ABSTRACT
Positive health outcomes are related to adults' religious congregational participation. For parents of children with chronic disease, structured daily care routines and/or strict infection control precautions may limit participation. For this exploratory study, we examined the relationship between congregational support and religious coping by parents of children with cystic fibrosis (CF) compared to parents for whom child health issues were not significant stressors. CF parents reported higher levels of emotional support from congregation members and use of religious coping. Within-group differences were found for CF parents by denominational affiliation. Congregational support for parents dealing with child chronic disease is important.
Subject(s)
Adaptation, Psychological , Attitude to Health , Cystic Fibrosis/psychology , Parents/psychology , Religion and Psychology , Social Support , Adolescent , Child , Child, Preschool , Female , Humans , Infant , MaleABSTRACT
Following attachment and internalization, mammalian reoviruses undergo intracellular proteolytic disassembly followed by viral penetration into the cytoplasm. The initiating event in reovirus disassembly is the cathepsin-mediated proteolytic degradation of viral outer capsid protein σ3. A single tyrosine-to-histidine mutation at amino acid 354 (Y354H) of strain type 3 Dearing (T3D) σ3 enhances reovirus disassembly and confers resistance to protease inhibitors such as E64. The σ3 amino acid sequence of strain type 3 Abney (T3A) differs from that of T3D at eight positions including Y354H. However, T3A displays disassembly kinetics and protease sensitivity comparable with T3D. We hypothesize that one or more additional σ3 polymorphisms suppress the Y354H phenotype and restore T3D disassembly characteristics. To test this hypothesis, we engineered a panel of reovirus variants with T3A σ3 polymorphisms introduced individually into T3D-σ3Y354H. We evaluated E64 resistance and in vitro cathepsin L susceptibility of these viruses and found that one containing a glycine-to-glutamate substitution at position 198 (G198E) displayed disassembly kinetics and E64 sensitivity similar to those properties of T3A and T3D. Additionally, viruses containing changes at positions 233 and 347 (S233L and I347T) developed de novo compensatory mutations at position 198, strengthening the conclusion that residue 198 is a key determinant of σ3 proteolytic susceptibility. Variants with Y354H in σ3 lost infectivity more rapidly than T3A or T3D following heat treatment, an effect abrogated by G198E. These results identify a regulatory network of residues that control σ3 cleavage and capsid stability, thus providing insight into the regulation of nonenveloped virus disassembly.
Subject(s)
Capsid Proteins/metabolism , Capsid/metabolism , Orthoreovirus, Mammalian/metabolism , Proteolysis , Amino Acid Substitution , Animals , Capsid Proteins/genetics , Cathepsin L/genetics , Cathepsin L/metabolism , Cell Line , Mice , Mutation, Missense , Orthoreovirus, Mammalian/genetics , Reoviridae Infections/genetics , Reoviridae Infections/metabolismABSTRACT
We defined the function of type I interferons (IFNs) in defense against reovirus strain type 1 Lang (T1L), which is a double-stranded RNA virus that infects Peyer's patches (PPs) after peroral inoculation of mice. T1L induced expression of mRNA for IFN-alpha, IFN-beta, and Mx-1 in PPs and caused localized intestinal infection that was cleared in 10 d. In contrast, T1L produced fatal systemic infection in IFNalphaR1 knockout (KO) mice with extensive cell loss in lymphoid tissues and necrosis of the intestinal mucosa. Studies of bone-marrow chimeric mice indicated an essential role for hematopoietic cells in IFN-dependent viral clearance. Dendritic cells (DCs), including conventional DCs (cDCs), were the major source of type I IFNs in PPs of reovirus-infected mice, whereas all cell types expressed the antiviral protein Mx-1. Neither NK cells nor signaling via Toll-like receptor 3 or MyD88 were essential for viral clearance. These data demonstrate a requirement for type I IFNs in the control of an intestinal viral infection and indicate that cDCs are a significant source of type I IFN production in vivo. Therefore, innate immunity in PPs is an essential component of host defense that limits systemic spread of pathogens that infect the intestinal mucosa.
