Detection of enterovirus RNA in clinical samples by nested polymerase chain reaction for rapid diagnosis of enterovirus infection

Molecular Genotyping of Circulating Enterovirus in the Lazio Region from 2012 to 2023

Enteroviruses (EVs) are ubiquitous viruses that circulate worldwide, causing sporadic or epidemic infections, typically during the summer and fall. They cause a broad spectrum of illnesses, ranging from an unspecified febrile clinical presentation to a severe illness. EVs are recognized to be the most frequent etiological agents of aseptic meningitis in children. However, as the infection is usually mild and self-limiting, it remains underestimated, and the epidemiology of EVs is poorly understood. To date, no vaccine or effective therapy for all types of enteroviruses is available, and EVs constitute a public health concern. Here, we investigated the molecular epidemiology of EV strains circulating in the Lazio region over a 10-year time span (2012-2023) by using a sequence-typing approach and phylogenetic analysis. The epidemiological trend of EV infection has undergone changes during the SARS-CoV-2 pandemic (2020-2021), which resulted in a modification in terms of the number of diagnosed cases and seasonality. From 2022, the circulation of EVs showed a behavior typical of the pre-pandemic period, although changes in predominantly circulating strains have been noted. Both epidemic and sporadic circulation events have been characterized in the Lazio region. Further analyses are needed to better characterize any strain with higher potential pathogenic power and to identify possible recombinant strains.

Detection of recombinant breakpoint in the genome of human enterovirus E11 strain associated with a fatal nosocomial outbreak

BACKGROUND

The aim of this study was to characterize the genome of a recombinant Enterovirus associated with severe and fatal nosocomial infection; it was typed as Echovirus 11 (E-11) according to the VP1 gene. Enterovirus infection is generally asymptomatic and self-limited, but occasionally it may progress to a more severe clinical manifestation, as in the case described here. Recombination plays a crucial role in the evolution of Enteroviruses (EVs) and has been recognized as the main driving force behind the emergence of epidemic strains associated with severe infection. Therefore, it is of utmost importance to monitor the circulation of recombinant strains for surveillance purposes.

METHODS

Enterovirus-RNA was detected in the serum and liver biopsy of patients involved in the nosocomial cluster by commercial One-Step qRT-PCR method and the Enterovirus strains were isolated in vitro. The EVs typing was determined by analyzing the partial-length of the 5'UTR and VP1 sequences with the web-based open-access Enterovirus Genotyping Tool Version 0.1. The amplicons targeting 5'UTR, VP1 and overlapping fragments of the entire genome were sequenced with the Sanger method. Phylogenetic analysis was performed comparing the VP1 and the full-genome sequences of our strains against an appropriate reference set of Enterovirus prototypes of the Picornaviridae genera and species retrieved from the Enterovirus Genotyping Tool. Recombination analysis was performed using RDP4 software.

RESULTS

The Neighbor-Joining tree of the VP1 gene revealed that the 4 patients were infected with an identical molecular variant of Echovirus 11 (E-11). While the phylogenetic and the RDP4 analysis of the full-genome sequences provided evidence that it was a chimeric strain between an E-11 and a Coxsackievirus B (CV-B).

CONCLUSIONS

The chimeric structure of the E-11 genome might have contributed to the severe infection and epidemic feature of the strain, but further biological characterizations are needed. The evidence reported in this study, highlights the limit of typing techniques based on the VP1 gene, as they fail to identify the emergence of recombinant strains with potentially more pathogenic or epidemic properties, thus providing only partial information on the epidemiology and pathogenesis of Enteroviruses.

Diagnostic Testing of Neurologic Infections

Neuroinfectious diseases continue to cause morbidity and mortality worldwide, with many emerging or reemerging infections resulting in neurologic sequelae. Careful clinical evaluation coupled with appropriate laboratory investigations still forms the bedrock for making the correct etiologic diagnosis and implementing appropriate management. The treating physician needs to understand the individual test characteristics of each of the many conventional candidate-based diagnostics: culture, pathogen-specific polymerase chain reaction, antigen, antibody tests, used to diagnose the whole array of neuroinvasive infections. In addition, there is a growing need for more comprehensive, agnostic testing modalities that can identify a diversity of infections with a single assay.

Detection of negative and positive RNA strand of poliovirus Sabin 1 and echovirus E19 by a stem-loop reverse transcription PCR

In this report a strand specific RT-PCR was established for the detection of the replicative negative RNA strand of poliovirus sabin 1 (Sabin1) and Echovirus 19 (E19) strains. The key for the successful conduction of the assay was the use of a specific reverse transcription primer targeting the 5'-UTR of enteroviruses that consisted of a stem-loop structure at the 5'-end and an enteroviral-specific sequence at the 3'-end. The stem loop RT-PCR was found to be an accurate and sensitive method, detecting even 10^-2 CCID₅₀ of poliovirus sabin 1 (Sabin1) and E19 strains 6 h postinfection (p.i.), while CPE appeared 3 days later. This assay was also validated in SiHa and Caski cell lines that are not used for the detection of enteroviruses. The negative RNA strand was detected 6 h and 12 h p.i. in SiHa and Caski cells, when these cell lines were inoculated with 10⁵ and 1 CCID₅₀ respectively, whereas CPE was observed 5 days p.i for SiHa cells and 8 days p.i for Caski cells and that only at 10⁵ CCID₅₀ . The results show that this approach may be used for replacing the time-consuming cell cultures in order to detect the active replication of enteroviruses.

SIGNIFICANCE AND IMPACT OF THE STUDY

Enteroviruses are positive stranded RNA viruses that may cause severe diseases. The conventional method for detection of active viral replication involves virus isolation in sensitive cell cultures followed by titration and seroneutralization. In this report, we describe the use of a stem-loop secondary structured oligonucleotide in RT-PCR assay for the detection of the replicative negative strand of the positive-stranded RNA of poliovirus sabin 1 and E19 strains. This approach proved to be a useful tool that may be used for replacing the time-consuming cell culture assays in order to detect the active replication of enteroviruses.

Multiplex-PCR for the detection of viruses in the CSF of infants and young children

We aimed to establish the utility of the Fast-track diagnostics Viral meningitis multiplex PCR kit for the diagnosis of central nervous system infection in infants. The multiplex assay had reduced sensitivity for the detection of enterovirus, the predominant pathogen in young infants, when compared to our in-house singleplex PCR. In our infant population, multiple singleplex PCR assays perform better than a multiplex assay for the detection of CSF viruses. J. Med. Virol. 89:559-561, 2017. © 2016 Wiley Periodicals, Inc.

