Neurodevelopment and cognition in children after enterovirus 71 infection

CD4 T-cell-independent antibody response reduces enterovirus 71 lethality in mice by decreasing tissue viral loads

Enterovirus 71 (EV71) has induced fatal encephalitis in hundreds of thousands of infants and young children in the Asia-Pacific region since the past decade. Lymphocyte and antibody responses have been suspected to aggravate EV71-induced neurological symptoms, so anti-inflammatory agents have been used to treat patients with neurological symptoms. In the present study, we found that mice deficient in CD4⁺ T cells were resistant to EV71 infection as wild-type mice, whereas mice deficient in B cells were highly susceptible to viral infection. Compensation of CD4 T-cell function by other immune cells was not likely, because wild-type mice depleted of CD4⁺ T cells were also resistant to viral infection. Infected CD4 T-cell-deficient mice produced virus-specific neutralizing antibodies, IgM and IgG. Moreover, adoptive transfer of the virus-specific antibody produced by infected CD4 T-cell-deficient mice protected B-cell-deficient mice from infection by reducing tissue viral loads. Collectively, our results show that the CD4 T-cell-independent antibody response promotes the survival of EV71-infected mice and suggest great potential for the use of vaccines and neutralizing antibodies to reduce fatal symptoms in patients.

The Pathogenesis and Prevention of Encephalitis due to Human Enterovirus 71

Human enterovirus 71 (HEV71) has emerged as a major cause of viral encephalitis in Southeast Asia, with increased epidemic activity observed since 1997. This is reflected in a large increase in scientific publications relating directly to HEV71. New research is elucidating details of the viral life cycle, confirming similarities between HEV71 and other enteroviruses. Scavenger receptor B2 (SCARB2) is a receptor for HEV71, although other receptors are likely to be identified. Currently, the only strategies to prevent HEV71-associated disease are early diagnosis and aggressive supportive management of identified cases. As more information emerges regarding the molecular processes of HEV71 infection, further advances may lead to the development of effective antiviral treatments and ultimately a vaccine-protection strategy. The protective efficacies of several inactivated HEV71 vaccines have been confirmed in animal models, suggesting that an effective vaccine may become available in the next decade.

Challenges to licensure of enterovirus 71 vaccines

Human enteroviruses usually cause self-limited infections except polioviruses and enterovirus 71 (EV71), which frequently involve neurological complications. EV71 vaccines are being evaluated in humans. However, several challenges to licensure of EV71 vaccines need to be addressed. Firstly, EV71 and coxsackievirus A (CA) are frequently found to co-circulate and cause hand-foot-mouth disease (HFMD). A polyvalent vaccine that can provide protection against EV71 and prevalent CA are desirable. Secondly, infants are the target population of HFMD vaccines and it would need multi-national efficacy trials to prove clinical protection and speed up the licensure and usage of HFMD vaccines in children. An international network for enterovirus surveillance and clinical trials is urgently needed. Thirdly, EV71 is found to evolve quickly in the past 15 years. Prospective cohort studies are warranted to clarify clinical and epidemiological significances of the antigenic and genetic variations between different EV71 genogroups, which is critical for vaccine design.

Identification of site-specific adaptations conferring increased neural cell tropism during human enterovirus 71 infection

Enterovirus 71 (EV71) is one of the most virulent enteroviruses, but the specific molecular features that enhance its ability to disseminate in humans remain unknown. We analyzed the genomic features of EV71 in an immunocompromised host with disseminated disease according to the different sites of infection. Comparison of five full-length genomes sequenced directly from respiratory, gastrointestinal, nervous system, and blood specimens revealed three nucleotide changes that occurred within a five-day period: a non-conservative amino acid change in VP1 located within the BC loop (L97R), a region considered as an immunogenic site and possibly important in poliovirus host adaptation; a conservative amino acid substitution in protein 2B (A38V); and a silent mutation in protein 3D (L175). Infectious clones were constructed using both BrCr (lineage A) and the clinical strain (lineage C) backgrounds containing either one or both non-synonymous mutations. In vitro cell tropism and competition assays revealed that the VP1₉₇ Leu to Arg substitution within the BC loop conferred a replicative advantage in SH-SY5Y cells of neuroblastoma origin. Interestingly, this mutation was frequently associated in vitro with a second non-conservative mutation (E167G or E167A) in the VP1 EF loop in neuroblastoma cells. Comparative models of these EV71 VP1 variants were built to determine how the substitutions might affect VP1 structure and/or interactions with host cells and suggest that, while no significant structural changes were observed, the substitutions may alter interactions with host cell receptors. Taken together, our results show that the VP1 BC loop region of EV71 plays a critical role in cell tropism independent of EV71 lineage and, thus, may have contributed to dissemination and neurotropism in the immunocompromised patient.

Clinical and analytical characteristics and short-term evolution of enteroviral meningitis in young infants presenting with fever without source

OBJECTIVE

The objective of this study was to describe the characteristics of the enteroviral meningitis diagnosed in a pediatric emergency department among infants younger than 3 months with fever without source and its short-term evolution.

METHODS

This was a retrospective, cross-sectional, 6-year descriptive study including all infants younger than 3 months who presented with fever without source and who were diagnosed with enteroviral meningitis.

RESULTS

A lumbar puncture was practiced at their first emergency visit in 398 (29.5%) of 1348 infants, and 65 (4.8%) were diagnosed with enteroviral meningitis, 33 of them (50.7%) between May and July. Among these 65 infants, 61 were classified as well-appearing; parents referred irritability in 16 (25.3%) of them (without statistical significance when compared with infants without meningitis). Forty-one (63.0%) had no altered infectious parameters (white blood cell [WBC] count between 5000 and 15,000/μL, absolute neutrophil count less than 10,000/μL, and C-reactive protein less than 20 g/L), and 39 (60%) had no pleocytosis. All of the 65 infants recovered well, and none of them developed short-term complications.

CONCLUSIONS

The symptoms in infants younger than 3 months with enteroviral meningitis were similar to those in infants with a self-limited febrile process without intracranial infection. C-reactive protein and WBC count were not good enteroviral meningitis predictors. Cerebrospinal fluid WBC count was normal in many of these infants, so performing a viral test is recommended for febrile infants younger than 3 months in which a lumbar puncture is practiced during warm months. The short-term evolution was benign.

ADHD-related symptoms, emotional/behavioral problems, and physical conditions in Taiwanese children with epilepsy

BACKGROUND/PURPOSE

Little is known about whether Asian children with epilepsy have more attention-deficit hyperactivity disorder (ADHD)-related symptoms, emotional/ behavioral problems, and physical conditions compared with those described in Western studies. The authors investigated the rates of ADHD-related symptoms, emotional/behavioral problems, and physical conditions among pediatric patients with epilepsy.

