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

Syndrome Evaluation System for Simultaneous Detection Pathogens Causing Acute Encephalitic Syndrome in India, Part-1: Development and Standardization of the Assay

A large number of organisms are known to cause acute encephalitic syndrome (AES). A number of diagnostic tests have to be performed in order to arrive at a probable pathogen causing AES thus making it a very time consuming, laborious and expensive. The problem is further compounded by the lack of availability of sufficient volume of Cerebrospinal fluid (CSF). Thus, there is an urgent need of a diagnostic tool for the simultaneous detection of all probable pathogens responsible for causing AES. Here we report the development of a novel diagnostic method, Syndrome Evaluation System (SES) for the simultaneous detection of 22 pathogens including RNA and DNA Viruses, bacteria, fungi, and parasite all endemic to India and Southeast Asia in a single sample using a novel multiplexing strategy. Syndrome Evaluation System (SES) involves isolation of nucleic acid, multiplex amplification of the DNA, and cDNA followed by identification of the amplified product by sequence specific hybridization on SES platform with the final read out being a visually recordable colored signal. The total time required to carry out this diagnostic procedure is 7 h. The SES was standardized using the commercially available vaccines, panels and cell culture grown quantified viruses/bacteria/fungi. The limit of detection (LOD) of SES ranged between 0.1 and 50 viral particles per ml of CSF and 100 to 200 bacterial cells or 5 parasites per ml of CSF, along with 100% specificity. Precision studies carried out as per the Clinical Laboratory Improvement Amendments (CLIA) guidelines, using two concentrations of each pathogen one the LOD and the other double the LOD, clearly demonstrated, that inter/intra assay variability was within the limits prescribed by the guidelines. SES is a rapid molecular diagnostic tool for simultaneous identification of 22 etiological agents of AES encountered both in sporadic and outbreak settings.

Mumps: An Emergency Medicine-Focused Update

BACKGROUND

Mumps is a Paramyxoviridae virus. This disease was rampant prior to introduction of the measles, mumps, and rubella vaccine, resulting in decreased incidence. This disease has demonstrated several outbreaks.

OBJECTIVE

This review provides a focused evaluation of mumps, an update on outbreaks, management recommendations, and ways to decrease transmission.

DISCUSSION

Clusters of mumps outbreaks continue to occur. The virus is a paramyxovirus, a single-stranded RNA virus. The vaccine can provide lifelong immunity if administered properly, though prior to 1967 and introduction of the vaccine, the virus was common. In the past decade, there have been several notable outbreaks. Humans are the only known hosts, with disease spread through exposure to droplets and saliva. Factors affecting transmission include age, compromised immunity, time of year, travel, and vaccination status. Upper respiratory symptoms, fever, and headache are common, with unilateral or bilateral parotitis, and the virus may spread to other systems. Diagnosis is clinical, though polymerase chain reaction and immunoglobulin testing are available. This review provides several recommendations for vaccine in pregnancy, patients living in close quarters, health care personnel, and those immunocompromised. Treatment is generally supportive, with emphasis on proper isolation to prevent widespread outbreaks. Although reporting regulations and procedures vary by state, mumps is reportable in most states.

CONCLUSIONS

Mumps is an easily spread virus. Although vaccination is the most effective way to prevent transmission, early recognition of the disease is crucial. As an emergency physician, it is important to recognize the clinical presentation, recommended testing, treatment, and isolation procedures.

Laboratory diagnosis of CNS infections by molecular amplification techniques

The initial presentation of symptoms and clinical manifestations of CNS infectious diseases often makes a specific diagnosis difficult and uncertain, and the emergence of polymerase chain reaction-led molecular techniques have been used in improving organism-specific diagnosis. These techniques have not only provided rapid, non-invasive detection of microorganisms causing CNS infections, but also demonstrated several neurologic disorders linked to infectious pathogens. Molecular methods performed on cerebrospinal fluid are recognized as the new 'gold standard' for some of these infections caused by microorganisms that are difficult to detect and identify. Although molecular techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations as well as strengths of these techniques must be clearly understood by both clinicians and laboratory personnel.

