Development and evaluation of a real-time RT-PCR assay on the LightCycler for the rapid detection of enterovirus in cerebrospinal fluid specimens

Non-polio enterovirus aseptic meningitis in infants up to three months of age, the bacterial mask of viral disease: A retrospective cohort study

BACKGROUND

Non-polio enterovirus aseptic meningitis (NPE-AM) is a self-limiting illness that can mimic serious bacterial infection (SBI) in infants during their first months of life.

OBJECTIVES

To compare the clinical features of febrile infants diagnosed with NPE-AM with those of infants who had SBI or non-bacterial infection (NBI).

STUDY DESIGN

A systematic series of febrile infants < 3-months-old hospitalized between 2010 and 2019 with febrile illness in a tertiary hospital. Clinical and laboratory data were compared between the three groups.

RESULTS

Overall 1278 infants were included; 207 (16.2%) had NPE-AM, 210 (16.4%) SBI and 861 (67.4%) NBI. The median age was 34 (IQR: 21.5-51.7) days. NPE-AM was documented in 25% of infants < 29 days and 9.9% of infants aged 29-90 days. Infants with NPE-AM or SBI had fever >39°C more frequently, 24.2% and 17.1% compared with 10% in infants with NBI (p < 0.001). Fever duration ≥ 2 days was reported in 3.4% of infants with NPE-AM vs 18.6% in SBI and 26.3% in NBI (p < 0001); rash occurred in 37.7% in NPE-AM compared to 4.6% in NBI and 5.7% in SBI (p < 0.001). The mean white blood count, C-reactive protein and absolute neutrophil count were significantly lower in infants with NPE-AM compared to infants with the SBI (p < 0.001) and similar to the means in infants with NBI (p = 0.848, 0.098 and 0.764 respectively). A high proportion of bloody tap 346/784 (53.1%) was detected. Infants with NPE-AM were more likely to be treated with antibiotics than infants with NBIs (88.9% vs 50.7%, p < 0.001), similarly to infants with SBIs (p = 0.571).

CONCLUSIONS

The clinical presentation of infants with NPE-AM that could mimic bacterial infection and the high rate of bloody taps may lead to more hospital admissions and antibiotic prescriptions. Rapid molecular testing for detection of NPE may be of additional value in the evaluation of febrile infants.

Enterovirus infection in febrile neonates: A hospital-based prospective cohort study

AIM

This study aims to investigate clinical characteristics and microbiological results and to assess the predictors for enterovirus infection in febrile neonates.

METHODS

A prospective cohort study was conducted on 334 febrile patients (age: 0.33-28 days) in 2011-2012 years. Enterovirus RNA was detected by reverse transcription polymerase chain reaction on faeces or cerebrospinal fluid (CSF). Clinical characteristics were compared, and non-conditional logistic regression analysis was performed to determine independent predictors for enterovirus infection.

RESULTS

There were 131 episodes of neonatal enterovirus infection (39.22%). Forty-eight (36.64%) developed respiratory symptoms, 69 (52.67%) had diarrhoea, 22 (16.79%) had poor feeding and 34 (25.95%) had rash. Eighteen (13.74%) had lower platelet counts, and CSF specimens were positive for enterovirus RNA in 44.27% (58/131) whose CSF revealed a mean white blood cell counts of 100.38 ± 147.97 cells/mm(3) (range: 2-668 cells/mm(3) ). The positivity of stool 38.92% (130/334) was significantly higher than that of CSF specimens 26.24% (58/221) for enterovirus RNA (P < 0.01). By logistic regression analysis, the following independently predicted enterovirus infection: abnormal CSF test (odds ratio (OR): 12.426, 95% confidence interval (CI): 5.633-27.413), thrombocytopenia (OR: 3.647, 95% CI: 1.312-10.136), duration of fever >3.25 (d) (OR: 2.293, 95% CI: 1.279-4.113), highest temperature >38.35 (°C) (OR: 2.094, 95% CI: 1.342-4.123) and negative bacterial culture (OR: 5.073, 95% CI: 1.504-17.114).

CONCLUSIONS

Our data indicated that enteroviruses should be routinely considered in the differential diagnosis of febrile neonates. The factors, which may predict the risk of neonatal enterovirus infection, were abnormal CSF test, thrombocytopenia, duration of fever >3.25 (d), highest temperature >38.35 (°C) and negative bacterial culture.

