Two-step PCR in the retrospective diagnosis of enteroviral viraemia

Human febrile illness caused by encephalomyocarditis virus infection, Peru

Encephalomyocarditis virus was identified in the serum of 2 febrile patients in Peru.

Etiologic studies of acute febrile disease were conducted in sites across South America, including Cusco and Iquitos, Peru. Patients’ clinical signs and symptoms were recorded, and acute- and convalescent-phase serum samples were obtained for serologic examination and virus isolation in Vero E6 and C6/36 cells. Virus isolated in Vero E6 cells was identified as encephalomyocarditis virus (EMCV) by electron microscopy and by subsequent molecular diagnostic testing of samples from 2 febrile patients with nausea, headache, and dyspnea. The virus was recovered from acute-phase serum samples from both case-patients and identified with cardiovirus-specific reverse transcription–PCR and sequencing. Serum samples from case-patient 1 showed cardiovirus antibody by immunoglobulin M ELISA (acute phase <8, convalescent phase >1,024) and by neutralization assay (acute phase <10, convalescent phase >1,280). Serum samples from case-patient 2 did not contain antibodies detectable by either assay. Detection of virus in serum strongly supports a role for EMCV in human infection and febrile illness.

Diagnosis of Enteroviral Meningitis by Use of Polymerase Chain Reaction of Cerebrospinal Fluid, Stool, and Serum Specimens

BACKGROUND

Because enteroviruses can be detected in various clinical samples during enteroviral meningitis, we analyzed the combined diagnostic utility of polymerase chain reaction (PCR) of cerebrospinal fluid (CSF), feces, and serum for detection of enterovirus in specimens obtained from adults with aseptic meningitis or encephalitis.

METHODS

PCR results were analyzed for 34 adults for whom enteroviral meningitis was diagnosed on the basis of virus isolation and antibody detection in our hospital during 1999-2003. PCR results were also analyzed for 77 adults with meningitis or encephalitis of another defined cause for whom this assay was used for diagnostic evaluation during that period.

RESULTS

Twenty-six (76%) of 34 CSF samples and 24 (96%) of 25 fecal samples collected from patients with enteroviral meningitis had positive PCR results. The diagnostic yield of the test was lower for CSF specimens obtained >2 days after clinical onset, compared with CSF collected < or =2 days after onset. Instead, PCR of feces was highly useful also later, because 12 of the 13 fecal specimens obtained 5-16 days after clinical onset had positive test results. None of 75 CSF samples and 2 of 48 fecal samples obtained from patients with nonenteroviral infection had positive PCR results. All serum samples were PCR negative.

CONCLUSIONS

PCR of fecal specimens obtained throughout the course of enteroviral meningitis had the highest clinical sensitivity for detecting enterovirus. It is recommended that, in addition to performance of CSF PCR, fecal samples collected from patients with suspected enteroviral meningitis should be tested by PCR, especially when the duration of symptoms is >2 days.

Postpericardiotomy syndrome: no evidence for a viral etiology

BACKGROUND

Postpericardiotomy syndrome has been considered a disorder induced by viral infection. This conclusion is based on serologic criterions, but these may be unreliable following either cardiopulmonary bypass or transfusion therapy. Previous studies have not verified the proposed etiology either by isolation of viruses, or by detection of their genome. We sought, therefore, to clarify the role, if any, of viruses in this syndrome.

METHODS AND RESULTS

We studied prospectively 149 children aged from 6 months to 16 years who were undergoing open heart surgery. Blood samples were collected from all prior to operation, and again 7 to 10 days post-operatively, and 47 were sampled at the time of development of symptoms of pericardial involvement. Serums were analyzed for the presence of IgM and IgG antibodies to cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. The polymerase chain reaction was used for amplification when assessing the genome of the enteroviruses. Cultures for viruses were established on samples of stool, urine, and throat swabs collected 7 days post-operatively, and at the time of postpericardial symptoms. Pericardial fluid obtained from 5 patients with the syndrome was cultured for viruses, and tested for enterovirus genome. On the basis of clinical and echocardiographic findings, 34 children were determined to have definite evidence of the syndrome, 13 were considered to have possible evidence, and the results from these patients were compared to those from patients with no pericardial symptoms, the latter being matched for age and transfusion status. We isolated viruses from one or more sites in five patients with definite evidence (16%), from one (9%) of those with possible evidence, and from seven (19%) of the controls. All serums and pericardial samples were negative for enterovirus genome. IgM antibodies were found in only 5 patients, three with symptoms of pericardial involvement and two without. Rates of seroconversion to IgG for the viruses were lower in the patients with symptoms of pericardial involvement compared to controls, but were strongly influenced by transfusion status.

