H1N1 Infection Research Articles

Differential lung gene expression changes in C57BL/6 and DBA/2 mice carrying an identical functional Mx1 gene reveals crucial differences in the host response

BackgroundInfluenza virus infections represent a major global health problem. The dynamin-like GTPase MX1 is an interferon-dependent antiviral host protein that confers resistance to influenza virus infections. Infection models in mice are an important experimental system to understand the host response and susceptibility to developing severe disease following influenza infections. However, almost all laboratory mouse strains carry a non-functional Mx1 gene whereas humans have a functional MX1 gene. Most studies in mice have been performed with strains carrying a non-functional Mx1 gene. It is therefore very important to investigate the host response in mouse strains with a functional Mx1 gene.ResultsHere, we analyzed the host response to influenza virus infections in two congenic mouse strains carrying the functional Mx1 gene from the A2G strain. B6.A2G-Mx1r/r(B6-Mx1r/r) mice are highly resistant to influenza A virus (IAV) H1N1 infections. On the other hand, D2(B6).A2G-Mx1r/r(D2-Mx1r/r) mice, although carrying a functional Mx1 gene, were highly susceptible, exhibited rapid weight loss, and died. We performed gene expression analysis using RNAseq from infected lungs at days 3 and 5 post-infection (p.i.) of both mouse strains to identify genes and pathways that were differentially expressed between the two mouse strains. The susceptible D2-Mx1r/r mice showed a high viral replication already at day 3 p.i. and exhibited a much higher number of differentially expressed genes (DEGs) and many DEGs had elevated expression levels compared to B6-Mx1r/r mice. On the other hand, some DEGs were specifically up-regulated only in B6-Mx1r/r mice at day 3 p.i., many of which were related to host immune response functions.ConclusionsFrom these results, we conclude that at early times of infection, D2-Mx1r/r mice showed a very high and rapid replication of the virus, which resulted in lung damage and a hyperinflammatory response leading to death. We hypothesize that the activation of certain immune response genes was missing and that others, especially Mx1, were expressed at a time in D2-Mx1r/r mice when the virus had already massively spread in the lung and were thus not able anymore to protect them from severe disease. Our study represents an important addition to previously published studies in mouse models and contributes to a better understanding of the molecular pathways and genes that protect against severe influenza disease.

Rapid adaptive substitution of L226Q in HA protein increases the pathogenicity of H9N2 viruses in mice

BackgroundSince the first human infection with H9N2 virus was reported in 1998, the number of cases of H9N2 infection has exceeded one hundred by 2021. However, there is no systematic description of the biological characteristics of H9N2 viruses isolated from humans. MethodsTherefore, this study analyzed the pathogenicity in mice of all available H9N2 viruses isolated from human cases in China from 2013 to 2021. ResultsAlthough most of the H9N2 viruses analyzed showed low or no pathogenicity in mice, the leucine to glutamine substitution at residue 226 (L226Q) in the hemagglutinin (HA) protein rapidly emerged during the adaptation of H9N2 viruses, and was responsible for severe infections and even fatalities. HA amino acid 226Q conferred a remarkable competitive advantage on H9N2 viruses in mice relative to viruses containing 226L, increasing their virulence, infectivity, and replication. ConclusionThus, our study demonstrates that the adaptive substitution HA L226Q rapidly acquired by H9N2 viruses during the course of infection in mice contributed to their high pathogenicity.

