Coronavirus HKU1 in Children, Brazil, 1995

To the Editor: Coronavirus HKU1 is a newly identifi ed human coronavirus (HCoV) that was reported fi rst in 2005 in Hong Kong Special Administrative Region, People's Republic of China; later in Australia, Europe, and the United States, and more recently in Brazil, demonstrating a global distribution (1–3). We examined the circulation of HCoV in Brazil and the possible presence of the new HCoV types, with special attention to coronavirus HKU1, in samples collected back to 1995, tested by using universal coronavirus PCR. The epidemiologic profi le of HCoV was retrospectively investigated with samples collected during March–December 1995 in a approved the study. Samples of nasopharyngeal aspirates were collected from 169 hospitalized children, ages 7 days–15 years, of whom 104 had respiratory symptoms, 23 had enteric disease, and 3 had both (4). The mean age of the study population was 19.6 months (median 7 months). Viral nucleic acid was extracted from specimens by using Trizol (Invitrogen, Carlsbad, CA, USA) following the manufacturer's instructions. Total RNA was then submitted to reverse transcription PCR with a High-Capacity cDNA Archive Kit (Applied Biosystems, Foster City, CA, USA) by using random primers according to the manufacturer's instructions. The cDNA obtained was screened with primers able to amplify a 220-bp product in the conserved polymerase region of all known HCoVs (5) and other coronaviruses (e.g., bovine coronavirus). We used cDNA obtained from cultured human rectal tumor cell line HRT-18G cells inoculated with bovine coronavirus strain Kakegawa as positive controls for PCR. In an attempt to improve the sensitivity of HKU1 detection, we analyzed samples with negative results by PCR with a nested PCR specifi c for coronavirus HKU1.