Influenza Virus Strains Research Articles

PROTECTIVE ACTIVITY OF HYBRID DERIVATIVES OF TRITERPENOID COUMA-RINS AGAINST INFLUENZA AND HERPES VIRUSES

The aim of this study was to evaluate the protective properties of new hybrid deriva-tives of triterpenoid-coumarins using models of lethal influenza pneumonia and herpetic con-junctivitis. Materials and Methods. Animals. The study used two types of animals: female Balb/c mice (16-18 g) and male guinea pigs (400 g). The study employed the influenza virus strain A/California/07/09 (H1N1)pdm09, adapted to mice, from the collection of the Research Insti-tute of Influenza, A.A. Smorodintsev, Ministry of Health of Russia. Passage history: E4/E3M8E1. Conclusions. The protective activity of some hybrid derivatives of triterpenoid-coumarin was studied in the model of lethal influenza pneumonia caused by the influenza vi-rus and in the model of herpetic conjunctivitis during therapeutic and preventive use. It was shown that in the model of lethal influenza pneumonia using high doses of the influen-za virus, the use of all compounds improved the dynamics of animal weight, even if the animal mortality coincided with that of the control group. All the tested compounds, except for AV-49, positively affected the dynamics of death in infected animals. The most active compounds were AV-41, AV-42, and AV-53, with protection indices of 45%, 56%, and 34%, respective-ly. When studying the activity of compounds AV-41, AV-49, and AV-54 with lower doses of the virus, the protective properties of AV-41 and AV-53 were preserved at levels comparable to the reference drug oseltamivir. When investigating the protective activity of AV-42 and AV-53 in the model of her-petic conjunctivitis, it was shown that both drugs reduced the severity of disease symptoms (both keratitis and blepharitis), though less effectively than the reference drug acyclovir. Based on the overall protective activity in both viral models, the group of new hybrid triterpe-noid-coumarin derivatives appears promising for further antiviral research.

OPTIMIZATION OF THE EXTRACTION PROCESS OF BIOLOGICALLY ACTIVE COMPLEXES FROM PSORALEA DRUPACEA BGE ROOTS

In recent years, due to the emergence of previously unknown types of viral diseases (avian influenza, swine flu type A/H1N1), the search for new drugs against bacteria and viruses has become a very pressing problem. Synthetic drugs, which, in addition to the obvious antiviral and antiviricidal action, have a number of side effects on the nervous, respiratory, digestive, hepatobiliary systems, and also cause allergic reactions as a result predominate among modern drugs in this field. In terms of side effects of herbal medicines, the advantage is to reduce the effects, since the biosynthesis of plant-based drugs does not contradict the biosynthesis of humans and animals. In the course of solving these current problems, it has been established that the dry extract obtained from the roots of Psoralea drupacea Bge. is active against strains of avian influenza viruses. The article presents the results of research related to the optimization of the extraction process of this substance. The influence of various factors of the extraction process: extractant nature, raw material grinding degree, extraction duration, extraction method (sedimentation (maceration), percolation, extraction with a boiling solvent in a Soxhlet apparatus) on the total yield of extractive substances and the amount of furocoumarins was studied. The results of the research demonstrated that the most effective extractant is ethanol, and the optimal degree of raw material grinding is 1.25 mm. The most optimal extraction method is raw material extraction with ethanol by Soxhlet apparatus. In this case, after 3 days, the dry extract yield was high (5.80%) and the maximum amount of furocoumarins was also high (72.34%). Nevertheless, maceration with stirring and heating can give good results, and the advantage of the process is its simplicity and the ability to increase the raw material upload.

Coupling antigens from multiple subtypes of influenza can broaden antibody and T cell responses.

The seasonal influenza vaccine contains strains of viruses from distinct subtypes that are grown independently and then combined. However, most individuals exhibit a more robust response to one of these strains and thus are vulnerable to infection by others. By studying a monozygotic twin cohort, we found that although prior exposure is a factor, host genetics are a stronger driver of subtype bias to influenza viral strains. We found that covalent coupling of heterologous hemagglutinin (HA) from different viral strains could largely eliminate subtype bias in an animal model and in a human tonsil organoid system. We proposed that coupling of heterologous antigens improves antibody responses across influenza strains by broadening T cell help, and we found that using this approach substantially improved the antibody response to avian influenza HA.