The evolution, pathogenicity and transmissibility of quadruple reassortant H1N2 swine influenza virus in China: A potential threat to public health

Swine are regarded as “intermediate hosts” or “mixing vessels” of influenza viruses, capable of generating strains with pandemic potential. From 2020 to 2021, we conducted surveillance on swine H1N2 influenza (swH1N2) viruses in swine farms located in Guangdong, Yunnan, and Guizhou provinces in southern China, as well as Henan and Shandong provinces in northern China. We systematically analyzed the evolution and pathogenicity of swH1N2 isolates, and characterized their replication and transmission abilities. The isolated viruses are quadruple reassortant H1N2 viruses containing genes from pdm/09 H1N1 (PB2, PB1, PA and NP genes), triple-reassortant swine (NS gene), Eurasian Avian-like (HA and M genes), and recent human H3N2 (NA gene) lineages. The NA, PB2, and NP of SW/188/20 and SW/198/20 show high gene similarities to A/Guangdong/Yue Fang277/2017 (H3N2). The HA gene of swH1N2 exhibits a high evolutionary rate. The five swH1N2 isolates replicate efficiently in human, canine, and swine cells, as well as in the turbinate, trachea, and lungs of mice. A/swine/Shandong/198/2020 strain efficiently replicates in the respiratory tract of pigs and effectively transmitted among them. Collectively, these current swH1N2 viruses possess zoonotic potential, highlighting the need for strengthened surveillance of swH1N2 viruses.

Prior Influenza Infection Mitigates SARS-CoV-2 Disease in Syrian Hamsters.

Seasonal infection rates of individual viruses are influenced by synergistic or inhibitory interactions between coincident viruses. Endemic patterns of SARS-CoV-2 and influenza infection overlap seasonally in the Northern hemisphere and may be similarly influenced. We explored the immunopathologic basis of SARS-CoV-2 and influenza A (H1N1pdm09) interactions in Syrian hamsters. H1N1 given 48 h prior to SARS-CoV-2 profoundly mitigated weight loss and lung pathology compared to SARS-CoV-2 infection alone. This was accompanied by the normalization of granulocyte dynamics and accelerated antigen-presenting populations in bronchoalveolar lavage and blood. Using nasal transcriptomics, we identified a rapid upregulation of innate and antiviral pathways induced by H1N1 by the time of SARS-CoV-2 inoculation in 48 h dual-infected animals. The animals that were infected with both viruses also showed a notable and temporary downregulation of mitochondrial and viral replication pathways. Quantitative RT-PCR confirmed a decrease in the SARS-CoV-2 viral load and lower cytokine levels in the lungs of animals infected with both viruses throughout the course of the disease. Our data confirm that H1N1 infection induces rapid and transient gene expression that is associated with the mitigation of SARS-CoV-2 pulmonary disease. These protective responses are likely to begin in the upper respiratory tract shortly after infection. On a population level, interaction between these two viruses may influence their relative seasonal infection rates.

Fufang Luohanguo Qingfei granules reduces influenza virus susceptibility via MAVS-dependent type I interferon antiviral signaling

Ethnopharmacological relevanceFufang Luohanguo Qingfei granules (LQG) is a Chinese patent medicine, clinically used to treat flu-like symptoms including cough with yellow phlegm, impeded phlegm, dry throat and tongue. However, the protective activity of LQG against influenza infection is indeterminate. Aim of the studyThis study is to investigate the therapeutic effect of LQG on influenza infection and elucidate its underlying mechanism. Materials and methodsIn vivo: A viral susceptible mouse model induced by restraint stress was established to investigate LQG's beneficial effects on influenza susceptibility. MAVS knockout (Mavs−/−) mice were used to verify the potential mechanism of LQG. In vitro: Corticosteroid (CORT)-treated A549 cells were employed to identify the active ingredients in LQG. Mice morbidity and mortality were monitored daily for 21 days. Histopathologic changes and inflammatory cytokines in lung tissues were examined by H&E staining and ELISA. RNA-seq was used to explore the signaling pathway influenced by LQG and further confirmed by qPCR. Immunoblotting and immunohistochemistry (IHC) were used to determine the protein levels. CO-IP and DARTS were applied to detect protein-protein interaction and compound-protein interaction, respectively. ResultsLQG effectively attenuated the susceptibility of restrained mice to H1N1 infection. LQG significantly boosted the production of IFN-β transduced by mitochondrial antiviral-signaling protein (MAVS), while MAVS deficiency abrogated its protective effects on restrained mice infected with H1N1. Moreover, in vitro studies further revealed that mogroside Ⅱ B, amygdalin, and luteolin are potentially active components of LQG. ConclusionThese results suggested that LQG inhibited the mitofusin 2 (Mfn2)-mediated ubiquitination of MAVS by impeding the E3 ligase synoviolin 1 (SYVN1) recruitment, thereby enhancing IFN-β antiviral response. Overall, our work elaborates a potential regimen for influenza treatment through reduction of stress-induced susceptibility.

