Influenza Virus

CAS No.	Product Name	Inquiry
913545-15-0	CEF6 CEF6, one of the the CEF control peptides, is a 9-aa-long peptide corresponding to aa 418-426 of the influenza A virus (H1N1) nucleocapsid protein.
913822-46-5	SC75741 SC75741 is a potent NF-κB inhibitor (EC50=200 nM).
91485-02-8	urolithin M5
91-64-5	Coumarin Coumarin is an edema modifier, known to stimulate macrophages to degrade extracellular albumin, allowing faster resorption of edematous fluids. It has anti-cancer, anti-inflammation, anti-virus and other pharmacological activities.
928659-17-0	Triazavirin Triazavirin is a broad-spectrum antiviral drug, effective against various strains of the Influenza A virus. Triazavirin inhibits the synthesis of viral RNA and DNA and replication of genomic fragments. Triazavirin might be a potential treatment for SARS-CoV-2.
932-53-6	6-Azathymine 6-Azathymine, a potent D-3-aminoisobutyrate-pyruvate aminotransferase inhibitor, inhibits DNA biosynthesis and has antibacterial and antiviral activities.
939655-35-3	Antiviral agent 58
945170-74-1	DS-22-inf-021
95258-13-2	Yadanziolide B Yadanziolide B is extracted from the seeds of Brucea javanica. It displays cytotoxic activities with IC50 values in the range of 3.00-5.81 uM.
959245-08-0	CBS1117 CBS1117 is an effective inhibitor of influenza A virus entry, which can inhibit influenza virus hemagglutinin.
97134-11-7	Pinellic acid
99390-76-8	BMY-27709
133550-34-2	AG 555 AG 555 is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (IC50 = 0.7 μM) with 50-fold and >140-fold selectivity over ErbB2 and insulin receptor kinase respectively.
480-41-1	Naringenin Naringenin is a natural predominant flavanone derived from plant food with antioxidant and anti-inflammatory activity. Naringenin reduces oxidative damage to DNA in vitro, and increases VLDL as well as cholesterol levels. Naringenin is used for the treatment of HCV infection. Naringenin can be used as nutritional supplement in health care products.
153436-53-4	AG-1478 AG-1478 (NSC 693255) is a selective EGFR inhibitor with IC50 of 3 nM; almost no activity on HER2-Neu, PDGFR, Trk, Bcr-Abl and InsR.
10537-47-0	Tyrphostin 9 Tyrphostin 9 is firstly designed as an EGFR inhibitor with IC50 of 460 μM, but is also found to be more potent to PDGFR with IC50 of 0.5 μM.
170449-18-0	AG 1478 hydrochloride The hydrochloride salt form of AG 1478, which has been found to be an epidermal growth factor receptor tyrosine kinase inhibitor.
33012-73-6	Cyanidin-3-O-sambubioside chloride Cyanidin 3-sambubioside chloride (Cyanidin-3-O-sambubioside chloride), a major anthocyanin, a natural colorant, and is a potent NO inhibitor. Cyanidin 3-sambubioside chloride is a H274Y mutation inhibitor, and inhibits influenza neuraminidase activity with an IC50 of 72 μM. Cyanidin 3-sambubioside chloride inhibits angiotensin-converting enzyme (ACE) activity and has antioxidant, anti-angiogenic and antiviral properties.
13292-46-1	Rifampicin It is a semi-synthetic antibiotic of the rifamycin group. It is an inhibitor of bacterial RNA polymerase and has antibacerial activity.
106500-25-8	Azadirachtin B Azadirachtin B is a drug analog of azadirachtin which was investigated in agrochemical studies of bioregulators for the antifeedant mode of action of parent molecule against Lepidoptera and locusts.

What is influenza virus?

Influenza virus, abbreviated as influenza virus, is an enveloped, segmented, negative-sense RNA virus of the family Orthomyxoviridae, which is the main pathogen causing influenza. Influenza viruses are weak and sensitive to environmental conditions. At room temperature, the virus can survive for about 2 hours, but can be inactivated by 30 minutes of exposure at 56°C. However, the virus can survive for several weeks at 0°C to 4°C and can be stored below -70°C or lyophilized for long periods of time. Viruses are also sensitive to dryness, sunlight, ultraviolet rays, and chemicals such as ether, formaldehyde, and lactic acid, and are easily inactivated.

Influenza virus disease

Influenza A and B viruses initiate infection by binding HA to sialic acid receptors on the surface of respiratory epithelial cells. The virus enters the cell through endocytosis, and the viral genome is transcribed and replicated within the nucleus, replicating a large number of new progeny viral particles, which spread through the mucous membranes of the respiratory tract and infect other cells. After influenza virus infects the human body, it can induce cytokine storm, leading to sepsis (Sepsis), acute respiratory distress syndrome (ARDS), shock, encephalopathy and multiple organ failure.

Influenza virus structure

Influenza viruses are generally spherical in shape, with a diameter of 80~120nm, and the virus isolated from patients for the first time is sometimes filamentous or rod-shaped. The virion structure mainly includes the nucleocapsid and envelope composed of viral nucleic acids and proteins.