Enteroviruses as major cause of microbiologically unexplained acute respiratory tract infections in hospitalized pediatric patients

OBJECTIVE

To assess the etiological role and the clinical characteristics of HRV and HEV infections in pediatric patients hospitalized for acute respiratory tract infections (ARTIs).

METHODS

RT-qPCR assays and molecular sequencing methods were used to identify HRV and HEV strains in nasopharyngeal aspirates of 309 hospitalized pediatric patients with microbiologically unexplained ARTIs and in 210 hospitalized pediatric patients without respiratory symptoms from September 2009 to June 2010 in France.

RESULTS

Among the 309 ARTI cases, 15 HEV and 172 HRV strains were identified whereas only 1 HEV and 37 HRV strains were observed in control patients (187 vs. 38: P < 10(-3)). HRV strains were identified in 150 of the 164 lower ARTIs whereas HEV strains were identified in only 14 of these cases. Among bronchiolitis and asthma exacerbation cases (n = 133), HEV infected cases were older (Median age (months) 36 vs. 11, P = 0.003) and were more frequently associated with a respiratory distress (P = 0.01) and a need for oxygen supply at the time of admission (P = 0.01) than cases infected by HRV strains.

CONCLUSION

HRV and HEV strains were identified as potential etiological causes of 60.5% of microbiologically unexplained ARTIs diagnosed in hospitalized pediatric cases. A higher clinical severity was observed in HEV infected bronchiolitis or asthma exacerbation cases in comparison to HRV infected cases.

Virus detection and semiquantitation in explanted heart tissues of idiopathic dilated cardiomyopathy adult patients by use of PCR coupled with mass spectrometry analysis

Viral detection in heart tissues has become a central issue for the diagnosis and exploration of the pathogenesis of idiopathic dilated cardiomyopathy (IDCM). In the present study, common cardiotropic viruses in 67 explanted heart samples of 31 IDCM adult patients were detected and semiquantified by using for the first time a new technology based on PCR assay coupled to electrospray ionization-time of flight mass spectrometry analysis (PCR-MS), with comparison to reference quantitative real-time PCR (RT-qPCR) assay. PCR-MS identified single or mixed enterovirus (EV) and parvovirus B19 (PVB19) infections in 27 (40.2%) of 67 samples, corresponding to 15 (48.3%) of the 31 patients, whereas RT-qPCR identified viral infections in 26 (38.8%) samples, corresponding to 16 (51.6%) of the patients. The PCR-MS results correlated well with EV and PVB19 detection by RT-qPCR (kappa = 0.85 [95% confidence interval {CI}, 0.72 to 1.00] and kappa = 0.82 [95% CI, 0.66 to 0.99], respectively). The levels of EV RNA (median, 550 [range, 178 to 3,200] copies/μg of total extracted nucleic acids) and of PVB19 DNA (median, 486 [range, 80 to 1,157] copies/μg of total extracted nucleic acids) were measured using PCR-MS and correlated with those obtained by RT-qPCR (r(2) = 0.57, P = 0.002 and r(2) = 0.64, P < 0.001 for EV and PVB19, respectively). No viruses other than EV and PVB19 strains were detected using the new PCR-MS technology, which is capable of simultaneously identifying 84 known human viruses in one assay. In conclusion, we identified single or mixed EV and PVB19 cardiac infections as potential causes of IDCM. The PCR-MS analysis appeared to be a valuable tool to rapidly detect and semiquantify common viruses in cardiac tissues and may be of major interest to better understand the role of viruses in unexplained cardiomyopathies.

Development of a reverse transcription-quantitative PCR assay for detection of salivirus/klassevirus

A broadly reactive and highly sensitive reverse transcription-quantitative PCR assay to detect salivirus/klassevirus was developed. By means of the developed assay, salivirus/klassevirus was detected in 13 (93%) raw sewage, 4 (29%) secondary-treated sewage, and 9 (16%) river water samples, with a maximum concentration of 9.7 × 10(6) copies/liter.

Technical and Clinical Niches for Point of Care Molecular Devices

A point of care (POC) device is one that is used outside of a central laboratory environment; generally near , or at the site of the patient/client. Point of care testing (POCT) varies from tests performed in physician’s office labs, or “satellite” or “stat” labs, to tests performed on tabletop instruments in a clinic area, to testing performed with hand-held instruments at the bedside. In peripheral lab settings, POCT may be performed by trained laboratory staff, but clinic and bedside POCT is frequently performed by staff who lack specialized laboratory training and whose primary job is something other than doing lab tests.

