Treatment of potentially life-threatening enterovirus infections with pleconaril

Antiviral therapy for respiratory tract infections

Viruses are important pathogens causing respiratory tract infections both in the community and health‐care facility settings. They are extremely common causes of morbidity in the competent hosts and some are associated with significant mortality in the compromised individuals. With wider application of molecular techniques, novel viruses are being described and old viruses are found to have new significance in different epidemiological and clinical settings. Some of these emerging pathogens may have the potential to cause pandemics or global spread of a severe disease, as exemplified by severe acute respiratory syndrome and avian influenza. Antiviral therapy of viral respiratory infections is often unnecessary in the competent hosts because most of them are self‐limiting and effective agents are not always available. In the immunocompromised individuals or for infections caused by highly pathogenic viruses, such as avian influenza viruses (AIV), antiviral treatment is highly desirable, despite the fact that many of the agents may not have undergone stringent clinical trials. In immunocompetent hosts, antiviral therapy can be stopped early because adaptive immune response can usually be mounted within 5–14 days. However, the duration of antiviral therapy in immunosuppressed hosts depends on clinical and radiological resolution, the degree and duration of immunosuppression, and therefore maintenance therapy is sometimes needed after the initial response. Immunotherapy and immunoprophylaxis appear to be promising directions for future research. Appropriate and targeted immunomodulation may play an important adjunctive role in some of these infections by limiting the extent of end‐organ damage and multi‐organ failure in some fulminant infections.

Hypogammaglobulinaemia

This article reviews the primary immunodeficiencies that result in hypogammaglobulinemia or predominantly antibody deficiency disorders. This group makes up the largest proportion of patients with primary immunodeficiency. Significant advances have been made in understanding the molecular basis and clinical characteristics of patients with the more severe forms of antibody deficiency in the last 6 years. Recognition of these disorders remains poor with significant diagnostic delay. The milder forms of antibody deficiency disorders, especially those with normal total serum immunoglobulin G levels, remain poorly characterized and understood. Further work remains to be done in understanding and recognizing these syndromes to benefit patient care and foster further knowledge of the immune system.

Enterovirus-associated encephalitis in the California encephalitis project, 1998-2005

BACKGROUND

Encephalitis is a relatively rare presentation of enterovirus (EV) infections. Clinical and epidemiologic characteristics of EV encephalitis (EVE) have not been well characterized.

METHODS

Patients with encephalitis enrolled in the California Encephalitis Project from 1998 to 2005 were tested for a range of pathogens, including EV, using a standardized diagnostic algorithm. EVE was categorized as "confirmed" (EV detected in cerebrospinal fluid [CSF] or brain tissue) or "possible" (EV found in respiratory or fecal specimens or serum EV immunoglobulin [Ig] M detected). We compared clinical and epidemiologic characteristics of EVE with those of other infectious encephalitis cases.

RESULTS

EVE was diagnosed in 73 (4.6%) of 1571 patients (45 confirmed cases, 28 possible cases); 11.1% of cases had other infectious causes. Patients with confirmed EVE were younger, although 27% were adults, who presented with significantly less severe symptoms. Serotypes identified in EVE cases correlated with the predominant serotype for the given year reported to the National Enterovirus Surveillance System at the Centers for Disease Control and Prevention. Two of 4 fatal EVE cases were associated with EV71.

CONCLUSION

EVs are an important cause of encephalitis cases requiring hospitalization, in both children and adults. Our data suggest that EVE severity varies by serotype, confirm the importance of CSF/brain tissue polymerase chain reaction, and demonstrate that serum IgM findings are of little value in diagnosing EVE.

Selective inhibitors of picornavirus replication

Picornaviruses cover a large family of pathogens that have a major impact on human but also on veterinary health. Although most infections in man subside mildly or asymptomatically, picornaviruses can also be responsible for severe, potentially life-threatening disease. To date, no therapy has been approved for the treatment of picornavirus infections. However, efforts to develop an antiviral that is effective in treating picornavirus-associated diseases are ongoing. In 2007, Schering-Plough, under license of ViroPharma, completed a phase II clinical trial with Pleconaril, a drug that was originally rejected by the FDA after a New Drug Application in 2001. Rupintrivir, a rhinovirus protease inhibitor developed at Pfizer, reached clinical trials but was recently halted from further development. Finally, Biota's HRV drug BTA-798 is scheduled for phase II trials in 2008. Several key steps in the picornaviral replication cycle, involving structural as well as non-structural proteins, have been identified as valuable targets for inhibition. The current review aims to highlight the most important developments during the past decades in the search for antivirals against picornaviruses.

Aseptic meningitis and viral myelitis

Meningitis and myelitis represent common and very infrequent viral infections of the central nervous system, respectively. The number of cases of viral meningitis that occurs annually exceeds the total number of meningitis cases caused by all other etiologies combined. Focal central nervous system infections, such as occur in the spinal cord with viral myelitis, are much less common and may be confused with noninfectious disorders that cause acute flaccid paralysis. This article reviews some of the important clinical features, epidemiology, diagnostic approaches, and management strategies for patients with aseptic meningitis and viral myelitis. Particular focus is placed on the diseases caused by enteroviruses, which as a group account for most aseptic meningitis cases and many focal infections of the spinal cord.

Antibody deficiency: Table 1

Antibody deficiencies may arise as primary disorders or secondary to a variety of diseases, drugs and other environmental/iatrogenic factors. Significant primary antibody deficiencies are relatively rare but, collectively, account for the majority of primary immunodeficiency syndromes encountered in clinical practice. The genetic basis of a number of primary deficiencies has been clarified, although there is considerable genotype/phenotype heterogeneity and the role of gene/environment interactions has yet to be fully elucidated. Primary antibody deficiency can present at any age. The hallmark clinical presentation is recurrent bacterial infection, but these disorders are also associated with a wide variety of other infectious and non-infectious complications and with a high incidence of chronic, structural tissue damage, particularly in the respiratory tract. Clinical recognition of primary antibody deficiency is frequently delayed with consequent increased morbidity, diminished quality of life and early mortality. Clinical laboratories can contribute to improved and timely detection through awareness of routine test results which may be overtly or indirectly suggestive of antibody deficiency. Secondary deficiency is associated with increased awareness, better recognition and earlier diagnosis than in primary disorders. Early liaison and referral of patients with suspected antibody deficiency for specialist opinion and prompt, appropriate therapy is central to the achievement of good clinical outcomes.