Characterization of the Increase in Narcolepsy following the 2009 H1N1 Pandemic in Sweden

(1) Background: In the context of the H1N1 pandemic and the Pandemrix vaccination campaign, an increased number of narcolepsy cases were noted in several countries. In Sweden, this phenomenon was attributed to the effect of the Pandemrix vaccination in the first place. Studies from China indicated that narcolepsy could occur as a consequence of the H1N1 infection itself. We performed an analysis of the increase, with a specific interest in age and sex distribution. We also aimed to validate the origin of the excess cases, post hoc. (2) Methods: Data for narcolepsy patients (ICD code G 47.4, both type 1 and type 2) distributed by sex and age at 5-year intervals, annually between 2005 and 2017, were retrieved from the National Patient Register. Information on the total population was collected from the Swedish Population Register. (3) Results: The number of narcolepsy cases increased markedly from 2009 to 2014 compared to the period before 2009. A particular increase in 2011 among children and teenagers was observed. The sex ratio did not change significantly during the study period. (4) Conclusions: Our results support an association between the increased prevalence of narcolepsy cases and Pandemrix vaccination, but the effect of the virus itself cannot be ruled out as a contributing factor.

Response of Human Retinal Microvascular Endothelial Cells to Influenza A (H1N1) Infection and the Underlying Molecular Mechanism.

Whether H1N1 infection-associated ocular manifestations result from direct viral infections or systemic complications remains unclear. This study aimed to comprehensively elucidate the underlying causes and mechanism. TCID50 assays was performed at 24, 48, and 72hours to verify the infection of H1N1 in human retinal microvascular endothelial cells (HRMECs). The changes in gene expression profiles of HRMECs at 24, 48, and 72hours were characterized using RNA sequencing technology. Differentially expressed genes (DEGs) were validated using real-time quantitative polymerase chain reaction and Western blotting. CCK-8 assay and scratch assay were performed to evaluate whether there was a potential improvement of proliferation and migration in H1N1-infected cells after oseltamivir intervention. H1N1 can infect and replicate within HRMECs, leading to cell rounding and detachment. After H1N1 infection of HRMECs, 2562 DEGs were identified, including 1748 upregulated ones and 814 downregulated ones. These DEGs primarily involved in processes such as inflammation and immune response, cytokine-cytokine receptor interaction, signal transduction regulation, and cell adhesion. The elevated expression levels of CXCL10, CXCL11, CCL5, TLR3, C3, IFNB1, IFNG, STAT1, HLA, and TNFSF10 after H1N1 infection were reduced by oseltamivir intervention, reaching levels comparable to those in the uninfected group. The impaired cell proliferation and migration after H1N1 infection was improved by oseltamivir intervention. This study confirmed that H1N1 can infect HRMECs, leading to the upregulation of chemokines, which may cause inflammation and destruction of the blood-retina barrier. Moreover, early oseltamivir administration may reduce retinal inflammation and hemorrhage in patients infected with H1N1.