Fullerenol C60(OH)36: Antioxidant, Cytoprotective, Anti-Influenza Virus Activity, and Self-Assembly in Aqueous Solutions and Cell Culture Media.

Viral infections and many other dangerous diseases are accompanied by the development of oxidative stress, which is a consequence of an increase in the level of the reactive oxygen species (ROS). In this regard, the search for effective antioxidants remains highly relevant. We tested fullerenol C60(OH)36 in the context of the connection between its self-assembly in aqueous solutions and cell culture media, antiradical activity, UV cytoprotective action, and antiviral activity against international reference strains of influenza virus A(H1N1)pdm09, A(H3N2), and B subtypes in vitro on the MDCK cell line. Various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, NMR and ESR spectrometry, MALDI-TOF mass spectrometry, thermal analysis (TGA and DSC), dynamic light-scattering (DLS), and ζ-potential measurements, were used to confirm the production of fullerenol and study its self-assembly in aqueous solutions and cell culture media. Fullerenol C60(OH)36 demonstrated the ability to scavenge •DPPH, •OH, O2•- radicals and 1O2 and was non-toxic in the range of the studied concentrations (up to 200 μg/mL) when incubated with MDCK cells for 24 h. In addition, fullerenol exhibited a cytoprotective effect under UV irradiation (EC50 = 29.7 ± 1.0 μM) and showed moderate activity against human influenza viruses of subtypes A(H1N1)pdm09 (SI = 9.9 ± 4.6) and A(H3N2) (SI = 12.5 ± 1.3) when determined by the hemagglutination assay (HA-test) and the MTT assay. At the same time, C60(OH)36 was ineffective in vitro against the actual strain of influenza B virus (Victoria lineage). The high bioavailability of fullerenol in combination with its cytoprotective effect, as well as its antiradical and antiviral activity combined with a relatively low toxicity, allows to consider it a promising compound for biomedical applications.

Wastewater monitoring of human and avian influenza A viruses in Northern Ireland: a genomic surveillance study

Influenza Aviruses (IAVs) are significant pathogens of humans and other animals. Although endemic in humans and birds, novel IAV strains can emerge, jump species, and cause epidemics, like the latest variant of H5N1. Wastewater-based epidemiology (WBE) has been shown capable of detecting human IAVs. We aimed to assess whether whole-genome sequencing (WGS) of IAVs from wastewater is possible and can be used to discriminate between circulating strains of human and any non-human IAVs, such as those of avian origin. Using a pan-IAV RT-quantitative PCR assay, six wastewater treatment works (WWTWs) across Northern Ireland were screened from Aug 1to Dec 5, 2022. Ananopore WGS approach was used to sequence RT-qPCR-positive samples. Phylogenetic analysis of sequences relative to currently circulating human and non-human IAVs was performed. Forcomparative purposes, clinical data (PCR test results) were supplied by The Regional Virus Laboratory, Belfast Health and Social Care Trust (Belfast, Northern Ireland, UK). We detected a dynamic IAV signal in wastewater from Sept 5, 2022, onwards across Northern Ireland, which did not show a clear positive relationship with the clinical data obtained for the region. Meta (mixed strain) whole-genome sequences were generated from wastewater samples displaying homology to only human and avian IAVstrains. The relative proportion of IAV reads of human versus avian origin differed across time and sample site. Adiversity in subtypes and lineages was detected (eg, H1N1, H3N2, and several avian). Avian segment 8related to those found in recent H5N1 clade 2.3.4.4b was identified. WBE affords a means to monitor circulating human and avian IAV strains and provide crucial genetic information. As such, WBE can provide rapid, cost-effective, year-round One Health surveillance to help control IAV epidemic and pandemic-related threats. However, optimisation of WBE protocols are necessary to ensure observed wastewater signals not only correlate with clinical case data, but yield information on the wider environmental pan-influenz-ome. Department of Health for Northern Ireland.

Debulking influenza and herpes simplex virus strains by a wide-spectrum anti-viral protein formulated in clinical grade chewing gum.

