Human Coronavirus NL63

Burtram C Fielding


Future Microbiol. 2011;6(2):153-159. 

In This Article

Abstract and Introduction


Respiratory tract infection is a leading cause of morbidity and mortality worldwide, especially among young children. Human coronaviruses (HCoVs) have only recently been shown to cause both lower and upper respiratory tract infections. To date, five coronaviruses (HCoV-229E, HCoV-OC43, SARS-CoV, HCoV-NL63 and HCoV HKU-1) that infect humans have been identified, four of which (HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU-1) circulate continuously in the human population. Human coronavirus NL63 (HCoV-NL63) was first isolated from the aspirate from a 7-month-old baby in early 2004. Infection with HCoV-NL63 has since been shown to be a common worldwide occurrence and has been associated with many clinical symptoms and diagnoses, including severe lower respiratory tract infection, croup and bronchiolitis. HCoV-NL63 causes disease in children, the elderly and the immunocompromised, and has been detected in 1.0–9.3% of respiratory tract infections in children. In this article, the current knowledge of human coronavirus HCoV-NL63, with special reference to the clinical features, prevalence and seasonal incidence, and coinfection with other respiratory viruses, will be discussed.


Acute respiratory tract infections (ARTIs) are among the most common causes of disease in humans.[1] The majority of ARTIs are caused by viruses with rhinovirus, respiratory syncytial virus, influenza virus, enterovirus, human metapneumovirus and parainfluenza virus considered the major pathogens.[1–3] Those most at risk of severe complications from these viral infections include young children, the elderly or persons with compromised cardiac, pulmonary or immune systems.[2,4] The high burden of disease caused by respiratory viruses in young children has led to the development of diagnostic tests and vaccines for the treatment of these infections.[5]

Until recently, it was commonly accepted that the known human coronaviruses (HCoVs), with the exception of severe acute respiratory syndrome Cov (SARS-CoV), mainly cause mild upper respiratory tract infections (URTIs).[6] For this reason, the circulation of HCoVs was not monitored and no attempt to develop vaccines or drugs against these viruses was made.[7] CoVs are ssRNA viruses that infect humans and animals. In animals, CoVs cause a wide spectrum of diseases, including respiratory, enteric, hepatic and neurological diseases, with symptoms ranging from mild to severe.[8,9] HCoVs causing URTIs were first isolated from patients in the 1960s,[8] with HCoV-229E and HCoV-OC43 the best characterized. Then, following the outbreak of SARS in China in 2003, three additional human coronaviruses were identified – SARS-CoV,[10–12] HCoV-NL63[13,14] and HCoV-HKU1.[15] Of the five known HCoVs, four (HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1) are circulating continuously in the human population.

This article aims to summarize the current knowledge of HCoV-NL63 with reference to the clinical features, prevalence and seasonal incidence, and coinfection with other respiratory viruses. Finally, perspectives for future developments in the field are discussed.


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