Infections by human coronavirus-NL in hospitalized children

Detection of subgenomic mRNA from endemic human coronavirus OC43 and NL63 compared to viral genomic loads, single virus detection and clinical manifestations in children with respiratory tract infections

BACKGROUND

The importance of endemic human coronavirus (HCoV) in children has been insufficiently elucidated upon. Our aims were to develop subgenomic (sg) mRNA tests for HCoV species OC43 and NL63, and to evaluate the relationships to HCoV genomic loads, single HCoV detections and clinical manifestations.

METHODS

We have used an 11-yearlong cohort study of children admitted with respiratory tract infection (RTI) and hospital controls. Nasopharyngeal aspirates were analyzed for HCoV subtypes OC43 and NL63 with in-house diagnostic PCR. Positive samples were tested with newly developed real-time PCRs targeting sg mRNA coding for the nucleocapsid protein.

RESULTS

OC43 sg mRNA was detected in 86% (105/122) of available OC43-positive samples in the RTI group, and in 63% (12/19) of control samples. NL63 sg mRNA was detected in 72% (71/98) and 71% (12/17) of available NL63-positive patient and control samples, respectively. In RTI samples, sg mRNA detection was strongly associated with a Ct value <32 in both diagnostic PCR tests (OC43: OR = 54, 95% CI [6.8-428]; NL63: OR = 42, 95% CI [9.0-198]) and single NL63 detections (OR = 6.9, 95% CI [1.5-32]). Comparing RTI and controls, only OC43 was associated with RTI when adjusted for age (aOR = 3.2, 95% CI [1.1-9.4]).

CONCLUSION

We found strong associations between OC43 and NL63 sg mRNA and high viral genomic loads. sg mRNA for OC43 was associated with RTI. The association between sg mRNA and clinical manifestations needs further evaluation.

Distinguishing viruses responsible for influenza-like illness

The many respiratory viruses that cause influenza-like illness (ILI) are reported and tracked as one entity, defined by the CDC as a group of symptoms that include a fever of 100 degrees Fahrenheit, a cough, and/or a sore throat. In the United States alone, ILI impacts 9-49 million people every year. While tracking ILI as a single clinical syndrome is informative in many respects, the underlying viruses differ in parameters and outbreak properties. Most existing models treat either a single respiratory virus or ILI as a whole. However, there is a need for models capable of comparing several individual viruses that cause respiratory illness, including ILI. To address this need, here we present a flexible model and simulations of epidemics for influenza, RSV, rhinovirus, seasonal coronavirus, adenovirus, and SARS/MERS, parameterized by a systematic literature review and accompanied by a global sensitivity analysis. We find that for these biological causes of ILI, their parameter values, timing, prevalence, and proportional contributions differ substantially. These results demonstrate that distinguishing the viruses that cause ILI will be an important aspect of future work on diagnostics, mitigation, modeling, and preparation for future pandemics.

The Human Coronaviruses

The human coronaviruses have been shown to be a major player in clinical microbiology and frequently occur as pathogens responsible for mild to severe respiratory infections. Moreover, two of the most dangerous viral respiratory infections are caused by novel coronaviruses, namely, the SARS and the MERS coronavirus. This chapter briefly summarizes the most important facts and knowledge required for the appropriate laboratory diagnostics of infections caused by the human coronaviruses.

Etiology and clinical features of viral bronchiolitis in infancy

BACKGROUND

Bronchiolitis is a common lower respiratory tract infection in infancy. The aim of this review is to present the clinical profile of viral bronchiolitis, the different culprit viruses and the disease severity in relation to the viral etiology.

DATA SOURCES

Databases including PubMed and Google Scholar were searched for articles about the clinical features of bronchiolitis and its viral etiology. The most relevant articles to the scope of this review were analyzed.

RESULTS

Currently there are two main definitions for bronchiolitis which are not identical, the European definition and the American one. The most common viral pathogen that causes bronchiolitis is respiratory syncytial virus which was identified in 1955; now many other viruses have been implicated in the etiology of bronchiolitis such as rhinovirus, adenovirus, metapneumovirus, and bocavirus. Several studies have attempted to investigate the correlation of bronchiolitis severity with the type of detected virus or viruses. However, the results were not consitent.