Self-service multimodal detection of subtype influenza A virus H5N1 by visual portable molecular imprinting sensor

At present, the ability to identify subtypes of influenza A virus (IAV) with high similarity in morphology, size, and surface structure is sufferedfrom significant challenges. In this study, we report on the development of a portable, multi-color, colorimetric molecular imprinting polymer (MIP)-based sensor that can specifically identify H5N1. To construct this sensor, using H5N1 as a template, the MIPs was obtained on the Fe3O4@ quantum dots (QDs) prepared in advance. Then, the Fe3+@PDA∼ Apt probe, which was designed for specificity for H5N1, was prepared by modifying the H5N1 ∼ Apt on the surface of the pre-prepared Fe3+-embedded dopamine nanoparticles. A sandwich structure would be formed via the specific combination of MIPs, H5N1 and Fe3+@PDA ∼ Apt. During detection, the fluorescence of QDs quenched, achieving the first detection mode of viruses through the change of fluorescence intensity. Subsequently, Fe3+ in the solution was released, K4[Fe(CN)6] and K3[Fe(CN)6] were added to achieve a multi-color colorimetric detection sensor visible to the naked eyes. The third detection mode can be achieved by detecting the absorbance of the solution by ultraviolet–visible. The sensor was capable of differentiating the target H5N1 virus from other IAV subtypes with high specificity and sensitivity (LOD = 11.6 fM), and the detection of the virus could be enabled by fluorescence spectroscopy, UV–vis spectrophotometry, and colorimetric indication three modes, to provide a reliable point-of-care detection method for ensuring the accurate treatment of patients with H5N1 infection. Importantly, the MIP-based sensor could conveniently achieve the self-service detection at a cost of only RMB in 0.28 yuan.

Uncovering the diagnostic value of white blood cell profiles in H1N1 screening

This research sought to evaluate the effectiveness of White Blood Cell (WBC) profiles as a screening method for promptly identifying H1N1 infection in individuals exhibiting symptoms of Influenza-like Illness (ILI) and undergoing throat swab testing for H1N1 through the RT-PCR technique. Seventy patients from a tertiary care hospital were included based on specific inclusion and exclusion criteria. Throat swab tests were conducted using RT-PCR, resulting in 35 positive and 35 negative cases for influenza A H1N1. Complete Blood Count (CBC) profiles, including total WBC counts, differential count, neutrophil to lymphocyte ratios, lymphocyte to monocyte ratios, and absolute monocyte count (AMC), were obtained for all subjects. Analysis of the obtained data revealed that increased symptoms, higher monocyte counts, and an Absolute Monocyte Count (AMC) exceeding 800 cells/mm³ were indicative of a higher likelihood of H1N1 positivity. The study suggests that utilizing WBC profiles, particularly the neutrophil to lymphocyte ratios, lymphocyte to monocyte ratios, and AMC, can serve as a valuable screening measure for the early detection of H1N1 infection. This approach may be especially beneficial in peripheral healthcare settings where the standard RT-PCR diagnostic method is time-consuming, enabling timely and appropriate intervention based on CBC results.

The lncRNA HCG4 regulates the RIG-I-mediated IFN production to suppress H1N1 swine influenza virus replication.

Influenza A virus (IAV) non-structural protein 1 (NS1) is a virulence factor that allows the virus to replicate efficiently by suppressing host innate immune responses. Previously, we demonstrated that the serine (S) at position 42 of NS1 in H1N1 swine influenza virus (SIV) is a critical residue in interferon (IFN) resistance, thus facilitating viral infections. Here, by lncRNA-seq, a total of 153 differentially expressed lncRNAs were identified, and the lncRNA HCG4 was selected due to its significantly higher expression after infection with the NS1 S42P mutant virus. Overexpression of HCG4 enhanced IFN-β production and suppressed SIV infection, highlighting the potential antiviral activity of HCG4 against SIV. Further investigation suggested that HCG4 served as a positive feedback mediator for RIG-I signaling. It alleviated the inhibitory effect on RIG-I K63-linked ubiquitination by NS1 protein, thereby resulting in an increase in RIG-I-mediated IFN production. Taken together, our findings demonstrate that HCG4 modulates the innate immune response to SIV infection through K63-linked RIG-I ubiquitination, providing insights into the role of lncRNAs in controlling viral infections.

