Acute meningoencephalitis caused by adenovirus serotype 26

Viral meningoencephalitis in pediatric solid organ or hematopoietic cell transplant recipients: a diagnostic and therapeutic approach

Neurologic complications, both infectious and non-infectious, are frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. Up to 46% of HCT and 50% of SOT recipients experience a neurological complication, including cerebrovascular accidents, drug toxicities, as well as infections. Defects in innate, adaptive, and humoral immune function among transplant recipients predispose to opportunistic infections, including central nervous system (CNS) disease. CNS infections remain uncommon overall amongst HCT and SOT recipients, compromising approximately 1% of total cases among adult patients. Given the relatively lower number of pediatric transplant recipients, the incidence of CNS disease amongst in this population remains unknown. Although infections comprise a small percentage of the neurological complications that occur post-transplant, the associated morbidity and mortality in an immunosuppressed state makes it imperative to promptly evaluate and aggressively treat a pediatric transplant patient with suspicion for viral meningoencephalitis. This manuscript guides the reader through a broad infectious and non-infectious diagnostic differential in a transplant recipient presenting with altered mentation and fever and thereafter, elaborates on diagnostics and management of viral meningoencephalitis. Hypothetical SOT and HCT patient cases have also been constructed to illustrate the diagnostic and management process in select viral etiologies. Given the unique risk for various opportunistic viral infections resulting in CNS disease among transplant recipients, the manuscript will provide a contemporary review of the epidemiology, risk factors, diagnosis, and management of viral meningoencephalitis in these patients.

Human Adenovirus Entry and Early Events during Infection of Primary Murine Neurons: Immunofluorescence Studies In Vitro

Human adenovirus (HAdV) is a common pathogen, which can lead to various clinical symptoms and-in some cases-central nervous system (CNS) dysfunctions, such as encephalitis and meningitis. Although the initial events of virus entry have already been identified in various cell types, the mechanism of neuronal uptake of adenoviruses is relatively little understood. The aim of this study was to investigate early events during adenoviral infection, in particular to determine the connection between cellular coxsackievirus and adenovirus receptor (CAR), clathrin, caveolin, and early endosomal proteins (EEA1 and Rab5) with the entry of HAdVs into primary murine neurons in vitro. An immunofluorescence assay and confocal microscopy analysis were carried out to determine HAdV4, 5, and 7 correlation with CAR, clathrin, caveolin, and early endosomal proteins in neurons. The quantification of Pearson's coefficient between CAR and HAdVs indicated that the HAdV4 and HAdV5 types correlated with CAR and that the correlation was more substantial for HAdV5. Inhibition of clathrin-mediated endocytosis using chlorpromazine limited the infection with HAdV, whereas inhibition of caveolin-mediated endocytosis did not affect virus entry. Thus, the entry of tested HAdV types into neurons was most likely associated with clathrin but not caveolin. It was also demonstrated that HAdVs correlate with the Rab proteins (EEA1, Rab5) present in early vesicles, and the observed differences in the manner of correlation depended on the serotype of the virus. With our research, we strove to expand knowledge regarding the mechanism of HAdV entry into neurons, which may be beneficial for developing potential therapeutics in the future.

Viral Encephalitis after Hematopoietic Cell Transplantation: A Systematic Review

Viral encephalitis is a rare but serious complication after hematopoietic cell transplantation (HCT). The nonspecific early signs and symptoms and rapid progression can make it difficult to diagnose and treat in a timely fashion. To better inform clinical decision making in post-HCT viral encephalitis, a systematic review of prior studies of viral encephalitis was performed, with the goal of characterizing the frequency of various infectious etiologies and their clinical course, including treatments and outcomes. A systematic review of studies of viral encephalitis was performed. Studies were included if they described a cohort of HCT recipients who were tested for at least 1 pathogen. Of 1613 unique articles initially identified, 68 met the inclusion criteria, with a total of 72,423 patients studied. A total of 778 cases of encephalitis were reported (1.1%). Human herpesvirus 6 (HHV-6) (n = 596), Epstein-Barr virus (n = 76), and cytomegalovirus (n = 33) were the most commonly reported causes of encephalitis, and HHV-6 encephalitis tended to occur the earliest, accounting for most cases prior to day +100 post-transplantation. Of 29,671 patients with available transplantation data, encephalitis was diagnosed in 282 of 4707 (6.0%) cord blood transplantation (CBT) recipients, in 372 of 24,664 (1.5%) non-CBT allogeneic HCT recipients, and in 5 of 300 (1.7%) autologous HCT recipients. Of the 282 CBT encephalitis cases, 270 (95.7%) were caused by HHV-6. Overall, 288 (37.0%) of the 778 patients with encephalitis died, and 75 deaths were attributable to encephalitis, with the time between diagnosis and death ranging from 3 to 192 days. Viral encephalitis occurs in approximately 1% of HCT recipients, and HHV-6 is the most common cause. Mortality following encephalitis in HCT recipients is high, indicating an urgent need for advancement in preventive and therapeutic strategies.

