H1N1 Virus Research Articles

Genetic diversity of highly pathogenic avian influenza H5N6 and H5N8 viruses in poultry markets in Guangdong, China, 2020-2022.

H5 highly pathogenic avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/96 (Gs/Gd) lineage continue to evolve and cause outbreaks in domestic poultry and wild birds, with sporadic spillover infections in mammals. The global spread of clade 2.3.4.4b viruses via migratory birds since 2020 has facilitated the introduction of novel reassortants to China, where avian influenza of various subtypes have been epizootic or enzootic among domestic birds. To determine the impact of clade 2.3.4.4b re-introduction on local HPAI dynamics, we analyzed the genetic diversity of H5N6 and H5N8 detected from monthly poultry market surveillance in Guangdong, China, between 2020 and 2022. Our findings reveal that H5N6 viruses clustered in clades 2.3.4.4b and 2.3.4.4h, while H5N8 viruses were exclusively clustered in clade 2.3.4.4b. After 2020, the re-introduced clade 2.3.4.4b viruses replaced the clade 2.3.4.4h viruses detected in 2020. The N6 genes were divided into two clusters, distinguished by an 11 amino acid deletion in the stalk region, while the N8 genes clustered with clade 2.3.4.4 H5N8 viruses circulating among wild birds. Genomic analysis identified 10 transient genotypes. H5N6, which was more prevalently detected, was also clustered into more genotypes than H5N8. Specifically, H5N6 isolates contained genes derived from HPAI H5Nx viruses and low pathogenic avian influenza in China, while the H5N8 isolates contained genes derived from HPAI A(H5N8) 2.3.4.4b and A(H5N1) 2.3.2.1c. No positive selection on amino acid residues associated with mammalian adaptation was found. Our results suggest expanded genetic diversity of H5Nx viruses in China since 2021 with increasing challenges for pandemic preparedness.IMPORTANCESince 2016/2017, clade 2.3.4.4b H5Nx viruses have spread via migratory birds to all continents except Oceania. Here, we evaluated the impact of the re-introduction of clade of 2.3.4.4b on highly pathogenic avian influenza (HPAI) virus genetic diversity in China. Twenty-two H5N6 and H5N8 HPAI isolated from monthly surveillance in two poultry markets in Guangdong between 2020 and 2022 were characterized. Our findings showed that clade 2.3.4.4h, detected in 2020, was replaced by clade 2.3.4.4b in 2021-2022. H5N6 (n = 18) were clustered into more genotypes than H5N8 (n = 4), suggesting that H5N6 may possess better replication fitness in poultry. Conversely, the H5N8 genotypes are largely derived from the clade 2.3.4.4b wild bird isolates. As clade 2.3.4.4b continues to spread via migratory birds, it is anticipated that the genetic diversity of H5N6 viruses circulating in China may continue to expand in the coming years. Continuous efforts in surveillance, genetic analysis, and risk assessment are therefore crucial for pandemic preparedness.

Assessing human B cell responses to influenza virus vaccines and adjuvants in a PBMC-derived in vitro culture system

In vitro systems based on human peripheral blood mononuclear cells (PBMCs) can bridge the gap between preclinical and clinical vaccine evaluation but have so far mainly been exploited to assess vaccine effects on antigen-presenting cells and T cells. Our study aimed to assess whether B cells present in PBMCs also respond to vaccines and reflect the effects of different vaccine formulations and adjuvants. We stimulated PBMCs with whole inactivated virus (WIV) or split virus (SIV) H5N1 influenza vaccine, with or without the addition of the adjuvant cytosine phosphoguanine (CpG) ODN 2395, and collected the cells and supernatants at different timepoints. B cell subsets were measured by flow cytometry, immunoglobulin (IgG) levels by ELISA, B cell-related genes by qPCR, and cytokine levels by intracellular staining. B cells differentiated more readily to plasmablasts and plasma cells and produced more IgG when PBMC cultures were stimulated with WIV than when stimulated with SIV. In line, PRDM1, XBP1, and AICDA, genes associated with the differentiation of B cells to antibody-secreting cells, were expressed at higher levels in WIV- than in SIV-stimulated PBMCs. The combination of WIV and CpG consistently induced the highest levels of antibody-secreting cell differentiation, IgG production, and B-cells secreting IL-6 and IL-10. Taken together, B cells in human PBMC cultures show distinct responses to different types of vaccines and vaccine/CpG combinations. This underlines the suitability of unfractionated PBMCs for evaluating vaccine effects on different types of human immune cells before running costly clinical trials.