METHODS

We recruited 61 patients with epilepsy, aged 6-16 years, and 122 age-, sex-, and parental education-matched school controls. Data on demographics, parental reports on the Child Behavior Checklist (CBCL) and Swanson, Nolan, and Pelham, version IV scale (SNAP-IV), and medical records were collected.

RESULTS

The average full-scale intelligence quotient of the case group was 95.8. There were 11 (18.0%), 7 (11.5%), 26 (42.6%), and 26 (42.6%) of children with epilepsy ever clinically diagnosed with developmental delay, overt ADHD symptoms, allergies reported by physicians, and behavior problems measured by the CBCL, respectively. Those children with epilepsy had more severe ADHD-related symptoms and a wider range of emotional/behavioral problems than controls (Cohen's d 0.36-0.80). The rate of potential cases of ADHD among children with epilepsy was 24.6%. A history of developmental delay predicted ADHD- related symptoms and internalizing and externalizing problems. Among children with epilepsy, a longer duration of treatment with antiepileptic drugs predicted externalizing problems, and an earlier onset of epilepsy predicted inattention and hyperactivity/impulsivity.

CONCLUSION

Our findings imply that clinicians should assess physical and emotional/behavioral problems among children with epilepsy in order to provide interventions to offset possible adverse psychiatric outcomes.

Characteristics of pediatric patients with enterovirus meningitis and no cerebral fluid pleocytosis

Human non-polio enterovirus (EV) is the most important cause of aseptic meningitis in children. Only a few studies report the lack of cerobrospinal fluid (CSF) pleocytosis in children with confirmed EV meningitis; however, the characteristics of these children have not been well defined. This paper describes the clinical and laboratory features of EV meningitis in children with no CSF pleocytosis. Clinical, laboratory, and virological data of Dutch patients <16 years diagnosed with EV meningitis, between 2003 and 2008, were analyzed retrospectively. Data of children with and without CSF pleocytosis were compared. A total of 149 children were infected with EV. Patients presented mainly with fever (n = 113), malaise (n = 43), abdominal pain (n = 47), and irritability (n = 61). Of the 60 patients with EV meningitis, 23 had no pleocytosis. Those who lacked CSF pleocytosis were younger [odds ratio (OR) 1.00; 95% confidence interval (CI) 1.000-1.002; p = 0.001], had experienced drowsiness more (OR 9.60; 95% CI 2.24-41.15; p = 0.002), had lower white blood cell counts (OR 0.73; 95% CI 0.61-0.89; p = 0.001), and had higher C-reactive protein (OR 1.13; 95% CI 1.03-1.23; p = 0.006) than those with pleocytosis.

CONCLUSION

These findings show that EV meningitis occurs in the absence of CSF pleocytosis, particularly in young infants, meaning that EV meningitis in this age group cannot be solely excluded by the absence of CSF pleocytosis. They also confirm the importance of genome detection in the diagnosis of EV meningitis in young infants.

Daphne Genkwa sieb. Et zucc. Water-soluble extracts act on enterovirus 71 by inhibiting viral entry

Dried flowers of Daphne genkwa Sieb. et Zucc. (Thymelaeaceae) are a Chinese herbal medicine used as an abortifacient with purgative, diuretic and anti-inflammatory activities. However, the activity of this medicine against enteroviral infections has not been investigated. The water-extract of dried buds of D. genkwa Sieb. et Zucc. (DGFW) was examined against various strains of enterovirus 71 (EV71) by neutralization assay, and its initial mode of action was characterized by time-of-addition assay followed by attachment and penetration assays. Pretreatment of DGFW with virus abolished viral replication, indicating that DGFW inhibits EV71 by targeting the virus. GFW exerts its anti-EV71 effects by inhibiting viral entry without producing cytotoxic side effects and thus provides a potential agent for antiviral chemotherapeutics.

Viral and host factors that contribute to pathogenicity of enterovirus 71

The single-stranded RNA virus enterovirus 71 (EV71), which belongs to the Picornaviridae family, has caused epidemics worldwide, particularly in the Asia–Pacific region. Most EV71 infections result in mild clinical symptoms, including herpangina and hand, foot and mouth disease. However, serious pathological complications have also been reported, especially for young children. The mechanisms of EV71 disease progression remain unclear. The pathogenesis of adverse clinical outcomes may relate to many factors, including cell tropism, cell death and host immune responses. This article reviews the recent advances in the identification of factors determining EV71 cell tropism, the associated mechanisms of viral infection-induced cell death and the interplay between EV71 and immunity.

Incidence rates of enterovirus 71 infections in young children during a nationwide epidemic in Taiwan, 2008-09

Objective

Enterovirus 71 (EV71) is causing life-threatening outbreaks in tropical Asia. In Taiwan and other tropical Asian countries, although nationwide EV71 epidemics occur cyclically, age-specific incidence rates of EV71 infections that are critical to estimate disease burden and design vaccine trials are not clear. A nationwide EV71 epidemic occurred in 2008–09 in Taiwan, which provided a unique opportunity to estimate age-specific incidence rates of EV71 infections.

Study Design

We prospectively recruited 749 healthy neonates and conducted follow-ups from June 2006 to December 2009. Sera were obtained from participants at 0, 6, 12, 24, and 36 months of age for measuring EV71 neutralizing antibody titers. If the participants developed suspected enterovirus illnesses, throat swabs were collected for virus isolation.

Results

We detected 28 EV71 infections including 20 symptomatic and 8 asymptomatic infections. Age-specific incidence rates of EV71 infection increased from 1.71 per 100 person-years at 0–6 months of age to 4.09, 5.74, and 4.97 per 100 person-years at 7–12, 13–24, and 25–36 months of age, respectively. Cumulative incidence rate was 15.15 per 100 persons by 36 months of age, respectively.

Conclusions

Risk of EV71 infections in Taiwan increased after 6 months of age during EV71 epidemics. The cumulative incidence rate was 15% by 36 months of age, and 29% of EV71 infections were asymptomatic in young children.

Enterovirus 71 (EV71) was first isolated in California, USA, in 1969. Since then, EV71 has been identified globally. Recently, EV71 caused several life-threatening outbreaks in young children in tropical Asia. Development of EV71 vaccines becomes national priority in several Asia countries including Taiwan. To design clinical trials of EV71 vaccines, age-specific incidence rates of EV71 infections are required to identify target populations, estimate disease burdens, select endpoints of clinical efficacy, and estimate sample size. In Taiwan, nationwide EV71 epidemics occurred every 3–4 years but age-specific incidences of EV71 infection are not available. In 2006, we initiated a prospective cohort study in northern Taiwan to recruit neonates and follow up them. In 2008–09, a nationwide EV71 epidemic occurred and we found that age-specific incidence rates of EV71 infection increased from 1.71 per 100 person-years at 0–6 months of age to 4.09, 5.74, and 4.97 per 100 person-years at 7–12, 13–24, and 25–36 months of age, respectively. The cumulative incidence rate was 15% by 36 months of age, and 29% of EV71 infections were asymptomatic in young children. These findings would be helpful to development of EV71 vaccines in Taiwan and other Asian tropical countries.