Viral infections of the central nervous system in Spain: a prospective study

The aim of the study was to determine the incidence of viruses causing aseptic meningitis, meningoencephalitis, and encephalitis in Spain. This was a prospective study, in collaboration with 17 Spanish hospitals, including 581 cases (CSF from all and sera from 280): meningitis (340), meningoencephalitis (91), encephalitis (76), febrile syndrome (7), other neurological disorders (32), and 35 cases without clinical information. CSF were assayed by PCR for enterovirus (EV), herpesvirus (herpes simplex [HSV], varicella-zoster [VZV], cytomegalovirus [CMV], Epstein-Barr [EBV], and human herpes virus-6 [HHV-6]), mumps (MV), Toscana virus (TOSV), adenovirus (HAdV), lymphocytic choriomeningitis virus (LCMV), West Nile virus (WNV), and rabies. Serology was undertaken when methodology was available. Amongst meningitis cases, 57.1% were characterized; EV was the most frequent (76.8%), followed by VZV (10.3%) and HSV (3.1%; HSV-1: 1.6%; HSV-2: 1.0%, HSV non-typed: 0.5%). Cases due to CMV, EBV, HHV-6, MV, TOSV, HAdV, and LCMV were also detected. For meningoencephalitis, 40.7% of cases were diagnosed, HSV-1 (43.2%) and VZV (27.0%) being the most frequent agents, while cases associated with HSV-2, EV, CMV, MV, and LCMV were also detected. For encephalitis, 27.6% of cases were caused by HSV-1 (71.4%), VZV (19.1%), or EV (9.5%). Other positive neurological syndromes included cerebellitis (EV and HAdV), seizures (HSV), demyelinating disease (HSV-1 and HHV-6), myelopathy (VZV), and polyradiculoneuritis (HSV). No rabies or WNV cases were identified. EVs are the most frequent cause of meningitis, as is HSV for meningoencephalitis and encephalitis. A significant number of cases (42.9% meningitis, 59.3% meningoencephalitis, 72.4% encephalitis) still have no etiological diagnosis.

Viral etiology of aseptic meningitis among children in southern Iran

Aseptic meningitis refers to a clinical syndrome of meningeal inflammation in which bacteria cannot be identified in the cerebrospinal fluid (CSF). The viral etiology and the epidemiological, clinical, and laboratory characteristics of aseptic meningitis among children aged 2 months to 15 years in Shiraz, southern Iran were determined. From May 2007 to April 2008, 65 patients were admitted to the hospital with aseptic meningitis. Seven viruses, non-polio human enteroviruses, mumps virus, herpes simplex virus (HSV), varicella-zoster virus (VZV), human cytomegalovirus (HCMV), human herpes virus type 6 (HHV-6), and Epstein-Barr virus (EBV) were investigated by polymerase chain reaction (PCR) method. Viruses were detected in 30 (46.2%) patients in whom non-polio human enterovirus and mumps virus were detected in 13 (43.3%) and 11 (36.7%), respectively. The remaining 6 (20%) of the cases were caused by HSV, VZV, HCMV, and HHV-6. Haemophilus influenzae and non-polio human enterovirus were detected in one patient simultaneously. Viral meningitis was found to be more frequent during spring and summer. The majority (66.6%) of the patients were treated in the hospital for 10 days and had received antibiotics in the case of bacterial meningitis. Rapid diagnosis of viral meningitis using PCR testing of CSF can help shorten hospitalization, and avoid the unnecessary use of antibiotics.

Detection of mumps virus RNA in cerebrospinal fluid of patients with neuromyelitis optica

Neuromyelitis optica (NMO) is an acute inflammatory disease that preferentially involves the optic nerves and spinal cord. Although many infectious agents, including mumps virus, are postulated to have a role in the pathogenesis of multiple sclerosis (MS), the relationship between NMO and infectious agents remains uncertain. To investigate the relationship between NMO and viruses that have special affinity for the central nervous system, we performed a nested polymerase chain reaction (PCR) to detect mumps virus or enterovirus RNA in cerebrospinal fluid samples from 13 patients with MS, 8 with NMO and 20 with other neurological diseases (ONDs). Nested PCR was positive for mumps virus in 2 (25%) of NMO patients, but in none of those with MS and ONDs. Moreover, nested PCR results became negative in the remission phase in the two PCR-positive NMO patients. Mumps virus may have some role in the pathogenesis of NMO.