Update in the diagnosis and management of central nervous system infections

Central nervous system (CNS) infections presenting to the emergency room include meningitis, encephalitis, brain and spinal epidural abscess, subdural empyema, and ventriculitis. These conditions often require admission to an intensive care unit (ICU) and are complications of ICU patients with neurologic injury, contributing significantly to morbidity and mortality. Reducing morbidity and mortality is critically dependent on rapid diagnosis and, perhaps more importantly, on the timely initiation of appropriate antimicrobial therapy. New insights into the role of inflammation and the immune response in CNS infections have contributed to development of new diagnostic strategies using markers of inflammation, and to the study of agents with focused immunomodulatory activity, which may lead to further adjunctive therapy in human disease.

Potential use of antiviral agents in polio eradication

In 1988, the World Health Assembly launched the Global Polio Eradication Initiative, which aimed to use large-scale vaccination with the oral vaccine to eradicate polio worldwide by the year 2000. Although important progress has been made, polio remains endemic in several countries. Also, the current control measures will likely be inadequate to deal with problems that may arise in the postpolio era. A panel convoked by the National Research Council concluded that the use of antiviral drugs may be essential in the polio eradication strategy. We here report on a comparative study of the antipoliovirus activity of a selection of molecules that have previously been reported to be inhibitors of picornavirus replication and discuss their potential use, alone or in combination, for the treatment or prophylaxis of poliovirus infection.

Synthesis and anti-CVB 3 evaluation of substituted 5-nitro-2-phenoxybenzonitriles

The synthesis and SAR of a series of 60 substituted 2-phenoxy-5-nitrobenzonitriles (analogues of MDL-860) as inhibitors of enterovirus replication (in particular of coxsackievirus B3 (CVB 3)) are reported. Several of the analogues inhibited CVB 3 and other enteroviruses at low-micromolar concentrations.

Potential use of antiviral agents in polio eradication

In 1988, the World Health Assembly launched the Global Polio Eradication Initiative, which aimed to use large-scale vaccination with the oral vaccine to eradicate polio worldwide by the year 2000. Although important progress has been made, polio remains endemic in several countries. Also, the current control measures will likely be inadequate to deal with problems that may arise in the postpolio era. A panel convoked by the National Research Council concluded that the use of antiviral drugs may be essential in the polio eradication strategy. We here report on a comparative study of the antipoliovirus activity of a selection of molecules that have previously been reported to be inhibitors of picornavirus replication and discuss their potential use, alone or in combination, for the treatment or prophylaxis of poliovirus infection.

Fatal coxsackievirus A-16 pneumonitis in adult

Coxsackievirus A-16 (CVA-16) is the agent of hand, foot, and mouth disease in children. We report a case of fatal pneumonitis in an adult due to a CVA-16 strain with a low (78.6%) rate of sequence homology with the reference strain. A modified, more virulent, strain of CVA-16 could be emerging.

Outbreak of Neurologic Enterovirus Type 71 Disease: A Diagnostic Challenge

BACKGROUND

Similar to poliovirus, enterovirus type 71 (EV71) causes severe disease, including aseptic meningitis, encephalitis, acute flaccid paralysis, and acute cardiopulmonary dysfunction. Large epidemics of EV71 infection have been reported worldwide.

METHODS

After recognition of a cluster of cases of EV71 disease, we reviewed records of patients with EV71 disease who required hospitalization at The Children's Hospital in Denver, Colorado, from 2003 through 2005. The presence of enterovirus was detected by reverse-transcriptase polymerase chain reaction (PCR) and/or viral culture of specimens from multiple sources, and the virus was typed as EV71 using genetic sequencing.

RESULTS

Eight cases of EV71 disease were identified in both 2003 and 2005. Fifty-six percent of patients with EV71 disease were < or = 6 months of age (range, 4 weeks to 9 years). All 16 patients had EV71 central nervous system infection. Enterovirus PCR (EV-PCR) of cerebrospinal fluid specimens yielded positive results for only 5 (31.2%) of the 16 patients; all of these patients were < 4 months of age and had less severe disease. However, EV-PCR of upper respiratory tract specimens yielded positive results for 8 (100%) of 8 patients, and EV-PCR of lower gastrointestinal tract specimens yielded positive results for 7 (87.5%) of 8 patients.

CONCLUSIONS

An outbreak of neurologic EV71 disease occurred in Denver, Colorado, during 2003 and 2005. Likely, EV71 disease remains unrecognized in other parts of the United States, because EV-PCR of cerebrospinal fluid frequently yields negative results. EV-PCR of specimens from the respiratory and gastrointestinal tracts had higher diagnostic yields than did EV-PCR of cerebrospinal fluid. EV71 infection should be considered in young children presenting with aseptic meningitis, encephalitis, acute flaccid paralysis, or acute cardiopulmonary collapse. EV71 infection may be an underrecognized emerging disease in the United States.