Comparison of the laboratory data between Kawasaki disease and enterovirus after intravenous immunoglobulin treatment

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology. The laboratory findings before and after intravenous immunoglobulin (IVIG) in KD have been discussed, but the characteristics of IVIG therapy still are unclear. This study aimed to compare laboratory data from patients with KD and enterovirus (EV) infection to evaluate the differences after IVIG therapy. The study enrolled 171 KD patients and 38 EV patients treated with a single dose of IVIG from 2003 to 2010. Laboratory data including total white blood cell counts (WBC) and hemoglobin (Hb), platelet, segment, lymphocyte, eosinophil, and monocyte levels were analyzed. Compared with the KD patients, the EV patients had higher Hb, lymphocyte, and monocyte levels and lower eosinophil levels before IVIG treatment (p < 0.05). After IVIG treatment, the KD patients had lower Hb and segment levels but higher platelet, lymphocyte, and eosinophil levels than the EV patients (p < 0.05). In the KD patients, the platelet, eosinophil, and monocyte levels increased after IVIG treatment, whereas Hb, WBC, and segment levels decreased significantly (p < 0.001). In the EV patients, eosinophil levels increased after IVIG treatment, whereas WBC and Hb levels decreased significantly (p < 0.05). The study results provide evidence that eosinophilia may be related to IVIG therapy in KD and EV patients. The KD patients had higher eosinophil levels both before and after IVIG therapy than the EV patients, which may have been due to the inflammatory mechanism of KD. The KD patients had higher platelet levels than the EV patients, suggesting that platelets are involved in the inflammatory response to KD.

Epidemic characteristics of hand, foot, and mouth disease in Shanghai from 2009 to 2010: Enterovirus 71 subgenotype C4 as the primary causative agent and a high incidence of mixed infections with coxsackievirus A16

BACKGROUND

Enterovirus 71 (EV71) has been the main causative agent of hand, foot, and mouth disease (HFMD) outbreaks in recent years. A significant increase in the number of HFMD cases in China over the last 3 y has made the public prevention and therapy of this disease a critical issue.

METHODS

A total of 3208 HFMD patients in Shanghai during the period 2009 to 2010 were analyzed; 437 clinical specimens were collected for the determination of causative pathogens. Eight of the isolated EV71 strains were sequenced and phylogenetically analyzed.

RESULTS

The widespread outbreak of HFMD in Shanghai was caused predominantly by EV71 (86.5%), and in part by coxsackievirus A16 (CA16) (6.9%). The high incidence of mixed infections with EV71 and CA16 (17.6% of the total CA16-infected cases) has never before been observed in China. Most HFMD patients (76.9%) were aged 1-4 y. Boys showed a higher HFMD prevalence rate (65.3%) than girls (34.7%). Phylogenetic analysis on the basis of the VP1 gene and the complete genome sequences revealed that the EV71 strains that circulated in Shanghai belonged to the C4 subgenotype.

CONCLUSIONS

EV71 subgenotype C4 was the major causative agent of the HFMD outbreak in Shanghai. A high incidence of mixed infections with EV71 and CA16 was also observed.

Lycorine reduces mortality of human enterovirus 71-infected mice by inhibiting virus replication

Human enterovirus 71 (EV71) infection causes hand, foot and mouth disease in children under 6 years old and this infection occasionally induces severe neurological complications. No vaccines or drugs are clinical available to control EV71 epidemics. In present study, we show that treatment with lycorine reduced the viral cytopathic effect (CPE) on rhabdomyosarcoma (RD) cells by inhibiting virus replication. Analysis of this inhibitory effect of lycorine on viral proteins synthesis suggests that lycorine blocks the elongation of the viral polyprotein during translation. Lycorine treatment of mice challenged with a lethal dose of EV71 resulted in reduction of mortality, clinical scores and pathological changes in the muscles of mice, which were achieved through inhibition of viral replication. When mice were infected with a moderate dose of EV71, lycorine treatment was able to protect them from paralysis. Lycorine may be a potential drug candidate for the clinical treatment of EV71-infected patients.

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

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

Molecular characterization and complete genome analysis of human enterovirus 71 and coxsackievirus A16 from children with hand, foot and mouth disease in Thailand during 2008-2011

Hand, foot and mouth disease (HFMD) has mostly been caused by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). CA 16 was the most common cause of HFMD in 2010. EV71 had a high prevalence in 2008-2009 and has been identified with a higher frequency since 2011. Nearly complete genome sequences of three EV71 strains (2008-2009 strains) and two CA16 strains (2010 strains) obtained from outbreaks in Thailand in 2008 to 2010 were characterized. Based on a phylogenetic tree of the complete VP1 region, three EV71 strains grouped into the B5, C1 and C4 genotypes, and two CA16 strains grouped into the C genotype. Based on sequence analysis, nucleotide changes were found to cluster in the internal ribosome entry site (IRES) element of the 5'-untranslated region (5'-UTR). Amino acid differences identified in all strains were located in the non-structural protein. These data also provide the molecular epidemiology of EV71 and CA16 outbreaks in Thailand.

Simple and rapid detection of human enterovirus 71 by reverse-transcription and loop-mediated isothermal amplification: cryopreservation affected the detection ability

Human enterovirus 71 (EV71) is the primary pathogen of hand, foot, and mouth disease (HFMD). EV71 infection may lead to neurologic damage, with higher incidence of fatality compared with other HFMD pathogens. An effective drug or vaccine against EV71 infection is currently unavailable. It is desirable to determine the pathogen of HFMD accurately and quickly for early treatment. In the current study, reverse-transcription and loop-mediated isothermal amplification (RT-LAMP) technology were developed to detect EV71. The efficacy of detecting EV71 was compared with regular nested reverse-transcription polymerase chain reaction (RT-PCR). After detecting 108 clinical specimens, results showed that RT-LAMP can specifically detect EV71, but not Coxsackie virus A16, and exhibited a specificity of 100% and a sensitivity of 97.1%, which was higher than regular RT-PCR. The findings indicate that RT-LAMP is a practical method for EV71 diagnostic applications, particularly in small county institutes of medical service. The detection ability of RT-LAMP was significantly affected by cryopreservation as the clinical specimens were repeatedly subject to freezing and thawing treatments.