HA N193D substitution in the HPAI H5N1 virus alters receptor binding affinity and enhances virulence in mammalian hosts

ABSTRACT During the 2021/2022 winter season, we isolated highly pathogenic avian influenza (HPAI) H5N1 viruses harbouring an amino acid substitution from Asparagine(N) to Aspartic acid (D) at residue 193 of the hemagglutinin (HA) receptor binding domain (RBD) from migratory birds in South Korea. Herein, we investigated the characteristics of the N193D HA-RBD substitution in the A/CommonTeal/Korea/W811/2021[CT/W811] virus by using recombinant viruses engineered via reverse genetics (RG). A receptor affinity assay revealed that the N193D HA-RBD substitution in CT/W811 increases α2,6 sialic acid receptor binding affinity. The rCT/W811-HA193N virus caused rapid lethality with high virus titres in chickens compared with the rCT/W811-HA193D virus, while the rCT/W811-HA193D virus exhibited enhanced virulence in mammalian hosts with multiple tissue tropism. Surprisingly, a ferret-to-ferret transmission assay revealed that rCT/W811-HA193D virus replicates well in the respiratory tract, at a rate about 10 times higher than that of rCT/W811-HA193N, and all rCT/W811-HA193D direct contact ferrets were seroconverted at 10 days post-contact. Further, competition transmission assay of the two viruses revealed that rCT/W811-HA193D has enhanced growth kinetics compared with the rCT/W811-HA193N, eventually becoming the dominant strain in nasal turbinates. Further, rCT/W811-HA193D exhibits high infectivity in primary human bronchial epithelial (HBE) cells, suggesting the potential for human infection. Taken together, the HA-193D containing HPAI H5N1 virus from migratory birds showed enhanced virulence in mammalian hosts, but not in avian hosts, with multi-organ replication and ferret-to-ferret transmission. Thus, this suggests that HA-193D change increases the probability of HPAI H5N1 infection and transmission in humans.

Integrated analysis of miRNA-mRNA expression of newly emerging swine H3N2 influenza virus cross-species infection with tree shrews

BackgroundCross-species transmission of zoonotic IAVs to humans is potentially widespread and lethal, posing a great threat to human health, and their cross-species transmission mechanism has attracted much attention. miRNAs have been shown to be involved in the regulation of IAVs infection and immunity, however, few studies have focused on the molecular mechanisms underlying miRNAs and mRNAs expression after IAVs cross-species infection.MethodsWe used tree shrews, a close relative of primates, as a model and used RNA-Seq and bioinformatics tools to analyze the expression profiles of DEMs and DEGs in the nasal turbinate tissue at different time points after the newly emerged swine influenza A virus SW2783 cross-species infection with tree shrews, and miRNA-mRNA interaction maps were constructed and verified by RT-qPCR, miRNA transfection and luciferase reporter assay.Results14 DEMs were screened based on functional analysis and interaction map, miR-760-3p, miR-449b-2, miR-30e-3p, and miR-429 were involved in the signal transduction process of replication and proliferation after infection, miR-324-3p, miR-1301-1, miR-103-1, miR-134-5p, miR-29a, miR-31, miR-16b, miR-34a, and miR-125b participate in negative feedback regulation of genes related to the immune function of the body to activate the antiviral immune response, and miR-106b-3p may be related to the cross-species infection potential of SW2783, and the expression level of these miRNAs varies in different days after infection.ConclusionsThe miRNA regulatory networks were constructed and 14 DEMs were identified, some of them can affect the replication and proliferation of viruses by regulating signal transduction, while others can play an antiviral role by regulating the immune response. It indicates that abnormal expression of miRNAs plays a crucial role in the regulation of cross-species IAVs infection, which lays a solid foundation for further exploration of the molecular regulatory mechanism of miRNAs in IAVs cross-species infection and anti-influenza virus targets.