Enteroviral central nervous system infections in children of the region of monastir, Tunisia: diagnosis, laboratory findings of cerebrospinal fluid and clinical manifestations

Human enteroviruses (HEV) are one of the major causes of central nervous system (CNS) infections in pediatrics. A prospective study was conducted to assess the epidemiological, clinical, and laboratory characteristics of enterovirus (EV) infections of the CNS in children under 15-years-old, suspected of having viral CNS infections and admitted to the Pediatric Department of Monastir University Hospital, Tunisia. Enteroviral RNA was detected by 5' NCR nested RT-PCR assay in 33 % (20 out of 60) of cerebrospinal fluid specimens, whereas only six samples (10 %) were EV positive in cell culture. EV-positive patients were clustered according to their clinical manifestations, predominantly diagnosed as aseptic meningitis (65 %) and meningoencephalitis (20 %). Fever, headache, vomiting, and neck stiffness were the most pronounced symptoms. Pleocytosis with the predominance of lymphocytes was observed in 60 % of EV positive specimens. Although patients suffering from EV infections were encountered throughout the year, most occurred during spring and summer months. Using VP1-2A nested RT-PCR and sequence analysis, three of the 20 positive HEV were identified as Echovirus (E)-9. This is the first report of a cluster of aseptic meningitis cases caused by E-9 in Monastir.

Detection of enterovirus RNA in cerebrospinal fluid: comparison of two molecular assays

Enterovirus (EV) and human parechovirus (HPeV) are a major cause of infection in childhood. A rapid diagnostic test may improve the management of patients with EV and HPeV infection. The aim of this study is to evaluate the performance of the GeneXpert enterovirus assay (GXEA) for detection of EV RNA compared to a user-developed reverse-transcriptase (RT) quantitative real-time PCR (qPCR) in routine clinical practice. Also a RT-qPCR assay for detection of HPeV RNA in different clinical samples was developed and evaluated. Cerebrospinal fluid (CSF) from 232 patients suspected for meningitis was collected and tested for EV and HPeV using RT-qPCR assays. In parallel an aliquot of the samples was tested using the GXEA and viral culture. EV RNA was detected in 22 (19.0%) and 28 (24.1%) of 116 samples using the GXEA and RT-qPCR assay, respectively. EV was isolated from 10 of 116 (8.6%) samples by viral culture. GXEA had a sensitivity, specificity, positive predictive value and negative predictive value of 82.1%, 100%, 100% and 96.2%, respectively. In this study, molecular assays were superior to viral culture for detecting EV RNA in CSF. GXEA showed a high specificity but a lower sensitivity for the detection of EV RNA compared to the RT-qPCR assay.

Molecular detection and characterization of human enteroviruses directly from clinical samples using RT-PCR and DNA sequencing

Enteroviruses are common human pathogens associated with a wide spectrum of symptoms ranging from asymptomatic infection to acute flaccid paralysis and neonatal multi-organ failure. Molecular methods that provide rapid diagnosis and increased sensitivity have been developed for the diagnosis of enterovirus infection using oligonucleotide primers complementary to conserved sequences located in the 5' untranslated region (UTR), but data generated from these regions are not sufficiently discriminatory for typing due to the lack of correlation between their nucleic acid sequence and serotype specificity. Sequences derived from the gene encoding the capsid VP1 correlate with serotype, and therefore provide the opportunity for the development of molecular typing methods consistent with present serogical methods. In this study, oligonucleotide primers that amplify a region of the 5'UTR to detect enterovirus RNA, and the region encoding the enterovirus VP1 N-terminus to characterize virus strains were used in nested and semi-nested RT-PCRs, respectively. The ability of the VP1 RT-PCR to amplify diverse viruses within genotypes and genogroups was confirmed by the correct identification of both prototype strains, and strains circulating currently of the same genotypes. The molecular methods proved their utility through the detection of enteroviruses that failed to grow in cell culture, their subsequent characterization and the characterization of strains that failed to serotype in neutralization assays. Molecular methods increased significantly the sensitivity of detection (P < 0.001) and of characterization (P < 0.01) of enteroviruses when compared to classical methods.

Application of a molecular panel to demonstrate enterotropic virus shedding by healthy and human immunodeficiency virus-infected patients

We used a molecular panel, targeting seven enteric viruses, to explore the advantage of using molecular methods to establish the etiology of enteric diseases and to evaluate the prevalence of enteric viruses in asymptomatic human immunodeficiency virus-infected patients. This approach favors rapidity and sensitivity of laboratory diagnosis of viral enteric syndromes.

Evaluation of a commercially available reverse transcription-PCR enzyme immunoassay (Enterovirus Consensus kit) for the diagnosis of enterovirus central nervous system infections

A commercial reverse transcription (RT)-PCR amplification method was compared with culture for the diagnosis of enterovirus meningitis. In total, 99 cerebrospinal fluid (CSF) specimens were examined with the Enterovirus Consensus kit and shell vial culture. RT-PCR allowed the amplification of enterovirus cDNA and its detection in a microtitre plate by hybridisation. Clinical information and CSF analysis were used to resolve the discrepancy in results. The detection limit of the RT-PCR assay was determined with the Third European Union Concerted Action Enterovirus Proficiency Panel. There were 34 true-positive CSF specimens. Of these, RT-PCR detected 33 (sensitivity 97%), while culture detected 19 (sensitivity 54.5%). RT-PCR failed to detect one culture-positive specimen that contained inhibitors. When samples from the Third European Union Concerted Action Enterovirus Proficiency Panel were tested, the RT-PCR method gave identical results to those expected. The Enterovirus Consensus kit was rapid and statistically more sensitive than culture (p < 0.01) for the detection of enteroviruses in CSF, and may offer considerable benefits in the clinical management of patients with enterovirus meningitis.

Vertical transmission of human echovirus 11 at the time of Bornholm disease in late pregnancy

We report a case of human echovirus 11 infection in a neonate at the time of Bornholm disease in late pregnancy of the mother. Mother and baby were found to be infected with the same virus, with a combination of diagnostic virologic techniques, demonstrating likely transmission from mother to baby around the time of delivery.

An approach based on RFLP assay to investigate outbreaks of enteroviral meningitis

BACKGROUND

Enteroviruses (EV) circulate worldwide and are a major cause for annual epidemics of meningitis in humans. During the last two decades, echovirus type 30 (E-30) has revealed to be one of the most prevalent enteroviruses at the origin of epidemics of EV meningitis.