CONCLUSIONS

For the time being, the diagnosis of bronchiolitis remains clinical. The isolation of the responsible respiratory pathogens does not seem to confer to the prognosis of the disease severity.

Commonly circulating human coronaviruses do not have a significant role in the etiology of gastrointestinal infections in hospitalized children

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Human coronaviruses (HCoVs) OC43, 229E, NL63 and HKU1 were detected in children.

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The association of HCoVs in acute gastroenteritis of children was assessed.

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Both stool and respiratory samples of children were studied by RT-PCR.

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HCoVs were often detected concomitantly in the stool and respiratory samples.

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HCoVs do not have a significant role in gastroenteritis of hospitalized children.

Background

Human coronaviruses (HCoVs) OC43, 229E, NL63 and HKU1 are common causes of respiratory infections. Over the years, it has been proposed that HCoVs play a possible role in gastrointestinal infections.

Objectives

To assess the role of HCoVs in acute gastroenteritis (AGE) in children.

Study design

Study was conducted at Tampere University Hospital over 2 years. Both stool and nasal swab samples were collected from 172 children with AGE, 545 with acute respiratory tract infection (ARTI) and 238 with symptoms of both. The samples were tested for HCoVs by RT-PCR.

Results

HCoVs were detected in 52 (5.4%) children: in 6.4% of those with AGE, 4.4% with ARTI and 7.1% with symptoms of both. HCoVs OC43, HKU1, 229E and NL63 were encountered in 13, 11, 13 and 15 cases, respectively. HCoVs were detected simultaneously in stool and nasal swab samples in 17 children, in nasal swabs alone in 33 children, and in the stools alone in two children. HCoVs were present in the stools of eight (4.7%) of the 172 children with AGE; in six of these cases, the nasal swab sample was also positive for the respective HCoV. Additionally, in six of the eight cases, the stool sample contained either rotavirus or calicivirus.

Conclusions

HCoVs can be detected in the stools of children with AGE, but usually together with well-known gastroenteritis viruses, and concomitantly in the respiratory tract. It appears that commonly circulating HCoVs do not have a significant role in the AGE of children admitted to hospital.

Characterization of human coronavirus OC43 and human coronavirus NL63 infections among hospitalized children <5 years of age

BACKGROUND

Multiplex molecular assays now make it possible for clinical laboratories to detect human coronaviruses (HCoVs). We investigated the clinical characteristics of HCoV-OC43 and HCoV-NL63 in patients <5 years of age during a recent coronavirus season.

METHODS

Respiratory viruses were detected using a multiplex molecular assay at St. Louis Children`s Hospital starting in November 2012. We analyzed demographic and clinical data from all patients <5 years of age with solo detection of HCoV-OC43 (n = 52) and HCoV-NL63 (n = 44) and for comparison, samples of children with respiratory syncytial virus, parainfluenza virus and picornaviruses.

RESULTS

During the study period, HCoV-OC43 (4%) was the 5th and HCoV-NL63 the 8th (2%) most common respiratory virus. Coinfections were detected in 35% and 38% of children with HCoV-OC43 and HCoV-NL63, respectively. Croup was more common with HCoV-NL63 (30%) than with HCoV-OC43 (2%). Lower respiratory tract infection occurred in 33% of children with HCoV-OC43 and 25% of children with HCoV-NL63. Severe illness was less common in HCoV-NL63, HCoV-OC43 and parainfluenza virus (14%, each) compared with respiratory syncytial virus (30%) and picornaviruses (26%; P = 0.055 for HCoVs combined compared with the other respiratory viruses) and occurred mainly in those with underlying medical conditions.

CONCLUSIONS

Infections caused by HCoV-OC43 and HCoV-NL63 are common and include some with lower respiratory tract involvement and severe disease, especially in children with underlying medical conditions. Overall, a substantial burden of disease associated with both HCoV-OC43 and HCoV-NL63 was observed for hospitalized children <5 years of age.