Lack of Herpes Simplex Virus (HSV) vaccine, low vaccination rates of Influenza viruses, waning immunity and viral transmission after vaccination underscore the need to reduce viral loads at their transmission sites. Oral virus transmission is several orders of magnitude higher than nasal transmission. Therefore, in this study, we evaluated neutralization of viruses using a natural viral trap protein (FRIL) formulated in clinical-grade chewing gum. FRIL is highly stable in the lablab bean powder (683days) and in chewing gum (790days), and fully functional (794days) when stored at ambient temperature. They passed the bioburden test with no aerobic bacteria, yeasts/molds, with minimal moisture content (1.28-5.9%). Bean gum extracts trapped HSV-1/HSV-2 75-94% in a dose-dependent manner through virus self-aggregation. Mastication simulator released >50% release of FRIL within 15min of chewing the bean gum. In plaque reduction assays, >95% neutralization of H1N1 and H3N2 required ∼40mg/mL, HSV-1 160mg/mL, and HSV-2 74mg/mL of bean gum for 1,000 copies/mL virus particles. Therefore, a 2000mg bean gum tablet has more than adequate potency for clinical evaluation and is safe with no detectable levels of glycosides. These observations augur well for evaluating bean gum in human clinical studies to minimize virus infection/transmission.

CaMKII-dependent non-canonical RIG-I pathway promotes influenza virus propagation in the acute-phase of infection.

Ca2+/calmodulin-dependent protein kinase II (CaMKII) is one of hundreds of host-cell factors involved in the propagation of type A influenza virus (IAV), although its mechanism of action is unknown. Here, we identified CaMKII inhibitory peptide M3 by targeting its kinase domain using affinity-based screening of a tailored random peptide library. M3 inhibited IAV cytopathicity and propagation in cells by specifically inhibiting the acute-phase activation of retinoic acid-inducible gene I (RIG-I), which is uniquely regulated by CaMKII. Downstream of the RIG-I pathway activated TBK1 and then IRF3, which induced small but sufficient amounts of transcripts of the genes for IFN α/β to provide the capped 5'-ends that were used preferentially as primers to synthesize viral mRNAs by the cap-snatching mechanism. Importantly, knockout of RIG-I in cells almost completely inhibited the expression of IFN mRNAs and subsequent viral NP mRNA early in infection (up to 6 h after infection), which then protected cells from cytopathicity 24 h after infection. Thus, CaMKII-dependent acute-phase activation of RIG-I promoted IAV propagation, whereas the canonical RIG-I pathway stimulated antiviral activity by inducing large amounts of mRNA for IFNs and then for antiviral proteins later in infection. Co-administration of M3 with IAV infection rescued mice from the lethality and greatly reduced proinflammatory cytokine mRNA expression in the lung, indicating that M3 is highly effective against IAV in vivo. Thus, regulation of the CaMKII-dependent non-canonical RIG-I pathway may provide a novel host-factor-directed antiviral therapy.IMPORTANCEThe recent emergence of IAV strains resistant to commonly used therapeutic agents that target viral proteins has exacerbated the need for innovative strategies. Here, we originally identified CaMKII-inhibitory peptide M3, which efficiently inhibits IAV-lethality in vitro and in vivo. M3 specifically inhibited the acute-phase activation of RIG-I, which is a novel pathway to promote IAV propagation. Thus, this pathway acts in an opposite manner compared with the canonical RIG-I pathway, which plays essential roles in antiviral innate immune response later in infection. The CaMKII-dependent non-canonical RIG-I pathway can be a promising and novel drug target for the treatment of infections.

Molecular diagnostics using the QIAstat-Dx syndromic device for covering avian influenza pandemic preparedness

