Synthesis and antiviral activity of PB1 component of the influenza A RNA polymerase peptide fragments

Production, Passaging Stability, and Histological Analysis of Madin-Darby Canine Kidney Cells Cultured in a Low-Serum Medium

Madin-Darby canine kidney (MDCK) cells are commonly used to produce cell-based influenza vaccines. However, the role of the low-serum medium on the proliferation of MDCK cells and the propagation of the influenza virus has not been well studied. In the present study, we used 5 of 15 culture methods with different concentrations of a mixed medium and neonatal bovine serum (NBS) to determine the best culture medium. We found that a VP:M199 ratio of 1:2 (3% NBS) was suitable for culturing MDCK cells. Furthermore, the stable growth of MDCK cells and the production of the influenza virus were evaluated over long-term passaging. We found no significant difference in terms of cell growth and virus production between high and low passages of MDCK cells under low-serum culture conditions, regardless of influenza virus infection. Lastly, we performed a comparison of the transcriptomics and proteomics of MDCK cells cultured in VP:M199 = 1:2 (3% NBS) with those cultured in VP:M199 = 1:2 (5% NBS) before and after influenza virus infection. The transcriptome analysis showed that differentially expressed genes were predominantly enriched in the metabolic pathway and MAPK signaling pathway, indicating an activated state. This suggests that decreasing the concentration of serum in the medium from 5% to 3% may increase the metabolic activity of cells. Proteomics analysis showed that only a small number of differentially expressed proteins could not be enriched for analysis, indicating minimal difference in the protein levels of MDCK cells when the serum concentration in the medium was decreased from 5% to 3%. Altogether, our findings suggest that the screening and application of a low-serum medium provide a background for the development and optimization of cell-based influenza vaccines.

"What Doesn't Kill You Makes You Stronger": Future Applications of Amyloid Aggregates in Biomedicine

Amyloid proteins are linked to the pathogenesis of several diseases including Alzheimer's disease, but at the same time a range of functional amyloids are physiologically important in humans. Although the disease pathogenies have been associated with protein aggregation, the mechanisms and factors that lead to protein aggregation are not completely understood. Paradoxically, unique characteristics of amyloids provide new opportunities for engineering innovative materials with biomedical applications. In this review, we discuss not only outstanding advances in biomedical applications of amyloid peptides, but also the mechanism of amyloid aggregation, factors affecting the process, and core sequences driving the aggregation. We aim with this review to provide a useful manual for those who engineer amyloids for innovative medicine solutions.

Investigational antiviral therapies for the treatment of influenza

INTRODUCTION

Influenza viral ribonucleoprotein complexes (vRNPs) play a key role in viral transcription and replication; hence, the recent development of novel anti-influenza drugs targeting vRNPs has garnered widespread interest.

AREAS COVERED

We discuss the function of the constituents of vRNPs and summarize those vRNPs-targeted synthetic drugs that are in preclinical and early clinical development.

EXPERT OPINION

vRNPs contain high-value drug targets; such targets include the subunits PA, PB1, PB2, and NP. Developing a new generation of antiviral therapies with strategies that utilize existing drugs, natural compounds originated from new resources and novel drug combinations may open up new therapeutic approaches to influenza.

Lactobacillus plantarum displaying conserved M2e and HA2 fusion antigens induces protection against influenza virus challenge

Avian influenza virus (AIV) can infect poultry, mammals, and other hosts and causes enormous economic losses to the global poultry industry. In this study, to develop a novel and potent oral vaccine based on Lactobacillus plantarum (L. plantarum) for controlling the spread of AIV in the poultry industry, we constructed a recombinant L. plantarum strain displaying the 3M2e-HA2 protein of the influenza virus and determined the effect of N/pgsA'-3M2e-HA2 against AIV in chicks. We first confirmed that the 3M2e-HA2 fusion protein was expressed on the surface of L. plantarum via flow cytometry and immunofluorescence experiments. Our experimental results demonstrated that chicks immunized with N/pgsA'-3M2e-HA2 could induce specific humoral, mucosal, and T cell-mediated immune responses, eliciting the host body to protect itself against AIV. Additionally, compared to oral administration, the intranasal immunization of chicks with N/pgsA'-3M2e-HA2 provided a stronger immune response, resulting in a potent protective effect that hindered the loss of body weight, decreasing pulmonary virus titers and reducing lung and throat pathological damages. Thus, our results indicate that our novel approach is an effective method of vaccine design to promote mucosal immunity.

