Seasonal distribution and phylogenetic analysis of human metapneumovirus among children in Osaka City, Japan.
BACKGROUND
Human metapneumovirus (hMPV) is one of the etiological agents of respiratory tract infection (RTI). Because clinical symptoms of hMPV resemble those caused by respiratory syncytial virus (RSV), clinical diagnosis of hMPV infection is difficult. Moreover, hMPV isolation using cultured cells is generally difficult and not efficient compared with reverse transcription-PCR (RT-PCR).


OBJECTIVE
To assess infection and seasonal distribution of hMPV associated with RTI among children in Osaka City, Japan.


METHODS
To detect the hMPV gene, we extracted viral RNA from clinical specimens of patients with RTI and performed RT-PCR or nested-PCR for the fusion (F) gene. hMPV-specific amplicons were sequenced and subjected to phylogenetic analysis.


RESULTS
From June 2004 to May 2005, we detected 29 (20.1%) hMPV strains among 144 clinical specimens. Fifteen strains were detected by RT-PCR and the remaining 14 by nested-PCR. Prevalence was principally in winter and spring with incidence peaking in April. We also detected the hMPV RNA from a patient with encephalitis. Approximately 80% of the hMPV-positive patients were younger than 3 years. To analyze these isolates precisely, a phylogenetic analysis using F gene was performed and demonstrated that Osaka City isolates of hMPV consists of two major genetic lineages each comprising two sublineages.


CONCLUSIONS
We found two major genetic lineages of hMPV in Osaka City, Japan. We also found that nested-PCR was an efficient method for detecting the hMPV gene in clinical specimens. Of the 28 patients presenting with hMPV infection, 1 patient had associated encephalitis suggesting that hMPV infection might play a role in inducing encephalitis.
Kaida
Atsushi
A
Department of Microbiology, Osaka City Institute of Public Health and Environmental Sciences, 8-34 Tojo-cho, Tennoji-ku, Osaka 543-0026, Japan. atsushi.kaida@iphes.city.osaka.jp
Iritani
Nobuhiro
N
Kubo
Hideyuki
H
Shiomi
Masashi
M
Kohdera
Urara
U
Murakami
Tsukasa
T
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D029121:Metapneumovirus / Q000235:genetics / Q000302:isolation & purification*; D018184:Paramyxoviridae Infections / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000821:virology; D012621:Seasons; D014760:Viral Fusion Proteins / Q000235:genetics
D014760:Viral Fusion Proteins