CONCLUSION

Our study has provided no evidence to support a viral etiology for the postpericardiotomy syndrome.

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.

Usefulness of nested PCR and sequence analysis in a nosocomial outbreak of neonatal enterovirus infection

BACKGROUND

Non-polio enterovirus infections are recognized in children during summer-fall seasons and they sometimes cause large outbreaks. We experienced a nosocomial infection in the neonatal nursery and echovirus type 7 was isolated from samples of four patients.

OBJECTIVES

We diagnosed the horizontal infection of four neonates by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) and the nucleotide sequence.

STUDY DESIGN

Total RNA was extracted from clinical isolates, serum samples and cerebrospinal fluid (CSF). We amplified enterovirus genome in the 5'-noncoding region by nested PCR and determined the nucleotide sequences.

RESULTS

Enterovirus genome was detected in all isolates, in the acute-phase sera in all four patients and in the CSF in one patient by the first PCR. By using nested PCR, the genome was detected from convalescent-phase sera in two patients. All enterovirus genome obtained from the nursery outbreak showed the same sequences with 100% homology.

CONCLUSION

We demonstrated the clinical advantages of RT-nested PCR from serum samples and the analysis of nucleotide sequencing gave the supportive evidence of identification of transmission pathway.

Enterovirus heart disease of adults: a persistent, limited organ infection in the presence of neutralizing antibodies

Detection of enterovirus RNA in endomyocardial biopsies (EMB) by reverse transcription/polymerase chain reaction (RT-PCR) is currently the preferred diagnostic procedure in suspected enterovirus heart disease (EHD), which can present clinically as myocarditis, dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). EMB and peripheral blood mononuclear cells (PBMC) of 44 patients with suspected EHD were examined by nested RT-PCR to investigate whether the myocardial enterovirus infection is limited to the heart or is generalized. Enterovirus RNA was detected in EMB, but not in PBMC, of 8 patients (3 of these suffered from ARVC), whereas EMB of 16 controls and PBMC of 45 controls were negative. In addition, enterovirus RNA was demonstrated in PBMC, but not in EMB, of a single patient with suspected EHD. A high sequence homology of the amplicons to coxsackievirus B3 was demonstrated in 7 patients, and to coxsackievirus B2 in two patients. In order to evaluate whether the myocardial enterovirus infection was acute or persistent, neutralization and complement fixation tests were performed for antibodies against the serotypes indicated by the nucleic acid sequences. Neutralizing antibodies were detected in the sera of all 9 patients, but complement fixing antibodies were demonstrated only in one EHD patient and in the patient positive for enterovirus RNA in PBMC. In conclusion, the molecular and serological data demonstrate that CVB3 predominates as cardiotropic enterovirus, and that the enterovirus replication is limited to the heart in EHD. Serological results support the hypothesis of myocardial enterovirus RNA persistence in spite of neutralizing antibodies.

Detection and rapid differentiation of human enteroviruses following genomic amplification

By employing a nested PCR (n-PCR) with specific primers derived from the 5' nontranslated and consensus region of the human enterovirus genome, we detected enterovirus RNA from 32 different serotypes of prototypic strains. A specific 297-bp fragment was amplified by this method from all of these strains. Not only was the method highly sensitive, detecting enterovirus RNA extracted from 0.01 50% tissue culture infective dose/50 microl (which is more sensitive than our current routine method of enterovirus diagnosis, based on the virus isolation and serotypic neutralization), but it was also relatively rapid. By using this technology, we also detected enterovirus RNA in uncultured specimens (including throat swabs and stools) from patients with respiratory illness and acute flaccid paralysis syndrome. This method enabled us to rapidly and directly distinguish enterovirus-infected specimens from nonenterovirus specimens in laboratory diagnosis. Furthermore, restriction fragment length polymorphism was assessed as an alternative means of differentiating various serotypes of prototypical enteroviruses. Fourteen of 16 human enterovirus-infected specimens exhibited restriction patterns identical to those of the corresponding prototypes.

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.

Detection of enteroviruses and rhinoviruses in clinical specimens by PCR and liquid-phase hybridization

