Prasad Pattanayak 14

15. HMPV is most likely spread from
infected individuals to others
through 1. secretions from coughing
and sneezing, 2. close personal
contact (ex. touching, shaking
hands, etc), and 3. touching objects
with viruses on them then touching
your mouth, nose, or eyes.
Dr Jyoti Prasad Pattanayak 15

16. Transmission
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.
Dr Jyoti Prasad Pattanayak 16

17. Treatment
No treatment is yet
known, but ribavirin has
shown effectiveness in
an animal model.
Dr Jyoti Prasad Pattanayak 17

18. Dr Jyoti Prasad Pattanayak
MBBS, PGDMCH, PGDHM, DCND
Senior Resident
IMS & SUM Hospital 3, Ganjam, Odisha
Dr Jyoti Prasad Pattanayak 18