Influenza A virus polymerase: an attractive target for next-generation anti-influenza therapeutics

The influenza RNA-dependent RNA polymerase (RdRP) is conserved among different types of influenza virus, playing an important part in transcription and replication. In this regard, influenza RdRP is an attractive target for novel anti-influenza drug discovery. Herein, we will introduce the structural and functional information of influenza polymerase; and an overview of inhibitors targeting the PA endonuclease and PB2 cap-binding site is provided, along with the approaches utilized for identification of these inhibitors. The protein-protein interactions (PPIs) of the three polymerase subunits: PA, PB1 and PB2, are described based on the published crystal structures, and inhibitors targeting the PA-PB1 interaction are introduced briefly.

The amyloidogenicity of the influenza virus PB1-derived peptide sheds light on its antiviral activity

The influenza virus polymerase complex is a promising target for new antiviral drug development. It is known that, within the influenza virus polymerase complex, the PB1 subunit region from the 1st to the 25th amino acid residues has to be is in an alpha-helical conformation for proper interaction with the PA subunit. We have previously shown that PB1(6-13) peptide at low concentrations is able to interact with the PB1 subunit N-terminal region in a peptide model which shows aggregate formation and antiviral activity in cell cultures. In this paper, it was shown that PB1(6-13) peptide is prone to form the amyloid-like fibrillar aggregates. The peptide homo-oligomerization kinetics were examined, and the affinity and characteristic interaction time of PB1(6-13) peptide monomers and the influenza virus polymerase complex PB1 subunit N-terminal region were evaluated by the SPR and TR-SAXS methods. Based on the data obtained, a hypothesis about the PB1(6-13) peptide mechanism of action was proposed: the peptide in its monomeric form is capable of altering the conformation of the PB1 subunit N-terminal region, causing a change from an alpha helix to a beta structure. This conformational change disrupts PB1 and PA subunit interaction and, by that mechanism, the peptide displays antiviral activity.

In vitro antiviral effects of Peganum harmala seed extract and its total alkaloids against Influenza virus

This research was aimed to evaluate the in vitro antiviral effect and the mechanism of the effect of Peganum. harmala seeds extract against influenza A virus infection using Madin-Darby canine kidney (MDCK) cells. In this research, ethyl alcohol extract of P. harmala seeds and its total alkaloids was prepared. The potential antiviral activity of the extract and its total alkaloids against influenza A/Puerto Rico/8/34 (H1N1; PR8) virus was assessed. The mode of action of the extract to inhibit influenza replication was investigated using virucidal activity, hemagglutination inhibition assay, time of addition assays, RNA replication, western blot analysis and RNA polymerase blocking assay. The crud extract of P. harmala seed and its total alkaloids showed the best inhibitory effect against influenza A virus replication in MDCK cells using MTT assay, TCID₅₀ method and hemagglutination assay. Our results indicated that the extract inhibits viral RNA replication and viral polymerase activity but did not effect on hemagglutination inhibition and virucidal activity. This study showed that, in vitro antiviral activity of P. harmala seed extract against influenza virus is most probably associated with inhibiting viral RNA transcription. Therefore, this extract and its total alkaloid should be further characterized to be developed as anti-influenza A virus agent.

Peptide-Induced Amyloid-Like Conformational Transitions in Proteins

Changes in protein conformation can occur both as part of normal protein functioning and during disease pathogenesis. The most common conformational diseases are amyloidoses. Sometimes the development of a number of diseases which are not traditionally related to amyloidoses is associated with amyloid-like conformational transitions of proteins. Also, amyloid-like aggregates take part in normal physiological processes such as memorization and cell signaling. Several primary structural features of a protein are involved in conformational transitions. Also the protein proteolytic fragments can cause the conformational transitions in the protein. Short peptides which could be produced during the protein life cycle or which are encoded by short open reading frames can affect the protein conformation and function.