Cleavage of the adaptor protein TRIF by enterovirus 71 3C inhibits antiviral responses mediated by Toll-like receptor 3

Enterovirus 71 (EV71) causes hand-foot-and-mouth disease and neurological complications in young children. Although the underlying mechanisms remain obscure, impaired or aberrant immunity is thought to play a role. In infected cells, EV71 suppresses type I interferon responses mediated by retinoid acid-inducible gene I (RIG-I). This involves the EV71 3C protein, which disrupts the formation of a functional RIG-I complex. In the present study, we report that EV71 inhibits the induction of innate immunity by Toll-like receptor 3 (TLR3) via a distinct mechanism. In HeLa cells stimulated with poly(I · C), EV71 inactivates interferon regulatory factor 3 and drastically suppresses interferon-stimulated gene expression. Notably, EV71 specifically downregulates a TRIF, TIR domain-containing adaptor inducing beta interferon (IFN-β). When expressed alone in mammalian cells, EV71 3C is capable of exhibiting these activities. EV71 3C associates with and induces TRIF cleavage in the presence of Z-VAD-FMK, a caspase inhibitor. TRIF cleavage depends on its amino acid pair Q312-S313, which resembles a proteolytic site of picornavirus 3C proteases. Further, site-specific 3C mutants with a defective protease activity bind TRIF but fail to mediate TRIF cleavage. Consequently, these 3C mutants are unable to inhibit NF-κB and IFN-β promoter activation. TRIF cleavage mediated by EV71 may be a mechanism to impair type I IFN production in response to Toll-like receptor 3 (TLR3) activation.

The virology and developments toward control of human enterovirus 71

Enterovirus 71 (EV71), a member of the Enterovirus genus in the Picornaviridae family, was first recognized as a dermotrophic virus that usually cause mild, self-limiting hand-foot-and-mouth disease (HFMD). However, EV71 infection can sometimes induce a variety of severe neurological complications and even death. Current large outbreaks of EV71 make this virus being a major public health issue. Intense effort has been made to address its underlying pathogenesis and to develop effective means for combating EV71 infections. Here, we aimed to provide an overview of cellular mechanisms underlying EV71 infection and to assess potential agents for prevention and treatment of EV71 infections.

Enterovirus-induced miR-141 contributes to shutoff of host protein translation by targeting the translation initiation factor eIF4E

Viruses rely on the host translation machinery to complete their life cycles. Picornaviruses use an internal ribosome entry site to initiate cap-independent protein translation and in parallel host cap-dependent translation is shut off. This process is thought to occur primarily via cleavage of host translation initiation factors eIF4GI and eIF4GII by viral proteases. Here we describe another mechanism whereby miR-141 induced upon enterovirus infection targets the cap-dependent translation initiation factor, eIF4E, for shutoff of host protein synthesis. Knockdown of miR-141 reduces viral propagation, and silencing of eIF4E can completely reverse the inhibitory effect of the miR-141 antagomiR on viral propagation. Ectopic expression of miR-141 promotes the switch from cap-dependent to cap-independent translation. Moreover, we identified a transcription factor, EGR1, which is partly responsible for miR-141 induction in response to enterovirus infection. Our results suggest that upregulation of miR-141 upon enterovirus infection can facilitate viral propagation by expediting the translational switch.

[Molecular diagnosis of respiratory enterovirus infections: Use of PCR and molecular identification for a best approach of the main circulating strains during 2008]

The PCR assays are currently used in diagnosis of enterovirus (EV) meningitis. Nevertheless, the use of molecular diagnosis of EV should be investigated in respiratory tract infections (RTI).

OBJECTIVES

To perform enterovirus molecular diagnostic tools, PCR and genotyping, in nasal samples for diagnostic and epidemiologic purposes.

METHODS

During 2008, 3612 nasal specimen (NS) were studied by IFD and MRC5 culture. Next, we realised successively viral isolation on HuH7 culture (for NS negative by IFD assay) and a duplex PCR enterovirus-rhinovirus for the 816 HuH7 positive supernatants. Furthermore, 327 NS collected from neonates were systematically tested by a real-time RT-PCR. This assay was used in routine for EV diagnosis setting in cerebrospinal fluid. Enterovirus genotyping was then performed for the 68 positive supernatants.

RESULTS

Thirty-five NS (0.97%) were positive for EV by culture (MRC5). A combination of both PCR assays, PEVRV and PEV, allowed an additional identification of 41 EV, eight EV-RV and 12 RV, increasing the number of positive to 96 NS (2.6%). Among the neonates, 32 NS (11.3%) were positive for EV by PEV. Of the 98 NS tested by the two PCR assays (PEV and PEVRV), 27 were positive and we detected 10 EV, five EV-RV and 12 RV. From January to December 2008, the circulation of EV showed the usual peak in June-July when a small outbreak of aseptic meningitis occurred and an additional autumnal peak corresponding to respiratory tract infections. Five main serotypes were isolated: 19 EV68 (29.7%), 12 CB3 (18.7%), nine E3 (14,1%), six CA9 (9.4%) and six CB1 (9.4%); the 19 EV68 were isolated in October-November and 17/19 (89.5%) of positive patients were hospitalised for severe respiratory diseases.

CONCLUSION

The use of molecular screening techniques (PCR assays and genotyping) on nasal samples collected from patients with respiratory infections allowed a prospective, effective and precise identification of circulating strains.

Enterovirus infections of the central nervous system

Enteroviruses (EV) frequently infect the central nervous system (CNS) and induce neurological diseases. Although the CNS is composed of many different cell types, the spectrum of tropism for each EV is considerable. These viruses have the ability to completely shut down host translational machinery and are considered highly cytolytic, thereby causing cytopathic effects. Hence, CNS dysfunction following EV infection of neuronal or glial cells might be expected. Perhaps unexpectedly given their cytolytic nature, EVs may establish a persistent infection within the CNS, and the lasting effects on the host might be significant with unanticipated consequences. This review will describe the clinical aspects of EV-mediated disease, mechanisms of disease, determinants of tropism, immune activation within the CNS, and potential treatment regimes.

Clinical features, diagnosis, and management of enterovirus 71

Although poliomyelitis has been mostly eradicated worldwide, large outbreaks of the related enterovirus 71 have been seen in Asia-Pacific countries in the past 10 years. This virus mostly affects children, manifesting as hand, foot, and mouth disease, aseptic meningitis, poliomyelitis-like acute flaccid paralysis, brainstem encephalitis, and other severe systemic disorders, including especially pulmonary oedema and cardiorespiratory collapse. Clinical predictors of severe disease include high temperature and lethargy, and lumbar puncture might reveal pleocytosis. Many diagnostic tests are available, but PCR of throat swabs and vesicle fluid, if available, is among the most efficient. Features of inflammation, particularly in the anterior horns of the spinal cord, the dorsal pons, and the medulla can be clearly seen on MRI. No established antiviral treatment is available. Intravenous immunoglobulin seems to be beneficial in severe disease, perhaps through non-specific anti-inflammatory mechanisms, but has not been tested in any formal trials. Milrinone might be helpful in patients with cardiac dysfunction.

