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Ethnopharmacological Relevance: Influenza virus infection is widely believed to cause mild symptoms, but can lead to high mortality and severe disease complicated by secondary bacterial pneumonia. Traditional Chinese medicine (TCM) has been proposed as a promising agent to treat respiratory viral infections. A herbal formula Lianhuaqingwen capsule (LHQW) comprising two prescriptions: Maxing Shigan decoction and Yinqiao San, has been used clinically to treat respiratory infection with immune regulatory effects. However, little is known about the capacity of LHQW against influenza-induced secondary bacterial pneumonia., Aim of Study: This study aimed to evaluate the efficacy and underlying mechanism of LHQW on influenza A virus A/PR/8/34 (PR8) secondary methicillin-resistant Staphy-lococcus aureus (MRSA) infection., Methods: The anti-adhesion activity of LHQW against PR8-induced MRSA infection was assessed in human lung epithelial (A549) cells and the effect of LHQW on the expression of intracellular adhesion molecule 1 (ICAM-1) was detected. Also, the mRNA expression levels of inflammatory cytokines upon lipopolysaccharide (LPS) stimulation in PR8-infected A549 cells were determined. The body weight change, survivals, viral titers, colonies and the pathological parameters after LHQW treatment in severe pneumonia model have all been systematically determined., Results: LHQW significantly reduced the adhesion of MRSA to PR8-infected A549 cells in a dose-dependent manner by suppressing the up-regulation of bacterial receptors. LHQW also markedly declined the overexpression of IL-6, IL-8, and TNF-α induced by LPS stimulated-A549 cells following influenza virus infection. Furthermore, the abnormal changes of lung index in dual-infection mice were relieved after administered with LHQW in preventive and therapeutic mode, but with no significantly difference (P > 0.05). LHQW could not effectively improve survival rate or prolong the survival time of mice (P > 0.05). LHQW (1000 mg/kg/d) administered prophylactically significantly decreased the lung viral titers (P < 0.05), slightly downregulated IL-6 but TNF-α, IL-1β levels and improved lung pathological inflammation including neutrophil infiltration, necrosis, which is consistent with the expression of inflammatory factors., Conclusions: LHQW inhibited influenza-induced bacterial adhesion by down-regulating the adhesion molecules with the improvement trend on severe pneumonia, indicating that it can be used as an adjuvant medication in severe viral-bacterial pneumonia therapy rather than as a single medication., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Chronic obstructive pulmonary disease (COPD) is a worldwide chronic inflammatory lung disease, and influenza A virus (IAV) infection is a common cause of acute exacerbations of COPD (AECOPD). Therefore, targeting viral infections represents a promising strategy to prevent the occurrence and development of inflammatory flare ups in AECOPD. Jianpiyifei II (JPYFII) is a traditional herbal medicine used in China to treat patients with COPD, and its clinical indications are not well understood. However, investigation of the anti-inflammatory effects and underlying mechanism using an animal model of smoking have been reported in a previous study by our group. In addition, some included herbs, such as Radix astragali and Radix aupleuri, were reported to exhibit antiviral effects. Therefore, the aim of the present study was to investigate whether JPYFII formulation relieved acute inflammation by clearing the IAV in a mouse model that was exposed to cigarette smoke experimentally. JPYFII formulation treatment during smoke exposure and IAV infection significantly reduced the number of cells observed in bronchoalveolar lavage fluid (BALF), expression of proinflammatory cytokines, chemokines, superoxide production, and viral load in IAV-infected and smoke-exposed mice. However, JPYFII formulation treatment during smoke exposure alone did not reduce the number of cells in BALF or the expression of Il-6, Tnf-a, and Il-1β. The results demonstrated that JPYFII formulation exerted an antiviral effect and reduced the exacerbation of lung inflammation in cigarette smoke (CS)-exposed mice infected with IAV. Our results suggested that JPYFII formulation could potentially be used to treat patients with AECOPD associated with IAV infection., (© 2021 The Author(s).)

Influenza pandemic is a constant major threat to public health caused by influenza A viruses (IAVs). IAVs are subcategorized by the surface proteins hemagglutinin (HA) and neuraminidase (NA), in which they are both essential targets for drug discovery. While it is of great concern that NA inhibitor oseltamivir resistant strains are frequently identified from human or avian influenza virus, structural and functional characterization of influenza HA has raised hopes for new antiviral therapies. In this study, we explored a structure-activity relationship (SAR) of pinanamine-based antivirals and discovered a potent inhibitor M090 against amantadine-resistant viruses, including the 2009 H1N1 pandemic strains, and oseltamivir-resistant viruses. Mechanism of action studies, particularly hemolysis inhibition, indicated that M090 targets influenza HA and it occupied a highly conserved pocket of the HA 2 domain and inhibited virus-mediated membrane fusion by "locking" the bending state of HA 2 during the conformational rearrangement process. This work provides new binding sites within the HA protein and indicates that this pocket may be a promising target for broad-spectrum anti-influenza A drug design and development.