Enterovirus 68 in pediatric patients hospitalized for acute airway diseases

Enterovirus 68 was detected in 10 respiratory specimens from pediatric patients hospitalized for acute wheezing or bronchitis during 2009 in the northeast of France. Viral loads ranged from 2 × 10(5) to 7.2 × 10(7) copies/ml. Alignment of 5' nontranslated regions and phylogenetic analysis of partial VP1 gene sequences show that these viruses clustered and belonged to clade C.

Rapid and sensitive identification of RNA from the emerging pathogen, coxsackievirus A6

Background

Hand, foot and mouth disease (HFMD) is caused by members of the family Picornaviridae in the genus Enterovirus. It has been reported that coxsackievirus A6 (CVA6) infections are emerging as a new and major cause of epidemic HFMD. Sporadic HFMD cases positive for CVA6 were detected in the mainland of China in recent years. To strengthen the surveillance of CVA6 infections and outbreak control, the clinical diagnosis is urgently needed to distinguish the CVA6 infection disease from other infections.

Methods

In order to develop a sensitive quantitative real-time RT-PCR assay for rapid detection of CVA6 RNA, primers and probe were designed to target the VP1 gene segment of CVA6. The conservation of the target segment was firstly analyzed by bioinformatic technology. The specificity of the real-time RT-PCR was further confirmed by detecting other related viruses and standard curves were established for the sensitivity evaluation. The pharyngeal swab samples from the EV71 and CVA16 unrelated HFMD patients were applied for CVA6 detection through the established method.

Results

Based on the primer–probe set to detect the target VP1 gene segment of CVA6, the quantitative real-time RT-PCR assay could discriminate CVA6 infection from other resemble viral diseases with a potential detection limit of 10 viral copies/ml. The specificity of the assay was determined by sequence alignment and experimentally tested on various related viruses. The standard curve showed that the amplification efficiency of templates with different concentrations of templates was almost the same (R² >0.99). Evaluation of the established method with pharyngeal swabs samples showed good accordance with the results from serology diagnosis.

Conclusion

This study is the first report developing a VP1 gene-based quantitative real-time RT-PCR for rapid, stable and specific detection of CVA6 virus. The real-time RT-PCR established in this study can be used as a reliable method for early diagnosis of CVA6 infection.

Detection of herpes simplex virus (1 and 2), varicella-zoster virus, cytomegalovirus, human herpesvirus 6 and enterovirus in immunocompetent Tunisian patients with acute neuromeningeal disorder

Enteroviruses (EVs) and human herpesviruses (HHVs) are involved frequently in acute neurological disorders of viral etiology. This study aimed to investigate the incidence of herpes simplex virus types-1 (HSV-1) and 2 (HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), human herpesvirus 6 (HHV-6) and human enteroviruses (EVs) in cerebrospinal fluid (CSF) samples of Tunisian immunocompetent patients with neuromeningeal disorders. The patients had been hospitalized at the Fattouma Bourguiba University Hospital (Monastir, Tunisia) between September 2007 and June 2009. At least one viral genome was detected in 58 (46%) out of 126 CSF samples collected. Enterovirus was detected in 31 of the positive samples (53.4%), CMV in 20 (34.5%), HSV-1 in 3 (5.2%), HSV-2 in 6 (10.3%), VZV in 4 (6.9%), HHV-6 in 2 (3.4%). More than one viral genome was detected in seven CSF samples, including CMV DNA in six of the samples. The high frequency of enteroviral infections in aseptic meningitis was confirmed. The detection of CMV DNA only suggests a direct role of this virus in the etiology of acute neuromeningeal disorder.

Clinical and microbiological evaluation of travel-associated respiratory tract infections in travelers returning from countries affected by pandemic A(H1N1) 2009 influenza

BACKGROUND

Although acute respiratory tract infections (RTI) have been recognized as a significant cause of illness in returning travelers, few studies have specifically evaluated the etiologies of RTI in this population.

METHODS

This prospective investigation evaluated travelers returning from countries with endemic influenza A(H1N1) 2009, and who were seen in our department at the onset of the outbreak (April-July 2009). Patients were included if they presented with signs of RTI that occurred during travel or less than 7 days after return from overseas travel. Patients were evaluated for microbial agents with RespiFinder plus assay, and throat culture according to clinical presentation.