Subject(s)
Bone Marrow Cells/immunology , Dendritic Cells/immunology , Interferon Type I/immunology , Orthoreovirus, Mammalian/immunology , Peyer's Patches/immunology , Reoviridae Infections/prevention & control , Animals , Immunohistochemistry , Interferon Type I/genetics , Interferon Type I/metabolism , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Peyer's Patches/virology , Reoviridae Infections/immunology , Reverse Transcriptase Polymerase Chain Reaction , Survival AnalysisABSTRACT
Infectious entry of the nonenveloped rotavirus virion requires proteolysis of the spike protein VP4 to mediate conformational changes associated with membrane penetration. We sequenced and characterized an isolate that was cultured in the absence of trypsin and found that it is more resistant to proteolysis than WT virus. A substitution mutation abrogates one of the defined trypsin-cleavage sites, suggesting that blocking proteolysis at this site reduces the overall kinetics of proteolysis. Kinetic analysis of the membrane penetration-associated conformational change indicated that the 'fold-back' of the mutant spike protein is slower than that of WT. Despite these apparent biochemical defects, the mutant virus replicates in an identical manner to the WT virus. These findings enhance an understanding of VP4 functions and establish new strategies to interrogate rotavirus cell entry.
Subject(s)
Capsid Proteins/genetics , Capsid Proteins/metabolism , Mutation , Rotavirus Infections/enzymology , Rotavirus Infections/virology , Rotavirus/physiology , Trypsin/metabolism , Amino Acid Sequence , Animals , Host-Pathogen Interactions , Humans , Macaca mulatta , Molecular Sequence Data , Protein Processing, Post-Translational , Rotavirus/chemistry , Rotavirus/genetics , Sequence Alignment , Virus Internalization , Virus ReplicationABSTRACT
We explored the role of Peyer's patch (PP) dendritic cell (DC) populations in the induction of immune responses to reovirus strain type 1 Lang (T1L). Immunofluorescence staining revealed the presence of T1L structural (sigma1) and nonstructural (sigmaNS) proteins in PPs of T1L-infected mice. Cells in the follicle-associated epithelium contained both sigma1 and sigmaNS, indicating productive viral replication. In contrast, sigma1, but not sigmaNS, was detected in the subepithelial dome (SED) in association with CD11c(+)/CD8alpha(-)/CD11b(lo) DCs, suggesting antigen uptake by these DCs in the absence of infection. Consistent with this possibility, PP DCs purified from infected mice contained sigma1, but not sigmaNS, and PP DCs from uninfected mice could not be productively infected in vitro. Furthermore, sigma1 protein in the SED was associated with fragmented DNA by terminal deoxy-UTP nick-end labeling staining, activated caspase-3, and the epithelial cell protein cytokeratin, suggesting that DCs capture T1L antigen from infected apoptotic epithelial cells. Finally, PP DCs from infected mice activated T1L-primed CD4(+) T cells in vitro. These studies show that CD8alpha(-)/CD11b(lo) DCs in the PP SED process T1L antigen from infected apoptotic epithelial cells for presentation to CD4(+) T cells, and therefore demonstrate the cross-presentation of virally infected cells by DCs in vivo during a natural viral infection.
Subject(s)
Antigens, Viral/metabolism , Apoptosis , Dendritic Cells/virology , Epithelial Cells/virology , Intestines/virology , Orthoreovirus, Mammalian/metabolism , Peyer's Patches/virology , Animals , CD11b Antigen/biosynthesis , CD11c Antigen/biosynthesis , CD4-Positive T-Lymphocytes/metabolism , CD8 Antigens/biosynthesis , Cell Division , Cell Line , Dendritic Cells/cytology , Dendritic Cells/metabolism , Epithelial Cells/metabolism , Female , Immunity, Mucosal , Intestinal Mucosa/metabolism , Keratins/metabolism , Mice , Mice, Inbred BALB C , Microscopy, Confocal , Microscopy, Fluorescence , Orthoreovirus, Mammalian/genetics , Peyer's Patches/metabolismABSTRACT
The cathepsin family of endosomal proteases is required for proteolytic processing of several viruses during entry into host cells. Mammalian reoviruses utilize cathepsins B (Ctsb), L (Ctsl), and S (Ctss) for disassembly of the virus outer capsid and activation of the membrane penetration machinery. To determine whether cathepsins contribute to reovirus tropism, spread, and disease outcome, we infected 3-day-old wild-type (wt), Ctsb(-/-), Ctsl(-/-), and Ctss(-/-) mice with the virulent reovirus strain T3SA+. The survival rate of Ctsb(-/-) mice was enhanced in comparison to that of wt mice, whereas the survival rates of Ctsl(-/-) and Ctss(-/-) mice were diminished. Peak titers at sites of secondary replication in all strains of cathepsin-deficient mice were lower than those in wt mice. Clearance of the virus was delayed in Ctsl(-/-) and Ctss(-/-) mice in comparison to the levels for wt and Ctsb(-/-) mice, consistent with a defect in cell-mediated immunity in mice lacking cathepsin L or S. Cathepsin expression was dispensable for establishment of viremia, but cathepsin L was required for maximal reovirus growth in the brain. Treatment of wt mice with an inhibitor of cathepsin L led to amelioration of reovirus infection. Collectively, these data indicate that cathepsins B, L, and S influence reovirus pathogenesis and suggest that pharmacologic modulation of cathepsin activity diminishes reovirus disease severity.
