Detection of human coronavirus NL63, human metapneumovirus and respiratory syncytial virus in children with respiratory tract infections in south-west Sweden

Abstract

Two recently detected viruses, human metapneumovirus (hMPV) and coronavirus NL63 (HCoV-NL63), have been associated with acute respiratory tract infections, particularly in young children. This study investigated the frequency of hMPV and HCoV-NL63 infections in Swedish children by screening 221 nasopharyngeal aspirates, collected between November 2003 and May 2005, from 212 children attending the paediatric department of a county hospital in Sweden or submitted from local general practitioners. The samples were originally submitted to be tested for respiratory syncytial virus (RSV), and were examined retrospectively for hMPV and HCoV-NL63 by RT-PCR. Of the 212 patients, 101 were positive for RSV (48%), 22 (10%) were positive for hMPV, and 12 (6%) were positive for HCoV-NL63. The frequency of HCoV-NL63 infection increased from 1% in 2003-2004 to 10% in 2004-2005. Sequence analysis of parts of the coronavirus genomes showed considerable similarity to the HCoV-NL63 prototype sequence. The study demonstrated that HCoV-NL63 and hMPV occur in south-west Sweden with essentially the same frequency, seasonal distribution and clinical characteristics as have been reported in other countries.

Figure 1

Age distribution of patients included in the study.

Figure 2

Monthly distribution of all samples (white bars), RSV‐positive samples (striped bars), hMPV‐positive samples (black bars) and HCoV‐NL63‐positive samples (grey bars).

Figure 3

Phylogenetic analysis of the HCoV‐NL63 isolates described in this study. Phylogenetic analysis was performed using the neighbour‐joining method of the MEGA program. The nucleotide distance matrix was generated by Kimura's two‐parameter estimation [39]. Bootstrap re‐sampling (1000 replicates) was used to provide approximate CIs on individual branches. Bootstrap values >70 are indicated. Sequences from several HCoV‐NL63 strains that have been submitted previously to GenBank from previous studies (AY46451–AY46458, AY675541–AY675553 and AY66005–AY66010) have been included in the analysis.