Frequent detection of enterovirus D68 and rhinovirus type C in children with acute respiratory infections

This study aimed to evaluate the prevalence of human rhinoviruses (HRVs) and the emergence of enterovirus D68 (EV-D68) in children. A total of 322 nasopharyngeal swab samples were provided from children with an initial diagnosis of upper and lower respiratory tract infections. A total of 34 and 70 cases were positive for EV-D68 and HRV, respectively. The phylogenetic analysis revealed that the clades A and B are the prevalent genotypes for EV-D68 and the HRV-positive samples belong to three types including HRV-A, HRV-B, and HRV-C. The results showed that EV-D68 and HRV-C are circulating in Iran especially in the winter.

Molecular typing and characterization of a novel genotype of EV-B93 isolated from Tibet, China

EV-B93 is a novel serotype within the Enterovirus B species and is uncommon worldwide. Currently, only one full-length genomic sequence (the prototype strain) has been deposited in the GenBank database. In this study, three EV-B93 were identified, including one from an acute flaccid paralysis (AFP) patient (named 99052/XZ/CHN/1999, hereafter XZ99052) and two from healthy children (named 99096/XZ/CHN/1999 and 99167/XZ/CHN/1999, hereafter XZ99096 and XZ99167, respectively) from Tibet in 1999 during the polio eradication program. The identity between the nucleotide and amino acid sequences of the Tibet EV-B93 strain and the EV-B93 prototype strain is 83.2%–83.4% and 96.8%–96.9%, respectively. The Tibet EV-B93 strain was found to have greater nucleotide sequence identity in the P3 region to another enterovirus EV-B107 as per a phylogenetic tree analysis, which revealed that recombination occurred. Seroepidemiology data showed that EV-B93 has not produced an epidemic in Tibet and there may be susceptible individuals. The three Tibet EV-B93 strains are temperature-resistant with prognosticative virulence, suggesting the possibility of a potential large-scale outbreak of EV-B93. The analyzed EV-B93 strains enrich our knowledge about this serotype and provide valuable information on global EV-B93 molecular epidemiology. What is more, they permit the appraisal of the serotype's potential public health impact and aid in understanding the role of recombination events in the evolution of enteroviruses.

Rac1-dependent endocytosis and Rab5-dependent intracellular trafficking are required by Enterovirus A71 and Coxsackievirus A10 to establish infections

Enterovirus A71 (EVA71) and Coxsackievirus A10 (CVA10) are representative types of Enterovirus A. Dependent on the host cell types, the EVA71 entry may utilize clathrin-, caveola-, and endophilin-A2-mediated endocytosis. However, the cell-entry and intracellular trafficking pathways of CVA10, using KREMEN1 as its receptor, are unclear. Here, we tested the relevant mechanisms through RNA interference (RNAi) and chemical inhibitors. We found that endocytosis of EVA71 and CVA10 in rhabdomyosarcoma (RD) cells engaged multiple pathways, and both viruses required Rac1. Interestingly, while CDC42 and Pak1 participated in EVA71 infection, PI3K played a role in CVA10 infection. The functions of Rab proteins in intracellular trafficking of CVA10 and EVA71 were examined by RNAi. Knockdown of Rab5 and Rab21 significantly reduced CVA10 infectivity, while knockdown of Rab5, Rab7 and Rab9 reduced EVA71 infectivity. Confocal microscopy confirmed the colocalization of CVA10 virions with Rab5 or Rab21, and colocalization of EVA71 virions with Rab5 or Rab7. Additionally, we observed that both CVA10 and EVA71 infections were inhibited by endosome acidification inhibitors, bafilomycin-A1 and NH₄Cl. Together, our findings comparatively illustrate the entry and intracellular trafficking processes of representative Enterovirus A types and revealed novel enterovirus intervention targets.