A case report of a premature infant with coxsackie B1 meningitis

This case report describes a 36-week gestational age infant diagnosed with coxsackie B1 meningitis at 20 days of age. A head ultrasound 5 days after diagnosis was consistent with cystic periventricular leukomalacia. The scientific literature does not clearly elucidate differences between bacterial and viral infections in infants. When difficulties arise, it is pertinent to consider a viral etiology for the underlying illness and obtain a detailed maternal and infant history focusing on clinical symptoms, seasonality, geographic location, exposure, and incubation period. Polymerase chain reaction is a rapid and sensitive diagnostic test for the identification of enteroviruses in cerebrospinal fluid, blood, urine, and throat specimens and should be performed as part of the general workup in the evaluation of a febrile infant with sepsis. In retrospect, it may have established an earlier diagnosis of meningitis, consequently preventing the unnecessary use of antibiotics, potentially decreasing the length of hospitalization, and eliminating the need for more detailed investigations to rule out other etiological factors. In addition, treatment with pleconaril may have affected the severity of the encephalitis. This article reviews the pathogenesis, clinical manifestations, and differential diagnoses of enteroviral infections, specifically focusing on the prevention, treatment, and prognosis of the disease and the implications for clinical practice.

Virus induces metal-binding proteins and changed trace element balance in the brain during the course of a common human infection (coxsackievirus B3) in mice

Autopsy of the brain has shown a change in trace element balance in some virus-infected individuals, but it is not known whether this event was a result of the infection. In the present study coxsackievirus B3 (CVB3) adapted to Balb/c mice was used to study whether infection induces gene expression of the metal-binding/transporting proteins metallothionein (MT1 and MT3) and divalent-metal transporter 1 (DMT1) and whether it changes the balance of trace elements in the brain. Virus and MT1, MT3, and DMT1 were quantitatively measured by RT-PCR on days 3, 6 and 9 of the infection. Trace elements (13) were measured in serum and the brain by ICP-MS. High numbers of virus were found in the brain on days 3 and 6, but virus counts were decreased and present only in 50% of the mice on day 9. Gene expression of MT1 tended to increase on all days, whereas that of MT3 only showed a minor and not significant increase on day 3. No clear effect was observed in the expression of DMT1. The increase of MT3 was correlated to the brain concentration of Cu. The Cu/Zn ratio in serum increased as a response to the infection. There was a similar decrease in Cd in serum and the brain. On day 6 of the infection, Hg increased in the brain (p<0.05) and was positively correlated to a concomitant decrease (p<0.05) in serum. Virus numbers in the brain were on day 6 positively correlated (p<0.05) to As concentrations. Enteroviral infections may therefore be an underlying factor regarding the changes in essential as well as potentially toxic trace elements in the brain.

Virology of the post-polio syndrome

The three poliovirus serotypes (PVs) cause acute paralytic poliomyelitis. Decades after being hit by polio, survivors may develop a condition known as post-polio syndrome (PPS). PPS is characterized by extreme fatigue, progressing muscular weakness and chronic pain. The pathogenesis is unclear and, thus, empirical therapies are employed. PVs are known to be able to persist in infected host cells both in vitro and in vivo. The understanding of PV genomes has made it possible to set up sensitive and specific molecular tests capable of detecting minute amounts of virus in samples from PPS patients. Current data indicate that complete PV genomes (or genomic fragments) remain present, decades after acute paralysis, in the CNS of these patients. Virus persistence is hypothesized to bring about chronic inflammation, immune-mediated injury and decreased expression of neurotrophic factors. Establishing a pathogenetic link between PV persistence and PPS would be extremely relevant to the development of an etiologic therapy aimed at virus eradication.

Anti-enterovirus activity and structure–activity relationship of a series of 2,6-dihalophenyl-substituted 1H,3H-thiazolo[3,4-a]benzimidazoles

Despite the fact that enteroviruses are implicated in a variety of human diseases, there is no approved therapy for the treatment of enteroviral infections. Here, a series of 2,6-dihalophenyl-substituted 1H,3H-thiazolo[3,4-a]benzimidazoles with anti-enterovirus activity is reported. The compounds elicit potent activity against coxsackievirus A9, echovirus 9 and 11 and all six strains of coxsackievirus B. A structure-activity relationship analysis revealed that the presence of substituents at position 6 of the tricyclic system positively influences the antiviral activity, whereas substitutions at position 7 are less favorable. In particular a 6-trifluoromethyl substitution leads to a substantial improvement of the antiviral activity as compared to the unsubstituted structure. Furthermore, an additional introduction of a 2-Cl, 6-F substitution on the phenyl at C-1 results in a further increase of the antiviral activity. Hence, 1-(2-chloro-6-fluorophenyl)-6-trifluoromethyl-1H,3H-thiazolo[3,4-a]benzimidazole results in a dose-dependent inhibition of viral replication with a 50% effective concentration (EC50) of 0.41 microg/ml without any detectable cytotoxicity at the highest concentration (100 microg/ml) tested.

Coxsackievirus-induced myocarditis: new trends in treatment

Myocarditis is a common inflammatory heart disease in children and young adults that may result in chronically dilated cardiomyopathy. Coxsackievirus B3 is the major etiologic agent of this disease. Current treatments for patients with viral myocarditis are almost entirely supportive. In recent years, some promising therapeutic candidates have emerged, including novel treatments and improvements of existing drugs. Among these are molecules that specially target virus entry, such as pleconaril, WIN 54954 and CAR-Fc; nucleic acid-based antiviral agents that inhibit viral translation and/or transcription, such as antisense oligodeoxynucleotide and short interfering RNA; and immunomodulatory agents that augment the host-protective immune responses to effectively clear viruses from target tissues, including interferons and immunoglobulins. In addition, certain new antiviral strategies, still in the early stages, include modulation of signal transduction pathways responsible for viral replication using enzyme inhibitors, which have revealed potential therapeutic targets for viral myocarditis. Finally, the progress in cellular cardiomyoplasty for end-stage therapy, in particular the preliminary clinical trials, is also discussed with respect to its potential future application.