An investigation of epidemic enterovirus 71 infection in Taiwan, 2008: clinical, virologic, and serologic features

BACKGROUND

Enterovirus 71 (EV71) is causing life-threatening hand-foot-mouth disease in Asia. In Taiwan, EV71 epidemics with different predominant genotypes occurred in 1998 (C2), 2000-2001 (B4), and 2004-2005 (C4). This genotype replacement may have important implications for vaccine development and prediction of epidemics. A nationwide EV71 outbreak occurred again in 2008, which provided a unique opportunity to characterize clinical, virologic, and serologic features of this epidemic.

METHODS

We analyzed clinical and virologic data of 111 EV71 patients hospitalized in 2008 and prospectively conducted follow-ups of healthy children from June 2006 to December 2008.

RESULTS

Among the 111 EV71 inpatients, 21 (19%) developed complications. Among the 21 complicated cases, 15 had central nervous system complication only, 2 had acute heart failure, and 4 had central nervous system and pulmonary complications. In the prospective study, 11 symptomatic infections and 4 asymptomatic infections were detected. Twenty-two EV71 isolates were genotyped, and 21 of them belong to genotype B5, which is phylogenetically close to B5 viruses circulating in Southeast Asia. Serologic tests show that children infected with B5 viruses have lower geometric mean titers of neutralizing antibody against genotype C4 than those against genotype B5 (P = 0.004, t test).

CONCLUSIONS

The 2008 nationwide EV71 epidemic was caused by genotype B5 that was likely introduced to Taiwan from Southeast Asia. Clinical features of the 2008 epidemic were not different from those observed before in Taiwan. Potential antigenic variations between genotype C4 and B5 viruses could be detected and its long-term epidemiologic significance needs further investigation to clarify.

Developments towards antiviral therapies against enterovirus 71

Enterovirus 71 (EV71) has emerged as a clinically important neurotropic virus that can cause acute flaccid paralysis and encephalitis, leading to cardiopulmonary failure and death. Recurring outbreaks of EV71 have been reported in several countries. The current lack of approved anti-EV71 therapy has prompted intense research into antiviral development. Several strategies--ranging from target-based chemical design to compound library screenings--have been employed, while others revisited compound series generated from antiviral developments against poliovirus and human rhinoviruses. These efforts have given rise to a diversity of antiviral candidates that include small molecules and non-conventional nucleic-acid-based strategies. This review aims to highlight candidates with potential for further clinical development based on their putative modes of action.

Inferring nonneutral evolution from contrasting patterns of polymorphisms and divergences in different protein coding regions of enterovirus 71 circulating in Taiwan during 1998-2003

Background

Enterovirus (EV) 71 is one of the common causative agents for hand, foot, and, mouth disease (HFMD). In recent years, the virus caused several outbreaks with high numbers of deaths and severe neurological complications. Despite the importance of these epidemics, several aspects of the evolutionary and epidemiological dynamics, including viral nucleotide variations within and between different outbreaks, rates of change in immune-related structural regions vs. non-structural regions, and forces driving the evolution of EV71, are still not clear.

Results

We sequenced four genomic segments, i.e., the 5' untranslated region (UTR), VP1, 2A, and 3C, of 395 EV71 viral strains collected from 1998 to 2003 in Taiwan. The phylogenies derived from different genomic segments revealed different relationships, indicating frequent sequence recombinations as previously noted. In addition to simple recombinations, exchanges of the P1 domain between different species/genotypes of human enterovirus species (HEV)-A were repeatedly observed. Contrasting patterns of polymorphisms and divergences were found between structural (VP1) and non-structural segments (2A and 3C), i.e., the former was less polymorphic within an outbreak but more divergent between different HEV-A species than the latter two. Our computer simulation demonstrated a significant excess of amino acid replacements in the VP1 region implying its possible role in adaptive evolution. Between different epidemic seasons, we observed high viral diversity in the epidemic peaks followed by severe reductions in diversity. Viruses sampled in successive epidemic seasons were not sister to each other, indicating that the annual outbreaks of EV71 were due to genetically distinct lineages.

Conclusions

Based on observations of accelerated amino acid changes and frequent exchanges of the P1 domain, we propose that positive selection and subsequent frequent domain shuffling are two important mechanisms for generating new genotypes of HEV-A. Our viral dynamics analysis suggested that the importation of EV71 from surrounding areas likely contributes to local EV71 outbreaks.

Comparison of clinical features between coxsackievirus A2 and enterovirus 71 during the enterovirus outbreak in Taiwan, 2008: a children's hospital experience

BACKGROUND/PURPOSE

Coxsackievirus A2 (Cox A2) was the predominant serotype in the enterovirus outbreak in Taiwan, 2008. However, detailed clinical features of Cox A2 infection have not been reported. In this study, we compared Cox A2 with enterovirus 71 (EV71) in terms of clinical manifestation and epidemiology during the 2008 enterovirus outbreak in Taiwan.

METHODS

A total of 280 hospitalized patients (97 with culture-proven EV71 infection and 183 with culture-proven Cox A2 infection) in 2008 at the Chang Gung Children's Medical Center were enrolled in this study. Epidemiologic data, clinical manifestations, and outcomes for these patients were collected and compared.

RESULTS

Both Cox A2 and EV71 serotypes peaked in June and declined soon afterwards. Seventy-one percent of the patients were younger than 3 years of age. Both groups had the same male-to-female ratio of 1.6:1. Patients with EV71 infection had a significantly longer hospitalization period (4.1 vs. 3.0 days, p< 0.001). Fever, fever for more than 3 days with a temperature above 39 degrees C, lethargy, poor activity, poor appetite and a myoclonic jerk were significantly associated with EV71 infection. Fever, or fever with a temperature above 39 degrees C, febrile seizure, elevated white cell counts, and elevated serum C-reactive protein concentrations were significantly associated with Cox A2 infection. Most patients with EV71 infection presented with hand-foot-mouth disease (78.3%), while most Cox A2-infected patients presented with herpangina (83.6%). Central nervous system complications were found in 18.6% of EV71-infected children, but only in 1.1% of Cox A2-infected children. All the patients with Cox A2 infection showed total recovery. One patient with EV71 infection died from encephalitis with cardiopulmonary failure, and 6.2% of EV71-infected children had neurologic sequelae.

CONCLUSION

Both Cox A2 and EV71 serotypes accounted for the enterovirus outbreak in Taiwanese children in 2008. Compared with those infected by EV71, the children with Cox A2 infection mostly presented with herpangina, had fewer central nervous system complications, and had better overall outcome.