Circulation of mumps virus genotypes in Spain from 1996 to 2007

Although the WHO recommends the use of genotyping as a tool for epidemiological surveillance for mumps, limited data on mumps virus (MV) genotype circulation that may be used to trace the patterns of virus spread are available. We describe the first complete series of data from Spain. The small hydrophobic region was sequenced from 237 MV-positive samples from several regions of Spain collected between 1996 and 2007. Six different genotypes were identified: A, C, D (D1), G (G1, G2), H (H1, H2), and J. Genotype H1 was predominant during the epidemic that occurred from 1999 to 2003 but was replaced by genotype G1 as the dominant genotype in the epidemic that occurred from 2005 to 2007. The same genotype G1 strain caused concomitant outbreaks in different parts of the world (the United States, Canada, and the United Kingdom). The remaining genotypes (genotypes A, C, D, and J) appeared in sporadic cases or small limited outbreaks. This pattern of circulation seems to reflect continuous viral circulation at the national level, despite the high rates of vaccine coverage.

Mumps: a resurgent disease with protean manifestations

Mumps has re-emerged as an infection in the developed world. Its epidemiology has changed, with the majority of cases now primarily affecting adolescents and adults. While mumps is easily suspected if parotitis is present, parotitis is absent in 10%-30% of symptomatic cases. Mumps is a systemic infection with a variety of extra-parotid complications. In Australia, mumps diagnosis is confirmed by antibody testing and reverse transcriptase-polymerase chain reaction techniques. Suitable specimens for testing are serum, saliva, urine and cerebrospinal fluid. Treatment is generally supportive, although intravenous immunoglobulin therapy may have a future role in mumps management. Interferon alpha-2b treatment may be considered specifically for mumps epididymo-orchitis. Mumps vaccine is included in the measles-mumps-rubella (MMR) vaccine. In Australia, this vaccine is routinely administered at the ages of 1 and 4 years. Serious reactions to the mumps components of the MMR vaccine are rare.

Mumps

Mumps is a common childhood infection caused by the mumps virus. The hallmark of infection is swelling of the parotid gland. Aseptic meningitis and encephalitis are common complications of mumps together with orchitis and oophoritis, which can arise in adult men and women, respectively; other complications include deafness and pancreatitis. Clinical diagnosis can be based on the classic parotid swelling; however, this feature is not present in all cases of mumps and can also occur in various other disorders. Laboratory diagnosis is based on isolation of virus, detection of viral nucleic acid, or serological confirmation (generally presence of IgM mumps antibodies). Mumps is vaccine-preventable, and one dose of mumps vaccine is about 80% effective against the disease. Routine vaccination has proven highly effective in reducing the incidence of mumps, and is presently used by most developed countries; however, there have been outbreaks of disease in vaccinated populations. In 2005, a large epidemic peaked in the UK, and in 2006 the American midwest had several outbreaks. In both countries, the largest proportion of cases was in young adults. In the UK, susceptible cohorts too old to have been vaccinated and too young to have been exposed to natural infections were the primary cause of the mumps epidemic. In the USA, effectiveness and uptake in combination appear not to have been sufficient to obtain herd immunity for mumps in populations such as college students.

Real-time reverse transcription-PCR assay for detection of mumps virus RNA in clinical specimens

The mumps virus is a negative-strand RNA virus in the family Paramyxoviridae. Mumps infection results in an acute illness with symptoms including fever, headache, and myalgia, followed by swelling of the salivary glands. Complications of mumps can include meningitis, deafness, pancreatitis, orchitis, and first-trimester abortion. Laboratory confirmation of mumps infection can be made by the detection of immunoglobulin M-specific antibodies to mumps virus in acute-phase serum samples, the isolation of mumps virus in cell culture, or by detection of the RNA of the mumps virus by reverse transcription (RT)-PCR. We developed and validated a multiplex real-time RT-PCR assay for rapid mumps diagnosis in a clinical setting. This assay used oligonucleotide primers and a TaqMan probe targeting the mumps SH gene, as well as primers and a probe that targeted the human RNase P gene to assess the presence of PCR inhibitors and as a measure of specimen quality. The test was specific, since it did not amplify a product from near-neighbor viruses, as well as sensitive and accurate. Real-time RT-PCR results showed 100% correlation with results from viral culture, the gold standard for mumps diagnostic testing. Assay efficiency was over 90% and displayed good precision after performing inter- and intraassay replicates. Thus, we have developed and validated a molecular method for rapidly diagnosing mumps infection that may be used to complement existing techniques.