OBJECTIVES

To design an approach to timely investigate epidemics due to EV. To apply this strategy to the outbreak of meningitis due to E-30 that occurred at the end of year 2000 in Marseilles, France.

STUDY DESIGN

The approach consisted to (i) determine whether the epidemic was caused by a dominant strain; (ii) identify the dominant strain by sequencing the first isolates during the outbreak; (iii) identify a restriction enzyme, capable to produce an Restriction fragment length polymorphism (RFLP) profile characteristic for the dominant strain, for rapid identification based on RFLP analysis of PCR products.

RESULTS AND CONCLUSIONS

A total of 394 samples were tested; 258 (corresponding to 177 patients) were positive for the presence of EV by cell culture and/or RT-PCR. Sequence analysis of a 785-bp PCR product (including the 5' end of the VP1 gene) performed for the 30 first isolates permitted to identify a RFLP profile that was specific of the dominant strain after enzymatic cleavage by Bst X1. This RFLP profile was observed in 246 out of 258 PCR products. This method of typing is rapid, simple and inexpensive, and may be applied for the epidemiological typing of EV in epidemic situations.

Coxsackievirus B3 sequences in the blood of a neonate with congenital myocarditis, plus serological evidence of maternal infection

A fatal case of myocarditis in a neonate is described. The clinical features were evident at birth, and enteroviral RNA was detected in the blood of the baby on the day of birth and again 10 days later by a generic enterovirus nested reverse transcription-polymerase chain reaction (RT-PCR) assay. The enterovirus RNA was subsequently retested by a separate, newly developed nested RT-PCR assay yielding a PCR product within the VP1 coding region suitable for sequencing. Identical 239-base pair sequences were obtained from the RNA of the two blood samples and this sequence most closely resembled coxsackievirus B3 (94% identity). The baby's mother was pyrexial immediately postpartum and an early antenatal serum and a serum sample collected 10 days postpartum tested in parallel for enterovirus IgM antibody showed negative to strong-positive seroconversion. Infection of the mother was the likely primary event with in utero transfer of the virus to the fetus in the last few days of pregnancy. Neonatal blood is a valuable specimen for enterovirus diagnosis by RT-PCR. A newly developed nested RT-PCR assay was successful in typing the enterovirus from stored RNA extracted directly from the blood samples. Serology for enterovirus IgM antibody can be useful for convalescent diagnosis of enterovirus infection in the mother, especially with earlier serum for comparison.

Molecular sub-grouping of enterovirus reference and wild type strains into distinct genetic clusters using a simple RFLP assay

RFLP analysis and sequencing of RT-PCR amplicons in previous studies revealed the existence of intra-serotypic variability in the 5'-UTR of human enteroviruses, complicating the use of this method to serotype isolates. During the present study, the available sequences of many enterovirus reference and wild type strains were analysed in an attempt to discover restriction sites that would rapidly and reliably aid the classification of human enteroviruses into specific sub-groups on the basis of their 5'-UTR for diagnostic and/or epidemiological purposes. Despite intratypic genetic variability in the 5'-UTR, the results of the sequence analysis, as well as data from the RFLP analysis of 61 enterovirus reference strains from 60 different serotypes and 123 clinical isolates showed that one restriction endonuclease, HpaII, may contribute to a reliable sub-classification of CAVs and the rest of enteroviruses, on the basis of 5'-UTR, into five genetic groups, which could be particularly useful in clinical and epidemiological studies. Although more sequence data from enterovirus reference and wild type strains may be required for the elaboration of a precise molecular identification system, the more possible genotypic classification into distinct clusters, as shown with the restriction enzyme HpaII, and the determination of the biological significance of this grouping (pathogenesis, epidemiology) might constitute an alternative means of enterovirus identification against conventional classification into distinct serotypes.

Rapid and sensitive routine detection of all members of the genus enterovirus in different clinical specimens by real-time PCR

We developed a rapid and sensitive method for the routine detection of all members of the enterovirus genus in different clinical specimens by using real-time TaqMan quantitative PCR. Multiple primer and probe sets were selected in the highly conserved 5'-untranslated region of the enterovirus genome. Our assay detected all 60 different enterovirus species tested, whereas no reactivity was observed with the viruses from the other genera of the picornaviridae family, e.g., hepatovirus and parechovirus. Weak cross-reactivity was observed with 7 of the 90 different high-titer rhinovirus stocks but not with rhinovirus-positive clinical isolates. Analysis of a well-characterized reference panel containing different enteroviruses at various concentrations demonstrated that the enterovirus real-time TaqMan PCR is as sensitive as most of the currently used molecular detection assays. Evaluation of clinical isolates demonstrated that the assay is more sensitive than the "gold standard" method, i.e., viral culture. Moreover, the PCR assay can be used on different clinical specimens, such as plasma, serum, nose and throat swabs, cerebrospinal fluid, and bronchoalveolar lavage, without apparent inhibition. Our data demonstrate that the real-time TaqMan PCR is a rapid and sensitive assay for the detection of enterovirus infection. The assay has a robust character and is easily standardized, which makes it an excellent alternative for the conventional time-consuming viral culture.

Development and evaluation of nucleic acid sequence based amplification (NASBA) for diagnosis of enterovirus infections using the NucliSens Basic Kit

BACKGROUND

Molecular methods based on RNA amplification are needed for sensitive detection of enteroviruses in clinical samples. Many 'in house' methods based on reverse-transcribed PCR (RT-PCR) could be difficult to use in the routine diagnostic laboratory since they tend to be time-consuming, use reagents from many different suppliers and include non-routine procedures.

OBJECTIVES

The aim of this study was to develop and evaluate methods based on nucleic acid sequence based amplification (NASBA) for detection of enterovirus sequences.

STUDY DESIGN

'In house' prepared and commercially available reagents were utilised to develop enterovirus-specific NASBA assays. Optimised methods were evaluated using clinical samples (cerebrospinal fluid, respiratory and stool samples), titred virus controls and in vitro produced synthetic RNA. Results for NASBA were compared with RT-PCR and virus culture.

RESULTS

Kit-based reagents gave an equivalent sensitivity to the more laborious 'in house' molecular assays (NASBA and RT-PCR) on clinical material and controls. All molecular methods picked up enterovirus positive clinical samples that were not identified by culture. End point detection sensitivity for the NASBA assay based on the NucliSens Basic Kit was <or=1 tissue culture infective dose 50% of a range of enteroviruses or <100 copies RNA input. The assay was specific for enteroviruses and did not pick up high titre rhinovirus preparations. Enterovirus Basic Kit NASBA results for clinical samples were easily obtained within a single working day.