Status presens of antiviral drugs and strategies: Part II: RNA VIRUSES (EXCEPT RETROVIRUSES)

More than 40 compounds have been formally licensed for clinical use as antiviral drugs, and half of these are used for the treatment of HIV infections. The others have been approved for the therapy of herpesvirus (HSV, VZV, CMV), hepadnavirus (HBV), hepacivirus (HCV) and myxovirus (influenza, RSV) infections. New compounds are in clinical development or under preclinical evaluation, and, again, half of these are targeting HIV infections. Yet, quite a number of important viral pathogens (i.e. HPV, HCV, hemorrhagic fever viruses) remain in need of effective and/or improved antiviral therapies.

Viruses and Viral Diseases

More than 40 compounds have been formally licensed for clinical use as antiviral drugs, and half of these are used for the treatment of human immunodeficiency virus (HIV) infections. The others have been approved for the therapy of herpesvirus (herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV)), hepadnavirus (hepatitis B virus (HBV)), hepacivirus (hepatitis C virus (HCV)), and myxovirus (influenza, respiratory synctural virus (RSV)) infections. New compounds are in clinical development or under preclinical evaluation, and, again, half of these target HIV infections. Yet, quite a number of important viral pathogens (i.e., human papilloma virus (HPV), HCV, hemorrhagic fever viruses) remain in need of effective and/or improved antiviral therapies.

Chronic Rhinoviral Infection in Lung Transplant Recipients

RATIONALE

Lung transplant recipients are particularly at risk of complications from rhinovirus, the most frequent respiratory virus circulating in the community.

OBJECTIVES

To determine whether lung transplant recipients can be chronically infected by rhinovirus and the potential clinical impact.

METHODS

We first identified an index case, in which rhinovirus was isolated repeatedly, and conducted detailed molecular analysis to determine whether this was related to a unique strain or to re-infection episodes. Transbronchial biopsies were used to assess the presence of rhinovirus in the lung parenchyma. The incidence of chronic rhinoviral infections and potential clinical impact was assessed prospectively in a cohort of 68 lung transplant recipients during 19 mo by screening of bronchoalveolar lavages.

MEASUREMENTS AND MAIN RESULTS

We describe 3 lung transplant recipients with graft dysfunctions in whom rhinovirus was identified by reverse transcriptase-polymerase chain reaction in upper and lower respiratory specimens over a 12-mo period. In two cases, rhinovirus was repeatedly isolated in culture. The persistence of a unique strain in each case was confirmed by sequence analysis of the 5'NCR and VP1 gene. In the index case, rhinovirus was detected in the lower respiratory parenchyma. In the cohort of lung transplant recipients, rhinoviral infections were documented in bronchoalveolar lavage specimens of 10 recipients, and 2 presented with a persistent infection.

CONCLUSIONS

Rhinoviral infection can be persistent in lung transplant recipients with graft dysfunction, and the virus can be detected in the lung parenchyma. Given the potential clinical impact, chronic rhinoviral infection needs to be considered in lung transplant recipients.

Enteroviral meningitis: natural history and outcome of pleconaril therapy

Enteroviral meningitis causes appreciable morbidity in adults, including hospitalization, decreased activity, and headache. Limited data define the natural history of disease. No antiviral therapeutic agent has demonstrated improved outcome in controlled clinical trials. Pleconaril, an inhibitor of enterovirus replication, was tested in two placebo-controlled clinical trials. Of 607 randomized patients in a multicenter, double-blind placebo-controlled study of pleconaril (200 mg three times daily versus an identical-appearing placebo), 240 patients were confirmed to have enterovirus infection. The time to headache resolution was evaluated by using Kaplan-Meier survival methodology. A Cox regression model evaluated multivariate factors associated with disease resolution. Resolution of headache in patients with concomitant moderate to severe nausea at baseline occurred at a median of 9.5 days in the absence of therapy and was reduced to 7.0 days for pleconaril recipients (P = 0.009). For a headache score of > 5 alone, treated patients resolved headache significantly more rapidly (P = 0.005). Males resolved headache 50% faster than females. Regardless of randomization group, patients with a baseline headache score of 5 or greater resolved headache 50% more slowly than patients with a baseline headache score of 4. No differences in either clinical or laboratory adverse events were noted. Over 50% of untreated patients had a persistent headache that was greater than 1 week in duration. Pleconaril shortened the course of illness compared to placebo recipients, especially in the early disease course. However, the benefit was achieved only modestly in a subgroup analysis of patients with more severe disease after adjusting for confounding variables.

Clinical and diagnostic findings of an echovirus meningitis outbreak in the north west of England

INTRODUCTION

An outbreak of echovirus meningitis occurred in the north west of England in 2001. This paper reviewed the clinical features and the role of different diagnostic methods.

METHODS

This was a prospective study of adults admitted to a regional infectious disease unit with a probable diagnosis of meningitis, March to August 2001.

RESULTS

Half the 40 cases were male; median age was 28 (range 16-51) years. Fifteen of 38 (39.5%) were smokers, and 20 of 24 (83.3%) had close contact with children. Median (range) duration of symptoms was 1.1 (0.25-7) days. Symptoms included headache (100%), photophobia (87.5%), and nausea (67.5%), and severity ranged from minimal signs to those consistent with a meningoencephalitis. The diagnosis was confirmed virologically in 29 of 40 (72%); echovirus 30 was isolated from six. Cerebrospinal fluid (CSF) enterovirus polymerase chain reaction (PCR) was positive in 26 of 32 (81%), and CSF virus culture in 3 of 16 (19%). Thirty one per cent of CSF samples had a neutrophil predominance, and 3 of 29 (10%) virologically confirmed cases had normal CSF microscopy and biochemistry.

CONCLUSION

CSF microscopy may be normal or suggest bacterial meningitis in a substantial minority of cases of echovirus meningitis. CSF PCR for enterovirus seems to be more sensitive than virus culture of CSF, although PCR does not yield information on circulating virus type. Early and accurate diagnosis could reduce both use of parenteral antibiotics and length of hospital stay with both morbidity and cost implications. Close contact with children may be a risk factor, particularly if good hygiene measures are not practised.