Mapping Attenuation Determinants in Enterovirus-D68

Enterovirus (EV)-D68 has been associated with epidemics in the United Sates in 2014, 2016 and 2018. This study aims to identify potential viral virulence determinants. We found that neonatal type I interferon receptor knockout mice are susceptible to EV-D68 infection via intraperitoneal inoculation and were able to recapitulate the paralysis process observed in human disease. Among the EV-D68 strains tested, strain US/MO-14-18949 caused no observable disease in this mouse model, whereas the other strains caused paralysis and death. Sequence analysis revealed several conserved genetic changes among these virus strains: nucleotide positions 107 and 648 in the 5′-untranslated region (UTR); amino acid position 88 in VP3; 1, 148, 282 and 283 in VP1; 22 in 2A; 47 in 3A. A series of chimeric and point-mutated infectious clones were constructed to identify viral elements responsible for the distinct virulence. A single amino acid change from isoleucine to valine at position 88 in VP3 attenuated neurovirulence by reducing virus replication in the brain and spinal cord of infected mice.

Clinical, etiological and epidemiological investigations of hand, foot and mouth disease in southern Vietnam during 2015 - 2018

Hand, foot and mouth disease (HFMD) continues to challenge Asia with pandemic potential. In Vietnam, there have been two major outbreaks occurring during 2011-2012 (>200,000 hospitalizations and >200 deaths) and more recently in 2018 (>130,000 hospitalizations and 17 deaths). Given the high burden and the complex epidemic dynamics of HFMD, synthesizing its clinical and epidemiological data remains essential to inform the development of appropriate interventions and design public health measures. We report the results of a hospital-based study conducted during 2015-2018, covering the severe HFMD outbreak recently documented in Vietnam in 2018. The study was conducted at three major hospitals responsible for receiving HFMD patients from southern Vietnam with a population of over 40 million. A total of 19 enterovirus serotypes were detected in 1196 HFMD patients enrolled in the clinical study during 2015-2018, with enterovirus A71 (EV-A71), coxsackievirus A6 (CV-A6), CV-A10 and CV-A16 being the major causes. Despite the emergence of coxsackieviruses, EV-A71 remains the leading cause of severe HFMD in Vietnam. EV-A71 was consistently detected at a higher frequency during the second half of the years. The emergence of EV-A71 subgenogroup C4 in late 2018 was preceded by its low activity during 2017-early 2018. Compared with EV-A71 subgenogroup B5, C4 was more likely to be associated with severe HFMD, representing the first report demonstrating the difference in clinical severity between subgenogroup C4 and B5, the two predominant EV-A71 subgenogroups causing HFMD worldwide. Our data have provided significant insights into important aspects of HFMD over four years (2015-2018) in Vietnam, and emphasize active surveillance for pathogen circulation remains essential to inform the local public health authorities in the development of appropriate intervention strategies to reduce the burden of this emerging infections. Multivalent vaccines are urgently needed to control HFMD.

A European multicentre evaluation of detection and typing methods for human enteroviruses and parechoviruses using RNA transcripts

Polymerase chain reaction (PCR) detection has become the gold standard for diagnosis and typing of enterovirus (EV) and human parechovirus (HPeV) infections. Its effectiveness depends critically on using the appropriate sample types and high assay sensitivity as viral loads in cerebrospinal fluid samples from meningitis and sepsis clinical presentation can be extremely low. This study evaluated the sensitivity and specificity of currently used commercial and in-house diagnostic and typing assays. Accurately quantified RNA transcript controls were distributed to 27 diagnostic and 12 reference laboratories in 17 European countries for blinded testing. Transcripts represented the four human EV species (EV-A71, echovirus 30, coxsackie A virus 21, and EV-D68), HPeV3, and specificity controls. Reported results from 48 in-house and 15 commercial assays showed 98% detection frequencies of high copy (1000 RNA copies/5 µL) transcripts. In-house assays showed significantly greater detection frequencies of the low copy (10 copies/5 µL) EV and HPeV transcripts (81% and 86%, respectively) compared with commercial assays (56%, 50%; P = 7 × 10-5 ). EV-specific PCRs showed low cross-reactivity with human rhinovirus C (3 of 42 tests) and infrequent positivity in the negative control (2 of 63 tests). Most or all high copy EV and HPeV controls were successfully typed (88%, 100%) by reference laboratories, but showed reduced effectiveness for low copy controls (41%, 67%). Stabilized RNA transcripts provide an effective, logistically simple and inexpensive reagent for evaluation of diagnostic assay performance. The study provides reassurance of the performance of the many in-house assay formats used across Europe. However, it identified often substantially reduced sensitivities of commercial assays often used as point-of-care tests.