RESULTS

A total of 113 travelers (M/F ratio 1.2:1; mean age 39 y) were included. They were mainly tourists (n = 50; 44.2%) mostly returning from North America (n = 65; 58%) and Mexico (n = 21; 18.5%). The median duration of travel was 23 days (range 2-540 d). The median lag time between return and onset of illness was 0.2 days (range 10 d prior to 7 d after). The main clinical presentation of RTI was influenza-like illness (n = 76; 67.3%). Among the 99 microbiologically evaluated patients, a pathogen was found by polymerase chain reaction (PCR) or throat culture in 65 patients (65.6%). The main etiological agents were influenza A(H1N1) 2009 (18%), influenza viruses (14%), and rhinovirus (20%). A univariate analysis was unable to show variables associated with influenza A(H1N1) 2009, whereas rhinorrhea was associated with viruses other than influenza (p = 0.04).

CONCLUSION

Despite the A(H1N1) 2009 influenza pandemic, rhinovirus and other influenza viruses were also frequent causes of RTI in overseas travelers. Real-time reverse transcription-PCR and nasopharyngeal swab cultures are useful diagnostic tools for evaluating travelers with RTI.

Development of a highly sensitive real-time one step RT-PCR combined complementary locked primer technology and conjugated minor groove binder probe

Background

Enterovirus (EV) infections are commonly associated with encephalitis and meningitis. Detection of enteroviral RNA in clinical specimens has been demonstrated to improve the management of patients, by ruling out other causes of disease.

Method

To develop a sensitive and reliable assay for routine laboratory diagnosis, we developed a real-time one step reverse transcription polymerase chain reaction (RT-PCR) assay with minor groove binder probes and primers modified with complementary locked primer technology (TMC-PCR). We checked the sensitivity of the developed assay by comparing it to a previously published TaqMan probe real-time one-step RT-PCR (TTN-PCR) procedure using enteroviral isolates, Enterovirus Proficiency panels from Quality Control on Molecular Diagnostics (QCMD-2007), and clinical specimens from patients with suspected EV infections.

Results

One hundred clinical specimens from 158 suspected viral meningitis cases were determined to be positive by the TMC-PCR assay (63.29%), whereas only 60 were found to be positive by the TTN-PCR assay (37.97%). The positive and negative agreements between the TMC-PCR and TTN-PCR assays were 100% and 59.2%, respectively.

Conclusion

This data suggest that the TMC-PCR assay may be suitable for routine diagnostic screening from patient suspected EV infection.

[Molecular diagnosis of respiratory enterovirus infections: Use of PCR and molecular identification for a best approach of the main circulating strains during 2008]

The PCR assays are currently used in diagnosis of enterovirus (EV) meningitis. Nevertheless, the use of molecular diagnosis of EV should be investigated in respiratory tract infections (RTI).

OBJECTIVES

To perform enterovirus molecular diagnostic tools, PCR and genotyping, in nasal samples for diagnostic and epidemiologic purposes.

METHODS

During 2008, 3612 nasal specimen (NS) were studied by IFD and MRC5 culture. Next, we realised successively viral isolation on HuH7 culture (for NS negative by IFD assay) and a duplex PCR enterovirus-rhinovirus for the 816 HuH7 positive supernatants. Furthermore, 327 NS collected from neonates were systematically tested by a real-time RT-PCR. This assay was used in routine for EV diagnosis setting in cerebrospinal fluid. Enterovirus genotyping was then performed for the 68 positive supernatants.

RESULTS

Thirty-five NS (0.97%) were positive for EV by culture (MRC5). A combination of both PCR assays, PEVRV and PEV, allowed an additional identification of 41 EV, eight EV-RV and 12 RV, increasing the number of positive to 96 NS (2.6%). Among the neonates, 32 NS (11.3%) were positive for EV by PEV. Of the 98 NS tested by the two PCR assays (PEV and PEVRV), 27 were positive and we detected 10 EV, five EV-RV and 12 RV. From January to December 2008, the circulation of EV showed the usual peak in June-July when a small outbreak of aseptic meningitis occurred and an additional autumnal peak corresponding to respiratory tract infections. Five main serotypes were isolated: 19 EV68 (29.7%), 12 CB3 (18.7%), nine E3 (14,1%), six CA9 (9.4%) and six CB1 (9.4%); the 19 EV68 were isolated in October-November and 17/19 (89.5%) of positive patients were hospitalised for severe respiratory diseases.