Infection-associated encephalopathies: their investigation, diagnosis, and treatment

Reduced level of consciousness is a common clinical finding in acutely sick patients. In the majority of cases a cause for the encephalopathy is readily identifiable,whilst in a minority the aetiology is more difficult to ascertain. Frequently the onset of encephalopathy is associated with, or follows, infection. The mechanisms through which infection leads to encephalopathy are diverse. They range from direct microbial invasion of the brain or its supporting structures, to remote, infection-triggered mechanisms such as acute disseminated encephalomyelitis. Most common however, is the encephalopathy caused through a remote effect of systemic sepsis-septic encephalopathy. This article discusses the clinical presentation and underlying pathogeneses of the acute encephalopathies associated with infection, aiming to aid both their recognition and treatment.

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.

Investigation of treatment failure in neonatal echovirus 7 infection

We describe a case of fatal neonatal enteroviral infection caused by echovirus 7. Multiple treatments, including specific antiviral therapy, were attempted and failed. Studies of the viral isolate, maternal plasma, intravenous immunoglobulin preparations and pleconaril were performed to identify potential causes for treatment failure.

National Institutes of Health-sponsored workshop on inflammation and immunity in dilated cardiomyopathy

Nonischemic dilated cardiomyopathy (DCM) is an uncommon cause of heart failure but has widespread importance because it is the cause of 45% of heart transplantations. Multiple experimental and clinical lines of evidence have implicated altered immunity in the pathogenesis of DCM. However, advances in the understanding of the mechanisms of altered immunity have not affected the diagnosis or treatment of DCM. In recognition of this problem, the National Institutes of Health sponsored an expert workshop with 2 aims: to review the current understanding of inflammation and immunity as they relate to DCM and to identify the most promising areas for future clinical research efforts in the field. This report summarizes the scientific opportunities, perceived needs and barriers, and workshop recommendations on research directions in DCM. The major recommendations from the members of the workshop are organized according to the following themes: cardiotropic viruses, innate and acquired immune responses, environmental factors, novel diagnostics, and novel therapeutics.

A guided tour through the antiviral drug field

Approximately 40 compounds have been formally licensed for clinical use as antiviral drugs, with half of these in use for the treatment of HIV infections. The remaining have been approved for use in the therapy of herpes virus (herpes simplex virus, varicella zoster virus and cytomegalovirus), hepadnavirus, hepacivirus and myxovirus (influenza and respiratory syncytial virus) infections. New compounds are in clinical development or under preclinical evaluation, and again, half of these are intended to target HIV infections. However, quite a number of important viral pathogens (i.e., human papillomavirus, hepatitis C virus and hemorrhagic fever viruses) remain in need of effective and/or improved antiviral therapies.

Few but severe viral infections in children with cancer: a prospective RT-PCR and PCR-based 12-month study

BACKGROUND

Treatment of low-risk febrile episodes with oral administered antibiotics at home is a new approach in pediatric oncology and protective isolation is loosened in more centers. The impact of viral respiratory infections in febrile diseases in this population is still unclear in terms of occurrence and morbidity.

PROCEDURE

A prospective follow-up study of all febrile episodes during 12 months in a pediatric oncology department with a high level of protective isolation was set-up with expanded molecular viral examinations. Reverse transcriptase polymerase chain reaction (RT-PCR) and PCR diagnostics of ten viruses, two atypical bacteria, and one fungus were performed and clinical information on all infections was registered.

RESULTS

A total of 250 febrile episodes in 66 patients were registered. In all, 198 respiratory secretions, predominantly oral washes, and 165 anal swabs were analyzed. Twenty-two infections were diagnosed: 7 rhinovirus infections, 4 respiratory syncytial virus (RSV) infections, 2 herpes simplex virus (HSV) infections, 2 varicella-zoster-virus (VZV) infections, 1 influenza B virus infection, 1 parainfluenza virus type 3 infection (PIV3), 1 human metapneumovirus (HMPV) infection, 1 enterovirus infection, 0 adenovirus infections, 0 influenza A virus infections, and 3 non-viral pneumonias: 1 M. Pneumonia, 1 C. Pneumonia, and 1 P. Carinii. The detected pathogens correlated well to the clinical disease. Patients with viral infections were as affected as patients with bacteria in the blood. One of 19 viral infections was lethal, a RSV pneumonia. C-reactive protein concentrations were not able to distinguish viral infections from bacteremias.

CONCLUSIONS

The applied sampling method was acceptable and molecular diagnosis of viruses, atypical bacteria and P. Carinii increased the microbiological verification of infections by 35%. Viral infections were few in our protected population but caused severe infectious complications in these patients.

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

BACKGROUND

Detection of enteroviral nucleic acid in cerebrospinal fluid (CSF) specimens has been demonstrated to improve the management of patients with aseptic meningitis.

OBJECTIVE

To develop on the LightCycler (LC) instrument a real-time RT-PCR assay based on TaqMan technology for the detection of enteroviruses (EV) in cerebrospinal fluid (CSF) specimens.

STUDY DESIGN

After evaluation of the analytical performances, seventy-four CSF samples collected prospectively from patients who have been suspected for a clinical diagnosis of meningitis were evaluated by two LC real-time RT-PCR assays and one conventional RT-PCR assay.

RESULTS

Our assay detected all 30 different EV species tested, whereas no reactivity was observed with other neurotropic viruses. The analytical sensitivity of both LC RT-PCR real-time assays was 1 TCID50 for LC one-step and two-step RT-PCR assays. Results for LC one-step and LC two-step RT-PCR were compared to results of the conventional RT-PCR: of the 74 CSF specimens tested, 11 were positive and 56 were negative by all methods. Four other specimens were positive for EV by at least two of the methods (including the LC two-step RT-PCR and the conventional RT-PCR), two other CSF specimens were positive by the LC two-step RT-PCR assay only, and another one CSF specimen was positive by the LC one-step RT-PCR assay only. No CSF specimens were negative by the LC two-step RT-PCR assay and positive by the conventional RT-PCR assay. The sensitivity, specificity, positive and negative predictive values of both LC RT-PCR assays by using conventional RT-PCR as the "gold standard" were, respectively, 73.3, 98.3, 91.7, 93.5% for the LC one-step RT-PCR and 100, 96.6, 88.2, 100% for the LC two-step RT-PCR. There was substantial agreement between the three assays (k=0.80).