Self-assembling nanoparticle vaccine elicits a robust protective immune response against avian influenza H5N6 virus in chickens

The continuous circulation and evolution of the H5N6 subtype highly pathogenic avian influenza virus (HPAIV) challenge the development of the global poultry industry and human public health security. To address the potential threat of the H5N6 virus, a secure and efficacious vaccine is urgent. In our research, a self-assembling nanoparticle vaccine presenting the hemagglutinin of the H5N6 AIV was developed based on the ferritin antigen display platform. The results showed that a single-dose vaccination of this nanoparticle vaccine elicited potent hemagglutination inhibition (HI) antibody responses and neutralizing antibody responses in the chickens. Meanwhile, the fused HA-ferritin nanoparticle vaccine induced significantly higher levels of Th1/Th2 immune responses. After a lethal attack with the H5N6 virus, the fused HA-ferritin nanoparticle vaccine conferred chickens with 100 % (10/10) challenge protection. Importantly, the fused HA-ferritin nanoparticle with only 28 hemagglutination units (HAU) provided chickens with immune protection comparable to commercial inactivated vaccines and protected the chickens from severe lung pathological damage. These results in our study support the superiority of ferritin as an antigen display platform and suggest that self-assembled nanoparticle vaccines based on this platform possess the potential as an avian influenza candidate vaccine.

Delivery of dendritic cells targeting 3M2e-HA2 nanoparticles with a CpG adjuvant via lysosomal escape of Salmonella enhances protection against H9N2 avian influenza virus

Avian influenza virus (AIV) subtype H9N2 still poses a great threat to the poultry farming industry and public health worldwide, and the development of a new influenza vaccine that is safe and conservative and able to address influenza virus mutations is highly promising for application. HA2, the neck of the HA protein, and M2e, the extracellular N-terminal structural domain of the M2 protein, are conserved and effective protective antigens.In this study, the HA2 sequences were fused with three M2e copies (H9N2, H1N1 and H5N1) to the norovirus VP1 protein via the SpyTag-SpyCatcher platform to form self-assembled nanoparticles and display antigenic proteins on its surface, yielding pYL262. The chicken dendritic cells (DCs) targeting the nanobody phage-54 were then fused to HA2-3M2e to yield pYL327. Finally, a synthesized 20-repeat CpG adjuvant gene fragment was inserted into pYL327, resulting in the plasmid pYL331. All the constructed plasmids were then transformed into the sifA gene-deficient Salmonella vector χYL56 for oral immunization.The results showed that sifA-deficient Salmonella could efficiently increase antigen-specific mucosal sIgA antibody titers, especially in alveolar lavage samples, whereas the presence of the phage-54 nanobody could dramatically increase intracellular IFN-γ mRNA levels, indicating its ability to enhance the Th1-type immune response. Finally, the presence of the CpG adjuvant clearly increased T-cell proliferation and promoted DC activation, with elevated splenic TLR21 levels observed. Strikingly, after oral immunization with χYL56 (pYL331), chickens were protected against challenge with the G57 genotype H9N2 virus, which presented similar or even better levels of virus shedding and body weight gain compared with the commercial inactivated vaccine, providing a new option for controlling H9N2 virus infection in the future.

Rapid and Safe Neutralization Assay for Circulating H5N1 Influenza Virus in Dairy Cows.

Rapid and safe neutralization assays are required for highly pathogenic avian influenza viruses, including a clade 2.3.4.4b H5N1 subtype recently found in cows. Here, we report a neutralization assay using luminescent virus-like particles. This assay has lower biosafety requirements and provides a larger dynamic range than conventional methods. We applied this technique to evaluate the cross-reactivity of neutralizing antibodies induced by clade 2.3.4.4b candidate vaccine viruses (CVVs) with the cow-derived H5N1 virus. Our findings indicate that these CVVs share antigenic characteristics with the cow-derived H5N1 virus, suggesting the potential efficacy of vaccines developed using these CVVs.