Isolation and molecular characterization of Adenovirus in suspected acute flaccid paralysis patients: A preliminary report from Pakistan

Human adenoviruses (HAdVs) usually cause asymptomatic or mild infection, but infrequently, they are responsible for various severe syndromes including neurological disorders. Various research studies have investigated the association of HAdVs with acute flaccid paralysis (AFP). The purpose of this study was to investigate the genetic diversity of HAdVs and their association with AFP. Stool samples from patients ≤ 12 years of age with suspected AFP were collected from all over Pakistan within the framework of poliovirus surveillance. Poliovirus- and enterovirus-negative samples were screened for HAdVs. For virus isolation, the human epithelial cell line HEp-2c was used, culture-positive samples were screened by nested PCR assay, and partial hexon gene sequences were used for genotype identification. Out of 172 samples, 94 were positive by virus isolation, 89 were positive by PCR, and 32 isolates were genotyped successfully. Phylogenetic analysis showed that the HAdVs belonged to species A (HAdV-A12 and A31), B (HAdV-B3 and B7), C (HAdV-C1 and C6), D (HAdV-D19 and D93), and F (HAdV-F41), showing 99-100% nucleotide sequence identity and 98.3-100% amino acid sequence identity). Most of these genotypes have been reported previously in AFP cases, but this is the first report of the detection of HAdV-D93 in stool samples from AFP cases. The detection of a significant fraction of the HAdVs genotypes indicates that these genetically distinct genotypes are circulating in Pakistan and suggests their possible role in the pathogenesis of AFP.

Vaccines based on replication incompetent Ad26 viral vectors: Standardized template with key considerations for a risk/benefit assessment

Replication-incompetent adenoviral vectors have been under investigation as a platform to carry a variety of transgenes, and express them as a basis for vaccine development. A replication-incompetent adenoviral vector based on human adenovirus type 26 (Ad26) has been evaluated in several clinical trials. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety and features of recombinant viral vector vaccines. This paper reviews features of the Ad26 vectors, including tabulation of safety and risk assessment characteristics of Ad26-based vaccines. In the Ad26 vector, deletion of E1 gene rendering the vector replication incompetent is combined with additional genetic engineering for vaccine manufacturability and transgene expression optimization. These vaccines can be manufactured in mammalian cell lines at scale providing an effective, flexible system for high-yield manufacturing. Ad26 vector vaccines have favorable thermostability profiles, compatible with vaccine supply chains. Safety data are compiled in the Ad26 vaccine safety database version 4.0, with unblinded data from 23 ongoing and completed clinical studies for 3912 participants in five different Ad26-based vaccine programs. Overall, Ad26-based vaccines have been well tolerated, with no significant safety issues identified. Evaluation of Ad26-based vaccines is continuing, with >114,000 participants vaccinated as of 4th September 2020. Extensive evaluation of immunogenicity in humans shows strong, durable humoral and cellular immune responses. Clinical trials have not revealed impact of pre-existing immunity to Ad26 on vaccine immunogenicity, even in the presence of Ad26 neutralizing antibody titers or Ad26-targeting T cell responses at baseline. The first Ad26-based vaccine, against Ebola virus, received marketing authorization from EC on 1st July 2020, as part of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen. New developments based on Ad26 vectors are underway, including a COVID-19 vaccine, which is currently in phase 3 of clinical evaluation.