CONCLUSIONS

The LC two-step RT-PCR assay is a rapid, sensitive and reliable method which can be routinely performed with CSF samples for diagnosis of EV infection and is an important improvement for optimal patient management.

Human enterovirus isolates from an outbreak typed using heteroduplex mobility analysis

Genotyping and serotyping of enteroviruses is important for epidemiological, prognostic, and therapeutic reasons. In this study clinical isolates of enterovirus 71 during an outbreak of childhood meningoencephalitis in Sydney, Australia were identified using heteroduplex mobility analysis (HMA) of products from RT-PCR amplification of the 5' untranslated region. Five enterovirus 71 isolates shared identical heteroduplex patterns and nucleotide sequences in the 5' untranslated region. A sixth isolate exhibited minor differences in heteroduplex pattern and sequencing confirmed the isolate varied by 1% at the nucleotide level. The use of multiple reference strains and the analysis of heteroduplex patterns increased the confidence of isolate identification, and allowed identification of strain variation which could be subsequently further analyzed using sequencing. HMA can be used to accurately distinguish identical and variant isolates derived from sporadic cases and clustered infections with enteroviruses, including those causing serious infections.

Pediatric central nervous system infections and inflammatory white matter disease

This article reviews the immunology of the central nervous system and the clinical presentation, diagnosis, and treatment of children with viral or parainfectious encephalitis. The emphasis is on the early recognition of treatable causes of viral encephalitis (herpes simplex virus), and the diagnosis and treatment of acute disseminated encephalomyelitis are described in detail. Laboratory and imaging findings in the two conditions also are described.

Quantitative PCR-enhanced immunoassay for measurement of enteroviral immunoglobulin M antibody and diagnosis of aseptic meningitis

A PCR-enhanced immunoassay (PIA) to detect enterovirus (EV) immunoglobulin M (IgM) for diagnosis of recent EV infection was recently developed. This test was compared with another EV IgM capture technique, the solid-phase reverse immunosorbent test (SPRIST). Fourteen of 43 serum samples from aseptic meningitis patients were positive by PIA, whereas 10 were positive by SPRIST. One of 39 control serum samples was weakly positive by PIA. A single-serum-dilution real-time PCR-based PIA for EV IgM (quantitative PIA [QPIA]) was also developed and evaluated against PIA, SPRIST, an EV IgM radioimmunoassay (RIA), and clinical data. A mixture of 12 EVs was used as the antigen. Results from investigating four groups of serum samples were as follows. (i) The nine PIA-positive serum samples in group 1 were all positive by QPIA. (ii) Group 2 consisted of 59 serum samples from aseptic meningitis patients. Nineteen of 30 serum samples (63%) taken at hospital admission were positive by QPIA. Of these, 17 were positive in EV PCR. (iii) None of the 30 control serum samples in group 3 were positive by QPIA. (iv) For the 24 serum samples in group 4, of which 11 were positive and 13 were negative by RIA, the QPIA results were completely concordant. The sensitivity and specificity of QPIA for diagnosis of EV infection were 70 and 80%, respectively. QPIA provides a rational strategy for the detection of EV IgM, allows the use of viral antigens with minimal purification, and needs no virus-specific reagents apart from those in the PCR. QPIA is a generally applicable method for the detection of viral IgM in IgM capture assays.

Detection of viral deoxyribonucleic acid in amniotic fluid: association with fetal malformation and pregnancy abnormalities

OBJECTIVE

To first test the hypothesis that the presence of viral nucleic acid in amniotic fluid (AF) is associated with an abnormal pregnancy outcome, and second, to determine if the overall rate of polymerase chain reaction (PCR) positivity and the distribution of virus types vary geographically.

STUDY DESIGN

Cytomegalovirus (CMV), parvovirus B19, adenovirus, enterovirus, herpes simplex virus, Epstein-Barr virus, and respiratory syncytial virus nucleic acids were sought in 423 AF samples obtained for clinical indications: 284 from the East Coast (EC) and 139 from the Midwest (MW).

RESULTS

Gestational age at sampling was 19.1 weeks for EC and 20.1 weeks for MW. 13.5% of karyotypically normal singleton pregnancies (57/423) had a positive AF PCR. 11% of AF PCR from the EC while 18% of AF PCR from the MW were positive (p = 0.06). The most commonly detected viruses were adenovirus (77%), enterovirus (12%), and CMV and parvovirus B19 (5% each). Twenty-four percent of sonographically abnormal pregnancies (33/136) had a positive AF PCR compared to only 8.4% (24/287) of normal pregnancies (p < 0.001).

CONCLUSION

A positive AF PCR is associated with an increased rate of fetal structural malformations, intrauterine growth restriction, hydrops and other fetal abnormalities. There were no significant geographic differences in the incidence of AF viral PCR positivity.