Subject(s)
Cathepsin B/genetics , Cathepsins/genetics , Cysteine Endopeptidases/genetics , Gene Expression Regulation , Reoviridae Infections/genetics , Reoviridae/metabolism , Animals , Brain/virology , Cathepsin B/metabolism , Cathepsin L , Cathepsins/metabolism , Cell Line , Cysteine Endopeptidases/metabolism , Inflammation , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Biological , Time FactorsABSTRACT
Reovirus induces apoptosis in cultured cells and in vivo. In cell culture models, apoptosis is contingent upon a mechanism involving reovirus-induced activation of transcription factor NF-kappaB complexes containing p50 and p65/RelA subunits. To explore the in vivo role of NF-kappaB in this process, we tested the capacity of reovirus to induce apoptosis in mice lacking a functional nfkb1/p50 gene. The genetic defect had no apparent effect on reovirus replication in the intestine or dissemination to secondary sites of infection. In comparison to what was observed in wild-type controls, apoptosis was significantly diminished in the CNS of p50-null mice following reovirus infection. In sharp contrast, the loss of p50 was associated with massive reovirus-induced apoptosis and uncontrolled reovirus replication in the heart. Levels of IFN-beta mRNA were markedly increased in the hearts of wild-type animals but not p50-null animals infected with reovirus. Treatment of p50-null mice with IFN-beta substantially diminished reovirus replication and apoptosis, which suggests that IFN-beta induction by NF-kappaB protects against reovirus-induced myocarditis. These findings reveal an organ-specific role for NF-kappaB in the regulation of reovirus-induced apoptosis, which modulates encephalitis and myocarditis associated with reovirus infection.
Subject(s)
Apoptosis/physiology , NF-kappa B p50 Subunit/metabolism , Reoviridae Infections , Reoviridae/physiology , Animals , Animals, Newborn , Brain/cytology , Brain/metabolism , Brain/virology , Cell Line , Heart/virology , In Situ Nick-End Labeling , Interferon-beta/genetics , Interferon-beta/metabolism , Intestinal Mucosa/metabolism , Intestines/cytology , Intestines/virology , Mice , Mice, Knockout , Myocarditis/pathology , Myocarditis/virology , Myocardium/cytology , Myocardium/metabolism , Myocardium/pathology , NF-kappa B p50 Subunit/genetics , Reoviridae/genetics , Reoviridae Infections/metabolism , Reoviridae Infections/pathology , Virus ReplicationABSTRACT
Infection of neonatal mice with some reovirus strains produces a disease similar to infantile biliary atresia, but previous attempts to correlate reovirus infection with this disease have yielded conflicting results. We used isogenic reovirus strains T3SA- and T3SA+, which differ solely in the capacity to bind sialic acid as a coreceptor, to define the role of sialic acid in reovirus encephalitis and biliary tract infection in mice. Growth in the intestine was equivalent for both strains following peroral inoculation. However, T3SA+ spread more rapidly from the intestine to distant sites and replicated to higher titers in spleen, liver, and brain. Strikingly, mice infected with T3SA+ but not T3SA- developed steatorrhea and bilirubinemia. Liver tissue from mice infected with T3SA+ demonstrated intense inflammation focused at intrahepatic bile ducts, pathology analogous to that found in biliary atresia in humans, and high levels of T3SA+ antigen in bile duct epithelial cells. T3SA+ bound 100-fold more efficiently than T3SA- to human cholangiocarcinoma cells. These observations suggest that the carbohydrate-binding specificity of a virus can dramatically alter disease in the host and highlight the need for epidemiologic studies focusing on infection by sialic acid-binding reovirus strains as a possible contributor to the pathogenesis of neonatal biliary atresia.