Adenovirus diseases: a systematic review and meta-analysis of 228 case reports

OBJECTIVE

The clinical characteristics of various adenovirus (ADV) infection are underexplored up till now. To investigate the risk factors, manifestation, current status of ADV species, treatment and prognosis of this disease.

METHODS

We performed a Pubmed and Embase systematic review for case report reporting the ADV infection to analyze the clinical characteristics of disease.

RESULTS

Initial database searched identified articles of which 168 (228 cases) were included in the final analysis. Previous solid organ transplantation [odds ratio (OR) = 3.45, 95% CI 1.31-9.08, P = 0.01], hematopoietic stem cell transplant (OR = 4.24, 95% CI 1.33-13.51, P = 0.01) and hematological malignancy (OR = 4.78, 95% CI 1.70-13.46, P = 0.01) were associated with increased risk of disseminated ADV infection. Use of corticosteroids (OR = 3.86, 95% CI 1.21-12.24, P = 0.02) was a significant risk factor for acquiring urinary tract infections. A total of six species (21 types) of ADV infection have been identified in 100/228 (43.9%) cases. ADV B was the most common species. ADV B species (26/60, 52.0% or 5/41, 12.2% P = 0.001) were more isolated in patients with ADV pneumonia. ADV C (13/15, 86.7% versus 35/86, 40.7% P = 0.001) species were more identified in patients with disseminated disease. The species associated with keratoconjunctivitis is only ADV D in our analysis. Urinary tract ADV infections were observed in ADV A/B/D species. Cidofovir (CDV) (82/228, 36.0%) remained the most commonly antiviral therapy in our cases, followed by ribavirin (15/228, 6.6%), ganciclovir (18/228, 7.9%), and brincidofovir (12/228, 5.3%). Brincidofovir was administered as salvage therapy in 10 cases. Death was reported in 81/228 (35.5%) patients. Mortality rate was higher among patients with gastrointestinal (GI) ADV infection (5/10, 50.0%), ADV pneumonia (20/45, 44.4%) and disseminated ADV infection (53/122, 43.4%).

CONCLUSION

Previous solid organ transplantation, hematopoietic stem cell transplant and hematological malignancy were risk factors for disseminated ADV infection. Use of corticosteroids was significant for urinary tract ADV infection. Different species correlated with different clinical manifestations of infection. Mortality rate was higher among patients with GI disease, pneumonia and disseminated disease. Our review clarified the current treatment of ADV infections, and more treatment required further investigation.

Perspective on Adenoviruses: Epidemiology, Pathogenicity, and Gene Therapy

Human adenoviruses are large (150 MDa) doubled-stranded DNA viruses that cause respiratory infections. These viruses are particularly pathogenic in healthy and immune-compromised individuals, and currently, no adenovirus vaccine is available for the general public. The purpose of this review is to describe (i) the epidemiology and pathogenicity of human adenoviruses, (ii) the biological role of adenovirus vectors in gene therapy applications, and (iii) the potential role of exosomes in adenoviral infections.

Molecular characterization of human adenoviruses in urban wastewaters using next generation and Sanger sequencing

Human adenoviruses (HAdVs) are of major public health importance and are associated with a variety of clinical manifestations, including gastroenteritis, respiratory, ocular and urinary tract infections. To study the occurrence, prevalence and diversity of HAdV species and types circulating in Italy, we conducted a large-scale molecular-epidemiological investigation, a yearlong monitoring of 22 wastewater treatment plants, covering 10 Italian regions, representative of northern, central, and southern Italy. A total of 141 raw sewage samples were collected from January to December 2013, and processed to detect and characterize by phylogenetic analysis a fragment of the hexon coding region of HAdVs. Nested PCR results showed the presence of HAdVs in 85 out of 141 samples (60% of samples). Fifty-nine samples were characterized by conventional Sanger sequencing as belonging to four HAdV species and four types: A (type 12, 5 samples), B (type 3, 8 samples), C (type 5, 1 sample) and F (type 41, 45 samples). The remaining 26 samples could not be characterized because of uninterpretable (mixed) electropherograms suggesting the presence of multiple species and/or types. Pools of characterized and uncharacterized PCR amplicons were further analyzed by next-generation sequencing (NGS). NGS results revealed a marked HAdV diversity with 16 additional types detected beyond the four types found by Sanger sequencing. Overall, 19 types were identified, belonging to HAdV species A-F: types 12 and 31 (species A), type 3 (species B), types 1, 2, and 5 (species C), types 9, 17, 24, 26, 37, 38, 42, 44, 48, and 70 (species D), type 4 (species E), and types 40 and 41(species F). An untypeable HAdV was also detected, showing similar percentages of identity with more than one prototype (types 15, 30, 56, and 59). Our findings documented the circulation of a wide variety of species and types in raw sewage, potentially able to affect other surface water environments and hence human health. Next-generation sequencing proved to be an effective strategy for HAdV genotyping in wastewater samples. It was able to detect a wide range of "less prevalent" types unidentified by conventional Sanger sequencing, confirming that studies based on conventional technologies may grossly underestimate the existence of some, possibly less common, types. Knowledge of the distribution of HAdV species and types would improve our understanding of waterborne HAdV-related health risks.