Whole-Genome Sequencing of Human Enteroviruses from Clinical Samples by Nanopore Direct RNA Sequencing

Enteroviruses are small RNA viruses that affect millions of people each year by causing an important burden of disease with a broad spectrum of symptoms. In routine diagnostic laboratories, enteroviruses are identified by PCR-based methods, often combined with partial sequencing for genotyping. In this proof-of-principle study, we assessed direct RNA sequencing (DRS) using nanopore sequencing technology for fast whole-genome sequencing of viruses directly from clinical samples. The approach was complemented by sequencing the corresponding viral cDNA via Illumina MiSeq sequencing. DRS of total RNA extracted from three different enterovirus-positive stool samples produced long RNA fragments, covering between 59% and 99.6% of the most similar reference genome sequences. The identification of the enterovirus sequences in the samples was confirmed by short-read cDNA sequencing. Sequence identity between DRS and Illumina MiSeq enterovirus consensus sequences ranged between 94% and 97%. Here, we show that nanopore DRS can be used to correctly identify enterovirus genotypes from patient stool samples with high viral load and that the approach also provides rich metatranscriptomic information on sample composition for all life domains.

Global profiling of the alternative splicing landscape reveals transcriptomic diversity during the early phase of enterovirus 71 infection

The alteration of host cell splicing is a major strategy favouring viral replication; however, the interaction between human tonsillar epithelial cells (HTECs) and enterovirus 71 (EV71) has not been fully elucidated. Here, a total of 201 differentially expressed genes (DEGs) and 3266 novel genes with coding potential were identified. A total of 3479 skipped exons (SEs), 515 alternative 3' splice sites (A3SSs), 391 alternative 5' splice sites (A5SSs), 531 mutually exclusive exons (MXEs) and 825 retained introns (RIs) were identified as significantly altered alternative splicing (AS) events. The enriched DEGs were mainly related to the cell cycle, spliceosome, and Toll-like receptor (TLR) signalling pathways. Finally, the replication of EV71 was significantly inhibited by TLR2 heterodimers. Our findings suggest that AS events induced by EV71 increase the transcriptomic diversity of HTECs in response to EV71 infection. Additionally, TLR2 heterodimers have the potential to protect HTECs against EV71.

Disseminated cortical and subcortical lesions in neonatal enterovirus 71 encephalitis

Enteroviruses are one of the most important causes of viral encephalitis in the neonatal period. However, the non-specificity of the symptoms presented renders its diagnosis challenging. Intracranial MRI has been reported to be a very useful imaging modality that can detect the characteristic white matter lesions around the periventricular regions. In this study, we report a case of a patient with neonatal encephalitis who presented with normal white blood cell counts in the initial cerebrospinal fluid analysis. A lumbar puncture retap identified pleocytosis, and polymerase chain reaction assays detected enterovirus 71 in the blood and stool samples. Furthermore, MRI revealed atypical disseminated cortical and subcortical white matter lesions on diffusion weighted images, and neuroradiological re-evaluation showed necrotic changes 2 weeks later. This unique case expands our knowledge of the spectrum of neurological disorders due to enterovirus 71 infection in neonatal period.

Differential Detection of Encapsidated versus Unencapsidated Enterovirus RNA in Samples Containing Pancreatic Enzymes-Relevance for Diabetes Studies