Subject(s)
Biliary Atresia/etiology , Mammalian orthoreovirus 3/pathogenicity , N-Acetylneuraminic Acid/physiology , Receptors, Virus/physiology , Reoviridae Infections/complications , Animals , Animals, Newborn , Antigens, Viral/metabolism , Bile Ducts/virology , Biliary Atresia/physiopathology , Biliary Atresia/virology , Cell Line , Encephalitis, Viral/etiology , Encephalitis, Viral/physiopathology , Encephalitis, Viral/virology , Genotype , Humans , Mammalian orthoreovirus 3/genetics , Mammalian orthoreovirus 3/physiology , Mice , Phenotype , Reoviridae Infections/physiopathology , Reoviridae Infections/virology , Tumor Cells, Cultured , Virulence/genetics , Virulence/physiology , Virus ReplicationABSTRACT
Mammalian Orthoreoviruses are important models for studies of viral pathogenesis. In the rat lung, Reovirus strain type 3 Dearing (T3D) induces substantially more inflammation than does strain type 1 Lang (T1L). To better understand mechanisms underlying differences in the host inflammatory response elicited by T1L and T3D, we characterized cytokine expression patterns induced by those strains after infection of THP-1 monocyte cells. THP-1 cells were adsorbed with either viable or ultraviolet- inactivated T1L and T3D and assayed for mRNA and protein production of growth-regulated oncogene-alpha (GRO-alpha), interleukin-8 (IL-8), or tumor necrosis factor-alpha (TNF-alpha). T3D stimulated mRNA and protein production of all three cytokines, whereas T1L stimulated mRNA and protein production of IL-8 and TNF-alpha but not GRO-alpha. In each case, T3D induced greater cytokine mRNA and protein expression than did T1L. Nonviable virus did not stimulate detectable cytokine secretion, suggesting a requirement for viral RNA synthesis in cytokine induction by THP-1 cells. A greater percentage of THP-1 cells was infected with T1L than T3D as assessed by infectious center assay, and T1L achieved higher yields of infectious progeny than did T3D in infected THP-1 cells as determined by plaque assay. These strain-dependent differences in cytokine responses and corresponding replication patterns in monocyte cells parallel findings made in studies of rat models of pneumonia and provide clues about how Reovirus interfaces with the host innate immune response to produce pulmonary disease.
Subject(s)
Cytokines/metabolism , Inflammation/virology , Mammalian orthoreovirus 3/immunology , Monocytes/virology , Orthoreovirus, Mammalian/immunology , Cell Line , Cytokines/genetics , Humans , Inflammation/immunology , Mammalian orthoreovirus 3/physiology , Orthoreovirus, Mammalian/physiology , Species Specificity , Virus ReplicationABSTRACT
The gp41 membrane-proximal external region (MPER) is a target for broadly neutralizing antibody responses against human immunodeficiency virus type 1 (HIV-1). However, replication-defective virus vaccines currently under evaluation in clinical trials do not efficiently elicit MPER-specific antibodies. Structural modeling suggests that the MPER forms an α-helical coiled coil that is required for function and immunogenicity. To maintain the native MPER conformation, we used reverse genetics to engineer replication-competent reovirus vectors that displayed MPER sequences in the α-helical coiled-coil tail domain of viral attachment protein σ1. Sequences in reovirus strain type 1 Lang (T1L) σ1 were exchanged with sequences encoding HIV-1 strain Ba-L MPER epitope 2F5 or the entire MPER. Individual 2F5 or MPER substitutions were introduced at virion-proximal or virion-distal sites in the σ1 tail. Recombinant reoviruses containing heterologous HIV-1 sequences were viable and produced progeny yields comparable to those with wild-type virus. HIV-1 sequences were retained following 10 serial passages in cell culture, indicating that the substitutions were genetically stable. Recombinant viruses engineered to display the 2F5 epitope or full-length MPER in σ1 were recognized by purified 2F5 antibody. Inoculation of mice with 2F5-containing vectors or rabbits with 2F5- or MPER-containing vectors elicited anti-reovirus antibodies, but HIV-1-specific antibodies were not detected. Together, these findings indicate that heterologous sequences that form α-helices can functionally replace native sequences in the α-helical tail domain of reovirus attachment protein σ1. However, although these vectors retain native antigenicity, they were not immunogenic, illustrating the difficulty of experimentally inducing immune responses to this essential region of HIV-1. IMPORTANCE Vaccines to protect against HIV-1, the causative agent of AIDS, are not approved for use. Antibodies that neutralize genetically diverse strains of HIV-1 bind to discrete regions of the envelope glycoproteins, including the gp41 MPER. We engineered recombinant reoviruses that displayed MPER epitopes in attachment protein σ1 (REO-MPER vectors). The REO-MPER vectors replicated with wild-type efficiency, were genetically stable, and retained native antigenicity. However, we did not detect HIV-1-specific immune responses following inoculation of the REO-MPER vectors into small animals. This work provides proof of principle for engineering reovirus to express antigenic epitopes and illustrates the difficulty in eliciting MPER-specific immune responses.