A novel cascade colorimetric biosensor based on three-way junction-initiated primer exchange reaction for detection of influenza virus

A novel biosensor based on a three-way junction (3WJ)-induced primer exchange reaction was developed for detection of the H1N1 virus. The target H1N1 RNA induced formation of a 3WJ. The subsequent assembly of two DNA probes triggered amplification of downstream strand displacement to copiously generate signal primers to initiate primer exchange reaction to form a long single-stranded sequence containing multiple G quadruplet repeats. Abundant G-quadruplex/hemin was formed in the presence of hemin, thus catalyzing a colorimetric reaction. The detection limit of the colorimetric biosensor was 34.32 fM with a linear relationship from 100 pM to 1 μM. By simply changing the sequence of the two probes based on the target-specific sequence, the biosensor can be easily extended to detect other viral RNA. The proposed biosensor successfully detected H1N1 RNA as a sensitive, portable, and cost-effective alternative to current methods.

Reassortment of newly emergent clade 2.3.4.4b A(H5N1) highly pathogenic avian influenza A viruses in Bangladesh.

Avian influenza active surveillance was conducted in Bangladesh from January 2022 to November 2023 in live-poultry markets (LPMs) and Tanguar Haor wetlands. The predominant viruses circulating in LPMs were low pathogenic avian influenza (LPAI) A(H9N2) and clade 2.3.2.1a highly pathogenic avian influenza (HPAI) A(H5N1) viruses. Non-H9N2 LPAIs were found at Tanguar Haor and at a lower prevalence in LPMs. Starting from June 2023, we detected novel genotypes of clade 2.3.4.4b A(H5N1) viruses from ducks in LPMs. The HA, NA, and M genes of these viruses are related to those of 2020 European clade 2.3.4.4b H5N1 viruses such as A/Eurasian wigeon/Netherlands/1/2020 (Netherlands/1). However, analyses of the other five gene segments' sequences identified three distinct genotypes (BD-G2, BD-G3, and BD-G4). BD-G2 viruses were closely related to the clade 2.3.4.4b H5N1 viruses that have been detected in Japan and nearby regions since November 2022. BD-G3 viruses were reassortants, with gene segments from other Eurasian LPAI viruses. BD-G4 viruses were similar to BD-G2 viruses, but their NS gene was accrued from contemporary Bangladeshi clade 2.3.2.1a A(H5N1) viruses. The ability of any of the clade 2.3.4.4b viruses to displace the long-entrenched 2.3.2.1a A(H5N1) viruses in Bangladesh is unknown.

Rapid Onset of Innate Response, Cytokine Signaling and Humoral Immunity in Inactivated LPAI-H9N2-Vaccinated Broilers

The development of effective and innovative vaccination strategies is urgently needed to better control the spread and transmission of the low-pathogenic avian influenza H9N2 subtype (LPAI-H9N2) in poultry. In addition, the enhancement of innate immunity by some of these innovative inactivated vaccines has not yet been investigated. Here, an experiment was conducted in commercial broiler chickens to compare the immune response to two different inactivated H9N2 vaccines. For this, Group 1 (G1) broilers were vaccinated with vaccine 1 [Nobilis® H9N2-P (pathogen-associated molecular patterns—PAMP) technology], broilers in G2 were vaccinated with vaccine 2 [an inactivated whole H9N2 virus (IWV) autogenous oil emulsion vaccine], while birds in G3 were not vaccinated. The study lasted 34 days. Innate immune parameters (phagocytic activity, nitric oxide, and lysozyme), cytokine signaling (IL-1β, IL-6, IL-8), humoral immunity using the hemagglutination inhibition (HI) test, and the gene expressions of IFN-γ and TLR-21 were assessed. The results showed a significant increase in innate immunity and modulatory cytokines at 24–48 h after the vaccination of G1 broilers, with a continuous increase until the end of the experiment. In addition, a significant increase in geometric mean HI titers was observed in G1 at 11 days post-vaccination (dpv), and a significant (p ˂ 0.05) upregulation of IFN-γ and TLR-21 was observed in the same group, G1, at 31 dpv compared to G2 and G3. Nobilis® H9N2-P may induce faster and stronger innate and active humoral immunity compared to another IWV, which may contribute to the protection of broilers against early H9N2 infections. However, challenge protection studies for several IWV vaccines, including PAMP-H9N2 against LPAI-H9N2, should be further evaluated in both specific pathogen-free (SPF) and commercial broilers.