Myositis in H1N1 Infection Compounds to Myasthenic Crisis.

Infection is an important trigger of myasthenic crisis (MC), and those infections manifest with pneumonia and muscle involvement may result in more frequent MC. We report two myasthenia gravis (MG) patients with H1N1 infection, and highlight the reasons for deterioration. Two patients with MG had H1N1 infection. The diagnosis of MG was confirmed by neostigmine, repetitive nerve stimulation, and anti-acetylcholine receptor antibody tests. H1N1 was confirmed by nucleic acid detection study, and myositis by creatinine kinase. The patient with pneumonia and myositis had MC needing mechanical ventilation for 10 days, and the other patient without myositis did not have MC. They were treated with oseltamivir 75 mg twice daily for 5 days, and the patients with MC received ceftriaxone intravenously. Both the patients were on prednisolone and azathioprine, and none received prior H1N1 vaccination. The lady with MC with myositis was discharged on day 27 in wheelchair bound state, and the other one patient without myositis or MC was discharged on 6th day with full recovery. These patients highlight the need for evaluation for myositis along with pneumonia in the MG patients with H1N1 infection. Vaccination in MG patients on immunosuppression may be useful.

Kako se pripremiti za pandemiju ptičjeg gripa H5N1 - pouke iz pandemije influence H1N1 iz 1918

In this paper, we highlight the significant challenges encountered during the influenza H1N1 pandemic of 1918. These lessons are being utilized to prepare for potential avian influenza H5N1 pandemic outbreaks, as this virus will impact both humans and food-serving animals. Preparation for this threat is crucial because H5N1 infections are already affecting the United States and many other countries.

Identification of dihydroorotate dehydrogenase inhibitor, vidofludimus, as a potent and novel inhibitor for influenza virus.

Influenza A virus (IAV) infection causes respiratory disease. Recently, infection of IAV H5N1 among mammals are reported in farmed mink. Therefore, to discover antivirals against IAV, we screened a compound library by using the RNA-dependent RNA polymerase (RdRp) assay system derived from H5N1 IAV including a drug-resistant PA mutant (I38T) and a viral polymerase activity enhancing PB2 mutant (T271A). Upon screening, we found vidofludimus can be served as a potential inhibitor for IAV. Vidofludimus an orally active inhibitor for dihydroorotate dehydrogenase (DHODH), a key enzyme for the cellular de novo pyrimidine biosynthesis pathway. We found that vidofludimus exerted antiviral activity against wild-type and drug-resistant mutant IAV, with effective concentrations (EC50 ) of 2.10 and 2.11 μM, respectively. The anti-IAV activity of vidofludimus was canceled by the treatment of uridine or cytidine through pyrimidine salvage synthesis pathway, or orotic acid through pyrimidine de novo synthesis pathway. This indicated that the main target of vidofludimus is DHODH in IAV RdRp expressing cells. We also produced recombinant seasonal IAV H1N1 virion and influenza B virus (IBV) RdRp assay system and confirmed vidofludimus also carried highly antiviral activity against seasonal IAV and IBV. Vidofludimus is a candidate drug for the future threat of IAV H5N1 infection among humans as well as seasonal influenza virus infection.

Risk distribution of human infections with avian influenza A (H5N1, H5N6, H9N2 and H7N9) viruses in China.