ABSTRACT
A rapid, reverse transcription-polymerase chain reaction (RT-PCR) procedure for the detection of reovirus RNA in cell culture is described. Total nucleic acids are extracted from a small volume of cell culture supernatant and reverse transcribed using random hexamers. An aliquot of cDNA is then utilized in nested PCR. The PCR primers correspond to sequences conserved between prototype reovirus strains type 1 Lang, type 2 Jones, and type 3 Dearing, as well as those of several reovirus field-isolate strains. Reactions are analyzed by agarose gel electrophoresis, and samples showing a band of the appropriate size in the first and second amplification, or in the second amplification alone, are designated as positive. This protocol allows for the rapid and sensitive detection of reovirus in cell culture. The RT-PCR methods described below can easily be adapted to the amplification of reovirus from other media, including preserved tissues, clinical specimens, and water.
Subject(s)
Genome, Viral , Reoviridae Infections/diagnosis , Reoviridae/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction , Buffers , Humans , Polymerase Chain Reaction/methods , RNA, Viral/genetics , RNA, Viral/isolation & purification , Reoviridae/genetics , Sensitivity and SpecificityABSTRACT
BACKGROUND: In 2001, Cincinnati Children's Hospital embarked on a journey to improve healthcare delivery to patients with cystic fibrosis (CF). Data from the Cystic Fibrosis Foundation National Patient Registry revealed our below-average clinical outcomes, prompting us to initiate improvement interventions. OBJECTIVE: To improve clinical outcomes for patients with CF through a comprehensive quality-improvement approach directed at increasing patient centredness and improving healthcare delivery. INTERVENTIONS: In 2001, we shared our below-average outcomes with patients, families and care providers. We instituted a quality-improvement steering committee with parental and hospital leadership, and our data-management support was restructured to provide real-time clinical data to monitor our progress. In 2002, our weekly chart conference changed to a prospective planning session and individualised daily schedules were created for inpatients. In 2003, an influenza vaccination campaign was initiated and our infection-control practices were redesigned. In 2005, best-practice guidelines were developed for airway-clearance therapy. In 2007, evidence-based clinical algorithms were designed and implemented and key care-team members were added. MEASUREMENTS: Primary outcome measures were median forced expiratory volume in 1 s per cent predicted (age range 6-17 years) and median body mass index percentile (age range 2-20 years). RESULTS: From 2000 to 2010, median forced expiratory volume in 1 s increased from 81.7% to 100.1% predicted and median body mass index increased from the 35th to the 55th centile. DISCUSSION: By focusing on specific outcomes, empowering families and patients, effectively using data, and standardising care processes, we transformed the culture and delivery of care for our patients with CF and learned valuable lessons potentially translatable to other chronic-care providers.
Subject(s)
Cystic Fibrosis/therapy , Delivery of Health Care/organization & administration , Patient Care Team/organization & administration , Quality Assurance, Health Care , Adolescent , Child , Cystic Fibrosis/physiopathology , Female , Health Care Surveys , Hospitals, Pediatric , Humans , Male , Ohio , Patient Care/methods , Program Evaluation , Quality Improvement , Time Factors , Young AdultABSTRACT
Current microscopy-based approaches for immunofluorescence detection of viral infectivity are time consuming and labor intensive and can yield variable results subject to observer bias. To circumvent these problems, we developed a rapid and automated infrared immunofluorescence imager-based infectivity assay for both rotavirus and reovirus that can be used to quantify viral infectivity and infectivity inhibition. For rotavirus, monolayers of MA104 cells were infected with simian strain SA-11 or SA-11 preincubated with rotavirus-specific human IgA. For reovirus, monolayers of either HeLa S3 cells or L929 cells were infected with strains type 1 Lang (T1L), type 3 Dearing (T3D), or either virus preincubated with a serotype-specific neutralizing monoclonal antibody (mAb). Infected cells were fixed and incubated with virus-specific polyclonal antiserum, followed by an infrared fluorescence-conjugated secondary antibody. Well-to-well variation in cell number was normalized using fluorescent reagents that stain fixed cells. Virus-infected cells were detected by scanning plates using an infrared imager, and results were obtained as a percent response of fluorescence intensity relative to a virus-specific standard. An expected dose-dependent inhibition of both SA-11 infectivity with rotavirus-specific human IgA and reovirus infectivity with T1L-specific mAb 5C6 and T3D-specific mAb 9BG5 was observed, confirming the utility of this assay for quantification of viral infectivity and infectivity blockade. The imager-based viral infectivity assay fully automates data collection and provides an important advance in technology for applications such as screening for novel modulators of viral infectivity. This basic platform can be adapted for use with multiple viruses and cell types.