Combined peptides of human enterovirus 71 protect against virus infection in mice

Human enterovirus 71 (EV71) is a cause of hand, foot and mouth disease (HMFD) in children under 6 years old, and could cause serious neurological complications in some patients. Numerous large outbreaks of EV71 caused HMFD have occurred recently in Asia, especially in China. The cross-reactivity of EV71 with human brain tissue was observed and the cross-reactivity inducing regions were identified in previously study, which suggested that there were two regions in structural proteins of virus should be avoided in the vaccine. Six peptides without cross-reactivity were selected and combined into three vaccine candidates and applied in further evaluation in neonatal mice. The Vac6 comprising the peptides of P(70-159), P(140-249), P(324-443) and P(746-876) of the structural proteins could provide effective protection on pups against virus infection, as shown in viral copies detection and histopathology examination. Immunohistochemical staining results indicated that Vac6 had no cross-reactivity with human brain tissues. Our results suggested that Vac6 could have potential clinical value against EV71 epidemics caused mainly by C4 strains in the mainland of China.

Cerebrospinal fluid detection of enterovirus genome in ALS: a study of 242 patients and 354 controls

Detection of enterovirus (EV) in the spinal cord of patients with amyotrophic lateral sclerosis (ALS) has been reported on post mortem central nervous system tissues. In cases of persistent infection, it is very likely that the EV genome might be detected in the cerebrospinal fluid (CSF). A study was conducted in seven French amyotrophic lateral sclerosis (ALS) centres between 1997 and 2002. A total of 242 ALS patients and 354 age- and sex-matched controls (non-ALS patients) were enrolled. A sensitive RT-PCR method was performed on the CSF to assess the presence of EV RNA; 14.5% of ALS patients were positive compared to 7.6% of controls (chi(2) value, 5.31; p = 0.02). Although EV infection has a seasonal pattern, we observed no seasonality in positive detection of the EV genome among ALS patients. There was no significant relationship among ALS patients between the initial clinical form or survival and the result of the RT-PCR. These findings suggest a relationship between the presence of EV sequences in CSF and ALS. Our study is consistent with the hypothesis that persistent EV infection can be one of the multiple factors involved in the development of ALS.

The 3C protein of enterovirus 71 inhibits retinoid acid-inducible gene I-mediated interferon regulatory factor 3 activation and type I interferon responses

Enterovirus 71 (EV71) is a human pathogen that induces hand, foot, and mouth disease and fatal neurological diseases. Immature or impaired immunity is thought to associate with increased morbidity and mortality. In a murine model, EV71 does not facilitate the production of type I interferon (IFN) that plays a critical role in the first-line defense against viral infection. Administration of a neutralizing antibody to IFN-alpha/beta exacerbates the virus-induced disease. However, the molecular events governing this process remain elusive. Here, we report that EV71 suppresses the induction of antiviral immunity by targeting the cytosolic receptor retinoid acid-inducible gene I (RIG-I). In infected cells, EV71 inhibits the expression of IFN-beta, IFN-stimulated gene 54 (ISG54), ISG56, and tumor necrosis factor alpha. Among structural and nonstructural proteins encoded by EV71, the 3C protein is capable of inhibiting IFN-beta activation by virus and RIG-I. Nevertheless, EV71 3C exhibits no inhibitory activity on MDA5. Remarkably, when expressed in mammalian cells, EV71 3C associates with RIG-I via the caspase recruitment domain. This precludes the recruitment of an adaptor IPS-1 by RIG-I and subsequent nuclear translocation of interferon regulatory factor 3. An R84Q or V154S substitution in the RNA binding motifs has no effect. An H40D substitution is detrimental, but the protease activity associated with 3C is dispensable. Together, these results suggest that inhibition of RIG-I-mediated type I IFN responses by the 3C protein may contribute to the pathogenesis of EV71 infection.

Recent advances in research on human enterovirus 71

Over the past decade, Human enterovirus (HEV)71 has emerged as a highly significant cause of viral encephalitis in the south-east Asian region. A pattern of increased epidemic activity has been observable since 1997, the cause of which is unclear. Ongoing investigations into the molecular basis of HEV71 infection and virulence, in particular viral translation and replication, have confirmed similarities between HEV71 and other enteroviruses, including the prototype species Poliovirus, but more work is required in this field. Although several putative receptors for HEV71 have been identified, it remains likely that other, as yet unidentified, receptors exist. Work in several established animal models for HEV71 infection has confirmed the protective efficacy of several inactivated vaccines. As more information emerges regarding the molecular processes involved in HEV71 infection, further advances may lead to the development of more effective antiviral treatments and, ultimately, a vaccine protection strategy.

Identification of microRNAs involved in the host response to enterovirus 71 infection by a deep sequencing approach

Role of microRNA (miRNA) has been highlighted in pathogen-host interactions recently. To identify cellular miRNAs involved in the host response to enterovirus 71 (EV71) infection, we performed a comprehensive miRNA profiling in EV71-infected Hep2 cells through deep sequencing. 64 miRNAs were found whose expression levels changed for more than 2-fold in response to EV71 infection. Gene ontology analysis revealed that many of these mRNAs play roles in neurological process, immune response, and cell death pathways, which are known to be associated with the extreme virulence of EV71. To our knowledge, this is the first study on host miRNAs expression alteration response to EV71 infection. Our findings supported the hypothesis that certain miRNAs might be essential in the host-pathogen interactions.

Emergence and re-emergence of viral diseases of the central nervous system

Neurologic disease is a major cause of disability in resource-poor countries and a substantial portion of this disease is due to infections of the CNS. A wide variety of emerging and re-emerging viruses contribute to this disease burden. New emerging infections are commonly due to RNA viruses that have expanded their geographic range, spread from animal reservoirs or acquired new neurovirulence properties. Mosquito-borne viruses with expanding ranges include West Nile virus, Japanese encephalitis virus and Chikungunya virus. Zoonotic viruses that have recently crossed into humans to cause neurologic disease include the bat henipaviruses Nipah and Hendra, as well as the primate-derived human immunodeficiency virus. Viruses adapt to new hosts, or to cause more severe disease, by changing their genomes through reassortment (e.g. influenza virus), mutation (essentially all RNA viruses) and recombination (e.g. vaccine strains of poliovirus). Viruses that appear to have recently become more neurovirulent include West Nile virus, enterovirus 71 and possibly Chikungunya virus. In addition to these newer challenges, rabies, polio and measles all remain important causes of neurologic disease despite good vaccines and global efforts toward control. Control of human rabies depends on elimination of rabies in domestic dogs through regular vaccination. Poliovirus eradication is challenged by the ability of the live attenuated vaccine strains to revert to virulence during the prolonged period of gastrointestinal replication. Measles elimination depends on delivery of two doses of live virus vaccine to a high enough proportion of the population to maintain herd immunity for this highly infectious virus.

