Pelargonium sidoides radix extract EPs 7630 reduces rhinovirus infection through modulation of viral binding proteins on human bronchial epithelial cells.

Bronchial epithelial cells are the first target cell for rhinovirus infection. The course of viral infections in patients with acute bronchitis, asthma and COPD can be improved by oral application of Pelargonium sidoides radix extract; however, the mechanism is not well understood. This study investigated the in vitro effect of Pelargonium sidoides radix extract (EPs 7630) on the expression of virus binding cell membrane and host defence supporting proteins on primary human bronchial epithelial cells (hBEC). Cells were isolated from patients with severe asthma (n = 6), moderate COPD (n = 6) and non-diseased controls (n = 6). Protein expression was determined by Western-blot and immunofluorescence. Rhinovirus infection was determined by immunofluorescence as well as by polymerase chain reaction. Cell survival was determined by manual cell count after live/death immunofluorescence staining. All parameters were determined over a period of 3 days. The results show that EPs 7630 concentration-dependently and significantly increased hBEC survival after rhinovirus infection. This effect was paralleled by decreased expression of the inducible co-stimulator (ICOS), its ligand ICOSL and cell surface calreticulin (C1qR). In contrast, EPs 7630 up-regulated the expression of the host defence supporting proteins ß-defensin-1 and SOCS-1, both in rhinovirus infected and un-infected hBEC. The expression of other virus interacting cell membrane proteins such as MyD88, TRL2/4 or ICAM-1 was not altered by EPs 7630. The results indicate that EPs 7630 may reduce rhinovirus infection of human primary BEC by down-regulating cell membrane docking proteins and up-regulating host defence proteins.

Structure-based virtual screening for the discovery of natural inhibitors for human rhinovirus coat protein.

Inhibitors of the human rhinovirus (HRV) coat protein are promising candidates to treat and prevent a number of upper respiratory diseases. The aim of this study was to find antiviral compounds from nature, focusing on the HRV coat protein. Through computational structure-based screening of an in-house 3D database containing 9676 individual plant metabolites from ancient herbal medicines, combined with knowledge from traditional use, we selected sesquiterpene coumarins from the gum resin asafetida as promising natural products. Chromatographic separation steps resulted in the isolation of microlobidene (1), farnesiferol C (2), farnesiferol B (3), and kellerin (4). Determination of the inhibition of the HRV-induced cytopathic effect for serotypes 1A, 2, 14, and 16 revealed a dose-dependent and selective antirhinoviral activity against serotype 2 for asafetida (IC50 = 11.0 microg/mL) and its virtually predicted constituents 2 (IC50 = 2.5 microM) and 3 (IC50 = 2.6 microM). Modeling studies helped to rationalize the retrieved results.

Antiviral effect of hyperthermic treatment in rhinovirus infection.

Human rhinoviruses (HRV) are recognized as the major etiologic agents for the common cold. Starting from the observation that local hyperthermic treatment is beneficial in patients with natural and experimental common colds, we have studied the effect of brief hyperthermic treatment (HT) on HRV replication in HeLa cells. We report that a 20-min HT at 45 degrees C is effective in suppressing HRV multiplication by more than 90% when applied at specific stages of the virus replication cycle. Synthesis of virus proteins is not affected by HT, indicating that the target for treatment is a posttranslational event. The antiviral effect is a transient cell-mediated event and is associated with the synthesis of the 70-kDa heat shock protein hsp70. Unlike poliovirus, rhinovirus infection does not inhibit the expression of hsp70 induced by heat. The possibility that hsp70 could play a role in the control of rhinovirus replication is suggested by the fact that a different class of HSP inducers, the cyclopentenone prostaglandins PGA1 and delta 12-PGJ2, were also effective in inhibiting HRV replication in HeLa cells. Inhibition of hsp70 expression by actinomycin D prevented the antiviral activity of prostaglandins in HRV-infected cells. These results indicate that the beneficial effect of respiratory hyperthermia may be mediated by the induction of a cytoprotective heat shock response in rhinovirus-infected cells.

In vitro and in vivo antipicornavirus activity of some phenoxypyridinecarbonitriles.

Nineteen phenoxypyridinecarbonitriles were initially evaluated for their in vitro activity against rhinoviruses (RV) 1A, 2, and 64 and coxsackievirus (Cox) A21 and for their oral prophylactic and therapeutic activity in Swiss albino mice challenged with Cox A21. On the basis of the results of these studies, one compound, 6-(3,4-dichlorophenoxy)-3-(ethylthio)-2-pyridinecarbonitrile, was selected for further evaluation. Expanded in vitro spectrum of activity studies showed that the MIC causing a 50% reduction in viral cytopathic effect in infected cultures (MIC50) was 3.0 micrograms/ml or less against 11 of 20 RV serotypes tested. The compound was only moderately active (MIC50, 5 to 7 micrograms/ml) against four of the RV serotypes evaluated, while RV 4, 5, 8, 13 and Hank's were relatively resistant to compound inhibition. Of the nine enteroviruses studied, only Cox A21, echovirus 12, poliovirus 2, and enterovirus 70 were inhibited at compound concentrations of less than 2.0 micrograms/ml. The compound provided significant protection to mice infected with a normally lethal dose of Cox A21 when administered in a single oral dose of 150 mg/kg (P less than 0.01) and during a regimen of continuous oral doses of 37.5 mg/kg per day (P less than 0.001). Mechanism of action studies indicated that the compound inhibited picornavirus uncoating or some earlier virus-host cell-associated event.