This study aimed to investigate epidemiologic characteristics of major human infection with avian influenza and explore the factors underlying the spatial distributions, particularly H5N6 and H9N2, as H9N2 could directly infect mankind and contribute partial or even whole internal genes to generate novel human-lethal reassortants such as H5N6. They pose potential threats to public health and agriculture. This study collected cases of H5N1, H5N6, H9N2, and H7N9 in China, along with data on ecoclimatic, environmental, social and demographic factors at the provincial level. Boosted regression tree (BRT) models, a popular approach to ecological studies, has been commonly used for risk mapping of infectious diseases, therefore, it was used to investigate the association between these variables and the occurrence of human cases for each subtype, as well as to map the probabilities of human infections. A total of 1,123 H5N1, H5N6, H9N2, and H7N9 human cases have been collected in China from 2011 to 2024. Factors including density of pig and density of human population emerged as common significant predictors for H5N1 (relative contributions: 5.3, 5.8%), H5N6 (10.8, 6.4%), H9N2 (11.2, 7.3%), and H7N9 (9.4, 8.0%) infection. Overall, each virus has its own ecological and social drivers. The predicted distribution probabilities for H5N1, H5N6, H9N2, and H7N9 presence are highest in Guangxi, Sichuan, Guangdong, and Jiangsu, respectively, with values of 0.86, 0.96, 0.93 and 0.99. This study highlighted the important role of social and demographic factors in the infection of different avian influenza, and suggested that monitoring and control of predicted high-risk areas should be prioritized.

Highly pathogenic avian influenza virus H5N1 infection in skua and gulls in the United Kingdom, 2022.

The reemergence of the highly pathogenic avian influenza virus (HPAIV) subtype H5N1 in the United Kingdom in 2021-2022 has caused unprecedented epizootic events in wild birds and poultry. During the summer of 2022, there was a shift in virus transmission dynamics resulting in increased HPAIV infection in seabirds, and consequently, a profound impact on seabird populations. To understand the pathological impact of HPAIV in seabirds, we evaluated the virus antigen distribution and associated pathological changes in the tissues of great skua (Stercorarius skua, n = 8), long-tailed skua (Stercorarius longicaudus, n = 1), European herring gull (Larus argentatus, n = 5), and black-headed gull (Chroicocephalus ridibundus, n = 4), which succumbed to natural infection of HPAIV during the summer of 2022. Cases were collected from Shetland, including Scatness (mainland), No Ness (mainland), Clumlie (mainland), Hermaness (island), Fair Isle (island), Noss (island), and the West Midlands, South East, and South West of England. Grossly, gizzard ulceration was observed in one great skua and pancreatic necrosis was observed in 4 herring gulls, with intralesional viral antigen detected subsequently. Microscopical analysis revealed neuro-, pneumo-, lymphoid-, and cardiomyotropism of HPAIV H5N1, with the most common virus-associated pathological changes being pancreatic and splenic necrosis. Examination of the reproductive tract of the great skua revealed HPAIV-associated oophoritis and salpingitis, and virus replication within the oviductal epithelium. The emergence of HPAIV in seabirds Stercorariidae and Laridae, particularly during summer 2022, has challenged the dogma of HPAIV dynamics, posing a significant threat to wild bird life with potential implications for the reproductive performance of seabirds of conservation importance.

A TiO2-adenine nanocomposite as modification material for screen-printed gold electrode to detect H1N1 (swine flu) virus: A disposable genosensor

A genosensor based on TiO2-adenine nanocomposites (NCs) modified screen-printed gold electrode surface (TA-SPGE) was immobilized with haemagglutinin (HA) gene specific probe containing 5′ amine group and investigated for swine flu virus (H1N1). Bare SPGE surface was modified by drop coating of the nanocomposites. The NCs and precursors were characterized structurally and morphologically by adopting various techniques such as Fourier Transform Infrared (FTIR) spectra, X-ray Diffraction (XRD) spectra, UV–Visible spectra, Raman spectra, Zeta sizer, Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive spectra (EDS) and High-Resolution Transmission Electron Microscopy (HR-TEM) with Selected Area Electron Diffraction (SAED) pattern. Electrochemical techniques termed as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectra (EIS) were employed for analytical detection of single-stranded viral genome in phosphate buffer saline (pH-7.2) by using methylene blue (MB) redox indicator. Moreover, the performance of designed electrode was optimized at different concentration, pH, and scan rates. The proposed genosensor revealed high sensitivity 10.6 μA/ng.cm2, lower detection limit (LOD) of 6.7 × 10-8 ng/mL and wide linear range of 3 × 10-8-3 × 10-3 ng/mL with regression coefficient of R2 = 0.989 towards swine flu virus DNA. Additionally, the modified genosensor revealed good stability and specificity against human DNA and various pathogens such as H3N2 influenza virus, Bacillus subtilis, Neisseria meningitidis, Staphylococcus aureus and Streptococcus pyogenes. The proposed genosensor is based on relatively simple methodology, quite amicable and could promptly be used as point-of-care test for swine flu virus detection.