CONCLUSION

The use of molecular screening techniques (PCR assays and genotyping) on nasal samples collected from patients with respiratory infections allowed a prospective, effective and precise identification of circulating strains.

Detection of enteroviruses from clinical specimens

Enteroviruses are positive stranded RNA viruses belonging to the genus Enterovirus of the Picornaviridae family. Human enteroviruses are transmitted through the fecal-oral route and have been shown to cause mild to life-threatening diseases. Various diagnostic methods have been developed to detect enteroviruses from clinical specimens but many were impeded by requirements for special reagents, lengthy procedures, low sensitivity or cross-reactivity. This chapter describes rapid and highly sensitive methods of enteroviral detection directly from clinical specimens based on a conventional one-step Reverse Transcription polymerase chain reaction (RT-PCR) and a one-step real-time RT-PCR.

Enhanced detection of enteroviruses in clinical samples by reverse transcription-PCR using complementary locked primer technology

To increase detection sensitivity, we modified primers using complementary locked primer (CLP) technology. The sensitivity of the reverse transcription-PCR (RT-PCR) with CLP-modified primers was 10- to 100-fold higher than that of RT-PCR without these primers. CLP-modified primers can increase sensitivity, providing a widely accessible method for molecular diagnosis.

Enterovirus infections in neonates

Enteroviruses, which include echoviruses, coxsackie A and B viruses, polioviruses and the 'numbered' enteroviruses, are among the most common viruses causing disease in humans. A large proportion of enteroviral infections occur in neonates and infants. There is a wide spectrum of clinical manifestations that can be caused by enterovirus infection with varying degrees of severity. In the neonatal age group, enteroviral infections are associated with significant morbidity and mortality, particularly when infection occurs antenatally. This review provides a detailed overview of the epidemiology and clinical features of enterovirus infections in the neonatal period. In addition, laboratory features and diagnostic investigations are discussed. A review of the currently available data for prophylactic and therapeutic interventions, including antiviral therapy, is also presented.

Rapid detection and quantitation of poliovirus and rhinovirus sequences in viral stocks and infected cells

Laboratories working with closely related viruses need simple and cost-effective ways to rapidly validate viral stocks, detect contamination and measure the abundance of viral RNA species. Using RT-PCR and specific primers an approach for the specific detection of rhinovirus type 14 (RV14) or poliovirus type 1 (PV1) is presented. It is demonstrated that viral sequences can be amplified directly from viral stocks or from infected cells. In addition, the utility of this protocol for the detection of low levels of contaminating PV1 in RV14 stocks is shown. Further, using quantitative real-time PCR It is shown that this approach can be used for the quantitative analysis of viral RNA and replication kinetics in infected cells. This method should be useful for laboratories working with PV and RV14 and could be adapted easily for use by laboratories working with other rhinovirus and enterovirus serotypes.

Performance of the GeneXpert enterovirus assay for detection of enteroviral RNA in cerebrospinal fluid

BACKGROUND

The GeneXpert Dx System allows for automated extraction, processing, amplification and real-time detection of target nucleic acids.

OBJECTIVES

To evaluate the performance of the Cepheid Xpert enterovirus (EV) assay for detection of EV RNA compared to a nucleic acid sequence based amplification (NASBA) assay and a user-developed TaqMan RT-PCR assay.

STUDY DESIGN

Assays were evaluated using a 12-member proficiency panel and up to 138 CSF specimens. Samples in which EV RNA was detected by two or more assays were considered true positives.

RESULTS

The GeneXpert, NASBA, and TaqMan assays correctly identified 10, 8, and 7 of 12 proficiency panel members, respectively. For detection of EV RNA in CSF, the sensitivities of the GeneXpert, NASBA, and TaqMan were 100%, 87.5%, and 96%, respectively. There were no false positives. Two samples tested by GeneXpert and NASBA yielded indeterminate or invalid results and could not be resolved.

CONCLUSIONS

The Xpert EV assay is a sensitive and specific method for detection of EV RNA in CSF specimens. The ease of use, random access capability, and minimal hands-on time with the automated GeneXpert system affords laboratories with little molecular diagnostics expertise an opportunity to complete a clinically useful testing within 2.5 h.