A sensitive method based on PCR followed by liquid-phase hybridization for detection of enterovirus and rhinovirus RNAs in clinical specimens and cell culture supernatants is described. RNA was extracted from stool samples, throat swabs, nasopharyngeal aspirates, cerebrospinal fluid, urine, and plasma with a commercial phenol-guanidinium-chloroform reagent and purified on a polysulfone membrane, on which the reverse transcriptase reaction was also done. Two sets of oligonucleotide primers from the 5' noncoding region of picornaviruses were selected for DNA amplification of 153-bp (enterovirus) and 120-bp (rhinovirus) regions. Double-stranded amplicons were digested into single strands with T7 gene 6 exonuclease and quantitated by an assay using a europium-labeled probe, streptavidin- and biotinylated probe-coated microtitration wells, and time-resolved fluorometry. The sensitivity of the assay was about one template molecule when purified coxsackievirus A9 RNA was used. All enterovirus prototype strains, except echoviruses 22 and 23, and clinical isolates grown in cell culture or suckling mice were strongly positive by the enterovirus PCR-hybridization, as were selected prototype strains and untyped isolates of rhinoviruses by the rhinovirus PCR-hybridization. In a series of 100 clinical specimens tested, the results for 92 agreed with virus culture results. The detection method described will be useful in etiopathogenic studies on enteroviruses and rhinoviruses.

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

Employing a nested polymerase chain reaction with primers from the 5' non-translated region of the enterovirus genome, we detected enteroviral RNA from patients with a variety of enterovirus-associated clinical syndromes. This technique was found to be sensitive (detecting enteroviral RNA extracted from 0.1 50% tissue culture infectious dose) and specific; no specific PCR product was detected from RNA extracts of a variety of non-enterovirus isolates. Although the technique is of comparable sensitivity to single round polymerase chain reaction followed by Southern blot hybridization, it was more rapid, since it enabled a diagnosis to be made within 1 day. Thus, using nested polymerase chain reaction we were able to detect enteroviral RNA in 31 of 46 clinical specimens from 17 of 23 patients with suspected enterovirus infections. The samples included cerebrospinal fluid, throat swabs, stool, vesicle fluid, peripheral blood lymphocytes, whole blood and pericardial effusion. In contrast virus was isolated in only 17 of 42 clinical specimens from 12 of 22 these patients. In preliminary studies, restriction endonuclease analysis of polymerase chain reaction products enabled us to distinguish between non-polio enteroviruses and poliovirus types 1, 2, and 3. This additional technique may be useful in distinguishing between such infections in polio-endemic countries where rapid public health measures may be required.

PCR for the diagnosis of enteroviral meningitis

A 2-step 'semi-nested' enterovirus PCR was developed and applied to CSF and serum specimens from 27 consecutive patients with aseptic meningitis. CSF and sera from 8 patients with non-enteroviral diagnoses were included as negative clinical controls. Enterovirus RNA was detected in CSF by PCR in 15 of the patients with aseptic meningitis, compared with 6 by virus culture. Acute-phase sera proved positive for enterovirus RNA in 11 patients, thus increasing the number of PCR-positive patients to 18. Convalescent-phase sera were all negative by PCR. The correlation of a positive or negative PCR result in CSF and/or serum versus combined conventional virology (serology and isolation from 1-3 sites, i.e. CSF, stool and throat) was 78%. All negative controls were negative by PCR. PCR is a reliable and sensitive diagnostic tool for the detection of enteroviral infections. Both CSF and acute-phase serum should be considered for testing.

Detection of enteroviral RNA by polymerase chain reaction in cerebrospinal fluid from patients with aseptic meningitis

An assay based on a 2-step (semi-nested) polymerase chain reaction (PCR) was developed and evaluated for detection of enterovirus-specific RNA in cerebrospinal fluid (CSF) from patients with aseptic meningitis of different etiology. The limit of detectability of enteroviral RNA was equivalent to about 0.25 tissue culture infective doses 50%. In samples, stored at -70 degrees C, analyzed without repeated thawing, enteroviral RNA was demonstrable in 21/22 CSF specimens from which an enterovirus had been isolated. Enteroviral RNA was shown to be degraded during freeze-thawing of the samples. In repeatedly freeze-thawed samples from 134 consecutive patients with aseptic meningitis, a lower sensitivity (34/48 = 0.71) was observed. In the latest phase of the study, comprising 35 consecutive patients, the PCR was performed in CSF stored at -20 degrees C without thawing. In this material, the PCR yielded positive results in 19 patients, whereas enteroviruses were isolated from 6 cases only. In the total clinical material of 169 patients, 67 (40%) were found positive by PCR, whereas an enterovirus was isolated from CSF in 54 (32%) cases. All the 13 isolated enterovirus serotypes found in the study were demonstrable by PCR, indicating that the assay is broad-reacting within the enterovirus group. The specificity appeared to be high, since all of 21 patients with non-enteroviral diagnoses were negative by the PCR test, except 1 with an Epstein-Barr virus infection. As serological evidence of enteroviral etiology was found in this patient, a dual infection seemed probable. This study indicates that enteroviral RNA can be detected in CSF by a 2-step PCR in meningitis caused by enterovirus and that the technique has the potential to become a screening method for routine diagnosis of enteroviral meningitis.