Modest antiviral activity of Toll-like receptor 3 (TLR3) against

Human respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections in infants and Toll-like receptors (TLRs) are the first line of host defense against such infections. In this study, we aimed to elucidate the antiviral effect of TLR3 against RSV infection. The human TLR3 gene was either transiently or stably overexpressed in A549 cells and they were infected with the Long strain of RSV. In both cases, RSV production determined by plaque assay was modestly but significantly decreased in the TLR3-overexpressed cells compared with control cells. Less interferon (IFN)-β, measured by ELISA, was produced in the supernatant of the TLR3- overexpressed cells. Neutralization of IFN-β in the supernatant of the TLR3-overexpressed cells failed to increase RSV production to the same level as controls. These results indicate that TLR3 has modest anti-RSV activity and IFN-β seems not to be a significant mediator of this activity

Identification and Characterization of Two Internal Cleavage and Polyadenylation Sites of Parvovirus B19 RNA

Polyadenylation of B19 pre-mRNAs at the major internal site, (pA)p1, is programmed by the nonconsensus core cleavage and polyadenylation specificity factor-binding hexanucleotide AUUAAA. Efficient use of this element requires both downstream and upstream cis-acting elements and is further influenced by an adjacent AAUAAC motif. The primary hexanucleotide element must be nonconsensus to allow efficient readthrough of P6-generated pre-mRNAs into the capsid-coding region. An additional cleavage and polyadenylation site, (pA)p2, 296 nucleotides downstream of (pA)p1 was shown to be used following both B19 infection and transfection of a genomic clone. RNAs polyadenylated at (pA)p2 comprise approximately 10% of B19 RNAs that are polyadenylated internally

Analysis of Nucleotide Sequences of Human Parvovirus B19 Genome Reveals Two Different Modes of Evolution, a Gradual Alteration and a Sudden Replacement: a Retrospective Study in Sapporo, Japan, from 1980 to 2008▿

There have been no long-term systematic analyses of the molecular epidemiology of human parvovirus B19 (B19V). We investigated the variations of nucleotide sequences of B19V strains collected in Sapporo, Japan, from 1980 to 2008. In that period, six outbreaks of erythema infectiosum occurred regularly at 5-year intervals. The B19V strains collected successively, regardless of the outbreak, were analyzed for nucleotide variation in the subgenomic NS1-VP1u junction. The isolated strains can be classified into 10 subgroups. Two patterns of change of endemic strains were observed. One was a dynamic replacement of strains that occurred almost every 10 years, and the other was a gradual change consisting of an accumulation of point mutations

The Expression Strategy of Goose Parvovirus Exhibits Features of both the Dependovirus and Parvovirus Genera

The RNA transcription profile of the goose parvovirus (GPV) was determined, and it is a surprising hybrid of features of the Parvovirus and Dependovirus genera of the Parvovirinae subfamily of the Parvoviridae. Similar to the Dependovirus adeno-associated virus type 5, RNAs transcribed from the GPV upstream P9 promoter, which encode the viral nonstructural proteins, were polyadenylated at a high efficiency at a polyadenylation site [(pA)p] located within an intron in the center of the genome. Efficient usage of (pA)p required a downstream element that overlaps with the polypyrimidine tract of the A2 3′ splice site of the central intron. An upstream element required for efficient use of (pA)p was also identified. RNAs transcribed from the P42 promoter, presumed to encode the viral capsid proteins, primarily extended through (pA)p and were polyadenylated at a site, (pA)d, located at the right end of the genome and ultimately spliced at a high efficiency. No promoter analogous to the Dependovirus P19 promoter was detected; however, similar to minute virus of mice and other members of the Parvovirus genus, a significant portion of pre-mRNAs generated from the P9 promoter were additionally spliced within the putative GPV Rep1 coding region and likely encode an additional, smaller, nonstructural protein. Also similar to members of the Parvovirus genus, detectable activity of the GPV P42 promoter was highly dependent on transactivation by the GPV Rep1 protein in a manner dependent on binding to a cis-element located in the P42 promoter

Fosfomycin Suppresses Chemokine Induction in Airway Epithelial Cells Infected with Respiratory Syncytial Virus▿

Respiratory syncytial virus (RSV) infects airway epithelial cells, causing bronchiolitis and pneumonia. Inflammation is mediated by various cytokines secreted from RSV-infected airway epithelial cells, and it promotes the pathogenesis of RSV-related diseases. Fosfomycin (FOF) is approved as a treatment for various bacterial infectious diseases, including respiratory infectious diseases, in Japan. FOF is suggested to exhibit immunomodulatory effects on lipopolysaccharide-stimulated monocytes and T lymphocytes, in addition to its antimicrobial activity. We investigated the effect of FOF on the cytokine production of an airway epithelial cell line, A549, infected with RSV. RSV-induced cytokines, such as regulated on activation, normal T-cell expressed and secreted (RANTES), interleukin-8 (IL-8), and IL-6, in infected A549 cells. We found that FOF decreased the levels of RSV-induced RANTES and IL-8 but not the level of RSV-induced IL-6. The RANTES promoter was activated by RSV infection. Site-directed mutagenesis analysis of the RANTES promoter showed that NF-κB-binding motifs had a critical role in RSV-induced RANTES promoter activity. A luciferase reporter gene assay and a DNA-binding assay indicated that FOF suppressed the NF-κB activity induced by RSV infection. These results demonstrate that FOF treatment suppresses the RSV-induced transcription of the chemokines RANTES and IL-8 in airway epithelial cells

Comparison of the Transcription Profile of Simian Parvovirus with That of the Human Erythrovirus B19 Reveals a Number of Unique Features

Simian parvovirus (SPV) is a member of the genus Erythrovirus and is closely related to the human parvovirus B19. Natural and experimental infection of monkeys with SPV resembles B19 infection of human. We report a detailed characterization of the viral RNAs and proteins generated following transfection of cloned SPV into COS cells and SPV infection of the human erythroid progenitor line UT-7/Epo-S1. SPV and B19 are 50% identical at the nucleotide level, and although their basic transcription and protein expression profiles were generally similar, there were also significant differences. SPV pre-mRNAs contain three introns, compared to two found for B19: an additional intron was found within the capsid-coding region. RNAs in which this intron was spliced were abundant and encoded the SPV 14-kDa protein (analogous to the B19 11-kDa protein), which initiated at an AUG in the exon preceding the third intron. Unlike B19, SPV RNAs were also spliced between the donor of the first intron and the acceptor of the second intron. The third intron was additionally spliced from a portion of these molecules; these mRNAs encoded the 14-kDa protein. A portion was not spliced further and encoded VP2. Like B19, SPV has a polyadenylation signal [AAUAAA (pA)p] in the middle of the genome, which directed efficient polyadenylation of both spliced and unspliced mRNAs (encoding a putative 10-kDa protein, analogous to the B19 7.5-kDa protein, and SPV NS1, respectively). The 14-kDa protein was localized to both in the nucleus and cytoplasm