In vitro antiviral activity and single-dose pharmacokinetics in humans of a novel, orally bioavailable inhibitor of human rhinovirus 3C protease

(E)-(S)-4-((S)-2-{3-[(5-methyl-isoxazole-3-carbonyl)-amino]-2-oxo-2H-pyridin-1-yl}-pent-4-ynoylamino)-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester (Compound 1) is a novel, irreversible inhibitor of human rhinovirus (HRV) 3C protease {inactivation rate constant (Kobs/[I]) of 223,000 M-1s-1}. In cell-based assays, Compound 1 was active against all HRV serotypes (35 of 35), HRV clinical isolates (5 of 5), and related picornaviruses (8 of 8) tested with mean 50% effective concentration (EC50) values of 50 nM (range, 14 to 122 nM), 77 nM (range, 72 to 89 nM), and 75 nM (range, 7 to 249 nM), respectively. Compound 1 inhibited HRV 3C-mediated polyprotein processing in infected cells in a concentration-dependent manner, providing direct confirmation that the cell-based antiviral activity is due to inhibition of 3C protease. In vitro and in vivo nonclinical safety studies showed Compound 1 to be without adverse effects at maximum achievable doses. Single oral doses of Compound 1 up to 2,000 mg in healthy volunteers were found to be safe and well tolerated in a phase I-ascending, single-dose study. Compound 1 estimated free observed maximum concentration in plasma (Cmax) for 500-, 1,000-, and 2,000-mg doses were higher than the protein binding-corrected EC50 required to inhibit 80% of the HRV serotypes tested. Treatment of HRV 52-infected cells with one to five 2-h pulses of 150 nM Compound 1 (corresponding to the Cmax at the 500-mg dose) was sufficient to effect a significant reduction in viral replication. These experiments highlight Compound 1 as a potent, orally bioavailable, irreversible inhibitor of HRV 3C protease and provide data that suggest that Cmax rather than the Cmin might be the key variable predicting clinical efficacy.

Frequent detection of respiratory viruses in adult recipients of stem cell transplants with the use of real-time polymerase chain reaction, compared with viral culture

Background. Respiratory virus infections have been recognized as important causes of severe pneumonia in patients who have undergone stem cell transplantation (SCT). Reported incidences of respiratory virus infection in adult SCT recipients vary in the literature from 3.5% to 36% when determined by viral culture. However, a more sensitive method to assess the presence of respiratory viruses in the lower airways may be important for delineation of the true incidence of respiratory virus—associated pneumonia and may be essential for guidance on implementation of antiviral therapy and prevention or limitation of nosocomial spread of infection with respiratory viruses.

Methods. To determine the incidence and severity of respiratory tract illness (RTI) and to assess the diagnostic value of real-time reverse-transcriptase polymerase chain reaction (RT-PCR) versus viral culture, 72 SCT recipients were monitored during a 6-month period.

Results. A respiratory virus was detected in 21% of episodes of RTI by viral culture and in 63% of RTI episodes by real-time RT-PCR (P < .0001). In lower respiratory tract illness, real-time RT-PCR was much more sensitive than viral culture for detection of respiratory virus (73% vs. 9%; P = .008). The mortality rate for patients with respiratory virus—associated lower respiratory tract illness (25%) was similar to rates reported elsewhere. Respiratory viruses (predominantly rhinovirus) were detected by real-time RT-PCR in 9% of samples obtained from symptom-free SCT recipients at predetermined times by real-time RT-PCR and by viral culture in 1% (P < .0001), indicating that asymptomatic shedding of respiratory viruses also occurs.

Conclusion. We conclude that, although asymptomatic shedding of respiratory virus occurs, respiratory viruses are frequent causes of RTI in SCT recipients.

Conservation of amino acids in human rhinovirus 3C protease correlates with broad-spectrum antiviral activity of rupintrivir, a novel human rhinovirus 3C protease inhibitor

The picornavirus 3C protease is required for the majority of proteolytic cleavages that occur during the viral life cycle. Comparisons of published amino acid sequences from 6 human rhinoviruses (HRV) and 20 human enteroviruses (HEV) show considerable variability in the 3C protease-coding region but strict conservation of the catalytic triad residues. Rupintrivir (formerly AG7088) is an irreversible inhibitor of HRV 3C protease with potent in vitro activity against all HRV serotypes (48 of 48), HEV strains (4 of 4), and untyped HRV field isolates (46 of 46) tested. To better understand the relationship between in vitro antiviral activity and 3C protease-rupintrivir binding interactions, we performed nucleotide sequence analyses on an additional 21 HRV serotypes and 11 HRV clinical isolates. Antiviral activity was also determined for 23 HRV clinical isolates and four additional HEV strains. Sequence comparison of 3C proteases (n = 58) show that 13 and 11 of the 14 amino acids that are involved in side chain interactions with rupintrivir are strictly conserved among HRV and HEV, respectively. These sequence analyses are consistent with the comparable in vitro antiviral potencies of rupintrivir against all HRV serotypes, HRV isolates, and HEV strains tested (50% effective concentration range, 3 to 183 nM; n = 125). In summary, the conservation of critical amino acid residues in 3C protease and the observation of potent, broad-spectrum antipicornavirus activity of rupintrivir highlight the advantages of 3C protease as an antiviral target.

Improved diagnosis on a daily basis of enterovirus meningitis using a one-step real-time RT-PCR assay

The detection of the enterovirus genome in cerebrospinal fluid (CSF) by PCR techniques has proved to be more sensitive than traditional cell culture for the diagnosis of enterovirus meningitis. However, PCR assays are time consuming and labor intensive, particularly if separate hybridization steps are used to confirm the specificity of positive findings. The aim of this study was to develop a one-step real-time RT-PCR assay with LightCycler (LC) technology that was sensitive, rapid, and easy to perform in routine practice. The enterovirus detection limit was determined by testing 10-fold limiting dilution series of cell culture stocks with the echovirus 25 (E-25) prototype strain and with the third European Union Quality Control Concerted Action (EU-QCCA) enterovirus proficiency panel. A total of 100 CSF specimens were investigated in a comparative study. With the E-25 strain, the detection limit of the real-time assay was 286 TCID50/ml (50% tissue culture infective dose). When samples of the EU-QCCA panel were tested, our assay gave identical results (detection limit down to 3.6 TCID50/ml) to those of the reference laboratory, which used one-step RT-PCR assay. When CSF specimens were tested, there was a correlation between the real-time assay and the conventional in-house assay in 96 of 100 CSFs tested. This one-step real-time assay allows rapid enterovirus detection in CSF since results are obtained in 3 hr as against 36 hr with the "in-house" RT-PCR assay. This new assay is now being used in routine practice, and allows diagnosis on a daily basis.