Adenovirus

Adenoviruses are a highly prevalent infection that can cause a range of clinical syndromes in immunocompromised patients, ranging from localized disease of the respiratory tract, gastrointestinal tract, or urinary tract to disseminated disease. Adenovirus infections may develop in this unique population as the result of primary infection or reactivation of latent virus. Disease can be potentially progressive with high rates of mortality in patients with pneumonia and disseminated disease. Fortunately, cidofovir and its lipid ester, brincidofovir, appear to be effective for the treatment of adenovirus, although neither is specifically approved for this indication. Adenovirus should always be considered when immunocompromised patients present with any clinical syndrome that could be compatible with adenoviral infection. Once disease is suspected, cultures or molecular testing of appropriate specimens should be obtained and blood should be sent for adenovirus polymerase chain reaction (PCR) whenever adenovirus is suspected. Monitoring of quantitative viral loads in blood is helpful in predicting response to therapy with a significant drop (>1 log) associated with a higher probability of clinical response.

Adenovirus: Epidemiology, Global Spread of Novel Serotypes, and Advances in Treatment and Prevention

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

A study on viral CNS inflammation beyond herpes encephalitis

The early diagnosis of herpes simplex virus encephalitis (HSVE) enables induction of antiviral therapy in this potentially life-threatening disease. The study aimed to determine clinical findings including cerebrospinal fluid (CSF) data and MRI imaging in HSVE patients and to identify features distinguishing HSVE from encephalitis of other viral etiologies. We retrospectively reviewed consecutive patients who were diagnosed with viral encephalitis between 2000 and 2014 at the University Hospital Halle. Forty-nine patients with viral encephalitis were identified. A viral etiology could be confirmed by PCR or antibody testing in 22/49 (44.9 %) of patients (15 (30.6 %) HSV, 5 (10.2 %) VZV, 2 (4.1 %) EBV). In HSVE, typical findings were focal slowing in electroencephalophy (EEG) (80 %, p = 0.021) and presence of cortical (86.7 %, p = 0.030) lesions in MRI. Restricted diffusion was particularly helpful in detection of early signal abnormalities in HSVE (p = 0.014). In 27/49 (55.1 %) of patients, no causative agent could be elucidated. In these patients, 15/27 (55.6 %) experienced a rather "benign" disease course with no MRI pathology despite initially HSVE mimicking clinical picture. However, CSF was significantly different showing a higher amount of granulocytes and activated lymphocytes. The remaining 12/27 (44.4 %) patients developed MRI changes consistent with encephalitis, in 4 of these patients, disease course was fatal. Beside PCR-based serology as standard procedure, MRI including diffusion-weighted images and EEG represent additional tools in early HSVE diagnosis. CSF cytology might be particularly supportive in differentiating likely benign forms of encephalitis.

Viral CNS infections in children from a malaria-endemic area of Malawi: a prospective cohort study

Background

Fever with reduced consciousness is an important cause of hospital admission of children in sub-Saharan Africa, with high mortality. Cerebral malaria, diagnosed when acute Plasmodium falciparum infection and coma are recorded with no other apparent reason, is one important cause. We investigated whether viruses could also be an important cause of CNS infection in such patients, and examined the relative contribution of viral pathogens and malaria parasitaemia.

