Comparison of virus isolation using the Vero E6 cell line with real-time RT-PCR assay for the detection of human metapneumovirus.
BACKGROUND
The use of cell culture for the diagnosis of human metapneumovirus (hMPV) infection is uncommon at present and molecular method such as reverse-transcription PCR (RT-PCR) has been widely and most commonly used as the preferred test. We aimed to compare the results of virus isolation using Vero E6 cells with real-time RT-PCR for the detection of hMPV, since such a comparison data is not available.


METHODS
Between December 2007 and July 2008, we obtained 224 nasopharyngeal swab specimens from patients with acute respiratory infection and tested by the two methods.


RESULTS
Forty-three (19.2%) were found positive by cell culture and 62 (27.7%) by real-time RT-PCR. Cell cultures were positive for 42 of 62 specimens found positive by real-time RT-PCR (67.7% sensitivity) and for 1 of 162 specimens found negative by real-time RT-PCR (99.4% specificity), respectively. The sensitivity of the cell culture was 76.2-87.5% (mean 81.8%) when specimens were collected within 3 days after the onset of symptoms, and the sensitivity decreased to 50% or less thereafter. Among specimens collected within 3 days after symptom onset, all of the real-time RT-PCR positive specimens having a viral load of more than 1.25x105 copies/ml were found positive by cell culture.


CONCLUSIONS
Cell culture using Vero E6 cell line has 81.8% sensitivity compared with the real-time RT-PCR method, when specimens are collected within 3 days after the onset of symptoms. Thus, this method is a useful method for epidemiological and virological research even in facilities with minimal laboratory resources.
Matsuzaki
Yoko
Y
Department of Microbiology, Yamagata Prefectural Institute of Public Health, Tokamachi 1-6-6, Yamagata 990-0031, Japan.
Mizuta
Katsumi
K
Takashita
Emi
E
Okamoto
Michiko
M
Itagaki
Tsutomu
T
Katsushima
Fumio
F
Katsushima
Yuriko
Y
Nagai
Yukio
Y
Nishimura
Hidekazu
H
D000293:Adolescent; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002648:Child; D002675:Child, Preschool; D002522:Chlorocebus aethiops; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D029121:Metapneumovirus / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D009305:Nasopharynx / Q000821:virology; D018184:Paramyxoviridae Infections / Q000175:diagnosis* / Q000821:virology; D012141:Respiratory Tract Infections / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014709:Vero Cells; D014773:Virology / Q000379:methods*