Effects of coronavirus infections in children

The isolation of the coronavirus (CoV) identified as the cause of severe acute respiratory syndrome and the detection of 2 new human CoVs (HCoV-NL63 and HCoV-HKU1) have led to studies of the epidemiology and clinical and socioeconomic effects of infections caused by all HCoVs, including those known since the late 1960s (HCoV-229E and HCoV-OC43). HCoV infections can be associated with respiratory and extrarespiratory manifestations, including central nervous system involvement. Furthermore, unlike other RNA viruses, HCoVs can easily mutate and recombine when different strains infect the same cells and give rise to a novel virus with unpredictable host ranges and pathogenicity. Thus, circulating HCoVs should be closely monitored to detect the spread of particularly virulent strains in the community at an early stage and to facilitate the development of adequate preventive and therapeutic measures.

Sole pathogen in acute bronchiolitis: is there a role for other organisms apart from respiratory syncytial virus?

BACKGROUND

Acute bronchiolitis (AB) is a common disease of young children with peak incidence during the winter season. Respiratory syncytial virus (RSV) is a major causative organism, yet recent relatively small sized studies have suggested an increased role of other organisms as sole or codetected organisms. The aim of this study was to assess the prevalence of sole- and mixed-organisms infections in hospitalized children with AB, using combined antigen-based and polymerase chain reaction assays (PCR).

METHODS

Sputum or nasal wash specimens obtained from 490 previously healthy children < or =2 years of age hospitalized with AB between December 1, 2005 and March 31, 2006 were tested: (1) For RSV, by rapid antigen detection test; (2) For RSV, influenza A, B, Parainfluenza 1 to 3, and adenovirus antigens by direct fluorescent assay; (3) For influenza A and B, RSV, Parainfluenza 1 to 3 viruses RNA by reverse transcription (RT) PCR assay; (4) For human metapneumovirus and rhinovirus RNA by RT real-time PCR assay; (5) For adenovirus, and Bordetella pertussis DNA by conventional PCR assays; (6) For human bocavirus DNA by real-tine PCR assays.

RESULTS

At least 1 organism was detected in 465 (91%) children. In 283 (61%), 117 (25%), and 23 (5%) children, 1, 2, and 3/4 organisms were detected, respectively. The most commonly detected organism was RSV, detected in 76%, and as a sole organism in 49%. Rhinovirus, human metapneumovirus, influenza virus A, bocavirus, Bordetella pertussis, and adenovirus were detected as a sole organism in 7%, 2.1%, 1%, 0.6%, 0.6%, and 0.2% of the children, respectively.

CONCLUSIONS

Respiratory organisms were detected in the majority of the children, of whom about one third suffered from mixed organism infection. RSV was the most prevalent sole detected organism. The relevance of all other organisms may be much less than previously suggested.

The pediatric burden of human coronaviruses evaluated for twenty years

BACKGROUND

The epidemiology of human coronaviruses (HCoVs) has not been established using reverse transcription polymerase chain reaction techniques in a specimen collection that spans decades.

METHODS

We used real-time RT-PCR for 3 HCoVs, HCoV 229E, OC43, and NL63, to test nasal wash specimens that had been obtained from a cohort of children <5 years of age with upper or lower respiratory infection (URI, LRI) who were comprehensively followed during the period from 1977 to 2001. Prospectively collected clinical data and archival samples were analyzed.

RESULTS

HCoV was detected in 92/1854 (5.0%) of available samples with no known viral etiology of which 9% were 229E, 59% OC43, and 33% NL63. This represented 10/119 (8.4%) of LRI samples and 82/1735 (4.7%) of URI samples. HCoV was not detected every year, but occurred episodically. The recently described HCoV-NL63 was detected as early as 1981. HCoV was associated with 11.4 LRI episodes/1000 child-years <5 years of age (all in children <2 years of age) and 67.3 URI episodes/1000 child-years <5 years of age.