Methods

We did a prospective cohort study in Blantyre, Malawi. From March 1, 2002, to Aug 31, 2004, we enrolled children aged between 2 months and 15 years who were admitted to hospital with suspected non-bacterial CNS infections. Children with a cerebrospinal fluid (CSF) white cell count of less than 1000 cells per μL and negative bacterial microscopy and culture were deemed to have suspected viral CNS infection. Blood was examined for asexual forms of P falciparum. PCR was done on CSF or on post-mortem brain biopsy specimens to detect 15 viruses known to cause CNS infection.

Findings

Full outcome data were available for 513 children with suspected viral CNS infection, of whom 94 (18%) died. 163 children (32%) had P falciparum parasitaemia, of whom 34 (21%) died. At least one virus was detected in the CNS in 133 children (26%), of whom 43 (33%) died. 12 different viruses were detected; adenovirus was the most common, affecting 42 children; mumps, human herpes virus 6, rabies, cytomegalovirus, herpes simplex virus 1, and enterovirus were also important. 45 (9%) of the 513 children had both parasitaemia and viral infection, including 27 (35%) of 78 diagnosed clinically with cerebral malaria. Children with dual infection were more likely to have seizures than were those with parasitaemia alone, viral infection only, or neither (p<0·0001). 17 (38%) of the 45 children with dual infection died, compared with 26 (30%) of 88 with viral infection only, 17 (14%) of 118 with parasitaemia only, and 34 (13%) of 262 with neither (p<0·0001). Logistic regression showed children with a viral CNS infection had a significantly higher mortality than did those who did not have a viral CNS infection (p=0·001).

Interpretation

Viral CNS infections are an important cause of hospital admission and death in children in Malawi, including in children whose coma might be attributed solely to cerebral malaria. Interaction between viral infection and parasitaemia could increase disease severity.

Funding

Wellcome Trust, US National Institutes of Health, and UK Medical Research Council.

Adenovirus infection associated with central nervous system dysfunction in children

BACKGROUND

Adenovirus is a common pathogen in the pediatric population. No reports systemically evaluated central nervous system (CNS) dysfunction associated with adenovirus.

OBJECTIVE

To describe the detailed clinical features of adenovirus-associated CNS dysfunction in children.

STUDY DESIGN

Of 3298 children with a throat virus culture positive for adenovirus treated at a university-affiliated hospital, from January 2000 to June 2008, in northern Taiwan, medical charts were retrospectively reviewed and those with CNS dysfunction were included.

RESULTS

109 (3.3%) children had signs or symptoms of CNS dysfunction on admission. The median age was 3.6 years and 81 (76%) were less than 5 years of age. 64 (59%) were male. The most frequently cited CNS symptoms were seizure (64%), altered state of consciousness (13%), visual hallucination (9.3%) and lethargy (7.5%). The most common diagnoses included febrile seizure (48%), encephalitis (26%), afebrile seizure (11%) and meningitis/meningismus (8.3%). 31 (46%) of 67 patients receiving electroencephalogram examination had abnormal findings and 13 (36%) of 36 with image studies had abnormal findings. Ninety-nine (91%) children returned to normal health, 7 (6.4%) had a sequel of seizure disorder, and 3 (2.7%) had major sequelae and none died. Nine serotypes were identified, with three major serotypes (types 3, 2 and 1).

CONCLUSION

CNS dysfunction was identified in 3.3% of children with adenoviral infection and most occurred in those <5 years old. The clinical prognosis seemed well. However, CNS dysfunction is a potentially serious complication of adenovirus infection in children.

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.

Imaging of central nervous system viral diseases

Viral infections of the central nervous system (CNS) are commonly encountered and there has been continued emergence of new neurotropic viruses which are being frequently recognized. These may present clinically as encephalitis, meningitis, encephalomyelitis, and encephalomyeloradiculitis. The clinical manifestations are usually nonspecific and diagnosis is usually based on the laboratory investigations. Imaging plays a role in its early detection and at times suggests the specific diagnosis that may help in early institution of appropriate therapy. In this review, we summarize the pathology, clinical, and imaging features of the common viral infections that affect the CNS.

Adenoviral infection presenting as an isolated central nervous system disease without detectable viremia in two children after stem cell transplantation

We report two cases of adenoviral meningoencephalitis in children following allogeneic stem cell transplantation. These cases showed four similarities: isolated neurological involvement, infiltrating hyperintensities next to the third ventricle on the cerebral magnetic resonance image, the absence of concomitant detectable adenoviral viremia, and a severe clinical outcome.