IntroductionA key factor in influenza pandemic preparedness is the ability to detect zoonotic influenza virus strains as they emerge in humans through spillover events, ideally before human-to-human transmission occurs. DesignIn this study, the utility of the QIAstat-Dx syndromic device for influenza surveillance was evaluated. Bioinformatic analysis was performed on all WHO-recommended influenza Candidate Vaccine Viruses (CVVs), including the common strains recommended for the 2023–2024 influenza vaccine composition in the northern hemisphere, and 16 different H5 highly pathogenic avian influenza virus (HPAIV) and two H9N2 low pathogenic avian influenza virus (LPAIV) strains. For laboratory validation, engineered gene fragments and real HPAIV and LPAIV samples were tested using the QIAstat-Dx Respiratory SARS-CoV-2 Panel. ResultsDuring the bioinformatic screening, common influenza strains were positive including influenza A subtypes, and all H5 HPAIV and LPAIV H9N2 were detected as Influenza A positive without subtype discrimination. In all cases, laboratory validation confirmed all bioinformatic results. ConclusionQIAstat-Dx can detect all tested potentially zoonotic influenza A virus strains, and discriminate them from human sesonal influenza A viruses, ensuring a correct diagnosis. Any tool available for surveillance and pandemic preparedness is essential for a rapid response to reduce healthcare costs and severity of future influenza pandemics.

Cross-neutralization of Influenza A by SARS-CoV-2 specific neutralizing antibodies and polyclonal plasma: Is pre-exposure to SARS-CoV-2 protective against Influenza A?

According to sparse information from various countries, the seasonal influenza virus circulation has drastically decreased during the COVID-19 pandemic. Here, we show the cross-reactivity of anti-SARS-CoV-2 antibodies against influenza viruses. Plasma samples were collected from 311 SARS-CoV-2 infected individuals. The samples were tested for antibody titers against SARS-CoV-2 by ELISA and seasonal influenza virus strains (influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria) using a Hemagglutination Inhibition Assay (HAI). In addition, SARS-CoV-2 antibody-positive but Influenza antibody-negative samples (n = 16) were investigated to determine the SARS-CoV-2 antibody-neutralizing potential against influenza viruses by microneutralization (MN) assay. The SARS-CoV-2 genomes were sequenced using Illumina next-generation sequencing, and an in-silico protein structural analysis was performed to identify epitope and antibody binding similarities between SARS-CoV-2 and influenza viruses. Among 16 samples that didn't contain antibodies against Influenza A strains (H1N1 and H3N2), five showed high (MN titer≥20), and six showed moderate (MN titer≥10) capability to neutralize Influenza A. Subsequent in-silico analysis revealed that most efficient binding (>8 kcal/mol) was found between the antibodies of SARS-CoV-2 delta variant (ΔG) with influenza A/H1N1 HA (Hemagglutinin), A/H3N2 HA, A/H1N1 NA (Neuraminidase), and A/H3N2 NA glycoproteins with −12.4, −9.3, −10.1, and −11.7 kcal/mol, respectively. This investigation revealed that neutralizing antibodies of the delta variant cross-reacted with the Influenza A virus, which might protect against influenza viruses and reduce and shift the seasonal influenza circulation during the COVID-19 pandemic. Our findings warrant further study to explain the probable mechanisms of this cross-reactivity.

Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021-2024).

Influenza viruses continue to be an important public health threat. Vaccination is the most effective measure to control the influenza virus circulation. However, these viruses are continuously evolving through antigenic drift/shift, and thus the vaccine efficiency is affected. The aim of this study was to characterize the viral strains circulating in Romania, in a population with declining vaccination coverage, during the last three cold seasons by evaluating the hemagglutinin antigenic relatedness to the vaccine strains. All the available sequences collected between August 2021 and June 2024 were analyzed by using phylogenetic analysis and the Pepitope model to predict vaccine efficacy. The results showed that the 2021/2022 influenza season was dominated by the circulation of highly diverse clades of A(H3N2) viruses with high mutational divergence as compared to the vaccine strain, which might contribute to the reduction in vaccine efficacy. During the 2022/2023 influenza season, both influenza A and B viruses were reported, with few antigenic site mutations. The 2023/2024 influenza season was dominated by the circulation of influenza A viruses: A/H1N1pdm09 clade 6B.1A.5a.2a and A/H3N2 clade 2a.3a.1. The clade 2a.3a.1 also showed high variability when compared to the vaccine strain, presumably leading to reduced vaccine efficacy. This study illustrates the high diversity of influenza viruses circulating in a population with low vaccination coverage during the previous cold seasons. The viral diversity impacted vaccine efficacy, hence the need for public health programs to increase vaccine uptake and improve vaccine formulation in order to limit viral transmission.