A TaqMan reverse transcription polymerase chain reaction (RT-PCR) in vitro potency assay for plasmid-based vaccine products

A TaqMan-based reverse transcription polymerase chain reaction (RT-PCR) assay has been developed as an in vitro potency assay to measure the most immediate biological activity of plasmid DNA (pDNA)-based products. The assay measures transgene-specific messenger RNA (mRNA) from cultured cells transfected with VCL-CB01, a bivalent pDNA-based human cytomegalovirus (CMV) vaccine. The forward and reverse primers have been designed to make the RT-PCR reaction selective for plasmid-derived mRNA and to allow discrimination of expression levels of individual plasmids in a multivalent pDNA vaccine. The relative potency of a vaccine lot is assessed by transfecting reference and test samples into cultured cells in parallel and analyzing total RNA from the cells by RT-PCR. Statistical analysis of dose response data from reference material supports a parallel-line model for calculating relative potency. Preliminary data demonstrate the ability of this assay to distinguish product potencies at 50, 75, 150, and 200% of the reference material. In addition, forced degradation of pDNA demonstrates that a decrease in relative potency as measured by the RT-PCR assay in vitro correlates well with a decrease in CMV DNA vaccine-mediated humoral immune responses in mice injected with the same material.

Rapid detection of enterovirus 71 by real-time TaqMan RT-PCR

BACKGROUND

Enterovirus 71 (EV71) is the main etiological agent of Hand, Foot and Mouth Disease (HFMD) and has been associated with neurological complications which resulted in fatalities during recent outbreaks in Asia Pacific region.

OBJECTIVE

Develop a real-time TaqMan RT-PCR for rapid detection of EV71.

STUDY DESIGN

Specific primers and probe were designed based on highly conserved VP1 region of EV71. The sensitivity of the real-time RT-PCR was evaluated with 67 clinical specimens collected from pediatric patients with suspected HFMD.

RESULTS

Our real-time TaqMan RT-PCR showed 100% specificity in detecting EV71 and showed an analytical sensitivity of 5 viral copies. High sensitivity was also achieved in detecting EV71 directly from clinical specimens.

CONCLUSIONS

Real-time TaqMan RT-PCR offers a rapid and sensitive method to detect EV71 from clinical specimens, and will allow quarantine measures to be taken more effectively during outbreaks.

Rapid routine detection of enterovirus RNA in cerebrospinal fluid by a one-step real-time RT-PCR assay

BACKGROUND AND OBJECTIVES

This study provides a one-step transcription/real-time (TaqMan probe) PCR assay (TM-PCR) with new consensus primer and probe sequences for generic detection of human pathogenic enteroviruses including difficult to detect ones like for instance Echovirus 30. The amplicon included parts of domain IV and V of the highly conserved internal ribosomal entry site. Generic detection was confirmed by testing a panel of 41 prototypes representing all five human enterovirus/poliovirus species.

STUDY DESIGN AND RESULTS

The 95% detection limit was found to be 100 copies per run using in vitro transcribed coxsackievirus B3 RNA. TM-PCR was compared to an in house nested-PCR assay implemented in detecting enterovirus RNA from CSF samples of patients suffering from meningitis and encephalitis. Concordant results were obtained in all samples (11 positive, 101 negative). Specificity was confirmed with laboratory strains of other neurotropic viruses, and by testing 76 CSF samples of patients with encephalomyelitis disseminata, which all gave negative results.

CONCLUSIONS

The new TM-PCR is a convincing alternative to conventional PCR protocols for the diagnosis of enterovirus meningitis. The one-step strategy limits hands on time and cross contamination risk combined with accelerated assay procedure of only 100 min.

Enrichment of cerebrospinal fluid samples on cell culture for enhancement of sensitivity of mumps and enterovirus detection by multiplex RT-PCR

It has been demonstrated that the detection of enteroviruses and mumps virus nucleic acid in cerebrospinal fluid (CSF) specimens improves the management of the patients with aseptic meningitis. To determine the effect of overnight enrichment of mumps and enteroviruses in CSF samples on cell culture for increasing the sensitivity of viral detection, we developed a multiplex reverse transcriptase-polymerase chain reaction (RT-PCR). CSFs were collected from 100 patients younger than 7 years. The samples were tested for the presence of enteroviruses and mumps virus by multiplex RT-PCR method. Negative samples in Multiplex RT-PCR were enriched for viral template RNAs by overnight culture of CSF samples on cells and followed by the optimized Multiplex RT-PCR. Overall, 35% of the CSF samples were positive for enteroviruses, whereas only 1% of CSF samples were positive for both viruses. After enriching in cell culture, 34% of the negative samples showed a positive polymerase chain reaction band for enteroviruses, and a 3% increase was observed for both viruses. The results showed that enrichment of viral template RNAs in cell culture can increase the sensitivity of the multiplex RT-PCR assay and provide a rapid and sensitive method for detection of viral infections.