The nucleocapsid is located at the core of the virion body and is arranged in a helical symmetrical arrangement, consisting of a viral single negative strand segmented RNA bound to one or several RNA-dependent RNA polymerases containing PB1, PB2, and PA, and covered by nuclear proteins (NPs), which together form ribonucleoproteins (RNPs). Nucleoprotein (NP) is the main structural protein, the antigen structure is stable, together with the M protein determines the type specificity of the virus, rarely mutates, and its antibodies have no ability to neutralize the virus. The main function of NS1 protein is to disarm the host interferon defense system in a variety of ways, and plays an important role in the process of viral transcription and infection.

The envelope is composed of an inner matrix protein (M) and an outer lipoprotein (LP), which has the function of maintaining the appearance and integrity of the virus. The structure of MP protein antigen is relatively stable and type-specific, and its antibodies have no ability to neutralize the virus. Among them, M1 protein is the main structural component of the virus, which is related to virus packaging, budding and morphology, and M2 protein is an ion channel intercaling protein, which is involved in viral replication. LPs are mainly derived from host cell membranes.

Fig.1 Structure of influenza virus particles. Fig.1 Structural diagram of Influenza virus. (Langer Dominik, et al., 2023)

Influenza virus genome

The genome of influenza virus is 13600bp in length, and the 12~13 nucleotides at its end are highly conserved, which is related to viral replication. Influenza A and B viruses have 8 RNA segments. Influenza C virus (ICV) lacks the NA gene fragment that forms neuraminidase (NA) and has only 7 RNA segments. The genome structure of influenza D virus (IDV) is the same as that of ICV, with only 7 RNA segments. Each RNA segment encodes a different protein, fragments 1~6 encode PB2, PB1, PA, hemagglutinin (HA), nuclear protein (NP) and neuraminidase (NA), fragment 7 encodes matrix proteins M1 and M2, and fragment 8 encodes non-structural proteins NS1 and NS2.

Types of influenza virus

To date, four types of influenza viruses have been identified based on the core proteins of influenza viruses: A , B, C, and D. Influenza A virus (IAV) can infect not only humans, but also poultry, pigs, cattle, horses and other animals. Influenza B virus (IBV) can infect humans and pigs. Influenza C virus (ICV) can infect humans and pigs. Influenza D virus (IDV) can infect cattle and pigs.

Influenza A viruses can be divided into several subtypes according to the different antigenicities of hemagglutinin (HA) and neuraminidase (NA) on the surface of the virus, and 18 (H1~H18) antigens have been found in HA and 11 (N1~N11) antigens in NA. There are currently two lineages of influenza B virus circulating in humans, namely the Yamagata and Victoria lineages. Influenza A virus is the only influenza virus known to cause an influenza pandemic, a global epidemic of influenza disease. Influenza C virus infection usually causes mild illness and is not thought to cause an epidemic in humans. Influenza D viruses mainly affect cattle and can spill over to other animals, but it is unclear whether they can infect humans and cause disease.

Influenza virus treatment

The treatment of influenza presents multiple challenges, especially in the management of patients with severe disease. Currently, four FDA-approved antiviral drugs are used to treat influenza, including Peramivir (Rapivab), Zanamivir (Relenza), Oseltamivir and Baloxavir (Xofluza). Among them, neuraminidase inhibitors (NAIs) such as Oseltamivir and Zanamivir, as well as the cap-dependent endonuclease inhibitor Baloxavir, are effective against influenza A and B viruses. Adamantanes are not currently recommended due to widespread resistance.

Neuraminidase inhibitors: Observational studies have shown that early use of NAIs significantly reduces mortality, especially when treatment is initiated within 48 hours of onset. However, the optimal therapeutic dose and duration of NAIs in hospitalized patients have not been determined, and enteral oseltamivir injection is recommended for patients whose inhalation of zanamivir may cause bronchospasm.

CAP-dependent endonuclease inhibitors: As a novel antiviral drug, Baloxavir has shown similar clinical efficacy to oseltamivir in patients with uncomplicated influenza, but its efficacy and safety in hospitalized patients need to be further studied. In addition, the use of glucocorticoids in patients with severe influenza is controversial, and some studies suggest that they may increase mortality and the risk of secondary infection, so routine use is not recommended except in exceptional circumstances.

Although antiviral treatments are available, research into influenza treatments continues to advance. Triple therapies of Amantadine, Ribavirin and Oseltamivir, as well as new therapies such as small molecule inhibitors of influenza virus proteins, monoclonal antibodies, and convalescent plasma, are in various stages of investigation. These emerging treatment strategies may offer new hope for patients with severe influenza. The core of influenza treatment remains symptomatic treatment and prevention of secondary infections, combined with appropriate antiviral drugs, to minimize mortality and risk of complications.

Reference

Langer, Dominik, et al., Potential of glycyrrhizic and glycyrrhetinic acids against influenza type A and B viruses: A perspective to develop new anti-influenza compounds and drug delivery systems. European Journal of Medicinal Chemistry 246 (2023): 114934.

※ Please kindly note that our services are for research use only.