CONCLUSIONS

NASBA is a suitable alternative to RT-PCR for sensitive amplification and detection of enterovirus sequences in a range of clinical specimens. The use of kit-based reagents will enable a wide range of laboratories to undertake molecular-based diagnostic procedures for RNA viruses and provide results within a time frame relevant to patient management.

High sequence divergence in the 5' non-coding region of reference Coxsackie B and ECHO viral strains and clinical isolates revealed by restriction fragment length polymorphism analysis

We report the restriction fragment length polymorphism (RFLP) patterns of a 440-bp-long 5' non-coding region (5' NCR) amplification target of all 34 reference Coxsackie B and ECHO (enteric cytopathic human orphan) enterovirus strains and a total of 42 serotypically pre-assigned clinical isolates, in order to afford meaningful comparisons among these patterns and those of polioviruses. The RFLP patterns of reference Coxsackie B strains differed from one another and from those of polio and ECHO reference enteroviruses except from Coxsackie B1 and B2, which, although they differed from one another, had identical RFLP patterns with ECHO 17 and 13, respectively. The 28 ECHO reference strains formed a more variable viral group including strains with RFLP patterns distinct from one another and from those of polio and Coxsackie B enteroviruses, and others with RFLP pattern identities common to other ECHO viruses and Coxsackie B1 and B2 but not polioviruses. The RFLP patterns of the clinical isolates and their corresponding serotypically assigned reference Coxsackie B and ECHO strains presented the most notable variations. The observed differences between serotype and genotype-dependent assignments within the 440-bp long 5' NCR target sequence of Coxsackie B and ECHO enteroviruses were in sharp contrast to the analogous situation with polioviruses. These findings support the specificity of the described method for clinical diagnostic genotyping of polioviruses and demonstrate that the 440-bp-long target sequence follows a different evolutionary process in polio and non-polio enteroviruses that is particularly prominent between reference non-polio strains and their serotypically assigned clinical isolates.

Serotype-specific detection of coxsackievirus A16 in clinical specimens by reverse transcription-nested PCR

We describe the development of a coxsackievirus A16 (CVA16) serotype-specific PCR which correctly differentiated between CVA16 and other enterovirus serotypes of both laboratory isolates and clinical specimens. The assay will be useful for monitoring CVA16 outbreaks and studying the disease association, epidemiology, and evolution of this common enterovirus serotype.

Multicenter proficiency testing of nucleic acid amplification methods for the detection of enteroviruses

A multicenter study of molecular detection of enteroviruses was conducted using a proficiency panel. Of 70 data sets, 46 (66%) reported correct results for samples containing at least 1 50% infective dose per ml and for negative samples. Variation in performance between laboratories demonstrates the need for ongoing quality control.

Enterovirus sequences resembling coxsackievirus A2 detected in stool and spleen from a girl with fatal myocarditis

A 10-year-old girl who died suddenly was found at post mortem to have myocarditis. Virus could not be cultured from post-mortem stool, spleen or heart but enterovirus RNA was detected in stool and spleen by PCR, and the stool caused flaccid paralysis in newborn suckling mice. A 654 base pair (bp) sequence from the capsid-coding region of the viral genome was amplified from an affected mouse and sequenced. Using this sequence, strain-specific nested primers were designed and used to amplify viral sequences directly from stool and spleen. These sequences were identical to each other and to that obtained from the infected mouse, and most closely resembled Coxsackievirus A2, an uncommon serotype rarely associated with myocarditis. Testing spleen tissue may be useful in etiological investigation of suspected viral myocarditis. PCR proved more sensitive than suckling mouse inoculation in detecting this Coxsackievirus, but a combination of both methods was required for genotypic characterization.

Diagnostic assessment of haemorrhagic rash and fever

AIMS

To establish criteria for early distinction between meningococcal disease and other conditions with similar clinical features, and to identify other causes for haemorrhagic rashes accompanied by fever.

METHODS

In a prospective study, 264 infants and children hospitalised with fever and skin haemorrhages were studied.

RESULTS

We identified an aetiological agent in 28%: 15% had meningococcal disease, 2% another invasive bacterial infection, 7% enterovirus infection, and 4% adenovirus infection. Five clinical variables distinguished between meningococcal disease and other conditions on admission: (1) skin haemorrhages of characteristic appearance; (2) universal distribution of skin haemorrhages; (3) maximum diameter of one or more skin haemorrhages greater than 2 mm; (4) poor general condition (using a standardised observation scheme); and (5) nuchal rigidity. If any two or more of these clinical variables were present, the probability of identifying a patient with meningococcal disease was 97% and the false positive rate was only 12%. This diagnostic algorithm did not identify children in whom septicaemia was caused by other bacterial species.

Molecular detection and identification of an enterovirus during an outbreak of aseptic meningitis

Stool samples from sixteen cases of children with meningitis originating from four different and geographically isolated parts of Greece were investigated for enteroviruses. The conventional method of cell culture in four different cell lines was initially used for the isolation of enteroviruses. The results showed a cytopathic effect (CPE) in all cases after two, or even more successive passages in only one cell line (RD), although a less-than-satisfactory CPE was obtained in many cases. Seroneutralization with RIVM mixed hyperimmune antisera followed and the isolates were typed as Coxsackie B viruses. The method of RT-PCR with enterovirus-specific primers targeted to the highly conserved 5'-UTR of the genome was initially used for the detection of enteroviruses from the inoculated cell cultures. A positive RT-PCR result was obtained for all of the clinical samples rapidly and accurately and the isolates were further characterized with the aid of Restriction Fragment Length Polymorphism (RFLP) analysis and Single Strand Conformation Polymorphism analysis (SSCP) of the amplicons. The RFLP analysis showed first of all that the isolates had an identical restriction pattern with Coxsackie B5 Faulkner reference strain with 4 out of 5 restriction enzymes and secondly, both RFLP and SSCP analysis indicated the epidemiological association of the isolates. The speed of the molecular methodology that was used in comparison with the conventional methods and its possible significance for the description of virus evolution and circulation in the populations is discussed.