Influenza virus immune imprinting dictates the clinical outcomes in ferrets challenged with highly pathogenic avian influenza virus H5N1.

Zoonotic transmission of H5N1 highly pathogenic avian influenza virus (HPAIV) into the human population is an increasing global threat. The recent 2022 HPAIV outbreak significantly highlighted this possibility, increasing concern in the general population. The clinical outcomes of H5N1 influenza virus exposure can be determined by an individual's primary influenza virus infection (imprinting) or vaccination status. Immunological imprinting with Group 1 - (H1N1, H2N2, and H2N3) increases survival rates following H5N1 viral infection compared to Group 2 - (H3N2) imprinted individuals. Vaccination against H5N1 influenza viruses can offer protection to at-risk populations; however, stockpiled inactivated H5N1 influenza vaccines are not readily available to the public. We hypothesize that the immunological response to vaccination and subsequent clinical outcome following H5N1 influenza virus infection is correlated with the immunological imprinting status of an individual. To test this hypothesis, our lab established a ferret pre-immune model of disease. Naïve ferrets were intranasally inoculated with seasonal influenza viruses and allowed to recover for 84 days prior to H5N1 virus infection. Ferrets imprinted following H1N1 and H2N3 virus infections were completely protected against lethal H5N1 influenza virus challenge (100% survival), with few to no clinical symptoms. In comparison, H3N2 influenza virus-imprinted ferrets had severe clinical symptoms, delayed disease progression, and a sublethal phenotype (40% mortality). Consecutive infections with H1N1 influenza viruses followed by an H3N2 influenza virus infection did not abrogate the immune protection induced by the original H1N1 influenza virus infection. In addition, ferrets consecutively infected with H1N1 and H2N3 viruses had no clinical symptoms or weight loss. H3N2 pre-immune ferrets were vaccinated with a broadly reactive H5 HA-based or H1 NA-based vaccine (Hu-CO 2). These ferrets were protected against H5N1 influenza virus challenge, whereas ferrets vaccinated with the H1N1 wild-type CA/09 rHA vaccine had similar phenotypes as non-vaccinated H3N2-imprinted ferrets with 40% survival. Overall, Group 2 imprinted ferrets, which were vaccinated with heterologous Group 1 HA vaccines, had redirected immune responses to Group 1 influenza viral antigens and rescued a sublethal phenotype to complete protection.

Different routes of infection of H5N1 lead to changes in infecting time

Influenza virus infection can result in a wide range of clinical outcomes from asymptomatic infection to severe disease and death. While there are undoubtedly many factors that contribute to the severity of disease, one possible contributing factor that needs more investigation is the route of infection. In this study, we use previously published data from cynomolgus macaques infected with A/Vietnam/1203/04 (H5N1) via either aerosol (with and without bronchoalveolar lavages (BAL)) or a combined intrabronchial, oral, and intranasal route. We fit a mathematical model of within host viral kinetics to the data and find that when the macaques are infected via the aerosol route with subsequent BAL, the infecting time is significantly lower than for the other two groups. A lower infecting time indicates that the virus spreads from cell to cell more rapidly for aerosol infection with BAL than for the combined deposition or aerosol deposition alone. This study helps elucidate the mechanism behind different infection outcomes caused by differences in routes of infection.