Using immunohistochemistry, enterovirus capsid proteins were demonstrated in pancreatic islets of patients with type 1 diabetes. Virus proteins are mainly located in beta cells, supporting the hypothesis that enterovirus infections may contribute to the pathogenesis of type 1 diabetes. In samples of pancreatic tissue, enterovirus RNA was also detected, but in extremely small quantities and in a smaller proportion of cases compared to the enteroviral protein. Difficulties in detecting viral RNA could be due to the very small number of infected cells, the possible activity of PCR inhibitors, and the presence—during persistent infection—of the viral genome in unencapsidated forms. The aim of this study was twofold: (a) to examine if enzymes or other compounds in pancreatic tissue could affect the molecular detection of encapsidated vs. unencapsidated enterovirus forms, and (b) to compare the sensitivity of RT-PCR methods used in different laboratories. Dilutions of encapsidated and unencapsidated virus were spiked into human pancreas homogenate and analyzed by RT-PCR. Incubation of pancreatic homogenate on wet ice for 20 h did not influence the detection of encapsidated virus. In contrast, a 15-min incubation on wet ice dramatically reduced detection of unencapsidated forms of virus. PCR inhibitors could not be found in pancreatic extract. The results show that components in the pancreas homogenate may selectively affect the detection of unencapsidated forms of enterovirus. This may lead to difficulties in diagnosing persisting enterovirus infection in the pancreas of patients with type 1 diabetes.

[Epidemiological and pathogenic characteristics of cases with severe and fatal hand, foot, and mouth disease caused by other enterovirus in Hebei province, 2013-2017]

Objective: To understand the epidemiological characteristics of cases with severe and fatal hand, foot, and mouth disease (HFMD) caused by other enterovirus in Hebei province, 2013-2017. Genetic characteristics of the main pathogen cosackie virus A6 (CoxA6) were also analyzed to further clarifying the characteristics and rules of genetic evolution on this virus. Methods: Descriptive epidemiological methods were used to analyze the distribution of severe and fatal cases with HFMD caused by other enterovirus in Hebei, 2013-2017. The VP1 sequences of CoxA6 were phylogenetically analyzed, using the Mega 5.2 software package. Results: A total of 86 severe and fatal cases with HFMD caused by other enterovirus were reported, accounting for 1.12%, comparing to all the HFMD caused by other enterovirus. Cases began to rise in April, and peaked in May-July. 65.12% of the cases occurred in children between 1 and 5 years old. The sex ratio between male and female was 1.39∶1. A total of 93.02% of the cases were children outside the child care settings. A total of 39 positive strains were identified, with positive isolation rate as 45.35%. Phylogenetic analysis on the VP1 sequences of CoxA6 strains in this study revealed that CoxA6 strains belonged to sub-genotypes D3a and D3b. Conclusions: Severe and fatal HFMD cases that caused by other enterovirus in Hebei province was with seasonal feature, consistent with the overall trend of this disease, 2013-2017. No new evolutionary branch appeared in the CoxA6 strain.

Involvement of VCP/UFD1/Nucleolin in the viral entry of Enterovirus A species

Valosin-containing protein (VCP) plays roles in various cellular activities. Recently, Enterovirus A71 (EVA71) infection was found to hijack the VCP protein. However, the mechanism by which VCP participates in the EVA71 life cycle remains unclear. Using chemical inhibitor, RNA interference and dominant negative mutant, we confirmed that the VCP and its ATPase activity were critical for EVA71 infection. To identify the factors downstream of VCP in enterovirus infection, 31 known VCP-cofactors were screened in the siRNA knockdown experiments. The results showed that UFD1 (ubiquitin recognition factor in ER associated degradation 1), but not NPL4 (NPL4 homolog, ubiquitin recognition factor), played critical roles in infections by EVA71. UFD1 knockdown suppressed the activity of EVA71 pseudovirus (causing single round infection) while it did not affect the viral replication in replicon RNA transfection assays. In addition, knockdown of VCP and UFD1 reduced viral infections by multiple human Enterovirus A serotypes. Mechanistically, we found that knockdown of UFD1 significantly decreased the binding and the subsequent entry of EVA71 to host cells through modulating the levels of nucleolin protein, a coreceptor of EVA71. Together, these data reveal novel roles of VCP and its cofactor UFD1 in the virus entry by EVA71.