Quantitative analysis of viral RNA kinetics in coxsackievirus B3-induced murine myocarditis: biphasic pattern of clearance following acute infection, with persistence of residual viral RNA throughout and beyond the inflammatory phase of disease

Although the association remains controversial, enteroviruses have been implicated in the aetiology of several chronic diseases of humans. To further understand the mechanism of enterovirus persistence and its relationship to organ pathology, virus infectivity and viral RNA kinetics in the heart and other target organs during acute and persistent phases of murine coxsackievirus B3 infection were investigated. These studies revealed a biphasic pattern of virus clearance. Thus, there was a rapid but incomplete clearance of viral RNA from the myocardium following the acute phase of virus replication, which paralleled the elimination of virus infectivity. The mean half-life of viral RNA between days 5 and 14 post-infection (p.i.) was 13.4 h. In contrast, a much slower rate of decline in viral RNA levels was observed during the post-infectious inflammatory phase of myocarditis. The mean half-life of viral RNA between days 14 and 90 p.i. was 14.1 days. Viral RNA persisted in the myocardium beyond the resolution of inflammation and was still detectable in a proportion of animals 90 days after infection. Clearance of viral RNA from other target organs occurred more rapidly, but the rate of clearance was largely independent of the level of viral RNA present during the acute phase of infection. Thus, while antiviral immune responses effectively eliminated infectious virus, clearance of residual viral RNA from the myocardium and other target organs was significantly delayed, despite a prolonged inflammatory response. These findings suggest that clearance of persistent enterovirus infection requires mechanisms different from those responsible for the elimination of virus infectivity.

A case of vaccine-associated paralytic poliomyelitis

Vaccine-associated paralytic poliomyelitis (VAPP) is a very rare complication of oral polio vaccine (OPV), seen predominantly with first exposure to OPV. Reversion of vaccine strain poliovirus to a more neurovirulent strain of the virus is thought to be necessary for paralytic disease to occur. Vaccine-associated poliomyelitis can occur in either recipients of the vaccine or in susceptible contacts. We describe an episode of VAPP in an infant in whom paralysis became evident at age 124 days, 14 days after administration of the second dose of OPV vaccine. The second dose of diphtheria-tetanus-pertussis- Haemophilus (DTPH) type-b vaccine had been given at the time of OPV administration, and the hepatitis B vaccine had been administered in the opposite leg. Paralysis was localized to the limb in which the DTPH had been injected.

Enteric virus infections and diarrhea in healthy and human immunodeficiency virus-infected children

Forty-three stool samples from 27 human immunodeficiency virus (HIV)-seropositive children and 38 samples from 38 HIV-negative children, collected during a 15-month period, were examined for enteric viruses. Diagnostic assays included enzyme immunoassays for rotavirus, adenovirus, and Norwalk virus; polyacrylamide gel electrophoresis for picobirnavirus and atypical rotavirus; and PCR for astrovirus and enterovirus. Specimens from HIV-positive children were more likely than those of HIV-negative children to have enterovirus (56 versus 21%; P < 0.0002) and astrovirus (12 versus 0%; P < 0.02), but not rotavirus (5 versus 8%; P > 0.5). No adenoviruses, picobirnaviruses, or Norwalk viruses were found. The rates of virus-associated diarrhea were similar among HIV-positive and HIV-negative children. Enteroviruses were excreted for up to 6 months in HIV-positive children; however, no evidence for prolonged excretion of poliovirus vaccine was observed. These results suggest that although infection with enterovirus and astrovirus may be frequent in HIV-infected children, enteric viruses are not associated with the diarrhea frequently suffered by these children.

Detection of microorganisms in the tracheal aspirates of preterm infants by polymerase chain reaction: association of adenovirus infection with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is recognized as an important cause of morbidity and mortality in preterm infants. Because the role of congenital infections in BPD has been debated, the purpose of this study was to test the hypothesis that detection of infectious agents in tracheal aspirate samples was associated with the development of BPD. Tracheal aspirate samples were obtained within the 1st week of life and screened by polymerase chain reaction for adenovirus, cytomegalovirus, parvovirus, enteroviruses, Ureaplasma urealyticum, Mycoplasma hominis, Mycoplasma pneumoniae, and Chlamydia species. BPD was defined as persistent oxygen dependence at 28 d of age and 36 wk postconceptional age (PCA). Infants that expired before these time points were excluded from statistical analysis. Out of 89 infants studied, at 28 d of life, 13 had expired, 45 had BPD, and 31 had no BPD (controls). At 36 wk PCA, 15 infants expired, 39 still had BPD, and 35 did not. A significant increase in the frequency of adenovirus genome was identified in BPD patients compared with controls, both at 28 d of life (12/45 = 27% versus 1/31 = 3%: p< or =0.01) and at 36 wk PCA (10/39 = 29% versus 2/35 = 6%: p = 0.01). Other microorganisms were rarely detected and not associated with the development of BPD. This is the first study reporting the frequency of detection of adenovirus DNA in tracheal aspirate samples obtained during the 1st week of life from infants with BPD and suggests that prenatal acquisition may be important in the development of BPD.

Nested PCR for rapid detection of mumps virus in cerebrospinal fluid from patients with neurological diseases

In this study, we have developed a reverse transcription (RT)-nested polymerase chain reaction (n-PCR) for the detection of mumps virus RNA in cerebrospinal fluid (CSF) from patients with neurological infections. A specific 112-bp fragment was amplified by this method with primers from the nucleoprotein of the mumps virus genome. The mumps virus RT-n-PCR was capable of detecting 0.001 PFU/ml and 0.005 50% tissue culture infective dose/ml. This method was found to be specific, since no PCR product was detected in each of the CSF samples from patients with proven non-mumps virus-related meningitis or encephalitis. Mumps virus RNA was detected in all 18 CSF samples confirmed by culture to be infected with mumps virus. Positive PCR results were obtained for the CSF of 26 of 28 patients that were positive for signs of mumps virus infection (i.e., cultivable virus from urine or oropharyngeal samples or positivity for anti-mumps virus immunoglobulin M) but without cultivable virus in their CSF. Overall, mumps virus RNA was detected in CSF of 96% of the patients with a clinical diagnosis of viral central nervous system (CNS) disease and confirmed mumps virus infection, while mumps virus was isolated in CSF of only 39% of the patients. Furthermore, in a retrospective study, we were able to detect mumps virus RNA in 25 of 55 (46%) CSF samples from patients with a clinical diagnosis of viral CNS disease and negative laboratory evidence of viral infection including mumps virus infection. The 25 patients represent 12% of the 236 patients who had a clinical diagnosis of viral CNS infections and whose CSF was examined at our laboratory for a 2-year period. The findings confirm the importance of mumps virus as a causative agent of CNS infections in countries with low vaccine coverage rates. In summary, our study demonstrates the usefulness of the mumps virus RT-n-PCR for the diagnosis of mumps virus CNS disease and suggests that this assay may soon become the "gold standard" test for the diagnosis of mumps virus CNS infection.

