Usutu virus growth in human cell lines: induction of and sensitivity to type I and III interferons.

The mechanisms of Usutu virus (USUV) pathogenesis are largely unknown. The aim of this study was to evaluate the sensitivity of USUV to interferon (IFN) and the capacity of USUV to stimulate IFN production. Initial experiments were conducted to characterize the susceptibility of human cell lines to USUV infection and to evaluate the single-growth cycle replication curve of USUV.

In vitro sensitivity of human metapneumovirus to type I interferons.

Human metapneumovirus (hMPV) has been recognized as an important respiratory pathogen. Due to its relatively recent discovery, only limited information is available on the relationship between hMPV and type I interferons (IFN). This study was designed to determine whether in vitro hMPV is sensitive to the antiviral activity of IFN-β, leukocyte IFN-α, and several IFN-α subtypes in a human Hep-2 cell line.

Pandemic 2009 H1N1 influenza virus is resistant to the antiviral activity of several interferon alpha subtypes.

Interferons (IFNs) are critically important in the control of influenza A virus infections. To better understand the pathogenic characteristics of the pandemic 2009 H1N1 influenza virus (pH1N1) from an innate immunity viewpoint, we investigated whether in vitro pH1N1 is sensitive to the antiviral activity of IFN beta, leukocyte IFN alpha, and several IFN alpha subtypes in a human lung adenocarcinoma epithelial cell line under single-growth cycle conditions. The results showed that 50% inhibitory concentration values against pH1N1 for various type I IFN preparations were higher than those against the IFN-sensitive encephalomyocarditis virus.

Human bocavirus infection in hospitalized children in Italy.

Background: Human bocavirus (HBoV) was first discovered in Sweden in 2005 and has now been found worldwide; however its role in clinically relevant diseases has not yet been clearly defined.

Objectives: To gain new insight into HBoV infection among children hospitalized with acute respiratory infections in Rome.

Methods: Between November 2004 and May 2007, 415 nasal washings were tested for the presence of an extensive range of respiratory viruses using molecular methods.

Severe acute respiratory syndrome coronavirus elicits a weak interferon response compared to traditional interferon-inducing viruses.

The aim of the present study is to investigate changes of interferon (IFN) production occurring over the first 48 h after infection of peripheral blood mononuclear cells (PBMCs) with severe acute respiratory syndrome (SARS) coronavirus (CoV) and to compare these changes to those induced by well-established IFN-inducing viruses, such as vesicular stomatitis (VSV) and Newcastle viruses (NDV). Experiments have been carried out using PBMCs of 10 different healthy donors. The results showed that the antiviral activity of IFN contained in the supernatant of SARS-CoV-infected PBMCs was lower than those induced by VSV and NDV.

Upregulation of interferon-induced genes in infants with virus-associated acute bronchiolitis.

To determine whether there is an airway IFN response in infants with acute bronchiolitis and to establish whether the rate of such a response is related to the severity of illness, the expression of some IFN-induced genes was measured in nasopharyngeal washes from 39 infants with acute bronchiolitis. The results indicate that in infants with a virus-associated acute bronchiolitis there is a strong activation of IFN system and that the severity of illness is inversely related to the level of expression of IFN-induced genes. This suggests that the IFN response plays an important role in determining virus-associated respiratory disease in early life.

Detection and typing by molecular techniques of respiratory viruses in children hospitalized for acute respiratory infection in Rome, Italy.

Detection of a broad number of respiratory viruses is not undertaken currently for the diagnosis of acute respiratory infection due to the large and always increasing list of pathogens involved. A 1-year study was undertaken on children hospitalized consecutively for acute respiratory infection in a Pediatric Department in Rome to characterize the viruses involved. Two hundred twenty-seven children were enrolled in the study with a diagnosis of asthma, bronchiolitis, bronchopneumonia, or laringo-tracheo bronchitis.

The synergistic interaction of interferon types I and II leads to marked reduction in severe acute respiratory syndrome-associated coronavirus replication and increase in the expression of mRNAs for interferon-induced proteins.

Interferon (IFN)-alpha, -beta and -gamma have been shown to be only marginally effective against severe acute respiratory syndrome coronavirus (SARS-CoV) replication in Vero cell lines. We investigated the combination of type I IFNs (IFN-alpha or -beta) and IFN-gamma for antiviral activity and found that such combinations synergistically inhibited SARS-CoV replication in Vero cells, using yield reduction assay and the isobologram and combination index methods of Chou and Talalay for evaluation. The highly synergistic anti-SARS-CoV action of type I IFNs and IFN-gamma parallels the marked increase in 2'-5'-oligoadenylate synthetase and p56 mRNAs following exposure in Vero cells to either IFN-alpha or -beta and IFN-gamma compared with the transcriptional levels obtained after stimulation with either IFN alone.