Age-related STING suppression in macrophages contributes to increased viral load during influenza a virus infection

Ageing is a major risk factor that contributes to increased mortality and morbidity rates during influenza A virus (IAV) infections. Macrophages are crucial players in the defense against viral infections and display impaired function during ageing. However, the impact of ageing on macrophage function in response to an IAV infection remains unclear and offers potential insight for underlying mechanisms. In this study, we investigated the immune response of young and aged human monocyte-derived macrophages to two different H1N1 IAV strains. Interestingly, macrophages of aged individuals showed a lower interferon response to IAV infection, resulting in increased viral load. Transcriptomic data revealed a reduced expression of stimulator of interferon genes (STING) in aged macrophages albeit the cGAS-STING pathway was upregulated. Our data clearly indicate the importance of STING signaling for interferon production by applying a THP-1 STING knockout model. Evaluation of mitochondrial function during IAV infection revealed the release of mitochondrial DNA to be the activator of cGAS-STING pathway. The subsequent induction of apoptosis was attenuated in aged macrophages due to decreased STING signaling. Our study provides new insights into molecular mechanisms underlying age-related immune impairment. To our best knowledge, we are the first to discover an age-dependent difference in gene expression of STING on a transcriptional level in human monocyte-derived macrophages possibly leading to a diminished interferon production.

Inno4Vac Workshop Report Part 1: Controlled Human Influenza Virus Infection Model (CHIVIM) Strain Selection and Immune Assays for CHIVIM Studies, November 2021, MHRA, UK.

Controlled human infection models (CHIMs) are a critical tool for the understanding of infectious disease progression, characterising immune responses to infection and rapid assessment of vaccines or drug treatments. There is increasing interest in using CHIMs for vaccine development and an obvious need for widely available and fit-for-purpose challenge agents. Inno4Vac is a large European consortium working towards accelerating and de-risking the development of new vaccines, including the development of CHIMs for influenza, respiratory syncytial virus and Clostridioides difficile. This report (in two parts) summarises a workshop held at the MHRA in 2021, focused on how to select CHIM candidate strains of influenza and respiratory syncytial virus (RSV) based on desirable virus characteristics and which immune assays would provide relevant information for assessing pre-existing and post-infection immune responses and defining correlates of protection. This manuscript (Part 1) summarises presentations and discussions centred around influenza CHIMs and immune assays (a second manuscript summarises RSV CHIM and immune assays: Inno4Vac workshop report Part 2: RSV CHIM strain selection and immune assays for RSV CHIM studies, November 2021, MHRA, UK).

Post-vaccination immunity and pneumonia incidence in medical workers in response to various flu vaccination regimens between the 1st and 2nd peaks of COVID-19 morbidity

Background.In the absence of a vaccine against SARS-CoV-2, seasonal influenza vaccination during the pandemic contributed to lowered COVID-19 susceptibility and severity. The study was aimed to assess the state of post-influenza vaccination immunity, pneumonia frequency and severity in medical workers after using various flu vaccination regimens, between the 1st and 2nd peaks of COVID-19 epidemic rise.Materials and methods.Comparatively analyzed data on the levels of antibodies against influenza virus strains and pneumonia incidence in 487 medical workers was carried out: 1st group — unvaccinated in 2020–2021 (n = 281), 2nd group — vaccinated against influenza (Sovigripp), (n = 98), 3rd group — received combined vaccination against influenza and pneumococcus (Prevenar 13), (n = 108).Results.6 months after vaccination, the highest rates of influenza virus were detected in the A(H3N2), the level of seroprotection (≥ 1:40) ranged from 49.0% in unvaccinated (1st group) to 53.4–53.2% in those who received combined vaccination (group III), as well as influenza alone (2nd group), p 0.05; for strain A(H1N1) the level of seroprotection in 1st group is 24.5%, lower (p 0.04) than in 2nd group — 32.7%, but does not differ from the levels of 40.4% in group III; for strain B the level of seroprotection is the lowest ranging from 19.4% in the group of unvaccinated subjects up to 22.4% in 2nd group and 23.4% in 3rd group. The pneumonia incidence in 1st group (3.9%), 2nd group (3.1%), 3rd group (4.6%) did not differ, however, among all vaccinated subjects severity of pneumonia clinical course was mild, whereas in unvaccinated employees, except for mild course (45.4%, 5 out of 11 people) pneumonia in 36.4% (4 out of 11 people) cases was assessed as moderate and in 18.2% (2 out of 11 people) cases — severe with fatal outcomes.Conclusion.The study showed that 6 months after seasonal influenza immunization between the 1st and 2nd peaks of COVID-19 epidemic rise, the immunogenicity of the vaccine meets the CPMP criterion for the A(H3N2) strain. In vaccinated patients, the proportion of pneumonia with COVID-19 clinical picture was mild in 100% of cases, and in unvaccinated patients in 36.4% of cases — of moderate severity and in 18.2% — severe with fatal outcome.

