A Plant Extract of Ribes nigrum folium Possesses Anti-Influenza Virus Activity In Vitro and In Vivo by Preventing Virus Entry to Host Cells

Infections with influenza A viruses (IAV) are still amongst the major causes of highly contagious severe respiratory diseases not only bearing a devastating effect to human health, but also significantly impact the economy. Besides vaccination that represents the best option to protect from IAV infections, only two classes of anti-influenza drugs, inhibitors of the M2 ion channel and the neuraminidase, often causing resistant IAV variants have been approved. That is why the need for effective and amply available antivirals against IAV is of high priority. Here we introduce LADANIA067 from the leaves of the wild black currant (Ribes nigrum folium) as a potent compound against IAV infections in vitro and in vivo. LADANIA067 treatment resulted in a reduction of progeny virus titers in cell cultures infected with prototype avian and human influenza virus strains of different subtypes. At the effective dose of 100 µg/ml the extract did not exhibit apparent harming effects on cell viability, metabolism or proliferation. Further, viruses showed no tendency to develop resistance to LADANIA067 when compared to amantadine that resulted in the generation of resistant variants after only a few passages. On a molecular basis the protective effect of LADANIA067 appears to be mainly due to interference with virus internalisation. In the mouse infection model LADANIA067 treatment reduces progeny virus titers in the lung upon intranasal application. In conclusion, an extract from the leaves of the wild black currant might be a promising source for the development of new antiviral compounds to fight IAV infections

Exogenous IFN-alpha Administration Reduces Influenza A Virus Replication in the Lower Respiratory Tract of Rhesus Macaques

To determine the role of innate immune responses in controlling influenza A virus replication, rhesus macaques (RM) were administered pegylated IFN-alpha prior to virus challenge. Systemic and mucosal pegylated IFN-alpha administration induced expression of the interferon-stimulated genes (ISG) MxA and OAS in the airways. RM treated with IFN-alpha 24 hours prior to influenza virus challenge had significantly lower peak vRNA levels in the trachea compared to untreated animals. In addition to blunting viral replication, IFN-alpha treatment minimized the weight loss and spike in body temperature after influenza infection of RM. These results confirm the importance of IFN-alpha induced innate immune responses in the rapid control of influenza A virus replication in primates

Investigations of antiviral mechanisms during influenza virus infection

Saisonale Influenza-Erkrankungen sind jährlich weltweit für circa 300.000 Todesfälle verantwortlich. Die Influenza-A-Virusinfektion behandelt man derzeit prophylaktisch mittels Impfungen oder therapeutisch mittels antiviralen Substanzen. Die Stammzusammensetzung des Impfstoffes muss jedes Jahr neu angepasst und verabreicht werden. Dieses dauert vom ersten Auftreten eines neuen saisonalen Influenzavirus-Stammes bis hin zum fertigen Impfstoff ca. 4-6 Monate. Ein weiteres Problem ist zudem die zunehmende Resistenzbildung zirkulierender Influenzaviren gegenüber den sich auf dem Markt befindlichen antiviralen Medikamenten. Diese Resistenzbildung macht es erforderlich, neue antiviral wirkende Substanzen und Ansatzpunkte zu entwickeln, die diese Probleme lösen. Einerseits wurde gezeigt, dass die Inhibition des Proteasoms durch einen spezifischen Proteasominhibitor (VL01) zu einer verminderten Zytokin-/Chemokin-Ausschüttung, sowie zu einer Reduktion der Viruslast führt. Andererseits konnte durch exogene Gabe niedriger IFN-alpha Dosen das angeborene Immunsystem so aktiviert werden, dass ein antiviraler Status generiert wurde, der es dem Immunsystem ermöglicht, schnell auf eine Influenzavirus-Infektion zu reagieren. Weitere Untersuchungen zur Pathogenese von Influenza-A-Viren zeigten, dass die Viren in der Lage sind, dendritische Zellen zu infizieren, die wiederum in den Thymus einwandern und die T-Zellentwicklung stören. Dies führt letztendlich zu einem der Pathogenitätsmechanismen, der Lymphopenie. Durch Impfstudien in knock-out Mäusen konnten immunologische Mechanismen identifiziert werden, die für die Kreuzprotektion eine wichtige Rolle spielen. Hierbei liegt der CD4+-T-Zellantwort eine wichtige Aufgabe zugrunde. Während einer Influenzavirus-Infektion kommt es häufig zu Influenza-assoziierten Sekundärinfektionen, wie z.B. bakteriellen Koinfektionen mit Pneumokokken oder Staphylokokken. Ein in diesem Zusammenhang bislang noch nicht aufgeklärtes Phänomen ist das des Influenza-assoziierten Schlaganfalls. Unsere Untersuchungen deuten daraufhin, dass die durch das Influenzavirus induzierte Hyperzytokinämie das Volumen des Schlaganfalls signifikant vergrößert. Wird im Mausmodell die Hyperzytokinämie durch exogene Substanzen reduziert, so verringert sich ferner das Infarktvolumen.Seasonal influenza causes annually world wide approximately 300.000 cases of death. The influenza-A-virus infection is currently treated prophylactically with vaccines or therapeutically with antiviral drugs. The vaccine has to develop and administered every year. From production to vaccination it takes approximately 4-6 month. Another problem is the emergence of new resistant viruses against the common antiviral drugs. These resistances promote an urgent need in developing new antiviral drugs. On one hand we could show that the inhibition of the proteasome leads to a reduced cytokine- and chemokine release as well as a reduction of progeny virus. On the other hand we are able to induce, with a low dose IFN-alpha treatment, the innate immune response against the influenza-A-virus. This induction leads to a reduced virus load in vitro and in vivo. Further investigations of the pathogenicity of influenza-A-virus infections shows that the virus is able to infect dendritic cells which reach the thymus and play an important role in lymphopenia. In vaccine studies with knock-out mice we could determine that CD4+ T-cells play an important role in cross-protection against influenza-A-virus infections. During influenza virus infections it often occur influenza-associated co-infections with pneumococcus or staphylococcus. A more and more influenza-associated co-infection is stroke. Our investigations reveal that the influenza induced hypercytokinemia is responsible for a stronger infarct volume of influenza infected and stroke treatment mice compared to control mice