Recombination Analysis of Non-Poliovirus Members of the Enterovirus C Species; Restriction of Recombination Events to Members of the Same 3DPol Cluster

Enteroviruses (EVs) are highly prevalent viruses worldwide. Recombination is known to occur frequently in EVs belonging to species Enterovirus A, Enterovirus B, and Enterovirus C. Although many recombinant vaccine-derived poliovirus (VDPV) strains have been reported, our knowledge on recombination in non-polio EVs in the species Enterovirus C is limited. Here, we combined a dataset consisting of 11 newly generated full-length Enterovirus C sequences and 180 publicly available sequences to study recombination dynamics in non-polio EVs. To identify recombination patterns, maximum likelihood phylogenetic trees of different genomic regions were constructed, and segregation analyses were performed. Recombination was observed between members of the same 3DPol cluster, but was rarely observed between members of different clusters. We hypothesize that this restriction may have arisen through their different compartmentalization in respiratory and enteric tracts related to differences in cellular tropisms so that the opportunity to recombine may not be available.

Characterization of Plaque Variants and the Involvement of Quasi-Species in a Population of EV-A71

Viral plaque morphologies in human cell lines are markers for growth capability and they have been used to assess the viral fitness and selection of attenuated mutants for live-attenuated vaccine development. In this study, we investigate whether the naturally occurring plaque size variation reflects the virulence of the variants of EV-A71. Variants of two different plaque sizes (big and small) from EV-A71 sub-genotype B4 strain 41 were characterized. The plaque variants displayed different in vitro growth kinetics compared to the parental wild type. The plaque variants showed specific mutations being present in each variant strain. The big plaque variants showed four mutations I97L, N104S, S246P and N282D in the VP1 while the small plaque variants showed I97T, N237T and T292A in the VP1. No other mutations were detected in the whole genome of the two variants. The variants showed stable homogenous small plaques and big plaques, respectively, when re-infected in rhabdomyosarcoma (RD) and Vero cells. The parental strain showed faster growth kinetics and had higher viral RNA copy number than both the big and small plaque variants. Homology modelling shows that both plaque variants have differences in the structure of the VP1 protein due to the presence of unique spontaneous mutations found in each plaque variant This study suggests that the EV-A71 sub-genotype B4 strain 41 has at least two variants with different plaque morphologies. These differences were likely due to the presence of spontaneous mutations that are unique to each of the plaque variants. The ability to maintain the respective plaque morphology upon passaging indicates the presence of quasi-species in the parental population.

Early Entry Events in Echovirus 30 Infection

Echovirus 30 (E30), a member of the enterovirus B species, is a major cause of viral meningitis, targeting children and adults alike. While it is a frequently isolated enterovirus and the cause of several outbreaks all over the world, surprisingly little is known regarding its entry and replication strategy within cells. In this study, we used E30 strain Bastianni (E30B) generated from an infectious cDNA clone in order to study early entry events during infection in human RD cells. E30B required the newly discovered Fc echovirus receptor (FcRn) for successful infection, but not the coxsackievirus and adenovirus receptor (CAR) or decay-accelerating factor (DAF), although an interaction with DAF was observed. Double-stranded RNA replication intermediate was generated between 2 and 3 h postinfection (p.i.), and viral capsid production was initiated between 4 and 5 h p.i. The drugs affecting Rac1 (NSC 23766) and cholesterol (filipin III) compromised infection, whereas bafilomycin A1, dyngo, U-73122, wortmannin, and nocodazole did not, suggesting the virus follows an enterovirus-triggered macropinocytic pathway rather than the clathrin pathway. Colocalization with early endosomes and increased infection due to constitutively active Rab5 expression suggests some overlap and entry to classical early endosomes. Taken together, these results suggest that E30B induces an enterovirus entry pathway, leading to uncoating in early endosomes.IMPORTANCE Echovirus 30 (E30) is a prevalent enterovirus causing regular outbreaks in both children and adults in different parts of the world. It is therefore surprising that relatively little is known of its infectious entry pathway. We set out to generate a cDNA clone and gradient purified the virus in order to study the early entry events in human cells. We have recently studied other enterovirus B group viruses, like echovirus 1 (EV1) and coxsackievirus A9 (CVA9), and found many similarities between those viruses, allowing us to define a so-called "enterovirus entry pathway." Here, E30 is reminiscent of these viruses, for example, by not relying on acidification for infectious entry. However, despite not using the clathrin entry pathway, E30 accumulates in classical early endosomes.