Reverse-transcription polymerase chain reaction detection of the enteroviruses

OBJECTIVE

This review focuses on commercial and in-house-developed reverse-transcription polymerase chain reaction (RT-PCR) assays used for the detection of enteroviral infections. In addition to providing details on the performance of RT-PCR, its specificity, and sensitivity, the clinical utility of this diagnostic method with specific reference to its impact on hospitalization and cost savings is addressed.

DATA SOURCES

MEDLINE was searched for reports relating to RT-PCR detection of the enteroviruses in adults and children. The search was restricted to studies reported in English language journals.

STUDY SELECTION

Reports documenting detailed information regarding the RT-PCR conditions, primers, sensitivity, specificity and, if relevant, clinical impact were selected for analysis.

DATA EXTRACTION

Details regarding method of extraction of the enteroviral genome, the primers used, RT-PCR conditions, and sensitivity and specificity of the assay were extracted from the literature. For reports detailing the use of RT-PCR in the clinical management of enteroviral infections in children, the reduction in duration of hospitalization and health care cost savings were recorded.

DATA SYNTHESIS

Reverse-transcription PCR can increase the yield of detection of enteroviruses from cerebrospinal fluid by a mean of approximately 20% over tissue culture. Reverse-transcription PCR of cerebrospinal fluid has been shown to exhibit sensitivity and specificity values of 86% to 100% and 92% to 100%, respectively. Reductions of 1 to 3 days of hospitalization per patient are predicted if RT-PCR is used to diagnose enteroviral meningitis in children.

CONCLUSIONS

Reverse-transcription PCR detection of enteroviral infections is an extremely rapid, sensitive, and specific diagnostic modality. Both commercial assays and assays developed in-house appear to be equivalent with regard to sensitivity and specificity. Reverse-transcription PCR diagnosis of enteroviral infections in children could reduce the length of hospitalization and result in significant health care cost savings.

Development and evaluation of quantitative-competitive PCR for quantitation of coxsackievirus B3 RNA in experimentally infected murine tissues

A method is described for quantitation of enterovirus RNA in experimentally infected murine tissues. Viral RNA was extracted from tissue samples and amplified by reverse transcriptase PCR in the presence of an internal standard RNA. The ratio of PCR product derived from viral RNA and internal standard RNA was then determined using specific probes in a post-PCR electrochemiluminescent hybridization assay. This provided an estimate of the viral RNA copy number in the original sample, and detection of PCR product derived from internal standard RNA validated sample processing and amplification procedures. RNA copy number correlated with viral infectivity of cell culture-derived virus, and one tissue culture infective dose was found to contain approximately 10(3) genome equivalents. The ratio of RNA copy number to infectivity in myocardial tissue taken from mice during the acute phase of coxsackievirus B3 myocarditis was more variable ranging from 10(4)-10(7), and was dependent on the stage of infection, reflecting differential rates of clearance for viral RNA and viral infectivity. The assay is rapid, and could facilitate investigations which currently rely upon enterovirus quantitation by titration in cell culture. This would be useful for experimental studies of viral pathogenesis, prophylaxis and antiviral therapy.

Multicenter quality assessment of PCR methods for detection of enteroviruses

We conducted a multicenter evaluation of commercial and in-house PCR methods for the detection of enteroviruses. Three coded panels of test and control RNA samples, artificial clinical specimens, and representative enterovirus serotypes were used to assess amplification methods, RNA extraction methods, and reactivities with different enterovirus serotypes. Despite several differences between PCR methods, there was good agreement, although some variation in sensitivity was observed. Most PCR methods were able to detect enterovirus RNA derived from 0.01 50% tissue culture infective dose (TCID50) and were able to detect at least 1 TCID50 of enterovirus in cerebrospinal fluid, stool, or throat swab specimens. Most were also able to detect a wide range of enterovirus serotypes, although serotypic identification was not possible. Some laboratories experienced false-positive results due to PCR contamination, which appeared to result mainly from cross-contamination of specimens during RNA extraction. Provided that this problem is overcome, these PCR methods will prove to be a sensitive and rapid alternative to cell culture for the diagnosis of enterovirus infection.

Rubella virus and chronic joint disease: is there an association?

Synovial fluid samples and/or biopsies from 79 patients with various chronic inflammatory joint diseases or traumatic joint injury were tested for rubella virus (RV) in order to confirm or refute results from other studies that suggested RV as a cause of chronic inflammatory joint disease. Sixty-eight of the 72 patients tested had RV antibodies. RV RNA was detected by reverse transcription-PCR in the synovial fluid cells from two patients. RV was also isolated by cell culture from the synovial fluid of one of these two patients. This patient was a 42-year-old female with common variable immune deficiency and Mycoplasma hominis arthritis, while the other was a 68-year-old female with rheumatoid arthritis. While these results fail to confirm that RV is associated with chronic inflammatory joint disease, they suggest that RV may persist within a joint and be reactivated when cell-mediated immunity is suppressed.

Detection by PCR of enteroviruses in cerebrospinal fluid during a summer outbreak of aseptic meningitis in Switzerland

Enteroviruses (EV) are among the most common causes of aseptic meningitis. Standard diagnostic techniques are often too slow and lack sensitivity to be of clinical relevance. EV RNA can be detected within 5 h by a commercially available reverse transcription-PCR (RT-PCR) test kit. Cerebrospinal fluid (CSF) samples from 68 patients presenting with aseptic meningitis during a summer outbreak in Switzerland were examined in parallel with cell culture and commercial RT-PCR. RT-PCR was positive in all 16 CSF specimens positive by cell culture (100%). In addition, 42 of 52 (80%) CSF samples negative by cell culture were PCR positive. In 26 of these 42 (62%) patients, viral culture from other sites (throat swab or stool) was also positive. The CSF virus culture took 3 to 7 days to become positive. Echovirus 30 was the type most often isolated in this outbreak. The sensitivity of CSF RT-PCR based on clinical diagnosis during this aseptic meningitis outbreak in patients with negative bacterial culture results was 85%, i.e., considerably higher than the sensitivity of CSF virus culture (24%). We conclude that this commercial RT-PCR assay allows a positive diagnosis with minimal delay and may thus influence clinical decisions.