Expression of influenza A H1N1 and H3N2 viruses Mosaic-HA1 antigens and evaluation of its immunogenicity in mice

Vaccination is the most effective measure for reducing and preventing influenza and related complications. In this study, we analyzed the mutation trend and the antigen dominant site changes of the amino acid sequence of hemagglutinin subunit 1 (HA1) of human influenza A virus (IAV) in the northern hemisphere from 2012 to 2022. According to the HA1 sequences of A/Darwin/6/2021 (H3N2) and A/Wisconsin/588/2019 (H1N1) recommended by the World Health Organization in the 2022 influenza season in northern hemisphere, we employed the mosaic algorithm to design three Mosaic-HA1 antigens through stepwise substitution. Mosaic-HA1 was expressed and purified in 293F cells and then mixed with the alum adjuvant at a volume ratio of 1:1. The mixture was used to immunize BALB/c mice, and the immunogenicity was evaluated. Enzyme-linked immunosorbent assay showed that Mosaic-HA1 induced the production of IgG targeting two types of HA1, the specific IgG titers for binding to H3 protein and H1 protein reached 105 and 103 respectively. The challenge test showed that Mosaic-HA1 protected mice from H3N2 or H1N1. This study designs the vaccines by recombination of major antigenic sites in different subtypes of IAV, giving new insights into the development of multivalent subunit vaccines against influenza.

Antiviral potential of copper and titanium dioxide nanoparticles against H1N1, Adenovirus 40 and herpes simplex virus type-II

The rising incidence of viral illnesses like influenza (H1N1), human adenovirus (AdV) 40, and herpes simplex virus type 2 (HSV-II) seriously threatens public health, necessitating the development of potent antiviral medications. The main objective of this study was to evaluate the antiviral activity of synthesized copper nanoparticles (Cu-NPs) and titanium dioxide nanoparticles (TiO2-NPs) against the three mentioned viruses. Characterization of these compounds was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) and UV–Vis spectroscopy techniques. The cytotoxicity and antiviral activity of viruses were investigated using the crystal violet technique. The main findings reveal that Cu-NPs had significant antiviral activity, especially against HSV-II, with an IC50 value of 20.449 μg/mL. However, this activity may be accompanied by marked cytotoxicity, indicated by a CC50 of 123.492 µg/mL, raising concerns about its safety for therapeutic use and its negative impact on human health. In contrast, TiO2-NPs show a more favorable safety profile, with a CC50 of 264.10 μg/mL, maintaining moderate antiviral activity against H1N1 and HSV-II, albeit with higher IC50 values compared to Cu-NPs. Based on these results, Cu-NPs and TiO2-NPs are both attractive candidates for the creation of new antiviral treatments, and more research into their mechanisms of action and their therapeutic uses is necessary.

Phosphorylation of S-S-S Motif in Nuclear Export Protein (NEP) Plays a Critical Role in Viral Ribonucleoprotein (vRNP) Nuclear Export of Influenza A and B Viruses.

The phosphorylation of three highly conserved serine residues S23, S24, and S25 (S-S-S motif) has been previously identified in NEP of influenza virus. However, it remains obscure whether and how this motif regulates the vRNPs nuclear export. Here the influenza A H5N6 viruses harboring NEP S23C, S24L, or S25L is generated, allowing to impair the phosphorylation on these sites without mutating viral NS1 protein. These mutations significantly inhibited vRNPs nuclear export are founded, decreased viral infectivity and attenuated virulence in mice. In addition, inhibition or knockout of ATM or CK2, two predicated Ser/Thr protein kinases that phosphorylate the S-S-S motif, impedes vRNP nuclear export and virus replication in cells and reduces the virulence in vivo. Moreover, treatment of NEP peptide mimics containing the S-S-S motif to competitively block NEP binding to the kinases reduces influenza virus replication in cells and mice. However, neither the inhibitors above nor the NEP peptide mimics significantly inhibit the replication of H5N6-DDD mutant, indicating phosphorylation of S-S-S motif is required for the vRNP nuclear export. This studies contribute to a better understanding of the mechanism by which NEP regulates vRNP nuclear export and provides novel insights into antiviral targets against influenza A and B viruses.