Subject(s)
Automation/methods , Fluorescent Antibody Technique/methods , Image Processing, Computer-Assisted/methods , Reoviridae/pathogenicity , Rotavirus/pathogenicity , Virology/methods , Cell Line , HumansABSTRACT
Human milk contains many bioactive components, including secretory IgA, oligosaccharides, and milk-associated proteins. We assessed the antiviral effects of several components of milk against mammalian reoviruses. We found that glucocerebroside (GCB) inhibited the infectivity of reovirus strain type 1 Lang (T1L), whereas gangliosides GD3 and GM3 and 3'-sialyllactose (3SL) inhibited the infectivity of reovirus strain type 3 Dearing (T3D). Agglutination of erythrocytes mediated by T1L and T3D was inhibited by GD3, GM3, and bovine lactoferrin. Additionally, α-sialic acid, 3SL, 6'-sialyllactose, sialic acid, human lactoferrin, osteopontin, and α-lactalbumin inhibited hemagglutination mediated by T3D. Using single-gene reassortant viruses, we found that serotype-specific differences segregate with the gene encoding the viral attachment protein. Furthermore, GD3, GM3, and 3SL inhibit T3D infectivity by blocking binding to host cells, whereas GCB inhibits T1L infectivity post-attachment. These results enhance an understanding of reovirus cell attachment and define a mechanism for the antimicrobial activity of human milk.
Subject(s)
Capsid Proteins/immunology , Mammalian orthoreovirus 3/immunology , Mammalian orthoreovirus 3/pathogenicity , Milk, Human/immunology , Orthoreovirus, Mammalian/immunology , Orthoreovirus, Mammalian/pathogenicity , Polysaccharides/immunology , Animals , Capsid Proteins/genetics , Cattle , Female , G(M3) Ganglioside/immunology , Gangliosides/immunology , Genes, Viral , HeLa Cells , Hemagglutination Inhibition Tests , Host-Pathogen Interactions/immunology , Humans , L Cells , Mammalian orthoreovirus 3/classification , Mammalian orthoreovirus 3/genetics , Mice , Milk, Human/virology , Oligosaccharides/immunology , Orthoreovirus, Mammalian/classification , Orthoreovirus, Mammalian/genetics , Reoviridae Infections/immunology , Reoviridae Infections/prevention & control , Reoviridae Infections/virology , Serotyping , Species Specificity , Virus AttachmentABSTRACT
Mammalian reoviruses infect respiratory and gastrointestinal epithelia and cause disease in neonates. Junctional adhesion molecule-A (JAM-A) is a serotype-independent receptor for reovirus. JAM-A localizes to tight junctions and contributes to paracellular permeability in polarized epithelia. To investigate the mechanisms of reovirus infection of polarized epithelial cells, we assessed reovirus replication, release, and spread after apical and basolateral adsorption to primary human airway epithelial cultures. Reovirus infection of human airway epithelia was more efficient after adsorption to the basolateral surface than after adsorption to the apical surface, and it was dependent on JAM-A. Reovirus binding to carbohydrate coreceptor sialic acid inhibited apical infection, which was partially ameliorated by treatment of the cultures with neuraminidase. Despite the preference for basolateral infection, reovirus was released from the apical surface of respiratory epithelia and did not disrupt tight junctions. These results establish the existence of an infectious circuit for reovirus in polarized human respiratory epithelial cells.