Comparison of mumps-IgM ELISAs in acute infection

BACKGROUND

In Scotland there has been an outbreak of mumps with over 4000 confirmed cases in the last 2 years. As laboratory diagnosis is usually requested on patients with symptoms, a prompt diagnosis early in the illness is required.

OBJECTIVES

To assess the performance of the five different commercial IgM-ELISAs used in Scottish Virus laboratories.

STUDY DESIGN

The Specialist Virology Laboratory (SVC) Edinburgh distributed a serum panel to all Scottish laboratories that diagnose mumps by IgM-ELISA. The panel consisted of 45 sera from patients with confirmed mumps (date of onset known for 44/45) and 11 sera from patients with alternative diagnoses. Each laboratory performed their own commercial IgM-ELISAs blindly and reported results to the SVC Edinburgh.

RESULTS

Sensitivity ranged from 24% to 51%. Assays performed better on samples taken later than 10 days after onset of symptoms. Specificity was about 82% for most assays.

CONCLUSION

The sensitivity of commercial mumps IgM-ELISAs varied greatly. The Microimmune mumps-IgM ELISA had the best overall sensitivity in acute serum specimens. Diagnostic laboratories should be developing the means to perform direct detection of mumps virus for acute presentation and requesting convalescent bloods, if acute blood samples have no detectable IgM.

Sensitivity and specificity of immunoglobulin G titer for the diagnosis of mumps virus in infected patients depending on vaccination status

The aim of the study was to evaluate the usefulness of serological detection of mumps IgM and titration of IgG in patients with acute parotitis according to their vaccination status. The detection of mumps virus RNA in saliva by RT-PCR was used as reference. 116 patients (109 of them previously vaccinated) with mumps RT-PCR-negative results and 21 (19 vaccinated) with mumps RT-PCR-positive results were studied. Mumps-specific IgM and IgG were assayed by EIA (Enzygnost, Dade Behring, Germany). IgM results were expressed as positive or negative. For IgG, several cut-offs were calculated using receiver operating characteristic (ROC) curves. Seven RT-PCR-positive and five RT-PCR-negative patients showed IgM-positive results (sensitivity 33.3% and specificity 95.7%). Among vaccinated patients, the sensitivity and specificity of IgM were 26.3% (5/19) and 99.1% (108/109). For IgG, a titer of 5,000 in all the patients showed a sensitivity of 76.2% (16/21) and a specificity of 83.6% (97/116). In vaccinated patients, the corresponding figures for this cut-off were 84.2% (16/19) and 83.5% (91/109), respectively. Although IgM detection against mumps is highly specific, its sensitivity is very low in immunized subjects. In this group, the titration of IgG could serve as an additional diagnostic tool.

Molecular identification of mumps virus genotypes from clinical samples: standardized method of analysis

A sensitive nested reverse transcription-PCR assay, targeting a short fragment of the gene encoding the small hydrophobic protein (SH gene), was developed to allow rapid characterization of mumps virus in clinical samples. The sensitivity and specificity of the assay were established using representative genotypes A, B, C, D, E, and F. Mumps virus RNA was characterized directly from cerebrospinal fluid (CSF) samples and in extracts of mumps virus isolates from patients with various clinical syndromes. Direct sequencing of products and subsequent phylogenetic analysis enabled genetic classification. A simple web-based system of sequence analysis was established. The study also allowed characterization of mumps virus strains from Argentina as part of a new subgenotype. This PCR assay for characterization of mumps infections coupled to a web-based analytical program provides a rapid method for identification of known and novel strains.