Structure of the enterovirus D68 RNA-dependent RNA polymerase in complex with NADPH implicates an inhibitor binding site in the RNA template tunnel

Enterovirus D68 (EV-D68) is an emerging viral pathogen belonging to the Enterovirus genus of the Picornaviridae family, which is a serious threat to human health and has resulted in significant economic losses. The EV-D68 genome encodes an RNA-dependent RNA polymerase (RdRp) 3D^pol, which is central for viral genome replication and considered as a promising target for specific antiviral therapeutics. In this study, we report the crystal structures of human EV-D68 RdRp in the apo state and in complex with the inhibitor NADPH, which was selected by using a structure-based virtual screening approach. The EV-D68-RdRp-NADPH complex is the first RdRp-inhibitor structure identified in the species Enterovirus D. The inhibitor NADPH occupies the RNA template binding channel of EV-D68 RdRp with a novel binding pocket. Additionally, residues involved in the NADPH binding pocket of EV-D68 RdRp are highly conserved in RdRps of enteroviruses. Therefore, the enzyme activity of three RdRps from EV-D68, poliovirus, and enterovirus A71 is shown to decrease when titrated with NADPH separately in vitro. Furthermore, we identified that NADPH plays a pivotal role as an RdRp inhibitor instead of a chain terminator during restriction of RNA-dependent RNA replication. In the future, derivatives of NADPH may pave the way for novel inhibitors of RdRp through compound modification, providing potential antiviral agents for treating enteroviral infection and related diseases.

Sequence analysis of the first B5 subgenogroup strain of enterovirus 71 isolated in Korea

Enterovirus A71 (EV71), the main etiological agent of handfoot- mouth disease (HFMD), circulates in many areas of the world and has caused large epidemics since 1997, especially in the Asia-Pacific region. In this study, we determined the full-genome sequence of CMC718, a newly isolated EV71 strain in Korea. The CMC718 genome was 7,415 nucleotides in length and was confirmed by whole-genome phylogenetic analysis to belong to the B5 genotype. In particular, CMC718 demonstrated maximum identity with strain M988 of the B5 genotype and numerous amino acid variants were detected in the 3D domain of the viral protein P3, which is consistent with the mutation pattern of a B5 strain isolated in 2012–2013. Comparison of the CMC718 sequence with other EV71 reference strains confirmed the relationship and genetic variation of CMC718. Our study was a full-genome sequence analysis of the first EV71 strain of the B5 genotype isolated in South Korea. This information will be a valuable reference for the development of methods for the detection of recombinant viruses, the tracking of infections, and the diagnosis of EV71.

Identification of Immunogenic Epitopes That Permit the Detection of Antigen-Specific T Cell Responses in Multiple Serotypes of Group B Coxsackievirus Infections

Coxsackievirus group B (CVB) contains six serotypes that can affect various organs. Some of these organ-specific diseases such as myocarditis and pancreatitis can be caused by more than one serotype. Thus, development of immunological tools common to multiple serotypes is desired. This is especially critical for analyzing antigen-specific T cell responses at a single cell level. To this end, we made efforts to identify the immunogenic epitopes of CVB3 leading us to localize three T cell epitopes within the viral protein 1 (VP1) namely, VP1 681-700, VP1 721-740 and VP1 771-790. First, we confirmed their immunogenicity in the immunization settings. Second, we sought to verify the ability of VP1 epitopes to bind major histocompatibility complex (MHC) class II (IA^k) molecules. Third, we created MHC class II (IA^k) dextramers and tetramers and ascertained the T cell responses to be antigen-specific. Fourth, we analyzed the T cell responses in animals infected with CVB3 and noted the magnitude of antigen-specific T cell responses occurring in the order of VP1 721-740 and VP1 681-700 followed by VP1 771-790 as verified by proliferation assay and IA^k tetramer staining. All epitopes induced interferon (IFN)-γ as a major cytokine. Finally, we investigated whether the VP1 tools generated for CVB3 can also be used to verify T cell responses in infections caused by other serotypes. To this end, we established the CVB4 infection model in A/J mice and found that the CVB4 infection led to the induction of IFN-γ-producing T cell responses primarily for VP1 721-740 and VP1 681-700. Thus, the VP1-specific tools, particularly IA^k tetramers can be used to monitor anti-viral T cell responses in multiple CVB serotypes.