Susceptibility of calf lung slice cultures to H5N1 influenza virus

The current outbreak of HPAI H5N1 virus infections in dairy cattle in the USA underscores the need for easily accessible methods to rapidly assess host susceptibility for infection with known and emerging influenza viruses. Here we show that ex vivo lung slice cultures from calves provide a useful method to rapidly screen host susceptibility to a range of influenza A viruses.

Edible bird’s nest: N- and O-glycan analysis and synergistic anti-avian influenza virus activity with neuraminidase inhibitors

Zoonotic avian influenza viruses have continued to infect people on occasion. During treatment, antiviral resistant viruses have occasionally emerged, highlighting the need for a novel strategy for treating human illness. After pancreatin treatment, edible bird's nest (EBN), swiftlet saliva consumed for health purposes, possesses anti-avian viral activity by inhibiting receptor-binding hemagglutinin (HA) activity. Glycan analysis revealed an abundance of α2,3Neu5Ac decoy receptors in pancreatin-treated EBN. Fucosylated tri-α2,3Neu5Ac tri-antennary N-glycans (N-35) and di-α2,3Neu5Ac core 2 O-glycans (O-15) are predominant, accounting for 53.46% and 44.66% of total N- and O-glycan amounts, respectively. Isobologram analysis revealed that the treated EBN had a strong synergistic effect with either oseltamivir carboxylate or zanamivir, a competitive inhibitor of receptor-destroying neuraminidases (NAs), against the avian H5N1 virus. Taken together, EBN has the potential to be developed as a food-derived avian viral trap to prevent and decrease avian virus infection as well as in combination with a viral releasing-NA inhibitor to increase therapeutic potency, reduce toxicity, delay resistance development, and potentially prevent pandemic onset.

Epidemiological and genetic characterization of the influenza A (H1N1) virus in Hangzhou City in 2023.

To explore and describe the epidemiological and genetic variation characteristics of the influenza A (H1N1) virus in Hangzhou City. Respiratory throat swab specimens collected from the fever clinic of the 903rd Hospital of the Chinese People's Liberation Army (PLA) between January and March 2023 were collected. The respiratory pathogen antigens were identified using the colloidal gold method, and those testing positive for influenza A virus antigens were confirmed and subtyped by RT-qPCR. Seventeen H1N1 isolates were selected to amplify hemagglutinin (HA) and neuraminidase (NA) gene sequences via RT-PCR, and sequencing was completed following the identification of the amplified products. The sequenced HA and NA sequences were spliced using DNASTAR software (version 5.0), and a phylogenetic tree was constructed using MEGA software (version 11.0) for genetic characterization. A total of 2,376 respiratory samples were tested, with 680 cases testing positive for influenza A. Of these, 129 positive cases of influenza A were randomly selected for typing, resulting in the isolation of 112 H1N1 subtypes and 17 H3N2 subtypes. The HA genes of 17 strains of influenza A (H1N1) were randomly selected for amino acid homology comparisons with two vaccine strains recommended by the WHO for 2023 (A/Wisconsin/67/2022 (H1N1) and A/Victoria/4897/2022 (H1N1)). The HA gene results showed identities of 98.24 to 98.65% and 98.41 to 98.82%, respectively, and the NA gene results were 98.79 to 99.15% and 98.94 to 99.29%, respectively. Fourteen amino acid sites were altered in the HA gene of the 17 strains, with some strains contributing to the Sa and Ca antigenic determinants, respectively. Seventeen strains had mutations in the NA gene at sites 13, 50, 200, 339, 382, and 469. The sequenced strains, vaccine strains, and some 2023 domestic representative strains independently formed a branch 6B.1A.5a.2a. The continuous evolutionary mutations of the H1N1 virus genes in Hangzhou City suggest the possibility of the virus escaping from the immune response. This study provides an experimental basis for evaluating the protective effect of the vaccine and formulating preventive measures against influenza in Hangzhou City.