Multicenter evaluation of the Amplicor Enterovirus PCR test with cerebrospinal fluid from patients with aseptic meningitis. The European Union Concerted Action on Viral Meningitis and Encephalitis

The Amplicor Enterovirus PCR test was compared with viral culture for the detection of enteroviruses in cerebrospinal fluid (CSF) specimens. In a multicenter study in which nine laboratories participated, a total of 476 CSF specimens were collected from patients with suspected aseptic meningitis. Sixty-eight samples were positive by PCR (14.4%), whereas 49 samples were positive by culture (10.4%), demonstrating that the Amplicor Enterovirus PCR test was significantly more sensitive than culture (P < 0.001). After discrepancy analysis the sensitivity and specificity of the Amplicor Enterovirus PCR test obtained by using viral culture as the "gold standard" were 85.7 and 93.9%, respectively. Our results with the CSF specimens collected in different countries demonstrate that the Amplicor test is capable of detecting a large variety of enterovirus serotypes and epidemiologically unrelated isolates in CSF specimens from patients with aseptic meningitis. The Amplicor Enterovirus PCR test is a rapid assay which can be routinely performed with CSF samples and is an important improvement for the rapid diagnosis of enteroviral meningitis.

Evaluation of a commercially available reverse transcription-PCR assay for diagnosis of enteroviral infection in archival and prospectively collected cerebrospinal fluid specimens

A commercially available reverse transcription (RT)-PCR method (AMPLICOR EV; Roche Diagnostic Systems, Inc., Branchburg, N.J.) was evaluated for detection of enteroviruses in cerebrospinal fluid from patients with neurological disease. This assay was compared with virus isolation in cell culture and an in-house RT-PCR method designed with a nonoverlapping region of the enteroviral genome. A panel of 200 cerebrospinal fluid specimens prospectively collected from patients with a wide variety of neurological symptoms, including 50 patients involved in three different outbreaks of acute aseptic meningitis, was assayed. A second panel of 97 archived cerebrospinal fluid specimens, stored for 2 to 5 years, from patients with aseptic meningitis associated with several enterovirus outbreaks was also studied. From the first panel, enteroviruses were detected in 13 of 50 specimens by cell culture (26%), in 43 of 50 specimens by AMPLICOR EV (86%), and in 46 of 50 specimens by the in-house assay (92%) from patients with aseptic meningitis associated with outbreak and 1 of 29, 3 of 29, and 4 of 29 specimens, respectively, from sporadic cases of aseptic meningitis. The remaining 121 cerebrospinal fluid specimens from patients with other neurological syndromes were negative by all tests. From the second panel, enteroviral RNA was detected by the AMPLICOR test (31 of 97 specimens, 32%) and the in-house assay (39 of 97 specimens, 40%). According to our results, patients with aseptic meningitis should be analyzed for enteroviral infection in cerebrospinal fluid by RT-PCR methods, and the AMPLICOR EV test is a suitable tool for performing such studies. Archival cerebrospinal fluid specimens are less suitable for evaluation of the performance of RT-PCR methods designed for enterovirus detection.

Molecular typing of enteroviruses: current status and future requirements. The European Union Concerted Action on Virus Meningitis and Encephalitis

Human enteroviruses have traditionally been typed according to neutralization serotype. This procedure is limited by the difficulty in culturing some enteroviruses, the availability of antisera for serotyping, and the cost and technical complexity of serotyping procedures. Furthermore, the impact of information derived from enterovirus serotyping is generally perceived to be low. Enteroviruses are now increasingly being detected by PCR rather than by culture. Classical typing methods will therefore no longer be possible in most instances. An alternative means of enterovirus typing, employing PCR in conjunction with molecular genetic techniques such as nucleotide sequencing or nucleic acid hybridization, would complement molecular diagnosis, may overcome some of the problems associated with serotyping, and would provide additional information regarding the epidemiology and biological properties of enteroviruses. We argue the case for developing a molecular typing system, discuss the genetic basis of such a system, review the literature describing attempts to identify or classify enteroviruses by molecular methods, and suggest ways in which the goal of molecular typing may be realized.

Rapid detection of different RNA respiratory virus species by multiplex RT-PCR: application to clinical specimens

BACKGROUND

The polymerase chain reaction (PCR) applied in diagnostic and epidemiologic investigations is very useful for sensitivity, specificity and time saving.

OBJECTIVE

We have developed a method for the detection of genomic RNA of two different species of virus, the influenza A virus (IA) and the respiratory syncytial virus (RS), which are responsible for clinical similarities. We applied this multiplex RT-PCR protocol on clinical specimens.

STUDY DESIGN

We describe a method which allows rapid diagnosis by performing a single retro-transcriptase (RT) reaction associated with the PCR (multiplex RT-PCR) on different genomes in a single sample. We have evaluated the sensitivity and the specificity of the multiplex test on positive controls, then, on RNA extracted from clinical specimens harvested from 15 children with respiratory symptoms during the spring-winter season 1997.

RESULTS AND CONCLUSIONS

The multiplex RT-PCR protocol, applied to respiratory specimens, allows the investigation of RNA IA virus and RS virus in a single sample at the same time. The detection of the etiologic viral agent is rapid and it is possible to evaluate incidental simultaneous infections.

Detection of coxsackievirus B3 in intestinal tissue of orally-infected mice by a standardized RT-PCR assay

BACKGROUND

Previous studies have reported the role of enteroviruses in chronic diseases, using in-house RT-PCR protocols. A well-standardized PCR assay (Amplicor enterovirus, Produits Roche) designed for the diagnosis of enterovirus meningitis in cerebrospinal fluids (CSF) was recently described.

OBJECTIVES

To evaluate this commercially-available PCR assay for the detection of enterovirus in intestinal biopsies.

STUDY DESIGN

In order to obtain large quantities of infected material, eight mice were inoculated orally with 2 x 10(5) 50% tissue culture infective doses (TCID50) of coxsackievirus B3 (CBV3); two mice were sacrificed every day from day 1 to day 4 post-infection. Stool specimens and small bowel fragments were taken from infected animals and controls. Four protocols of RNA extraction from intestinal tissue were compared. Extracted RNA was then tested by the Amplicor assay and by a seminested in-house PCR.

RESULTS

The best results were obtained with a commercial reagent using a combination of guanidium thiocyanate and phenol (TRI Reagent, Sigma). This procedure allowed the detection of enteroviral RNA in intestinal samples of 7/8 and 8/8 infected mice by Amplicor assay and seminested PCR, respectively, whereas only five samples were tested positive by conventional cell culture. When tested on serial dilutions of CBV3 mixed with intestinal tissue, a sensitivity of 0.2 TCID50/mg was achieved with both PCR assays.

CONCLUSIONS

The data demonstrate that the Amplicor enterovirus assay, which is designed to avoid false-positive amplifications, can be used, with a slight modification of the RNA extraction step, for the detection of enterovirus in specimens different from CSF such as intestinal tissue.