Coxsackievirus B3 Infection of Human Neural Progenitor Cells Results in Distinct Expression Patterns of Innate Immune Genes

Coxsackievirus B3 (CVB3), a member of Picornaviridae family, is an important human pathogen that causes a wide range of diseases, including myocarditis, pancreatitis, and meningitis. Although CVB3 has been well demonstrated to target murine neural progenitor cells (NPCs), gene expression profiles of CVB3-infected human NPCs (hNPCs) has not been fully explored. To characterize the molecular signatures and complexity of CVB3-mediated host cellular responses in hNPCs, we performed QuantSeq 3′ mRNA sequencing. Increased expression levels of viral RNA sensors (RIG-I, MDA5) and interferon-stimulated genes, such as IFN-β, IP-10, ISG15, OAS1, OAS2, Mx2, were detected in response to CVB3 infection, while IFN-γ expression level was significantly downregulated in hNPCs. Consistent with the gene expression profile, CVB3 infection led to enhanced secretion of inflammatory cytokines and chemokines, such as interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1). Furthermore, we show that type I interferon (IFN) treatment in hNPCs leads to significant attenuation of CVB3 RNA copy numbers, whereas, type II IFN (IFN-γ) treatment enhances CVB3 replication and upregulates suppressor of cytokine signaling 1/3 (SOCS) expression levels. Taken together, our results demonstrate the distinct molecular patterns of cellular responses to CVB3 infection in hNPCs and the pro-viral function of IFN-γ via the modulation of SOCS expression.

Rhinovirus C15 Induces Airway Hyperresponsiveness via Calcium Mobilization in Airway Smooth Muscle

Rhinovirus (RV) exposure evokes exacerbations of asthma that markedly impact morbidity and mortality worldwide. The mechanisms by which RV induces airway hyperresponsiveness (AHR) or by which specific RV serotypes differentially evoke AHR remain unknown. We posit that RV infection evokes AHR and inflammatory mediator release, which correlate with degrees of RV infection. Furthermore, we posit that rhinovirus C-induced AHR requires paracrine or autocrine mediator release from epithelium that modulates agonist-induced calcium mobilization in human airway smooth muscle. In these studies, we used an ex vivo model to measure bronchoconstriction and mediator release from infected airways in human precision cut lung slices to understand how RV exposure alters airway constriction. We found that rhinovirus C15 (RV-C15) infection augmented carbachol-induced airway narrowing and significantly increased release of IP-10 (IFN-γ-induced protein 10) and MIP-1β (macrophage inflammatory protein-1β) but not IL-6. RV-C15 infection of human airway epithelial cells augmented agonist-induced intracellular calcium flux and phosphorylation of myosin light chain in co-cultured human airway smooth muscle to carbachol, but not after histamine stimulation. Our data suggest that RV-C15-induced structural cell inflammatory responses are associated with viral load but that inflammatory responses and alterations in agonist-mediated constriction of human small airways are uncoupled from viral load of the tissue.

Use of a Glycan Library Reveals a New Model for Enteric Virus Oligosaccharide Binding and Virion Stabilization