Subject(s)
Orthoreovirus, Mammalian/pathogenicity , Reoviridae Infections/virology , Respiratory Mucosa/virology , Respiratory Tract Infections/virology , Animals , Cell Adhesion Molecules/metabolism , Cell Polarity/physiology , Electric Impedance , Humans , Immunoglobulins/metabolism , Immunohistochemistry , L Cells , Mice , Microscopy, Confocal , Neuraminidase/pharmacology , Orthoreovirus, Mammalian/metabolism , Reassortant Viruses/pathogenicity , Receptors, Cell Surface , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , Tight Junctions/metabolism , Tight Junctions/virology , Virus SheddingABSTRACT
Mammalian orthoreoviruses (reoviruses) are highly tractable experimental models for studies of double-stranded (ds) RNA virus replication and pathogenesis. Reoviruses infect respiratory and intestinal epithelium and disseminate systemically in newborn animals. Until now, a strategy to rescue infectious virus from cloned cDNA has not been available for any member of the Reoviridae family of dsRNA viruses. We report the generation of viable reovirus following plasmid transfection of murine L929 (L) cells using a strategy free of helper virus and independent of selection. We used the reovirus reverse genetics system to introduce mutations into viral capsid proteins sigma1 and sigma3 and to rescue a virus that expresses a green fluorescent protein (GFP) transgene, thus demonstrating the tractability of this technology. The plasmid-based reverse genetics approach described here can be exploited for studies of reovirus replication and pathogenesis and used to develop reovirus as a vaccine vector.
Subject(s)
RNA Viruses/genetics , RNA, Double-Stranded/genetics , Reoviridae Infections/genetics , Vaccines, Synthetic , Viral Vaccines , Animals , Disease Models, Animal , Genome, Viral , Mammals , Plasmids , RNA Viruses/immunology , RNA, Double-Stranded/immunology , Recombination, Genetic , Reoviridae/genetics , Reoviridae/immunology , Reoviridae Infections/immunology , TransfectionABSTRACT
We previously described a filament-based antibody recognition assay (FARA) that generates ELISA-like sandwich structures immobilized on a filament. FARA allows the coupling of antibodies to precise locations along a filament, on-line fluorescence detection of captured pathogen, and feedback-directed filament motion. These properties suggest that this approach might be useful as an automated means to rapidly classify unknown pathogens. In this report, we describe validation of the novel decision tree aspect of this technology using mammalian reovirus. Based on available antibodies, we developed a decision tree algorithm to detect virus with increasing specificity at each level of the tree. Using three strains of reovirus and a bacteriophage control, our system correctly classified the reovirus strains at a concentration of 2 x 10(12) virions ml(-1) and M13K07 phage at 3 x 10(11) virions ml(-1). Classification of reovirus strain type 3 Dearing (T3D) required three levels of testing: general reovirus classification in level 1, serotype 3 classification in level 2, and final T3D strain classification in level 3. Strain T3SA + also required three levels of testing before a final classification was returned in level 3. Classification of strain type 1 Lang (T1L) required two levels of testing. M13K07 phage detection required only one level of testing for classification. These results indicate that automated pathogen classification using FARA is feasible. Furthermore, the simplicity of the design could be exploited for development of more complex sub-classification networks with additional levels and branches.
Subject(s)
Antibodies, Viral/immunology , Biosensing Techniques/instrumentation , Fluoroimmunoassay/instrumentation , Reoviridae/immunology , Reoviridae/isolation & purification , Biosensing Techniques/methods , Equipment Design , Equipment Failure Analysis , Fluoroimmunoassay/methods , Reoviridae/classificationABSTRACT
Mammalian reoviruses are internalized into cells by receptor-mediated endocytosis. Within the endocytic compartment, the viral outer capsid undergoes acid-dependent proteolysis resulting in removal of the sigma3 protein and proteolytic cleavage of the mu1/mu1C protein. Ammonium chloride (AC) is a weak base that blocks disassembly of reovirus virions by inhibiting acidification of intracellular vacuoles. To identify domains in reovirus proteins that influence pH-sensitive steps in viral disassembly, we adapted strain type 3 Dearing (T3D) to growth in murine L929 cells treated with AC. In comparison to wild-type (wt) T3D, AC-adapted (ACA-D) variant viruses exhibited increased yields in AC-treated cells. AC resistance of reassortant viruses generated from a cross of wt type 1 Lang and ACA-D variant ACA-D1 segregated with the sigma3-encoding S4 gene. The deduced sigma3 amino acid sequences of six independently derived ACA-D variants contain one or two mutations each, affecting a total of six residues. Four of these mutations, I180T, A246G, I347S, and Y354H, cluster in the virion-distal lobe of sigma3. Linkage of these mutations to AC resistance was confirmed in experiments using reovirus disassembly intermediates recoated with wt or mutant sigma3 proteins. In comparison to wt virions, ACA-D viruses displayed enhanced susceptibility to proteolysis by endocytic protease cathepsin L. Image reconstructions of cryoelectron micrographs of three ACA-D viruses that each contain a single mutation in the virion-distal lobe of sigma3 demonstrated native capsid protein organization and minimal alterations in sigma3 structure. These results suggest that mutations in sigma3 that confer resistance to inhibitors of vacuolar acidification identify a specific domain that regulates proteolytic disassembly.