Development of enterovirus 71 vaccines

Enterovirus 71 (EV71) was first isolated in 1969 in California, USA. Several epidemic outbreaks with high mortality rates have occurred in European and Asian Countries (Bulgaria in 1975, Hungary in 1978, Malaysia in 1997, Taiwan in 1998 and China in 2008). EV71 CNS involvement may be associated with neurological sequelae, delayed neurodevelopment and reduced cognitive functioning. Since poliovirus was nearly eradicated by vaccination, EV71 is now considered as one of the top candidates for new vaccine development against human enteroviruses. Recently, several EV71 vaccine candidates, including live-attenuated virus, inactivated whole virus, recombinant viral protein, virus-like particle and DNA vaccines, have been evaluated in animals but no clinical trial has yet been conducted. Based on historical experiences with poliovirus vaccines and animal studies, the inactivated whole-virus vaccines are feasible and could be licensed readily, so these are targeted for preparing clinical trials in several organizations in Asia.

Neural pathogenesis of enterovirus 71 infection

Enterovirus 71 (EV71) is a neurotropic pathogen that can cause severe neural diseases and complications on infected patients. Clinical observations showed that EV71-induced immune responses may be associated with virus induced neurogenic pulmonary edema. Here reviewed studies that discovered several host molecules as potential factors for EV71 virulence.

The cross-reactivity of the enterovirus 71 to human brain tissue and identification of the cross-reactivity related fragments

Background

EV71 occasionally cause a series of severe neurological symptoms, including aseptic meningitis, encephalitis, and poliomyelitis-like paralysis. However, the neurological destruction mechanism was remained to be clarified. This study described the cross reaction between EV71 induced IgG and human brain tissue.

Results

Cross reaction of the IgG from 30 EV71 infected patients' sera to human tissues of cerebra was observed, which suggested that some EV71 antigens could induce IgG cross-reactivity to human cerebra. To identify the regions of EV71 virus that containing above antigens, the polypeptide of virus was divided into 19 peptides by expression in prokaryotes cell. Mouse anti-sera of these peptides was prepared and applied in immunohistochemical staining with human adult and fetus brain tissue, respectively. The result indicated the 19 peptides can be classified into three groups: strong cross-reactivity, weak cross-reactivity and no cross-reactivity with human brain tissue according the cross reaction activity. Then, the increased Blood Brain Barrier (BBB) permeability and permits IgG entry in neonatal mice after EV71 infection was determined.

Conclusion

EV71 induced IgG could enter BBB and cross-reacted with brain tissue in EV71 infected neonatal mice, and then the peptides of EV71 that could induce cross-reactivity with brain tissue were identified, which should be avoided in future vaccine designing.

Human enterovirus 71 and hand, foot and mouth disease

Hand, foot and mouth disease (HFMD) is generally a benign febrile exanthematous childhood disease caused by human enteroviruses. The route of transmission is postulated to be faeco-oral in developing areas but attributed more to respiratory droplet in developed areas. Transmission is facilitated by the prolonged environmental survival of these viruses and their greater resistance to biocides. Serious outbreaks with neurological and cardiopulmonary complications caused by human enterovirus 71 (HEV-71) seem to be commoner in the Asian Pacific region than elsewhere in the world. This geographical predilection is unexplained but could be related to the frequency of intra- and inter-typic genetic recombinations of the virus, the host populations' genetic predisposition, environmental hygiene, and standard of healthcare. Vaccine development could be hampered by the general mildness of the illness and rapid genetic evolution of the virus. Antivirals are not readily available; the role of intravenous immunoglobulin in the treatment of serious complications should be investigated. Monitoring of this disease and its epidemiology in the densely populated Asia Pacific epicentre is important for the detection of emerging epidemics due to enteroviruses.

Extracorporeal life support for treatment of children with enterovirus 71 infection-related cardiopulmonary failure

PURPOSE

Enterovirus 71 (EV71) infection leading to cardiopulmonary failure (CPF) is rare, but usually fatal. In such cases, intensive cardiorespiratory support is essential for survival. In this study, we report our experience in the treatment of EV71-related CPF with extracorporeal life support (ECLS).

METHODS

This was a retrospective study of a total of 13 children, aged 16 +/- 10 months, with EV71-related hemodynamically unstable CPF, which was refractory to conventional treatments, who were rescued by transsternal ECLS from 2000 to 2008. The clinical manifestations and outcomes of the 13 children (present cohort) were compared with those of 10 children (past cohort) who had EV71-related CPF without ECLS between 1998 and 2000.

RESULTS

Among these 13 patients, 10 were successfully weaned off ECLS and survived. The myocardial recovery time was 71 +/- 28 (median, 69) h, and the ECLS duration was 93 +/- 33 (median, 93) h. Six surviving patients had a good neurological outcome at hospital discharge. All surviving patients had some neurological sequelae but showed improvement at follow-up, including dysphagia in nine, central hypoventilation in seven, limb weakness in six and seizure in three. The present cohort had better neurological outcomes (46 vs. 0%, P = 0.005) and a higher survival rate (77 vs. 30%, P = 0.024) than the past cohort, respectively.

CONCLUSIONS

Patients with EV71-related CPF supported by ECLS had a higher survival rate and fewer neurological sequelae than those who only received conventional treatments. ECLS is an effective alternative method for treatment of children with refractory EV71-related CPF.

Enterovirus 71: epidemiology, pathogenesis and management

Enterovirus 71 (EV71) has emerged as a major cause of neurological threat in the world following the eradication of poliovirus. Most EV71 infections commonly result in hand-foot-mouth disease or herpangina, and some cases are associated with brainstem encephalitis and acute flaccid paralysis. Mortality was high in EV71 brainstem encephalitis complicated with pulmonary edema, particularly in children below 5 years of age. Destruction of vasomotor in the brainstem by EV71 produces autonomic nervous system dysregulation prior to the pulmonary edema. The pulmonary edema is the result of increased pulmonary vascular permeability caused by the direct brainstem lesions and/or a systemic inflammatory response syndrome produced by the release of cytokines and chemokines. There is currently no specific antiviral agent to treat or vaccine to prevent EV71 diseases. Treating severe EV71 brainstem encephalitis patients with intravenous IgG and milrinone is associated with significantly decreased mortality by attenuated sympathetic activity and cytokine production.

Enterovirus 71 Infection of Human Dendritic Cells

Enterovirus 71 (EV71) causes death and long-term neurologic sequelae in hundreds of thousands of young children, but its pathogenesis remains elusive. Dendritic cells (DCs) play a crucial role in antiviral immunity by functioning as professional antigen-presenting cells to prime T cells and by secreting cytokines to modulate immune responses. Here, we show that EV71 productively infected human immature DCs and expressed viral antigen in DCs. EV71 entry into DCs was partially mediated by DC-SIGN. Further analyses revealed that EV71 increased the viability, activation, release of cytokines, interleukin-6, interleukin-12, and tumor necrosis factor-α in DCs. Moreover, EV71 enabled DCs to stimulate T-cell proliferation. Collectively, these findings suggest that EV71 infection of human DCs in vivo is very likely to elicit protective immunity, because in infected mice, both T cells and IL-6 function to reduce mortality.

