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Open Access Research article

Comparison of virus isolation using the Vero E6 cell line with real-time RT-PCR assay for the detection of human metapneumovirus

Yoko Matsuzaki18, Katsumi Mizuta2*, Emi Takashita3, Michiko Okamoto49, Tsutomu Itagaki5, Fumio Katsushima6, Yuriko Katsushima6, Yukio Nagai7 and Hidekazu Nishimura4

Author Affiliations

1 Course of Clinical Nursing, Yamagata University Faculty of Medicine, Iida-nishi, 2-2-2, Yamagata, 990-9585, Japan

2 Department of Microbiology, Yamagata Prefectural Institute of Public Health, Tokamachi 1-6-6, Yamagata, 990-0031, Japan

3 Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo, 208-0011, Japan

4 Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino-ku Miyagino 2-8-8, Sendai, 983-8520, Japan

5 Yamanobe Pediatric Clinic, Yamanobe 2908-14, Yamagata, 990-0301, Japan

6 Katsushima Pediatric Clinic, Minamidate 4-4-12, Yamagata, 990-2461, Japan

7 Nagai Children's Clinic, Miyagino-ku Miyagino 1-25-10, Sendai, 983-0045, Japan

8 Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-nishi 2-2-2, Yamagata, 990-9585, Japan

9 Department of Virology Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan

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BMC Infectious Diseases 2010, 10:170  doi:10.1186/1471-2334-10-170

Published: 14 June 2010

Abstract

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 1.25×105 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.