Detection of enteroviral RNA and specific DNA of herpesviruses by multiplex genome amplification

A reverse transcription (RT) multiplex polymerase chain reaction (PCR) assay was developed to allow rapid, sensitive and simultaneous detection of enteroviral RNA and herpesviral DNA specific sequences in a single tube. The method involves a reverse transcription step followed by a multiplex nested PCR in which the combination of primers amplifies cDNA from enteroviruses and specific herpesviruses DNA. Nested amplification utilises primers designed to anneal into the amplification product from the first reaction. Individual viruses were then detected and differentiated by the size of their PCR products determined using ethidium bromide stained agarose gels. To exclude false negatives due to sample inhibitors an internal amplification control, a cloned fragment of DNA from Pseudorabies virus (PRV DNA) was included in the reaction mixture. Detection levels between 0.01 and 0.001 TCID50 of prototype strains of Polio and Coxsackie type B viruses and between 1 and 100 molecules of cloned-DNA of herpesviruses prototype strains were achieved. The RT multiplex PCR method proved capable of detecting enteroviral RNA or herpesviral DNA in cerebro spinal fluid (CSF) samples from patients with aetiologically well characterized encephalitis or aseptic meningitis.

Rapid diagnosis of enterovirus infection by a new one-step reverse transcription-PCR assay

The AMPLICOR Enterovirus Test was evaluated with 103 cerebrospinal fluid (CSF) specimens. Twenty-seven CSF specimens were culture positive. With the AMPLICOR test, enterovirus RNA was detected in 34 specimens. Compared with culture, the AMPLICOR test gave a sensitivity of 96.3% and a specificity of 100%. The sensitivity of culture was 79.4% in comparison with the AMPLICOR test.

Detection of swine vesicular disease virus RNA by reverse transcription-polymerase chain reaction

Two polymerase chain reaction (PCR) assays are described for the detection of swine vesicular disease virus (SVDV) RNA, a reverse transcription PCR (RT-PCR) and a reverse transcription nested PCR (RT-nPCR). Both the RT-PCR and RT-nPCR were able to detect representative members of each of seven phylogenetically distinct groups of SVDV and gave negative results with a range of porcine enteroviruses and of viruses responsible for vesicular conditions in pigs. When combined with a commercial kit for rapid RNA extraction, the RT-PCR was useful for the detection of SVDV in samples of epithelium and faeces from animals with clinical SVD. The addition of a second amplification step to create a nested PCR (RT-nPCR) increased the sensitivity of the technique for the detection of viral RNA (vRNA) in SVDV infected tissue culture fluid by a factor of approximately 1,000, for 100 TCID50 for the RT-PCR to 0.1 TCID50 for RT-nPCR. When combined with a more elaborate extraction procedure for RNA, the RT-nPCR was considerably more sensitive than virus isolation in tissue culture for detecting SVDV in nasal swabs, tissues, and faeces collected from pigs between 7 days and 176 days after infection with a recent European isolate of SVDV. However, stringent conditions are necessary for carrying out the RT-nPCR to minimise the possibility of contamination.

The development of an antigen capture polymerase chain reaction assay to detect and type human enteroviruses

Antigen capture polymerase chain reaction (AC-PCR) is a technique that combines the advantages of PCR with those of antibody mediated methods, to detect and type human enteroviruses. Virus particles are captured by specific antisera and RNA is released by heat denaturation to generate the substrate for reverse transcription and PCR. Use of this technique results in purification of human enteroviruses from tissue culture and 10% faecal samples in a serotype-specific manner allowing both rapid detection and a direct correlation between serological and genetic typing methods. The sensitivity of AC-PCR was comparable with that of PCR protocols employing a conventional organic solvent based extraction procedure.

Evaluation of the Roche Amplicor polymerase chain reaction assay for detection of enteroviruses in cerebrospinal fluid and its potential impact on patient management

OBJECTIVE: To evaluate the Roche Amplicor polymerase chain reaction assay (APCR) by comparing the detection of enteroviruses from cerebrospinal fluid (CSF) by the Roche assay with detection by viral culture and to determine whether routine use of enteroviral PCR will affect patient management. METHODS: One hundred and sixty-three CSF specimens were tested by APCR and viral culture. Some of the discrepant specimens were resolved by retesting with an in-house PCR assay. Other discrepant results were resolved by testing the patients' serum by APCR or by viral culture of throat and stool specimens. RESULTS: Thirty CSF specimens were positive by APCR, and 18 of these were positive by viral culture. There were no APCR-negative, viral-culture-positive CSF specimens. Six of the 12 discrepant specimens were resolved as true positives. CONCLUSIONS: The APCR assay was more rapid and sensitive than viral culture for detection of enteroviruses from CSF. Routine use of this assay has the potential to reduce the amount of antibiotics used and the number of patient days spent in hospital.

Rapid detection of enterovirus in clinical specimens using PCR and microwell capture hybridization assay

A rapid detection method of enteroviral RNA in clinical samples using PCR and a microwell capture hybridization assay is described. PCR products were labelled directly by digoxigenin-dUTP during the amplification step. The labelled amplicons were hybridized with a biotinylated oligo-probe and captured on commercially available test microwells coated with streptavidin. The hybridized amplicons labelled with digoxigenin were detected using anti-digoxigenin Fab fragments conjugated to peroxidase and colorimetric reaction automatically measured. This method detected as few as 0.01 PFU/100 microl of biological sample with a result obtained within 8 h. Using this method, we were able to detect enteroviral RNA in 23 of 35 clinical specimens from 16 of 17 patients with suspected acute or chronic enteroviral infection. The samples included cerebrospinal fluid, broncho-pulmonary lavage, pericardial effusion, throat swabs, stools, sera, muscular and myocardial biopsies. In contrast, virus was isolated in cell culture in only 8 of 28 clinical specimens from 6 of the 17 patients. This easy-to-perform assay has useful potential in the rapid detection of enterovirus in acute or chronic infection. This methodology could be used for a rapid qualitative detection of other RNA viruses.

Enteroviral polymerase chain reaction in the investigation of aseptic meningitis

We used a nested polymerase chain reaction (nPCR) to seek evidence for enteroviruses in clinical samples from patients with symptoms of aseptic meningitis. When compared with conventional virus isolation methods on a total of 366 samples collected during 1994-1995, an increase in positivity from 6% to 27% was shown. The results indicate that nPCR would be a valuable aid to the laboratory diagnosis of enteroviral infections as it can detect those enteroviruses that cannot be identified by current isolation methods.