Molecular methods for diagnosis of viral encephalitis

Hundreds of viruses cause central nervous system (CNS) disease, including meningoencephalitis and postinfectious encephalomyelitis, in humans. The cerebrospinal fluid (CSF) is abnormal in >90% of cases; however, routine CSF studies only rarely lead to identification of a specific etiologic agent. Diagnosis of viral infections of the CNS has been revolutionized by the advent of new molecular diagnostic technologies to amplify viral nucleic acid from CSF, including PCR, nucleic acid sequence-based amplification, and branched-DNA assay. PCR is ideally suited for identifying fastidious organisms that may be difficult or impossible to culture and has been widely applied for detection of both DNA and RNA viruses in CSF. The technique can be performed rapidly and inexpensively and has become an integral component of diagnostic medical practice in the United States and other developed countries. In addition to its use for identification of etiologic agents of CNS disease in the clinical setting, PCR has also been used to quantitate viral load and monitor duration and adequacy of antiviral drug therapy. PCR has also been applied in the research setting to help discriminate active versus postinfectious immune-mediate disease, identify determinants of drug resistance, and investigate the etiology of neurologic disease of uncertain cause. This review discusses general principles of PCR and reverse transcription-PCR, including qualitative, quantitative, and multiplex techniques, with comment on issues of sensitivity, specificity, and positive and negative predictive values. The application of molecular diagnostic methods for diagnosis of specific infectious entities is reviewed in detail, including viruses for which PCR is of proven efficacy and is widely available, viruses for which PCR is less widely available or for which PCR has unproven sensitivity and specificity, and nonviral entities which can mimic viral CNS disease.

Viral meningitis

Viruses probably account for most cases of acute meningitis. Viral meningitis is often assumed to be a largely benign disease. For the commonest pathogens causing meningitis, enteroviruses, this is usually the case; however, for many of the other pathogens causing viral meningitis, and for common pathogens in the immunocompromised or infants, viral meningitis is frequently associated with substantial neurological complications and a significant mortality. Diagnostic methods for rapid and accurate identification of pathogens have improved over recent years, permitting more precise and earlier diagnoses. There have been fewer developments in therapies for viral meningitis, and there remain no effective therapies for most pathogens, emphasising the importance of prevention and early diagnosis. This review focuses on the presentation, diagnosis and management of viral meningitis and also covers the prevention of meningitis for pathogens where effective vaccines are available.

Antenatal diagnosis of intrauterine infection with coxsackievirus B3 associated with live birth

BACKGROUND: Prior reported cases of stillbirth and neonates infected with enteroviruses suggest transplacental infection. We present a case of fetal infection with coxsackievirus B3, diagnosed antenatally and resulting in live birth. CASE: A pregnant woman presented at 26 weeks with fetal tachycardia and non-immune hydrops fetalis. Coxsackievirus B3 was cultured from amniotic fluid. Maternal antibody to coxsackievirus B3 was positive at 1:512. At 32 weeks, the fetus deteriorated and was delivered. Cord blood antibody to coxsackievirus B3 was positive at a higher titer. Following neonatal death, brain and placental tissues were positive for enterovirus ribonucleic acid by polymerase chain reaction. CONCLUSION: Intrauterine infection by enteroviruses should be considered in the differential diagnosis of non-immune hydrops fetalis. Antenatal diagnosis of coxsackievirus B3 infection is associated with poor outcome.

Antivirals and antiviral strategies

In this article, the usefulness, or potential usefulness, of the currently licensed antiviral drugs and those in clinical or preclinical development is evaluated. The main conclusions are:

For the treatment of polyomavirus, papillomavirus, adenovirus and poxvirus infections, the acyclic nucleoside phosphonates such as cidofovir have the greatest potential.

For the treatment of HSV and VZV infections, (val)acyclovir, famciclovir and brivudin are important.

For the treatment of CMV infections, (val)ganciclovir, cidofovir and foscarnet are the most promising.

Ribavirin is proposed for the treatment of (−)RNA virus (such as arenavirus and bunyavirus) infections, whereas IFN and IFN inducers are envisaged for the treatment of (+)RNA virus infections, particularly picornavirus (for example, coxsackie B) and togavirus (for example, Western, Eastern and Venezuelan equine encephalitis virus) infections.

For the treatment of HCV infections, pegylated IFN, in combination with ribavirin, is currently recommended, although compounds targeted at the HCV protease and RNA-dependent RNA polymerase have also been developed.

For the therapy and prophylaxis of influenza virus infections, the neuraminidase inhibitors zanamivir and oseltamivir are the current drugs of choice.

Among the paramyxoviruses, human metapneumovirus (hMPV) and respiratory syncytial virus (RSV) are the viruses for which antiviral therapy is most required. Although ribavirin is available for the treatment of RSV infections, it is not ideal, and therefore, new compounds are required for the treatment of hMPV and RSV infections.

A plethora of 'old' and 'new' compounds are available or are being developed for the treatment of HIV infections. Multiple drug regimens might be beneficial for HIV treatment.

For other virus infections —rotavirus, and Ebola, Marburg and other haemorrhagic virus infections — the choice of potential antiviral agents is rather limited, however, SAH hydrolase inhibitors such as 3-deazaneplanocin A are currently the most promising.

In recent years, the demand for new antiviral strategies has increased markedly. There are many contributing factors to this increased demand, including the ever-increasing prevalence of chronic viral infections such as HIV and hepatitis B and C, and the emergence of new viruses such as the SARS coronavirus. The potential danger of haemorrhagic fever viruses and eradicated viruses such as variola virus being used as bioterrorist weapons has also increased the profile of antiviral drug discovery. Here, the virus infections for which antiviral therapy is needed and the compounds that are available, or are being developed, for the treatment of these infections are described.