The Development and Use of Reporter Influenza B Viruses

A potential Chinese medicine monomer against influenza A virus and influenza B virus: isoquercitrin

BACKGROUND

Influenza viruses, especially Influenza A virus and Influenza B virus, are respiratory pathogens and can cause seasonal epidemics and pandemics. Severe influenza viruses infection induces strong host-defense response and excessive inflammatory response, resulting in acute lung damage, multiple organ failure and high mortality. Isoquercitrin is a Chinese medicine monomer, which was reported to have multiple biological activities, including antiviral activity against HSV, IAV, SARS-CoV-2 and so on. Aims of this study were to assess the in vitro anti-IAV and anti-IBV activity, evaluate the in vivo protective efficacy against lethal infection of the influenza virus and searched for the more optimal method of drug administration of isoquercitrin.

METHODS

In vitro infection model (MDCK and A549 cells) and mouse lethal infection model of Influenza A virus and Influenza B virus were used to evaluate the antiviral activity of isoquercitrin.

RESULTS

Isoquercitrin could significantly suppress the replication in vitro and in vivo and reduced the mortality of mouse lethal infection models. Compared with virus infection group, isoquercitrin mitigated lung and multiple organ damage. Moreover, isoquercitrin blocked hyperproduction of cytokines induced by virus infection via inactivating NF-κB signaling. Among these routes of isoquercitrin administration, intramuscular injection is a better drug delivery method.

CONCLUSION

Isoquercitrin is a potential Chinese medicine monomer Against Influenza A Virus and Influenza B Virus infection.

Cellular glycan modification by B3GAT1 broadly restricts influenza virus infection

Communicable respiratory viral infections pose both epidemic and pandemic threats and broad-spectrum antiviral strategies could improve preparedness for these events. To discover host antiviral restriction factors that may act as suitable targets for the development of host-directed antiviral therapies, we here conduct a whole-genome CRISPR activation screen with influenza B virus (IBV). A top hit from our screen, beta-1,3-glucuronyltransferase 1 (B3GAT1), effectively blocks IBV infection. Subsequent studies reveal that B3GAT1 activity prevents cell surface sialic acid expression. Due to this mechanism of action, B3GAT1 expression broadly restricts infection with viruses that require sialic acid for entry, including Victoria and Yamagata lineage IBVs, H1N1/H3N2 influenza A viruses (IAVs), and the unrelated enterovirus D68. To understand the potential utility of B3GAT1 induction as an antiviral strategy in vivo, we specifically express B3GAT1 in the murine respiratory epithelium and find that overexpression is not only well-tolerated, but also protects female mice from a lethal viral challenge with multiple influenza viruses, including a pandemic-like H1N1 IAV. Thus, B3GAT1 may represent a host-directed broad-spectrum antiviral target with utility against clinically relevant respiratory viruses.

A Virion-Based Combination Vaccine Protects against Influenza and SARS-CoV-2 Disease in Mice

Vaccines targeting SARS-CoV-2 have been shown to be highly effective; however, the breadth against emerging variants and the longevity of protection remains unclear. Postimmunization boosting has been shown to be beneficial for disease protection, and as new variants continue to emerge, periodic (and perhaps annual) vaccination will likely be recommended. New seasonal influenza virus vaccines currently need to be developed every year due to continual antigenic drift, an undertaking made possible by a robust global vaccine production and distribution infrastructure. To create a seasonal combination vaccine targeting both influenza viruses and SARS-CoV-2 that is also amenable to frequent reformulation, we have developed an influenza A virus (IAV) genetic platform that allows the incorporation of an immunogenic domain of the SARS-CoV-2 spike (S) protein onto IAV particles. Vaccination with this combination vaccine elicited neutralizing antibodies and provided protection from lethal challenge with both pathogens in mice. This approach may allow the leveraging of established influenza vaccine infrastructure to generate a cost-effective and scalable seasonal vaccine solution for both influenza and coronaviruses.

IMPORTANCE The rapid emergence of SARS-CoV-2 variants since the onset of the pandemic has highlighted the need for both periodic vaccination “boosts” and a platform that can be rapidly reformulated to manufacture new vaccines. In this work, we report an approach that can utilize current influenza vaccine manufacturing infrastructure to generate combination vaccines capable of protecting from both influenza virus- and SARS-CoV-2-induced disease. The production of a combined influenza/SARS-CoV-2 vaccine may represent a practical solution to boost immunity to these important respiratory viruses without the increased cost and administration burden of multiple independent vaccines.

Potential of MicroRNAs As Biomarkers and Therapeutic Targets in Respiratory Viruses: A Literature Review

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through recognition of cognate sequences and interference of transcriptional, translational, or epigenetic processes. Hundreds of miRNA genes have been found in diverse viruses, and many of these are phylogenetically conserved. Respiratory viruses are the most frequent causative agents of disease in humans, with a significant impact on morbidity and mortality worldwide. Recently, the role of miRNAs in respiratory viral gene regulation, as well as host gene regulation during disease progression, has become a field of interest. This review highlighted the importance of various miRNAs and their potential role in fighting with respiratory viruses as therapeutic molecules with a focus on COVID-19.

A Comprehensive Roadmap Towards the Generation of an Influenza B Reporter Assay Using a Single DNA Polymerase-Based Cloning of the Reporter RNA Construct

The mini-genome reporter assay is a key tool for conducting RNA virus research. However, procedural complications and the lack of adequate literature pose a major challenge in developing these assay systems. Here, we present a novel, yet generic and simple, cloning strategy for the construction of an influenza B virus reporter RNA template and describe an extensive standardization of the reporter RNP/polymerase activity assay for monitoring viral RNA synthesis in an infection-free setting. Using this assay system, we showed for the first time the effect of viral protein NS1 and host protein kinase C delta (PKCD) on influenza B virus RNA synthesis. In addition, the assay system showed promising results in evaluating the efficacy of antiviral drugs targeting viral RNA synthesis and virus propagation. Together, this work offers a detailed protocol for the standardization of the influenza virus minigenome assay and an excellent tool for screening of host factors and antivirals in a fast, user-friendly, and high-throughput manner.

Reverse genetics for influenza B viruses and recent advances in vaccine development

Influenza B virus is a respiratory pathogen that affects more severely the pediatric and elderly populations. There are two lineages of influenza B virus that seem to have differential predilection for age groups. Both lineages can co-circulate during the influenza season however one is usually more prominent than the other depending on the season. There are no defined indicators to predict which lineage will dominate in any given season. In recent years, the addition of viruses from both lineages to the seasonal influenza vaccine formulation has improved vaccine protection, although quadrivalent vaccines are not available worldwide. Reverse genetics has facilitated advancements in the field of vaccine development against influenza B virus. Different strategies have been explored showing promising results that could potentially lead to the development broadly protective influenza B virus vaccines.

Host Protective Immune Responses against Influenza A Virus Infection

Influenza viruses cause infectious respiratory disease characterized by fever, myalgia, and congestion, ranging in severity from mild to life-threating. Although enormous efforts have aimed to prevent and treat influenza infections, seasonal and pandemic influenza outbreaks remain a major public health concern. This is largely because influenza viruses rapidly undergo genetic mutations that restrict the long-lasting efficacy of vaccine-induced immune responses and therapeutic regimens. In this review, we discuss the virological features of influenza A viruses and provide an overview of current knowledge of the innate sensing of invading influenza viruses and the protective immune responses in the host.