Evaluation of LightCycler as a platform for nucleic acid sequence-based amplification (NASBA) in real-time detection of enteroviruses

The nucleic acid sequence-based amplification (NASBA) assay has been demonstrated to be more sensitive for detection of enteroviruses (EV) than RT-PCR. Many laboratories, however, do not have a dedicated instrument for the NASBA assay. This study aimed to evaluate the use of the Roche LightCycler as a platform for performing the NASBA assay for detection of EV. A diverse subgenera of EV were used to assess the specificity of the NASBA assay, including coxsackie, echovirus, poliovirus, and other enteroviruses together with related and unrelated viruses, including rhinovirus, respiratory syncytial virus, herpes simplex virus, adenovirus, influenza virus A, and cytomegalovirus. All species of EV tested were successfully detected using NASBA and no cross reactivity with other viruses was observed. Using serial dilutions of EV to assess sensitivity, the NASBA assay was compared to an in-house EV RT-PCR assay. The NASBA assay demonstrated a higher level of sensitivity. Fifty-one clinical samples positive for EV by viral culture were also evaluated. All NASBA results obtained were concordant with viral culture results. This study confirmed that the NASBA assay for the detection of EV could be readily performed on the LightCycler and easily incorporated into the workflow of a diagnostic laboratory equipped with a LightCycler, thereby eliminating the need for additional instrumentation.

Aseptic meningitis

PURPOSE OF REVIEW

To highlight some of the recent key epidemiologic and clinical diagnostic dilemmas of aseptic meningitis and to evaluate some tests that may help distinguish aseptic compared with bacterial meningitis.

RECENT FINDINGS

Enteroviruses remain the most common cause of aseptic meningitis. Certain enteroviruses (e.g. coxsackie B5, echovirus 6, 9 and 30) are more likely to cause meningitis outbreaks, while others (coxsackie A9, B3 and B4) are mostly endemic. Nucleic acid tests are more sensitive than cultures in diagnosing enteroviral infections. In centers where the turnaround time for these tests is less than 24 h, there can be substantial cost savings and avoidance of unnecessary treatment of aseptic meningitis with antibiotics. Serum and stool specimens are important adjunct samples for diagnosing enteroviral infections in children. Cerebrospinal fluid protein (> or = 0.5 g/l) and serum procalcitonin (> or = 0.5 ng/ml) appear to be useful laboratory markers for distinguishing between bacterial and aseptic meningitis in children aged 28 days to 16 years, but they have relatively low sensitivity and specificity.

SUMMARY

Enteroviruses are the major causes of aseptic meningitis. The major focus of diagnosis remains ruling out bacterial infection or confirming enteroviral etiology of infection. Properly implemented nucleic acid tests have the potential to reduce cost and unnecessary treatment.

Detection and monitoring of virus infections by real-time PCR

The employment of polymerase chain reaction (PCR) techniques for virus detection and quantification offers the advantages of high sensitivity and reproducibility, combined with an extremely broad dynamic range. A number of qualitative and quantitative PCR virus assays have been described, but commercial PCR kits are available for quantitative analysis of a limited number of clinically important viruses only. In addition to permitting the assessment of viral load at a given time point, quantitative PCR tests offer the possibility of determining the dynamics of virus proliferation, monitoring of the response to treatment and, in viruses displaying persistence in defined cell types, distinction between latent and active infection. Moreover, from a technical point of view, the employment of sequential quantitative PCR assays in virus monitoring helps identifying false positive results caused by inadvertent contamination of samples with traces of viral nucleic acids or PCR products. In this review, we provide a survey of the current state-of-the-art in the application of the real-time PCR technology to virus analysis. Advantages and limitations of the RQ-PCR methodology, and quality control issues related to standardization and validation of diagnostic assays are discussed.