Multi-Electrode Extended Gate Field Effect Transistors Based on Laser-Induced Graphene for the Detection of Vitamin C and SARS-CoV-2.

Despite the clinical data showing the importance of ascorbic acid (AA or vitamin C) in managing viral respiratory infections, biosensors for their simultaneous detection are lacking. To address this need, we developed a portable and wireless device for simultaneous detection of AA and SARS-CoV-2 virus by integrating commercial transistors with printed laser-induced graphene (LIG) as the extended gate. We studied the effect of laser printing pass number and showed that with two laser printing passes (2-pass LIG), the sensor sensitivity and limit of detection (LOD) for AA improved by a factor of 1.6 and 12.8, respectively. Using complementary characterization methods, we attribute the improved response to a balanced interplay of crystallinity, defect density, surface area, surface roughness, pore density and diameter, and mechanical integrity/stability. These factors enhance analyte transport, reduce noise/variability, and ensure consistent sensor performance, making 2-pass LIG the most effective material in this work. Our sensors exhibit promising performance for detecting AA with a selective response in the presence of common salivary interfering molecules, with sensitivity and LOD of 73.67 mV/dec and 54.04 nM in 1× phosphate buffered saline and 81.05 mV/dec and 78.34 nM in artificial saliva, respectively. We also showed that functionalization of the 2-pass LIG gate with S-protein antibody enables the detection of SARS-CoV-2 protein antigens with an ultralow LOD of 52 zg/mL─an improvement of more than 10-fold compared to 1-pass LIG─and 4 particles/mL for virion mimics with a selective response against influenza virus and multiple human coronavirus strains. With low signal drift/hysteresis and wireless capabilities, the developed device holds great potential for improving at-home monitoring and clinical decision-making.

Multiplexed Antibody Sequencing and Profiling of the Human Hemagglutinin-specific Memory B Cell Response following Influenza Vaccination.

Influenza virus is a highly contagious respiratory pathogen causing between 9.4 and 41 million infections per year in the United States in the last decade. Annual vaccination is recommended by the World Health Organization, with the goal to reduce influenza severity and transmission. Ag-specific single B cell sequencing methodologies have opened up new avenues into the dissection of the Ab response to influenza virus. The improvement of these methodologies is pivotal to reduce the associated costs and optimize the operational workflow and throughput, especially in the context of multiple samples. In this study, PBMCs and serum samples were collected longitudinally from eight influenza vaccinees either vaccinated yearly for four consecutive influenza seasons or once for one season. Following the serological and B cell profiling of their polyclonal Ab response to a panel of historical, recent, and next-generation influenza vaccine hemagglutinin (HA) and virus strains, a single multiplexed Ag-specific single B cell sequencing run allowed to capture HA-specific memory B cells that were analyzed for preferential Ig H chain/L chain pairing, isotype/subclass usage, and the presence of public BCR clonotypes across participants. Binding and functional profiles of representative private and public clonotypes confirmed their HA specificity, and their overall binding and functional activity were consistent with those observed at the polyclonal level. Collectively, this high-resolution and multiplexed Ab repertoire analysis demonstrated the validity of this optimized methodology in capturing Ag-specific BCR clonotypes, even in the context of a rare B cell population, such as in the case of the peripheral Ag-specific memory B cells.

Oral co-administration of Lactiplantibacillus plantarum 16 and Lacticaseibacillus rhamnosus P118 improves host defense against influenza A virus infection.