CONCLUSIONS

HCoV-NL63 and OC43 are associated with a significant proportion of LRI in children less than 2 years of age and a substantial number of medically attended URI episodes.

Review of new and newly discovered respiratory tract viruses in children

Respiratory tract viral infection continues to be among the most common reasons for emergency department visits and hospitalization of children, particularly infants younger than 1 year, in the United States. Throughout the years, clinicians have considered respiratory syncytial virus followed by influenza as the most common pathogens responsible. Over the past decade, new viruses have been discovered through both more specific testing and the finding of new agents causing infection. This includes human metapneumovirus, which leads to similar but often epidemiologically more severe clinical symptoms than respiratory syncytial virus. Other agents responsible for lower respiratory tract infection include Coronavirus (severe acute respiratory syndrome), Bocavirus, and others. This review serves to focus on some of the recent literature on these agents and the clinical impact they have on pediatric lung infection.

Respiratory pathogens in children with and without respiratory symptoms

OBJECTIVES

To investigate the occurrence of respiratory pathogens in samples from children with and without respiratory symptoms and to identify whether age and/ or coinfections modify the impact of respiratory pathogens on symptoms.

STUDY DESIGN

In a prospective longitudinal study, 18 children were sampled biweekly for respiratory pathogens, irrespective of respiratory symptoms. Polymerase chain reaction was performed for 13 respiratory pathogens. Episodes were defined "asymptomatic" if no symptoms of any respiratory tract illness were present between 1 week before and 1 week after sampling.

RESULTS

A total of 230 samples were collected. In 56% of the symptomatic episodes, a pathogen was detected, compared with 40% of the asymptomatic episodes (P = .03). Rhinovirus and coronaviruses were most prevalent in both symptomatic and asymptomatic episodes. In the youngest children, 9% of the pathogen-positive episodes were asymptomatic, compared with 36% in the oldest children (P = .01). Multiple pathogens were found in 17% of the symptomatic episodes and in 3% of the asymptomatic episodes (P = .02).

CONCLUSIONS

Respiratory pathogens are frequently detected in samples from children with no respiratory symptoms. Symptomatic cases occurred more often in younger children and with detections of more than 1 respiratory pathogen.

Comparison of automated microarray detection with real-time PCR assays for detection of respiratory viruses in specimens obtained from children

Respiratory virus infections are a major health concern and represent the primary cause of testing consultation and hospitalization for young children. We developed and compared two assays that allow the detection of up to 23 different respiratory viruses that frequently infect children. The first method consisted of single TaqMan quantitative real-time PCR assays in a 96-well-plate format. The second consisted of a multiplex PCR followed by primer extension and microarray hybridization in an integrated molecular diagnostic device, the Infiniti analyzer. Both of our assays can detect adenoviruses of groups A, B, C, and E; coronaviruses HKU1, 229E, NL63, and OC43; enteroviruses A, B, C, and D; rhinoviruses of genotypes A and B; influenza viruses A and B; human metapneumoviruses (HMPV) A and B, human respiratory syncytial viruses (HRSV) A and B; and parainfluenza viruses of types 1, 2, and 3. These tests were used to identify viruses in 221 nasopharyngeal aspirates obtained from children hospitalized for respiratory tract infections. Respiratory viruses were detected with at least one of the two methods in 81.4% of the 221 specimens: 10.0% were positive for HRSV A, 38.0% for HRSV B, 13.1% for influenzavirus A, 8.6% for any coronaviruses, 13.1% for rhinoviruses or enteroviruses, 7.2% for adenoviruses, 4.1% for HMPV, and 1.5% for parainfluenzaviruses. Multiple viral infections were found in 13.1% of the specimens. The two methods yielded concordant results for 94.1% of specimens. These tests allowed a thorough etiological assessment of respiratory viruses infecting children in hospital settings and would assist public health interventions.

