Human coronavirus NL-63 infections in children: a 1-year study

Abstract

Human coronavirus NL63 (HCoV-NL63), a newly discovered coronavirus, has been associated with acute respiratory tract infections (ARI). Important questions pertaining to the contribution of HCoV-NL63 to ARI and its impact on public health remain. We reviewed HCoV-NL63 in specimens collected from 13 November 2002 to 31 December 2003 from the Stollery Children's Hospital on patients of <17 years of age to assess the role of this virus in ARI in children. Twenty-six of 1,240 specimens (2.1%) from seven outpatients and 19 inpatients aged 7 days to 9.5 years tested positive for HCoV-NL63 by reverse transcription-PCR. The majority of outpatients (86%) had upper respiratory tract infections, while the majority of inpatients (58%) had bronchiolitis. Peak HCoV-NL63 activity occurred in March. These results provide further evidence of the importance of HCoV-NL63 in ARI in children.

FIG. 1.

Number of specimens and percentage positive for HCoV-NL63 per month.

FIG. 2.

Phylogenetic analysis of HCoV-NL63 isolates. Nucleotide sequences were determined for nucleotides 5856 to 6280 of the 1a gene. The corresponding gene sequences from previously reported Dutch, Canadian, and Australian HCoV-NL63 isolates were also included. Phylogenetic analysis was performed using the neighbor-joining method of the MEGA2 program. The Dutch reference strain is indicated by HCoV-NL63, and the previous Dutch, Canadian, Belgian, and Australian isolates are indicated by NDL, CAN, BE03, and Q03, respectively, followed by the isolate number (e.g., NDL-246). The isolates presented in this study are in bold and indicated by the isolate number and the year (e.g., 140-02).

FIG. 3.

Alignment of partial nucleotide sequences of the 1a gene of representative cluster 1 and 2 HCoV-NL63 strains. Only residues that differ from isolate HCoV-NL63 are shown. Identical nucleotides are represented by periods, and nucleotide positions are indicated at the ends of the lines. The five conserved changes between the cluster 1 and 2 isolates are boxed.