Subject(s)
Ammonium Chloride/pharmacology , Capsid Proteins/genetics , Reoviridae/physiology , Viral Proteins/genetics , Adaptation, Physiological , Animals , Capsid Proteins/chemistry , Cathepsin L , Cathepsins/metabolism , Cysteine Endopeptidases/metabolism , Cysteine Proteinase Inhibitors/pharmacology , Drug Resistance, Viral/genetics , L Cells/drug effects , Mice , Models, Molecular , Molecular Sequence Data , Mutation , Reoviridae/chemistry , Reoviridae/drug effects , Serial Passage , Viral Proteins/chemistry , Viral Regulatory and Accessory Proteins , Virus AssemblyABSTRACT
Mice infected with reovirus develop abnormalities in glucose homeostasis. Reovirus strain type 3 Abney (T3A) was capable of systemic infection of nonobese diabetic (NOD) mice, an experimental model of autoimmune diabetes. Reovirus antigen was detected in pancreatic islets of T3A-infected mice, and primary cultures of pancreatic islets from NOD mice supported T3A growth. Significantly fewer T3A-infected animals compared to uninfected controls developed diabetes. However, despite the alteration in diabetes penetrance, insulitis was evident in T3A-infected mice. These results suggest that viral infection of NOD mice alters autoimmune responses to beta-cell antigens and thereby delays development of diabetes.
Subject(s)
Diabetes Mellitus/immunology , Diabetes Mellitus/physiopathology , Mammalian orthoreovirus 3/pathogenicity , Pancreatic Diseases/physiopathology , Reoviridae Infections/complications , Reoviridae Infections/immunology , Animals , Animals, Newborn , Autoimmune Diseases/immunology , Autoimmune Diseases/physiopathology , Female , Islets of Langerhans/immunology , Islets of Langerhans/physiopathology , Islets of Langerhans/virology , Mice , Mice, Inbred NOD/virology , Pancreatic Diseases/immunology , Pancreatic Diseases/virology , Reoviridae Infections/virologyABSTRACT
Reovirus infections are initiated by the binding of viral attachment protein sigma1 to receptors on the surface of host cells. The sigma1 protein is an elongated fiber comprised of an N-terminal tail that inserts into the virion and a C-terminal head that extends from the virion surface. The prototype reovirus strains type 1 Lang/53 (T1L/53) and type 3 Dearing/55 (T3D/55) use junctional adhesion molecule A (JAM-A) as a receptor. The C-terminal half of the T3D/55 sigma1 protein interacts directly with JAM-A, but the determinants of receptor-binding specificity have not been identified. In this study, we investigated whether JAM-A also mediates the attachment of the prototype reovirus strain type 2 Jones/55 (T2J/55) and a panel of field-isolate strains representing each of the three serotypes. Antibodies specific for JAM-A were capable of inhibiting infections of HeLa cells by T1L/53, T2J/55, and T3D/55, demonstrating that strains of all three serotypes use JAM-A as a receptor. To corroborate these findings, we introduced JAM-A or the structurally related JAM family members JAM-B and JAM-C into Chinese hamster ovary cells, which are poorly permissive for reovirus infection. Both prototype and field-isolate reovirus strains were capable of infecting cells transfected with JAM-A but not those transfected with JAM-B or JAM-C. A sequence analysis of the sigma1-encoding S1 gene segment of the strains chosen for study revealed little conservation in the deduced sigma1 amino acid sequences among the three serotypes. This contrasts markedly with the observed sequence variability within each serotype, which is confined to a small number of amino acids. Mapping of these residues onto the crystal structure of sigma1 identified regions of conservation and variability, suggesting a likely mode of JAM-A binding via a conserved surface at the base of the sigma1 head domain.