Viral encephalitis after allogeneic stem cell transplantation: a rare complication with distinct characteristics of different causative agents

BACKGROUND

Limited data are available on characteristics of viral encephalitis in patients after allogeneic stem cell transplantation.

DESIGN AND METHODS

We analyzed 2,628 patients after allogeneic stem cell transplantation to identify risk factors and characteristics of viral encephalitis.

RESULTS

Viral encephalitis occurred in 32 patients (1.2%, 95% confidence interval 0.8%-1.6%) and was associated with the use of OKT-3 or alemtuzumab for T-cell depletion (P < 0.001) and an increased mortality (P = 0.011) in comparison to patients without viral encephalitis. Detected viruses included human herpesvirus-6 (28%), Epstein-Barr virus (19%), herpes simplex virus (13%), JC virus (9%), varicella zoster virus (6%), cytomegalovirus (6%) and adenovirus (3%). More than one virus was identified in 16% of the patients. The median onset time was 106 days after allogeneic stem cell transplantation for the total group of 32 patients, but onset times were shortest in those with human herpesvirus-6 encephalitis and longest in those with JC virus-associated progressive multifocal leukoencephalopathy. The probability of a sustained response to treatment was 63% (95% confidence interval 44%-82%) with a median survival of 94 (95% confidence interval 36-152) days after onset, but significant variation was found when considering different causative viruses. Patients with herpes simplex virus encephalitis had the most favorable outcome with no encephalitis-related deaths.

CONCLUSIONS

The use of OKT-3 or alemtuzumab for in vivo T-cell depletion is associated with an increased risk of viral encephalitis after allogeneic stem cell transplantation. Different viruses are frequently associated with distinct characteristics such as onset time, response to treatment and outcome.

A hitchhiker's guide to the nervous system: the complex journey of viruses and toxins

To reach the central nervous system (CNS), pathogens have to circumvent the wall of tightly sealed endothelial cells that compose the blood-brain barrier. Neuronal projections that connect to peripheral cells and organs are the Achilles heels in CNS isolation. Some viruses and bacterial toxins interact with membrane receptors that are present at nerve terminals to enter the axoplasm. Pathogens can then be mistaken for cargo and recruit trafficking components, allowing them to undergo long-range axonal transport to neuronal cell bodies. In this Review, we highlight the strategies used by pathogens to exploit axonal transport during CNS invasion.

35-year-old HIV-positive woman with Basal forebrain mass

A 35-year-old African American woman with HIV/AIDS presented with altered mental status. A CT of the head revealed an infiltrating hypodense intra-axial mass within the basal forebrain. Lumbar puncture showed a lymphocytic pleocytosis, elevated protein and low glucose. PCR analysis of the CSF was negative for Mycobacterium tuberculosis, HSV, VZV, CMV and JC virus. There was low positivity for EBV DNA. Serologic studies were consistent with past infections with EBV and CMV and were negative for toxoplasmosis, histoplasmosis, Cryptococcus and West Nile virus. VDRL was non-reactive. CSF and blood cultures were negative. She soon expired. Post-mortem examination of the patient's brain showed a poorly delineated area of softening and hemorrhage within the basal forebrain. Histologic examination revealed necrotizing encephalitis with perivascular lymphocytes and glial cells with numerous cytoplasmic and intranuclear inclusions. Immunohistochemistry was strongly positive for adenovirus and negative for HSV, CMV, SV40 and EBV. Electron microscopy confirmed the presence virions consistent with adenovirus. We conclude that adenovirus is a rare and sometimes unsuspected cause of encephalitis that may present as a forebrain mass lesion.