Identification of respiratory viruses in asymptomatic subjects: asymptomatic respiratory viral infections

The medical literature of the past 4 decades was searched regarding respiratory virus detection by polymerase chain reaction and conventional methods (culture, antigen detection, serology) in asymptomatic subjects in an attempt to determine the prevalence and clinical significance of such viruses in normal persons.

Phylogenetic analysis of human coronavirus NL63 circulating in Italy

Background

Five known human coronaviruses infect the human respiratory tract: HCoV-OC43, HCoV-229E, SARS-CoV, HCoV-NL63 and HCoV-HKU1.

Objectives

To evaluate the prevalence of HCoV-NL63 in hospitalized adult patients and to perform molecular characterization of Italian strains.

Study Design

HCoV-NL63 was sought by RT-PCR in 510 consecutive lower respiratory tract (LRT) samples, collected from 433 Central-Southern Italy patients over a 1-year period. Phylogenetic analysis was performed by partial sequencing of S and ORF1a. Additional S sequences from Northern Italy were included in the phylogenetic trees.

Results

HCoV-NL63 was detected in 10 patients (2.0%) with symptomatic respiratory diseases, mainly during winter. Phylogenetic analysis indicated a certain degree of heterogeneity in Italian isolates. The ORF1a gene clustering in phylogenetic trees did not match with that of the S gene.

Conclusions

As observed by others, HCoV-NL63 is often associated with another virus. Phylogenetic characterization of HCoV-NL63 circulating in Italy indicates that this virus circulates as a mixture of variant strains, as observed in other countries.

Frequency of detection of respiratory viruses in the lower respiratory tract of hospitalized adults

BACKGROUND

Respiratory infections are the most common infections in humans. The prevalence of respiratory viruses in adults is largely underestimated, and relevant data mostly concern infants and children.

OBJECTIVES

To evaluate the prevalence of respiratory viruses in adults hospitalized in Italy.

STUDY DESIGN

During April 2004--May 2005, 510 consecutive lower respiratory tract samples were prospectively collected. These were evaluated with a molecular panel that detected 12 respiratory viruses.

RESULTS

Two hundred and fifteen samples were positive for at least one viral pathogen, with an overall sample prevalence of 42.2%. Human rhinoviruses (HRVs) were the most commonly detected viruses (32.9%), followed by influenza virus (FLU)-A (9.0%); the other viruses were 2% or less. Multiple agents were detected in 30 samples from 29 patients, resulting in a co-infection rate of 6.7%.

CONCLUSIONS

This study shows a high prevalence of viruses in the lower respiratory tract samples of hospitalized adults, mostly HRV and FLU-A. It is not possible to establish the role of viruses detected at low frequency, but our findings suggest the necessity to consider them as potential causes or precursors of lower respiratory tract infections (LRTIs).

Identification of new human coronaviruses

To date, there are still a variety of human infections with unknown etiology. Identification of previously unrecognized viral agents in patient samples is of great medical interest but remains a major technical challenge. Acute respiratory tract infections are responsible for considerable morbidity and mortality in humans and animals. A variety of viruses, bacteria and fungi are associated with respiratory tract illness. Most of the respiratory viruses belong to the Paramyxoviridae, Orthomyxoviridae, Picornaviridae, Adenoviridae and Coronaviridae families. No pathogens can be detected in a relatively large proportion of patients with respiratory disease, partially owing to limitations of current diagnostic assays but also since some infections are caused by as yet unknown pathogens. This review will focus on human coronaviruses. In the mid 1960s, two human coronaviruses were identified that cause the common cold: human coronaviruses (HCoV)-229E and HCoV-OC43. The recent outbreak of severe acute respiratory syndrome-CoV and subsequent identification of two additional human coronaviruses (HCoV-NL63 and HCoV-HKU1) has drawn attention to this virus family. This review summarizes the knowledge of current methodologies for identifying novel human coronavirus species. Furthermore, information on the discovery of known human coronaviruses will be presented.

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.