Novel reassortant H2N2 low pathogenic avian influenza virus in live bird markets in the Northeastern United States, 2019-2023

ABSTRACT The H2N2 avian influenza viruses (AIV) have been reported in the Northeast United States of America (USA) live bird market (LBM) system since 2014. In this study, we investigated the genetic evolution and characterized molecular markers of the recent H2N2 AIVs in LBMs in the Northeast USA. Phylogenetic analyses revealed that the LBM H2N2 lineage has evolved into three distinct subgroups (groups A.1, A.2, and A.3). The group A.1 viruses and some transient reassortants evolved through several independent reassortment events between the LBM H2N2 lineage and North American wild bird-origin AIVs. Separately, a group of phylogenetically distinct novel H2N2 viruses (group B) identified in LBMs completely originated from wild birds, independent from the previous LBM H2N2 lineage that has persisted since 2014. While no molecular evidence of mammalian adaptation was found, the novel H2N2 viruses in the LBM system underscore the importance of updated risk assessments for potential human transmission.

Update and narrative review of avian influenza (H5N1) infection in adult patients.

The avian influenza is a serious infection caused by influenza virus that is native to birds. Avian influenza remains a global challenge due to high transmission and mortality rates. The highly pathogenic strain of H5N1 resulted in significant outbreaks and deaths globally since the late 1800s. The most recent outbreaks in wild birds, domestic birds, and cows with some genetic variations and mutations among H5N1 strains has raised major concerns about potential transmission and public health risks. Symptoms range from asymptomatic to mild flu-like illness to severe illness that requires hospitalization. There are multiple vaccines in development for humans to protect against avian influenza, specifically the H5N1 virus. This includes a cell-based vaccine approved by the FDA for people aged 6 months and older who are at higher risk of exposure to the H5N1 virus called Audenz. Chemoprophylaxis against avian influenza following a suspected exposure should be started as soon as possible or no later than 48 h, and it is recommended to be continued for 7 days. The majority of avian influenza viruses are susceptible to neuraminidase inhibitors and cap-dependent endonuclease inhibitor. Neuraminidase inhibitors are the mainstay of the avian influenza treatment and includes oseltamivir, peramivir, and zanamivir. Baloxavir marboxil is a cap-dependent endonuclease inhibitor. This clinical review aims to highlight the background, epidemiology, clinical presentation, complications and current treatment and prevention strategies for avian influenza H5N1.

Potential antiviral activity of rhamnocitrin against influenza virus H3N2 by inhibiting cGAS/STING pathway in vitro.

Influenza remains a serious issue for public health and it's urgent to discover more effected drugs against influenza virus. Rhamnocitrin, as a flavonoid, its effect on influenza virus infection remains poorly explored. In this study, rhamnocitrin showed antiviral effect and anti-apoptosis on influenza virus A/Aichi/2/1968 (H3N2) in MDCK cells and A549 cells. In addition, molecular docking revealed that rhamnocitrin have good binding activity with the target proteins cGAS and STING, molecular dynamic simulation and surface plasmon resonance showed that rhamnocitrin could form a stable complex with the above proteins. Moreover, the qPCR and western blot assays further verified that rhamnocitrin could reduce type I IFN and proinflammatory cytokines production by inhibiting the cGAS/STING pathway. Taken together, the results suggest that rhamnocitrin could be a potential anti-viral agent against influenza.

Dose sparing enabled by immunization with influenza vaccine using orally dissolving film

Influenza vaccine delivered by orally dissolving film vaccine (ODFV) is a promising approach. In this study, we generated three ODFVs each comprising pulluan and trehalose with different doses of inactivated A/Puerto Rico/8/34, H1N1 virus (ODFV I, II, III) to evaluate their dose-sparing effect in mice. The ODFVs were placed on the tongues of mice to elicit immunization and after 3 immunizations at 4-week intervals, mice were challenged with a lethal dose of A/PR/8/34 to assess vaccine-induced protection. The 3 ODFVs containing 50, 250, or 750 μg of inactivated viruses elicited virus-specific antibody responses and virus neutralization in a dose-dependent manner. Dose-dependent antibody responses were also observed from the mucosal tissue samples, and also from antibody-secreting cells of the lungs and spleens. ODFV-induced cellular immunity, particularly germinal center B cells and T cells were also dose-dependent. Importantly, all 3 ODFVs evaluated in this study provided complete protection by strongly suppressing the pro-inflammatory cytokine production and lung virus titers. None of the immunized mice underwent noticeable weight loss nor succumbed to death, a phenomenon that was only observed in the infection challenge controls. These results indicated that the protection conferred by a low dose influenza vaccine formulated in ODF is comparable to that of a high-dose vaccine, thereby enabling vaccine dose sparing effect.

