Human Coronaviruses Before SARS

Abstract & Commentary

Synopsis: Human coronavirus OC43 accounted for 6% of respiratory illnesses studied in Normandy during a single season.

Source: Vabret A, et al. An outbreak of coronavirus OC43 respiratory infection in Normandy, France. Clin Infect Dis. 2003;36:985-989.

Vabret and colleagues in Normandy examined 1803 respiratory specimens collected from October 2000 through April 2001 for the presence of genomic material of human coronaviruses (HCoV) 229 and OC43 using RT-PCR assays. Overall, a virus was detected in samples from 189 (37.8%) of 501 patients. HCoV OC43 was detected in samples from 30 (6%) of 501 patients that were submitted from February 8 through March 27; HCoV 229 was not detected. RSV was detected in specimens from 6.1% of patients, influenza virus A in 7.8%, influenza virus B in 7.2%, parainfluenza virus 3 in 1%, rhinovirus in 6.4%, enterovirus in 1%, and adenovirus in 2%. Testing was not performed for the presence of human metapneumovirus.

HCoV OC43 was detected in 29 nasal aspirates and 1 bronchial aspirate. The virus was isolated from all age groups. Sixty percent of those from whom HCoV OC43 was isolated had fever, 57% had gastrointestinal symptoms, 37% rhinitis, 30% pharyngitis, 13% otitis, and 3% laryngitis. Approximately one-third had lower respiratory tract infection, including bronchitis (17%), bronchiolitis (10%), and pneumonia (7%). One of the 2 patients with pneumonia was a heart transplant recipient, while the other was 84 years of age.

Comment by Stan Deresinski, MD, FACP

The identification of the etiologic agent of SARS as a novel coronavirus has stimulated interest in this group of RNA viruses, making this publication quite timely. The SARS coronavirus is sufficiently distinct from previously known coronaviruses for it to comprise a new group (Group IV). HCoV 229 and HCoV OC43, previously the only known coronaviruses to infect humans, belong, respectively, to Groups I and II; Groups III consists of only animal, mostly avian, coronaviruses. The other coronaviruses infect a range of mammalian hosts, causing respiratory, neurologic, and enteric disease.1

Coronaviruses contain a single positive-sense RNA strand comprised of approximately 3000 nucleotides, making it the largest known RNA virus genome. Viral replication occurs in 2 steps. Initially, viral RNA is translated to create an RNA-dependent RNA polymerase, which is then used to copy a minus-strand RNA from the positive-strand genomic RNA. Messenger RNAs are transcribed from this minus-strand RNA, as is viral genomic RNA.

HCoV OC43 and HCoV 229 together account for approximately one-third of common colds. Most infections occur in winter or spring, often in epidemics, which may occur irregularly (HCoV OC43) or at approximately 2-4 year intervals (HCoV 229). Lower respiratory tract infection, including pneumonia and pleuritis, occurred in one-third of marine recruits during an outbreak.2

Vabret and colleagues found that "digestive problems" were noted in 58% of the coronavirus-infected patients. This is of interest given that diarrhea has frequently been present in SARS patients and with the suggestion that one of the routes by which SARS transmission may occur is fecal-oral. While there has been no unequivocal evidence that the previously known coronaviruses cause acute enteric infection, they have been detected in feces.

Dr. Deresinski is Clinical Professor of Medicine, Stanford; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center.

References

1. McIntosh K. Coronaviruses. In: Richman DD, Whitley RJ, Hayden FG, eds. Clinical Virology. New York, NY: Churchill Livingstone; 1997.

2. Wenzel RP, et al. Coronavirus infections in military recruits. Am Rev Respir Dis. 1974;109:621-624.