Rapid and sensitive detection of mumps virus RNA directly from clinical samples by real-time PCR

A rapid, sensitive, and specific assay to detect mumps virus RNA directly from clinical specimens using a real-time PCR assay was developed. The assay was capable of detecting five copies of standard plasmid containing cDNA from the mumps virus F gene. No cross-reactions were observed with other members of Paramyxoviridae, or with viruses or bacteria known to be meningitis pathogens. Seventy-three clinical samples consisting of throat swabs collected from patients with parotitis, and cerebrospinal fluid (CSF) collected from patients with aseptic meningitis, were examined with a real-time PCR assay developed by the authors, reverse-transcription nested-PCR (RT-n-PCR), and virus isolation using cell culture. Like the RT-n-PCR assay, the real-time PCR assay could detect mumps virus RNA in approximately 70% of both throat swabs and CSF samples, while, by tissue culture, mumps virus was isolated from only approximately 20% of CSF and 50% of throat swab samples. In addition, the real-time PCR assay could be developed easily into a quantitative assay for clinical specimens containing more than 1,800 copies of mumps virus RNA/ml by using serial dilutions of the standard plasmid. The results suggest that the real-time PCR assay is useful for identification of mumps virus infections, not only in typical cases, but also in suspected cases, which show only symptoms of meningitis or encephalitis.

A case of mumps conjunctivitis: detection of the virus RNA by nested PCR in tear sample

Mumps is a disease caused by a virus that can infect many parts of the body, especially the parotid salivary glands. A case of epidemic parotitis in an adult female affected by bilateral conjunctivitis is presented. Mumps virus was detected in tear samples by reverse transcription nested polymerase chain reaction (RT-n-PCR). The conjunctivitis resolved completely within 11 d.

Rapid and quantitative detection of mumps virus RNA by one-step real-time RT-PCR

We developed a new TaqMan-based one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for detection and quantification of mumps virus RNA. Oligos targeting the matrix protein gene of mumps virus were designed by using our oligo designing and analyzing software, Oligoware 1.0. Oligos's specificity was tested with 5 strains (4 laboratory isolated and 1 Jeryl Lynn strain) of mumps virus. The suggested TaqMan-based one-step real-time RT-PCR assay correctly detected the 4 laboratory-isolated strains and 1 Jeryl Lynn strain. To confirm the specificity of the TaqMan PCR assay, parainfluenza type 1, 2, 3 strains, sendai virus, and measles virus (vaccine strain) were tested, and no cross-reactivity was observed between mumps and tested strains. In addition, a BLAST (NCBI) search showed no genomic cross-reactivity with other viruses or cells. Testing of the assay's reproducibility was repeated several times, and the same results were achieved. The new assay was able to quantify the concentrations of mumps virus gene ranging from 10(1) to 10(8) copies per reaction sensitively with generated plasmid standards. In addition, it was shown that a significant correlation (R2 = 0.9564) between genome number as determined by one-step real-time RT-PCR and the corresponding number of plaque in paired samples was found with regression analysis. The results of one-step real-time RT-PCR assay also corresponded well to those of nested PCR. We conclude that our one-step real-time RT-PCR assay is a reliable, specific, and sensitive tool for the diagnosis of mumps virus. We consider that these results come from highly conserved primers and probe set that were designed with Oligoware 1.0.

Molecular analysis of cerebrospinal fluid in viral diseases of the central nervous system

The use of nucleic acid (NA) amplification techniques has transformed the diagnosis of viral infections of the central nervous system (CNS). Because of their enhanced sensitivity, these methods enable detection of even low amounts of viral genomes in cerebrospinal fluid. Following more than 10 years of experience, the polymerase chain reaction or other NA-based amplification techniques are nowadays performed in most diagnostic laboratories and have become the test of choice for the diagnosis of several viral CNS infections, such as herpes encephalitis, enterovirus meningitis and other viral infections occurring in human immunodeficiency virus-infected persons. Furthermore, they have been useful to establish a viral etiology in neurological syndromes of dubious origin and to recognise unusual or poorly characterised CNS diseases. Quantitative methods have provided a valuable additional tool for clinical management of these diseases, whereas post-amplification techniques have enabled precise genome characterisation. Current efforts are aiming at further improvement of the diagnostic efficiency of molecular techniques, their speed and standardisation, and to reduce the costs. The most relevant NA amplification strategies and clinical applications of to date will be the object of this review.

Molecular Techniques in the Diagnosis of Central Nervous System Infections

Development of polymerase chain reaction (PCR)-based molecular techniques has initiated a revolution in the field of diagnostic microbiology. These techniques have not only provided rapid, noninvasive detection of microorganisms that cause central nervous system (CNS) infections, but have also demonstrated that several neurologic disorders are linked to infectious agents. While PCR-based techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations, as well as strengths, of these techniques must be clearly understood by both clinicians and laboratory personnel to ensure proper utilization.