Influenza remains one of the major epidemic diseases worldwide, and rapid virus replication and collateral lung tissue damage caused by excessive pro-inflammatory host immune cell responses lead to high mortality rates. Thus, novel therapeutic agents that control influenza A virus (IAV) propagation and attenuate excessive pro-inflammatory responses are needed. Polysaccharide extract from Radix isatidis, a traditional Chinese herbal medicine, exerted potent anti-IAV activity against human seasonal influenza viruses (H1N1 and H3N2) and avian influenza viruses (H6N2 and H9N2) in vitro. The polysaccharides also significantly reduced the expression of pro-inflammatory cytokines (IL-6) and chemokines (IP-10, MIG, and CCL-5) stimulated by A/PR/8/34 (H1N1) at a range of doses (7.5 mg/mL, 15 mg/mL, and 30 mg/mL); however, they were only effective against progeny virus at a high dose. Similar activity was detected against inflammation induced by avian influenza virus H9N2. The polysaccharides strongly inhibited the protein expression of TLR-3 induced by PR8, suggesting that they impair the upregulation of pro-inflammatory factors induced by IAV by inhibiting activation of the TLR-3 signaling pathway. The polysaccharide extract from Radix isatidis root therefore has the potential to be used as an adjunct to antiviral therapy for the treatment of IAV infection.

The influenza pandemics have resulted in significant morbidity and mortality worldwide. Animal models are useful in the study of influenza virus pathogenesis. Because of various limitations in current laboratory animal models, it is essential to develop new alternative animal models for influenza virus research aimed at understanding the viral and host factors that contribute to virus infection in human.

Background: Viral pathogens were more commonly reported than previously estimated in community-acquired pneumonia (CAP) patients. However, the real role of virus was still controversial.Methods: Consecutive adult patients with CAP between April and December, 2009 were prospectively enrolled. A four-fold or greater increase of IgG-titres against respiratory viruses in pair sera was tested by means of hemagglutination inhibition assay or indirect immunofluorescence. Swab samples were tested by cell culture and/or nucleic amplification tests. Viral etiology was considered definitive if at least one of the above tests was positive.Results: Viral etiology was established in fifty-two (34.9%) of 149 CAP patients, twenty-two (81.5%) of 27 influenza like illness patients, and none of 75 volunteer controls. Forty-seven CAP patients were infected by a single virus (24 influenza A virus, 5 influenza B, 10 parainfluenza virus type 3 [PIV-3], 2 PIV-1, 2 adenovirus, 2 human rhinovirus and 2 coronavirus OC43), five cases by two or three viruses co-infection. Fever ≥ 39°C (66.7%), fatigue (64.6%), and purulent sputum (52.1%) was the most common symptoms in viral pneumonia patients. On multivariate analysis, myalgia was included in the model for pneumonia associated with influenza infection. In the CURB-65 model only influenza infection was found independently associated with severe disease (CURB-65 score ≥ 3) out of variables, including age(years), sex, current smoking status, sick contact with febrile patients, numbers of comorbidity, presence of influenza infection, presence of PIV infection, with P = 0.021, OR 7.86 (95% CI 1.37-45.04).Conclusion: Respiratory virus was not a bystander, but pathogenic in pneumonia and was a common cause of CAP.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still ongoing and currently the most striking epidemic disease. With the rapid global spread of SARS-CoV-2 variants, new antivirals are urgently needed to avert a more serious crisis. Inhibitors from traditional medicines or natural plants have shown promising results to fight COVID-19 with different mechanisms of action. To provide comprehensive and promising approaches to the medical community in the fight against this epidemic by reviewing potential plant-derived anti-SARS-CoV-2 inhibitors. Structural databases such as TCMSP (http://lsp.nwu.edu.cn/tcmsp.php), TCM Database @ Taiwan (http://tcm.cmu.edu.tw/), BATMAN-TCM (http://bionet.ncpsb.org/batman-tcm/) and TCMID (http://www.megabionet.org/tcmid/), as well as PubMed, Sci Finder, Research Gate, Science Direct, CNKI, Web of Science and Google Scholar were searched for relevant articles on TCMs and natural products against SARS-CoV-2. Seven traditional Chinese medicines formulas have unique advantages in regulating the immune system for treating COVID-19. The plant-derived natural compounds as anti-SARS-CoV-2 inhibitors were identified based on 5 SARS-CoV-2 key proteins, namely, angiotensin-converting enzyme 2 (ACE2), 3 C-like protease (3CLpro), papain-like protease (PLpro), spike (S) protein, and nucleocapsid (N) protein. A variety of natural products, such as flavonoids, terpenoids, phenols, and alkaloids, were identified, which could be used as potential SASR-Cov-2 inhibitors. These shed new light on the efficient discovery of SASR-Cov-2 inhibitors from natural products.

Numerous viral pneumonia cases have been reported in Wuhan, Hubei in December 2019. The pathogen has been identified as a novel coronavirus, which was named severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). The biological characteristics and pathogenesis mechanism of SARS‐CoV‐2 are unclear and under progress. At present, no specific preventive and therapeutic drugs are available. Animal models can reproduce the viral replication cycle and the significant functions of respiratory coronavirus infection and are urgently needed to evaluate the efficacy of drugs and vaccines, the transmission route of respiratory coronavirus, clinical features, and so on. We reviewed the current animal models of respiratory coronavirus (SARS‐CoV, MERS‐CoV, and SARS‐CoV‐2) infection and made a comparative analysis of the route of inoculation, virus replication, clinical signs, histopathology, application, advantages, and disadvantages. Animal models of respiratory coronavirus include susceptible animal models, genetically modified models, and various animal models of infected virus adaptation strains, such as nonhuman primates, mice, hamsters, ferrets, New Zealand rabbits, cats, and other animal models, all of which have distinct advantages and limitations. This review will provide relevant information and important insights for disease management and control.