Human respiratory coronavirus HKU1 versus other coronavirus infections in Italian hospitalised patients

Background Human respiratory coronavirus (hCoV) HKU1 infections were reported for the first time in 2005 in Hong Kong. Objective To investigate epidemiological, clinical, and diagnostic features of HKU1 infections. Study design Longitudinal, prospective study from November 2005 through May 2006 in a hospitalised patient population. Results Overall, 48/426 (11.3%) patients were found to be infected by hCoV acute respiratory tract infections (ARTI). Of these, 10 (19.2%) were caused by HKU1 (6 single infections and 4 coinfections) during the period January–May 2006. Diagnosis was made by using RT-PCR for all four hCoVs, and in parallel, in-house developed group-specific monoclonal antibodies (MAbs) for HKU1 and 229E. HKU1-specific MAb was able to retrospectively identify 8 of 10 HKU1 strains detected by RT-PCR. Phylogenetic analysis showed that four HKU1 strains were genotype A and six genotype B. In HKU1-infected patients, the predominant clinical symptom was rhinorrhea (nine patients). Within group II hCoV, HKU1-infected patients had a significantly lower rate of lower ARTI compared to OC43-infected patients. Conclusion HKU1 hCoV strains circulated in northern Italy during the winter–spring season 2005–2006. Both HKU1 genotypes were detected. HKU1-specific MAb may contribute to the rapid diagnosis of HKU1 infections currently performed by RT-PCR.