OBJECTIVEHuman coronavirus (CoV)-HKU1 (HCoV-HKU1) was first isolated by Woo et al in Hong Kong. Several successive reports confirmed retrospectively that this new human coronavirus was circulating in different countries worldwide. However, the impact and the role of the emerging HCoV-HKU1 were not defined in children with ARTI. The objective of this study was to investigate the molecular epidemiology and clinical characteristics of HCoV-HKU1 infection in children with ARTI in Lanzhou, China.

METHODNasopharyngeal aspiration (NPA) samples were collected from 301 children with ARTI at the First Hospital of Lanzhou University, Gansu Province, China, between November 2007 and October 2008. Demographic data and clinical findings of these children were collected at the same time. The informed consent was obtained from their parents. This study protocol was approved by the hospital ethics committee. The reverse transcription polymerase chain reaction (RT-PCR) was employed to screen HCoV-HKU1. Furthermore, other common respiratory viruses were screened in HCoV-HKU1 positive samples. All PCR positive products were sequenced, and phylogenetic analysis was conducted.

RESULTThe overall frequency of HCoV-HKU1 infection was 5.0% (15/301). The HCoV-HKU1 pol gene sequences shared a 95.8% - 99.6% nucleotide identity with the human coronavirus-HKU1 strain, whereas the amino acid identity was 90.7% - 99.3%. The phylogenetic analysis revealed that the HCoV-HKU1 strain pol gene clustered with the HCoV-HKU1 strain N15 genotype B (no. DQ415911); 11 of 15 HCoV-HKU1 positive sample tested were mixed-infection. HCoV-HKU1 was detected only from November to April. Positive specimens peaked in November. Children with HCoV-HKU1 infection varied in age from 15 day to 12-years (median age, 10 months). The clinical diagnoses of HCoV-HKU1 positive patients included those with AURI and LURI. The clinical presentations of HCoV-HKU1 positive children included fever, cough, sputum production, diarrhea, vomiting; pharynx engorgement, crackles, and wheezing. The mean hospital stay of the 14 patients was 9.9 days. Six of 15 HCoV-HKU1 positive patients had an underlying illness, and they were all inpatients (hospital stay, mean, 11.2 days). There was no statistically significant difference in the detection rate between the two groups with and without underlying illnesses.

CONCLUSIONHuman CoV-HKU1 infection exists in children with respiratory tract infections in Lanzhou region. A single HCoV-HKU1 genotype B was circulating locally. The symptoms and clinical diagnoses of those infected with HCoV-HKU1 had no specificity as compared with patients with other common respiratory viruses infection.