Avian influenza A (H5N1) virus in dairy cattle: origin, evolution, and cross-species transmission.

Since the emergence of highly pathogenic avian influenza virus (HPAIV) H5N1 of clade 2.3.4.4b as a novel reassortant virus from subtype H5N8, the virus has led to a massive number of outbreaks worldwide in wild and domestic birds. Compared to the parental HPAIV H5N8 clade 2.3.4.4b, the novel reassortant HPAIV H5N1 displayed an increased ability to escape species barriers and infect multiple mammalian species, including humans. The virus host range has been recently expanded to include ruminants, particularly dairy cattle in the United States, where cattle-to-cattle transmission was reported. As with the avian 2.3.4.4.b H5N1 viruses, the cattle-infecting virus was found to transmit from cattle to other contact animals including cats, raccoons, rodents, opossums, and poultry. Although replication of the virus in cows appears to be mainly confined to the mammary tissue, with high levels of viral loads detected in milk, infected cats and poultry showed severe respiratory disease, neurologic signs, and eventually died. Furthermore, several human infections with HPAIV H5N1 have also been reported in dairy farm workers and were attributed to exposures to infected dairy cattle. This is believed to represent the first mammalian-to-human transmission report of the HPAIV H5N1. Fortunately, infection in humans and cows, as opposed to other animals, appears to be mild in most cases. Nevertheless, the H5N1 bovine outbreak represents the largest outbreak of the H5N1 in a domestic mammal close to humans, increasing the risk that this already mammalian adapted H5N1 further adapts to human-to-human transmission and starts a pandemic. Herein, we discuss the epidemiology, evolution, pathogenesis, and potential impact of the recently identified HPAIV H5N1 clade 2.3.4.4b in dairy cattle in the United States. Eventually, interdisciplinary cooperation under a One Health framework is required to be able to control this ongoing HPAIV H5N1 outbreak to stop it before further expansion of its host range and geographical distribution.

An epidemiologic surveillance study based on wastewater and respiratory specimens reveals influenza a virus prevalence and mutations in Taiyuan, China during 2023–2024

BackgroundInfluenza is a major cause of morbidity and mortality. Influenza A virus (IAV) is one of the most important pathogens causing influenza and often causes global pandemics due to its tendency to mutate. We aim to use epidemiology based on wastewater and respiratory specimens to understand the occurrence of influenza A virus infections in Taiyuan City.MethodsA retrospective epidemiology surveillance was carried out at the First Hospital of Shanxi Medical University (FHSMU) and five wastewater treatment plants (WTPs) in Taiyuan city from 2023 to 2024. Reverse transcription real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect influenza A viruses in wastewater and respiratory specimens. High-throughput whole genome sequencing was performed on 17 strains obtained in this study, and subsequent analyses included characterization, phylogenetic construction, amino acid mutation analysis, and antigenic structural variability assessment.Results520 wastewater samples and 1,203 throat swab samples were collected. We detected RNA concentration from pH1N1 and H3N2 viruses in wastewater and got 17 genome sequences (5 of pH1N1 and 12 of H3N2) in respiratory specimens. Whole-genome sequencing showed co-prevalence of pH1N1 viruses in the branches of 6B.1 A.5a.2a.1 and H3N2 viruses in the branches of 3 C.2a1b.2a.2a.3a.a in Taiyuan from 2023 to 2024. Moreover, a HA mutation (N138D), predicted to be of high phenotypic consequence, was found in 8 Taiyuan H3N2 sequences.ConclusionThis study highlights the predominant presence of pH1N1 and H3N2 strains in Taiyuan. The analysis also identified amino acid site variations in the HA antigenic epitopes in H3N2 strains, which may contribute to immune escape.