Influenza is an important zoonotic disease that persistently threatens global public health. While it is widely acknowledged that probiotics can modulate the host response to protect the host against infectious disease, the prophylactic efficacy on respiratory viral infection and the detailed mechanism remains elusive. Lactobacillus, the most commonly used probiotic widely applied in food production, has garnered significant attention. In our study utilizing both C57BL/6 and BALB/c mouse models, we explored the protective effect against two strains of influenza virus, A/Mink/China/01/2014(H9N2) and A/California/04/2009(H1N1), through the administration of Lactiplantibacillus plantarum strain 16 (L. plantarum 16) and Lacticaseibacillus rhamnosus strain P118 (L. rhamnosus P118), aiming to identify robust probiotic strains with antiviral properties. Our findings indicate that administering L. plantarum 16 or L. rhamnosus P118 alone does not provide sufficient protection against influenza. However, the co-administration of L. plantarum 16 and L. rhamnosus P118 dramatically reduces viral titers in the respiratory tract and lung, thereby markedly alleviating the clinical symptoms, improving prognosis, and reducing mortality. The mechanisms underlying this effect involve the modulation of host gut microbiota and metabolism through the co-administration of L. plantarum 16 and L. rhamnosus P118, resulting in enrichment of Firmicutes and enhancement of phenylalanine-related metabolism, ultimately leading to an augmentation of the antiviral immune response. Notably, we identified that the circulating metabolic molecule 2-Hydroxycinnamic acid plays a significant role in combating influenza. Our data suggest the potential utility of L. plantarum 16 and L. rhamnosus P118 two-bacterium or 2-Hydroxycinnamic acid in preventing influenza.IMPORTANCEVaccination represents the most optimal strategy to control influenza. Nevertheless, influenza viruses constantly evolve due to antigenic drift and shift, leading to the need for regular updates on influenza vaccines. Additionally, vaccination failure poses significant challenges to influenza prevention. Therefore, it is essential and beneficial to identify novel or universal antiviral measures to protect against influenza. While cumulative data suggest that probiotics offer protection against infectious diseases, the specific mechanisms, such as the effective metabolites or components, remain largely unknown. Our research discovered the capacity of combinational two-bacterium Lactiplantibacillus plantarum 16 and Lacticaseibacillus rhamnosus P118 to fight against influenza infection in a mouse model. The protection may occur through modulating the host's gut microbiota and metabolism, further influencing the host's antiviral immune response. Notably, we have identified a novel metabolic molecule, 2-Hydroxycinnamic acid, capable of enhancing antiviral response and restricting viral replication in vivo.

Contribution of immunoglobulin products in influencing seasonal influenza infection and severity in antibody immune deficiency patients receiving immunoglobulin replacement therapy.

Seasonal and pandemic influenza infection present a potential threat to patients with antibody deficiency. The acceptance and effect of the current recommendation for annual vaccination against influenza for patients with antibody deficiency is not well investigated and due to antigenic drift or shift the protective capacity of regular IgG replacement therapy (IgRT) is considered low. This narrative review considers the effect of influenza vaccination in immunodeficient patients and discusses available information on the effect of immunoglobulin products on seasonal influenza infectivity and severity in antibody deficiency patients receiving IgRT. The humoral immune response to seasonal influenza vaccination is reduced in patients with antibody immune deficiency. However, there is no evidence that the proportion of patients with primary antibody deficiency who develop influenza illness, and the severity of such illness, is increased when compared with the general population. The IgRT that patients receive has been shown to contain neutralizing antibodies as a consequence of past flu infections against both the hemagglutinin and neuraminidase surface proteins and other viral internal proteins of different influenza A virus strains. Studies have demonstrated not only significant levels of specific but also cross-reactive antibodies against seasonal influenza virus strains. Thus, despite the yearly changes in influenza viral antigenicity that occur, IgRT could potentially contribute to the protection of patients against seasonal influenza. Currently, only limited clinical data are available confirming a preventative effect of IgRT with respect to seasonal influenza infection. In conclusion, there is some evidence that IgRT could contribute to protection against seasonal influenza in patients with antibody-related immunodeficiency. However, additional clinical data are needed to confirm the extent and relevance of this protection and identify the main responsible virus targets of that protection.

