Clinical and molecular epidemiological features of coronavirus HKU1-associated community-acquired pneumonia

Background. Recently, we described the discovery of a novel group 2 coronavirus, coronavirus HKU1 (CoV-HKU1), from a patient with pneumonia. However, the clinical and molecular epidemiological features of CoV-HKU1-associated pneumonia are unknown. Methods. Prospectively collected (during a 12-month period) nasopharyngeal aspirates (NPAs) from patients with community-acquired pneumonia from 4 hospitals were subjected to reverse-transcription polymerase chain reaction, for detection of CoV-HKU1. The epidemiological, clinical, and laboratory characteristics of patients with CoV-HKU1-associated pneumonia were analyzed. The pol, spike (S), and nucleocapsid (N) genes were also sequenced. Results. NPAs from 10 (2.4%) of 418 patients with community-acquired pneumonia were found to be positive for CoV-HKU1. All 10 cases occurred in spring and winter. Nine of these patients were adults, and 4 had underlying diseases of the respiratory tract. In the 6 patients from whom serum samples were available, all had a 4-fold change in immunoglobulin (Ig) G titer and/or presence of IgM against CoV-HKU1. The 2 patients who died had significantly lower hemoglobin levels, monocyte counts, albumin levels, and oxygen saturation levels on admission and had more-extensive involvement visible on chest radiographs. Sequence analysis of the pol, S, and N genes revealed 2 genotypes of CoV-HKU1. Conclusions. CoV-HKU1 accounts for 2.4% of community-acquired pneumonia, with 2 genotypes in the study population. Without performance of diagnostic tests, the illness was clinically indistinguishable from other community-acquired pneumonia illnesses.