Diseases caused by enterovirus 71 infection

The purpose of this review was to explore the epidemiology, pathogenesis, virology, and management of enterovirus 71 (EV71) infection. Published literature was surveyed by Medline using the keyword "EV71." The reported incidence of cases of hand-foot-mouth disease/herpangina varied from year to year; seasonal variations in incidence were observed, with a peak in incidence during the summer season. Most cases of hand-foot-mouth disease/herpangina hospitalized for complications occurred in children less than 5 years old. The brainstem was the most likely major target of EV71 infection. Different enteroviruses cocirculate in the community annually. The emergence of the EV71 epidemic in the Asia Pacific region has been associated with the circulation of 5 genetic lineages (genotypes B3, B4, C1, C2, C4) that appear to be undergoing rapid evolutionary changes. The relationship between the gene structure of the EV71 virus and the factors that ensure its survival, ease of transmission, and evasion of immunity is still unclear. EV71 central nervous system involvement causes serious clinical illness, death, and long-term neurologic and psychiatric disorders in young children. EV71 infection has emerged as an important public health problem. Vaccine development is recommended for the prevention of EV71 infection in the future.

Neurodevelopmental outcomes following ganciclovir therapy in symptomatic congenital cytomegalovirus infections involving the central nervous system

BACKGROUND

Ganciclovir protects against hearing deterioration in infants with symptomatic congenital cytomegalovirus (CMV) disease involving the central nervous system (CNS).

OBJECTIVES

To assess the neurodevelopmental impact of ganciclovir therapy in this population.

STUDY DESIGN

100 neonates were enrolled into a controlled Phase III study of symptomatic congenital CMV involving the CNS, and were randomized to either 6 weeks of intravenous ganciclovir or no treatment. Denver developmental tests were performed at 6 weeks, 6 months, and 12 months. For each age, developmental milestones that > or =90% of normal children would be expected to have achieved were identified. The numbers of milestones not met ("delays") were determined for each subject. The average number of delays per subject was compared for each treatment group.

RESULTS

At 6 months, the average number of delays was 4.46 and 7.51, respectively, for ganciclovir recipients and "no treatment" subjects (p=0.02). At 12 months, the average number of delays was 10.06 and 17.14, respectively (p=0.007). In a multivariate regression model, the effect of ganciclovir therapy remained statistically significant at 12 months (p=0.007).

CONCLUSIONS

Infants with symptomatic congenital CMV involving the CNS receiving intravenous ganciclovir therapy have fewer developmental delays at 6 and 12 months compared with untreated infants. Based on these data as well as the previously published data regarding ganciclovir treatment and hearing outcomes, 6 weeks of intravenous ganciclovir therapy can be considered in the management of babies with symptomatic congenital CMV disease involving the CNS. If treatment is initiated, it should be started within the first month of life and patients should be monitored closely for toxicity, especially neutropenia. Since existing data only address the treatment of symptomatic congenital CMV disease involving the CNS, these data cannot be extrapolated to neonates with other manifestations of CMV disease, including asymptomatic babies and symptomatic babies who do not have CNS involvement.

Sialylated glycans as receptor and inhibitor of enterovirus 71 infection to DLD-1 intestinal cells

Background

Many viruses recognize specific sugar residues, particularly sulfated or sialylated glycans, as the infection receptors. A change of sialic acid (2-6)-linked galactose (SA-α2,6Gal) to SA-α2,3Gal determines the receptor for avian flu infection. The receptor for enterovirus 71 (EV71) infection that frequently causes fatal encephalitis in Asian children remains unclear. Currently, there is no effective vaccine or anti-virus agent for EV71 infection. Using DLD-1 intestinal cells, this study investigated whether SA-linked glycan on DLD-1 intestinal cells was a receptor for EV71, and whether natural SA-linked sugars from human milk could block EV71 infection.

Results

EV71 specifically infected DLD-1 intestinal cells but not K562 myeloid cells. Depletion of O-linked glycans or glycolipids, but not N-linked glycans, significantly decreased EV71 infection of DLD-1 cells. Pretreatment of DLD-1 cells with sialidase (10 mU, 2 hours) significantly reduced 20-fold EV71 replication (p < 0.01). Taken together, these results suggest that SA-linked O-glycans and glycolipids, but not N-glycans, on DLD-1 cells were responsible for EV71 infection. Purified SA-α2,3Gal and SA-α2,6Gal from human milk significantly inhibited EV71 infection of DLD-1 cells, indicating terminal SA-linked glycans could be receptors and inhibitors of EV71 infection.

Conclusion

This is the first in the literature to demonstrate that EV71 uses SA-linked glycans as receptors for infection, and natural SA-linked glycans from human milk can protect intestinal cells from EV71 infection. Further studies will test how a SA-containing glycan can prevent EV71 in the future.

Apoptosis of hippocampal pyramidal neurons is virus independent in a mouse model of acute neurovirulent picornavirus infection

Many viruses, including picornaviruses, have the potential to infect the central nervous system (CNS) and stimulate a neuroinflammatory immune response, especially in infants and young children. Cognitive deficits associated with CNS picornavirus infection result from injury and death of neurons that may occur due to direct viral infection or during the immune responses to virus in the brain. Previous studies have concluded that apoptosis of hippocampal neurons during picornavirus infection is a cell-autonomous event triggered by direct neuronal infection. However, these studies assessed neuron death at time points late in infection and during infections that lead to either death of the host or persistent viral infection. In contrast, many neurovirulent picornavirus infections are acute and transient, with rapid clearance of virus from the host. We provide evidence of hippocampal pathology in mice acutely infected with the Theiler's murine encephalomyelitis picornavirus. We found that CA1 pyramidal neurons exhibited several hallmarks of apoptotic death, including caspase-3 activation, DNA fragmentation, and chromatin condensation within 72 hours of infection. Critically, we also found that many of the CA1 pyramidal neurons undergoing apoptosis were not infected with virus, indicating that neuronal cell death during acute picornavirus infection of the CNS occurs in a non-cell-autonomous manner. These observations suggest that therapeutic strategies other than antiviral interventions may be useful for neuroprotection during acute CNS picornavirus infection.

Enterovirus 71 maternal antibodies in infants, Taiwan

Enterovirus 71 (EV71) causes life-threatening disease outbreaks in young children in Asia. This cohort study was conducted to understand the dynamics of maternal EV71 antibodies in Taiwanese young infants. Approximately 50% of neonates had detectable EV71 neutralizing antibodies, which declined to almost undetectable levels by 6 months of age.