Enteric viruses infect the gastrointestinal tract, and bacteria can promote replication and transmission of several enteric viruses. Viruses can be inactivated by exposure to heat or bleach, but poliovirus, coxsackievirus B3, and reovirus can be stabilized by bacteria or bacterial polysaccharides, limiting inactivation and aiding transmission. We previously demonstrated that certain N-acetylglucosamine (GlcNAc)-containing polysaccharides can stabilize poliovirus. However, the detailed virus-glycan binding specificity and glycan chain length requirements, and thus the mechanism of virion stabilization, have been unclear. A previous limitation was our lack of defined-length glycans to probe mechanisms and consequences of virus-glycan interactions. Here, we generated a panel of polysaccharides and oligosaccharides to determine the properties required for binding and stabilization of poliovirus. Poliovirus virions are nonenveloped icosahedral 30-nm particles with 60 copies of each of four capsid proteins, VP1 to VP4. VP1 surrounds the 5-fold axis, and our past work indicates that this region likely contains the glycan binding site. We found that relatively short GlcNAc oligosaccharides, such as a six-unit GlcNAc oligomer, can bind poliovirus but fail to enhance virion stability. Virion stabilization required binding of long GlcNAc polymers of greater than 20 units. Our data suggest a model where GlcNAc polymers of greater than 20 units bind and bridge adjacent 5-fold axes, thus aiding capsid rigidity and stability. This study provides a deeper understanding of enteric virus-bacterial glycan interactions, which are important for virion environmental stability and transmission.IMPORTANCE Enteric viruses are transmitted through the fecal-oral route, but how enteric viruses survive in the environment is unclear. Previously, we found that bacterial polysaccharides enhance poliovirus stability against heat or bleach inactivation, but the specific molecular requirements have been unknown. Here, we showed that certain short-chain oligosaccharides can bind to poliovirus but do not increase virion stability. Long-chain polysaccharides bind and may bridge adjacent sites on the viral surface, thus increasing capsid rigidity and stability. This work defines the unique interactions of poliovirus and glycans, which provides insight into virion environmental stability and transmission.

Molecular Characterization and Clinical Description of Non-Polio Enteroviruses Detected in Stool Samples from HIV-Positive and HIV-Negative Adults in Ghana

In the post-polio eradication era, increasing attention is given to non-polio enteroviruses. Most of the data about enteroviruses in sub-Saharan Africa are related to acute flaccid paralysis surveillance and target the pediatric population. This study aimed to investigate the presence of enterovirus in PLHIV (people living with HIV) and HIV-negative individuals in Ghana. Stool samples from HIV-positive individuals (n = 250) and healthy blood donors (n = 102) attending the Komfo Anokye Teaching Hospital in Kumasi, Ghana, were screened by real-time PCR for enterovirus. Molecular typing of the VP1 region was performed. Enterovirus-positive samples were tested for norovirus, adenovirus, rotavirus, sapovirus, and cosaviruses. Twenty-six out of 250 HIV-positive subjects (10.4%) and 14 out of 102 HIV-negative individuals (13.7%) were detected enterovirus-positive, not showing a significant different infection rate between the two groups. HIV-negative individuals were infected with Enterovirus C strains only. HIV-positive participants were detected positive for species Enterovirus A, Enterovirus B, and Enterovirus C. Co-infections with other viral enteric pathogens were almost exclusively detected among HIV-positive participants. Overall, the present study provides the first data about enteroviruses within HIV-positive and HIV-negative adults living in Ghana.

Enterovirus A71 capsid protein VP1 increases blood-brain barrier permeability and virus receptor vimentin on the brain endothelial cells

Enterovirus A71 (EV-A71) is the major cause of severe hand-foot-and-mouth diseases (HFMD), especially encephalitis and other nervous system diseases. EV-A71 capsid protein VP1 mediates virus attachment and is the important virulence factor in the EV-A71pathogenesis. In this study, we explored the roles of VP1 in the permeability of blood-brain barrier (BBB). Sera albumin, Evans blue, and dextran leaked into brain parenchyma of the 1-week-old C57BL/6J mice intracranially injected with VP1 recombinant protein. VP1 also increased the permeability of the brain endothelial cells monolayer, an in vitro BBB model. Tight junction protein claudin-5 was reduced in the brain tissues or brain endothelial cells treated with VP1. In contrast, VP1 increased the expression of virus receptor vimentin, which could be blocked with VP1 neutralization antibody. Vimentin expression in the VP1-treated brain endothelial cells was regulated by TGF-β/Smad-3 and NF-κB signal pathways. Moreover, vimentin over-expression was accompanied with compromised BBB. From these studies, we conclude that EV-A71 virus capsid protein VP1 disrupted BBB and increased virus receptor vimentin, which both may contribute to the virus entrance into brain and EV-A71 CNS infection.