Impact of human coronavirus infections in otherwise healthy children who attended an emergency department

This prospective clinical and virological study of 2,060 otherwise healthy children aged <15 years of age (1,112 males; mean age ± SD, 3.46 ± 3.30 years) who attended the Emergency Department of Milan University's Institute of Pediatrics because of an acute disease excluding trauma during the winter season 2003–2004 was designed to compare the prevalence and clinical importance of human coronaviruses (HCoVs) in children. Real‐time polymerase chain reaction (PCR) in nasopharyngeal aspirates revealed HCoV infection in 79 cases (3.8%): 33 HCoV‐229E (1.6%), 13 HCoV‐NL63 (0.6%), 11 HCoV‐OC43 (0.5%), none HCoV‐HKU1 genotype A, and 22 (1.1%) co‐detections of a HCoV and another respiratory virus. The HCoVs were identified mainly in children with upper respiratory tract infection; there was no significant difference in clinical presentation between single HCoV infections and HCoV co‐infections. Diagnostic methods were used in a limited number of patients, and the therapy prescribed and clinical outcomes were similar regardless of the viral strain. There were a few cases of other members of the households of HCoV‐positive children falling ill during the 5–7 days following enrollment. These findings suggest that HCoV‐229E and HCoV‐OC43 have a limited clinical and socioeconomic impact on otherwise healthy children and their household contacts, and the HCoV‐NL63 identified recently does not seem to be any different. The quantitative and qualitative role of HCoV‐HKU1 genotype A is apparently very marginal. J. Med. Virol. 78:1609–1615, 2006. © 2006 Wiley‐Liss, Inc.

Clinical disease in children associated with newly described coronavirus subtypes

OBJECTIVES

Coronaviruses cause upper respiratory illness and occasionally lower tract disease in susceptible populations. In this study we examined the prevalence of 4 human coronaviruses, including subtypes OC43, 229E, and the recently described NL63 and HKU1 in a pediatric population presenting to a children's hospital.

PATIENTS AND METHODS

Specimens collected over a 1-year period from pediatric patients presenting with acute respiratory illness were analyzed for the presence of 4 coronavirus subtypes using consensus and subtype-specific real-time reverse-transcription polymerase chain reaction assays. The demographic and clinical characteristics associated with coronavirus infection were examined retrospectively.

RESULTS

Coronaviruses were detected in 66 of 1043 children. Eight, 11, 19, and 28 specimens were positive for subtypes 229E, NL63, OC43, and HKU1, respectively. Coronaviruses were detected throughout the study period; all 4 of the subtypes were present simultaneously in December. The acute clinical features were similar across subtypes. Of 32 children infected with a coronavirus as the sole respiratory pathogen, 13 had lower respiratory tract disease. Children whose only detectable respiratory virus was a coronavirus were more likely to have underlying chronic disease than were children coinfected with another respiratory virus.

CONCLUSIONS

Although 4 subtypes of coronavirus were detected, the recently discovered coronavirus subtypes NL63 and HKU1 accounted for the majority of coronaviruses detected in our cohort of mostly hospitalized children with respiratory symptoms. New subtypes likely represent a substantial portion of previously unexplained respiratory illnesses.

Role of cell culture for virus detection in the age of technology

Viral disease diagnosis has traditionally relied on the isolation of viral pathogens in cell cultures. Although this approach is often slow and requires considerable technical expertise, it has been regarded for decades as the "gold standard" for the laboratory diagnosis of viral disease. With the development of nonculture methods for the rapid detection of viral antigens and/or nucleic acids, the usefulness of viral culture has been questioned. This review describes advances in cell culture-based viral diagnostic products and techniques, including the use of newer cell culture formats, cryopreserved cell cultures, centrifugation-enhanced inoculation, precytopathogenic effect detection, cocultivated cell cultures, and transgenic cell lines. All of these contribute to more efficient and less technically demanding viral detection in cell culture. Although most laboratories combine various culture and nonculture approaches to optimize viral disease diagnosis, virus isolation in cell culture remains a useful approach, especially when a viable isolate is needed, if viable and nonviable virus must be differentiated, when infection is not characteristic of any single virus (i.e., when testing for only one virus is not sufficient), and when available culture-based methods can provide a result in a more timely fashion than molecular methods.