Mouse adenovirus type 1-induced breakdown of the blood-brain barrier

Infection with mouse adenovirus type 1 (MAV-1) results in fatal acute encephalomyelitis in susceptible mouse strains via infection of brain endothelial cells. Wild-type (wt) MAV-1 causes less brain inflammation than an early region 3 (E3) null virus in C57BL/6 mice. A mouse brain microvascular endothelial cell line infected with wt MAV-1 had higher expression of mRNAs for the proinflammatory chemokines CCL2 and CCL5 than mock- and E3 null virus-infected cells. Primary mouse brain endothelial cells infected with wt virus had elevated levels of CCL2 compared to mock- or E3 null virus-infected cells. Infection of C57BL/6 mice with wt MAV-1 or the E3 null virus caused a dose-dependent breakdown of the blood-brain barrier, primarily due to direct effects of virus infection rather than inflammation. The tight junction proteins claudin-5 and occludin showed reduced surface expression on primary mouse brain endothelial cells following infection with either wt MAV-1 or the E3 null virus. mRNAs and protein for claudin-5, occludin, and zona occludens 2 were also reduced in infected cells. MAV-1 infection caused a loss of transendothelial electrical resistance in primary mouse brain endothelial cells that was not dependent on E3 or on MAV-1-induced CCL2 expression. Taken together, these results demonstrate that MAV-1 infection caused breakdown of the blood-brain barrier accompanied by decreased surface expression of tight junction proteins. Furthermore, while the MAV-1-induced pathogenesis and inflammation were dependent on E3, MAV-1-induced breakdown of the blood-brain barrier and alteration of endothelial cell function were not dependent on E3 or CCL2.

Molecular characterization of adenoviral infections in Cuba: report of an unusual association of species D adenoviruses with different clinical syndromes

Adenoviruses are common pathogens that are responsible for a wide variety of infectious syndromes. The objectives of this study were to identify and characterize members of different adenovirus species at the molecular level and to describe the correlation between viruses and clinical syndromes during a period of 4 years. Between 2002 and 2006, 45 of 512 respiratory specimens (8%) from patients with acute respiratory tract infection tested positive for adenovirus. Four adenovirus isolates from samples sent for enterovirus isolation were also analyzed. This research identified 49 confirmed cases of human adenovirus infection by PCR and/or viral culture. The most common diagnosis was upper respiratory infection (44%). Human adenovirus D was the major species found (59%), followed by Human adenovirus C (36%) and Human adenovirus B (4%). Human adenovirus 5 was the major serotype found producing bronchiolitis, followed by human adenovirus 6. In patients with upper respiratory infection, the major serotype found was human adenovirus 17. Viruses of the species Human adenovirus D were identified in seven (77%) cases of acute febrile syndrome. Four isolates from clinical materials obtained from patients with encephalitis, acute flaccid paralysis and meningoencephalitis were identified as belonging to the species Human adenovirus D. Our data demonstrate a surprising result about the identification of an unusual association of viruses of the species Human adenovirus D with different clinical syndromes. This observation could be evaluated as a possible indicator of the emergence of a novel strain but further studies are required.

A myocarditis outbreak with fatal cases associated with adenovirus subgenera C among children from Havana City in 2005

BACKGROUND

Among multiple causes of acute myocarditis, viral infection, especially that due to enteroviruses and adenoviruses, is the leading cause. In the summer 2005 an outbreak of a febrile syndrome accompanied by acute cardiac decompensation occurred in infants and young children in Havana City. Eleven patients had a rapid evolution of disease and there were 8 fatalities from cardiac failure secondary to myocarditis.

OBJECTIVE

The aim of the present study was to determine the etiological agent responsible for this outbreak.

STUDY DESIGN

Children admitted to the pediatric hospitals of Havana City from July 3 to August 2 with this clinical presentation were studied. Forty samples of necropsy tissue, cerebrospinal fluid, stools and serum were tested by molecular methods for 14 respiratory viruses, 6 herpesviruses and generic enteroviruses and flavirus and alfaviruses. Viral isolation was performed in A-549 cells. Isolated viruses were typed by sequence analysis.

RESULTS

Adenovirus genome was detected in 6 of the 8 fatal cases-the lungs in 5 (63%) and the myocardium in 3 (37%). In two fatal cases, viral genome was detected in both lung and myocardium. Adenovirus was isolated in five fatal cases. In all three non-fatal cases, adenovirus genome was detected and adenovirus was isolated into two. Sequence analysis showed that adenovirus type 5 was the only isolate from fatal cases and adenovirus 1 the only isolate in non-fatal cases. No other viruses were found by PCR or isolation techniques.

CONCLUSION

Adenovirus was the etiologic agent implicated in this myocarditis outbreak and adenovirus type 5 was associated with fatal outcome.