Microbiota-derived acetate is associated with functionally optimal virus-specific CD8+ T cell responses to influenza virus infection via GPR43-dependent metabolic reprogramming

ABSTRACT The microbiota-associated factors that affect host susceptibility and adaptive immunity to influenza A virus (IAV) infection have not been fully elucidated. By comparing the microbiota composition between survivors and mice that succumbed to IAV strain PR8 infection, we identified that the commensal bacterium Blautia coccoides protects antibiotics (Abx)-treated or germ-free (GF) mice from PR8 infection by inducing functionally optimal virus-specific CD8+ T cell responses. Administration of exogenous acetate reproduced the protective effect of B. coccoides monocolonization in Abx and GF mice, enhancing oxidative phosphorylation and glycolysis as well as secretion of IFN-γ and granzyme B in virus-specific CD8+ T cells, dependent on GPR43 signaling and acetyl-CoA synthetase 2. Thus, we have demonstrated that microbiota-derived acetate possesses an antiviral effect that induces an optimal virus-specific CD8+ T cell response to IAV PR8 infection via GPR43-dependent metabolic reprogramming.

Ruhao Dashi granules exert therapeutic effects on H1N1 influenza virus infection by altering intestinal microflora composition.

Antiviral medications for influenza could be ineffective due to the emergence of resistant influenza virus strains. Ruhao Dashi (RHDS) granules possess anti-inflammatory and antibacterial effects. The present study aimed to determine the efficacy of RHDS granules in treating influenza-infected mice and the mechanism underlying this treatment as well as its effect on the intestinal flora composition of the infected mice. The HPLC-UV method was used to identify the active components of RHDS granules. ICR mice were infected with influenza A virus (IAV) H1N1 subtype through a nasal drip. After the influenza mice model was successfully established, the pathological changes in the lungs were observed for 5 days after gavage treatment with 0.9% sterile saline and low, medium, and high doses (0.07, 0.14, and 0.28 g/mL, respectively) of RHDS granules. The serum levels of the cytokines IL-6 and TNF-α and sIgA were detected by ELISA. Real-time fluorescence quantitative PCR and western blotting assay were performed to determine the expression levels of the tight junction (TJ) proteins claudin-1, occludin, and zonula occludens-1 (ZO-1) in colon tissues. Furthermore, 16S rRNA gene sequencing of feces samples was conducted to assess the effect of RHDS granules on the gut microbiota. RHDS granules exerted a protective effect on the lung tissues of IAV-infected mice; moreover, the granules reduced the synthesis of proinflammatory cytokines and increased the relative expression levels of claudin-1, occludin, and ZO-1 in colon tissues. Furthermore, RHDS granule treatment increased the relative abundance of Lactobacillus, Akkermansia, and Faecalibaculum and decreased the relative abundance of Muribaculaceae; thus, RHDS granules could stabilize the intestinal microbiota to some extent. RHDS granules exert a therapeutic effect on IAV-infected mice probably by modifying the structural composition of their intestinal microbiota.

Reverse zoonotic transmission of human seasonal influenza to a pig herd in Sweden.

In January 2023, a Swedish piglet-producing farm with 2800 sows in production (SIP) was diagnosed with IAV (Influenza A virus) and the isolates were shown to cluster with the human seasonal influenza (2022/2023). In December 2022, employees with flu like symptoms tended to the pigs and a few weeks later, respiratory signs appeared in different age groups; sows in farrowing units were anorectic and pyrectic. Lung and nasal swabs were tested positive for IAV and other respiratory infectious agents. Blanket vaccination against H1N1pdm09 of sows and gilts was initiated but discontinued for sows after 2 treatments. Biosecurity measures aiming to reduce the spread of virus were implemented. However, the compliance to follow the protocol was moderate.Combining immunity and strict sanitary measures is crucial to control virus circulation. As the farmer discontinued sow vaccination and just partly increased biosecurity, this may have contributed to ongoing virus circulation and clinical signs in pigs, even 5 months post-diagnosis. Although H1N1pdm09 already had been found in the herd in 2017, there were no clinical signs or diagnostic results indicating continuous circulation of this or other IAV strains afterwards. However, this cannot be entirely excluded. Swine IAVs pose a risk of reintroduction into the human population, highlighting the importance of vaccination of farm workers against seasonal influenza.