Group Group IV ((+)ssRNA) Family Coronaviridae Genus Betacoronavirus | Order Nidovirales Subfamily Coronavirinae Rank Species | |
Similar Betacoronavirus, Coronaviridae, Nidovirales, Bovine coronavirus, Transmissible gastroenteritis coronavirus | ||
Human coronavirus HKU1 (HCoV-HKU1) is a positive-sense, single-stranded RNA virus with the HE gene, which distinguishes it as a group 2, or betacoronavirus. It was discovered in January 2005 in two patients in Hong Kong.
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Discovery of HCoV-HKU1
HCoV-HKU1 was first identified in January, 2005, in a 71-year-old man who was hospitalized with an acute respiratory distress and radiolographically confirmed bilateral pneumonia. The man had recently returned to Hong Kong from Shenzhen, China.
Virology
Woo, et al., were unsuccessful in their attempts to grow a cell line from HCoV-HKU1 but were able to obtain the complete genomic sequence. Phylogenetic analysis showed that HKU1 is most closely related to the mouse hepatitis virus (MHV), and is distinct in that regard from the only other known group 2 human coronavirus, HCoV-OC43.
When the RNA-dependent RNA polymerase (RdRp), spike (S), and nucleocapsid (N) genes were analyzed, incompatible phylogenetic relationships were discovered. Complete genome sequencing of 22 strains of HCoV-HKU1 confirmed this was due to natural recombination.
Epidemiology
A trace back analysis of SARS negative nasopharyngeal aspirates from patients with respiratory illness during the SARS period in 2003, identified the presence of CoV-HKU1 RNA in the sample from a 35-year-old woman with pneumonia.
Following the initial reports of the discovery of HCoV-HKU1, the virus was identified that same year in 10 patients in northern Australia. Respiratory samples were collected between May and August (winter in Australia). Investigators found that most of the HCoV-HKU1–positive samples originated from children in the later winter months.
The first known cases in the Western hemisphere were discovered in December, 2002 by clinical virologists at Yale-New Haven Hospital in New Haven, Connecticut who were curious to discover if HCoV-HKU1 was in their area. They conducted a study of 851 infants and children over a 7-week period from December 2001 to February 2002. The children were also tested for Human respiratory syncytial virus (RSV), parainfluenza viruses (types 1–3), influenza A and B viruses, and adenovirus by direct immunofluorescence assay as well as human metapneumovirus and HCoV-NH by Real-time polymerase chain reaction (RT-PCR). All tested negative. Out of the 851 children, two tested positive for HCoV-HKU1. The researchers reported that the strain identified in New Haven is similar to the strain found in Hong Kong. This strain found in New Haven is sometimes referred to as HCoV-NH, for New Haven where it was discovered.
In July 2005, six cases were reported in France. In these cases, French investigators utilized improved techniques for recovering the virus from nasopharyngeal aspirates and from stool samples.