Human Coronavirus-NL63 infections in Korean children, 2004-2006

Background

Human coronavirus-NL63 (HCoV-NL63) has been isolated from children with respiratory tract infections and its prevalence in Korea has not been reported.

Objectives

This study was designed to investigate the presence and the clinical features of HCoV-NL63 during two winter seasons.

Study design

During April 2004–April 2006, nasopharyngeal specimens from children hospitalized with acute respiratory disease were tested for common respiratory viruses, including RSV, influenza A, influenza B, parainfluenza viruses, and adenovirus by IFA. hMPV infection was excluded by nested RT-PCR using primers for F-gene. To detect HCoV-NL63, previously described nested PCR assays for 1a and 1b were used. PCR products of the 1a gene for HCoV-NL63 were sequenced.

Results

Out of 872 nasopharyngeal aspirate from children aged under 16 years, 14 (1.7%) were positive for HCoV-NL63. Most of the patients had croup (64.2%) or bronchiolitis (21.4%). The peak prevalence was found in November (28.5%). Most were collected between November 2004 and February 2005.

Conclusions

HCoV-NL63 may be one of the causative agents of acute respiratory tract infection, especially croup.

A prospective hospital-based study of the clinical impact of non-severe acute respiratory syndrome (Non-SARS)-related human coronavirus infection

Background. In addition to the human coronaviruses (HCoVs) OC43 and 229E, which have been known for decades to cause infection in humans, 2 new members of this genus have recently been identified: HCoVs NL63 and HKU1. Their impact as a cause of respiratory tract disease in adults at risk for complications needs to be established.

Methods. We prospectively assessed the clinical impact of coronavirus infection (excluding cases of severe acute respiratory syndrome) among hospitalized adults. All patients with respiratory disease for whom bronchoalveolar lavage was performed were screened by reverse-transcriptase polymerase chain reaction for the presence of all 4 HCoVs.

Results. HCoV was identified in 29 (5.4%) of 540 bronchoalveolar lavage fluid specimens from 279 subjects (mean age, 51 years; 63% male). HCoV OC43 was identified most frequently (12 isolates), followed by 229E (7 isolates), NL63 (6 isolates), and HKU1 (4 isolates). In all, 372 (69%) of 540 bronchoalveolar lavage fluid specimens were negative for bacteria, and 2 persons were coinfected with other respiratory viruses. Transplantation was the most common underlying condition. Of the 29 patients who had HCoV identified in their bronchoalveolar lavage fluid specimens, 9 (31%) were hospitalized in the intensive care unit, 22 (76%) presented to the hospital with acute respiratory symptoms, 16 (55%) presented with cough and/or sputum, 13 (45%) presented with dyspnea, 16 (55%) had experienced prior respiratory infection, and 18 (62%) had a new infiltrate that was visible on chest radiograph. The most frequent final diagnosis was a lower respiratory tract infection.

Conclusions. The recently discovered HCoVs NL63 and HKU1 contribute significantly to the overall spectrum of coronavirus infection. Our study also suggests that coronaviruses contribute to respiratory symptoms in most cases.

Human Coronaviruses: What Do They Cause?

SARS-CoV, human coronavirus NL63 (HCoV-NL63) and HCoV-HKU1 were first described in 2003, 2004 and 2005 respectively. Nevertheless, discovery of three new human coronaviruses does not necessary represent a sudden increase in emerging infections by new coronaviruses. Only SARS-CoV has recently been introduced to the human population; the other two have been circulating in humans for a long time. HCoV-HKU1 and HCoV-NL63 are respiratory coronaviruses, are frequently found during lower and upper respiratory tract infections, have spread worldwide, and prefer the winter season. These characteristics do not differ greatly from the symptoms described for the ‘old’ viruses HCoV-229E and HCoV-OC43. This report presents an overview of the current knowledge of the four human coronavirus that are now circulating in the human population.