Structural Convergence and Water-Mediated Substrate Mimicry Enable Broad #Neuraminidase #Inhibition by #Human #Antibodies

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.11.27.625426v1?rss=1

Abstract
Influenza has been responsible for multiple global pandemics and seasonal epidemics and claimed millions of lives. The imminent threat of a panzootic outbreak of avian influenza H5N1 virus underscores the urgent need for pandemic preparedness and effective countermeasures, including monoclonal antibodies (mAbs). Here, we characterize human mAbs that target the highly conserved catalytic site of viral neuraminidase (NA), termed NCS mAbs, and the molecular basis of their broad specificity. Cross-reactive NA-specific B cells were isolated by using stabilized NA probes of non-circulating subtypes. We found that NCS mAbs recognized multiple NAs of influenza A as well as influenza B NAs and conferred prophylactic protections in mice against H1N1, H5N1, and influenza B viruses. Cryo-electron microscopy structures of two NCS mAbs revealed that they rely on structural mimicry of sialic acid, the substrate of NA, by coordinating not only amino acid side chains but also water molecules, enabling inhibition of NA activity across multiple influenza A and B viruses, including avian influenza H5N1 clade 2.3.4.4b viruses. Our results provide a molecular basis for the broad reactivity and inhibitory activity of NCS mAbs targeting the catalytic site of NA through substrate mimicry.

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#aH1n1 #aH5n1 #abstract #avianInfluenza #AVIANINFLUENZA #birdFlu #h5n1 #health #influenzaB #monoclonalAntibodies #news #research #SEASONALINFLUENZA

Boosting #neuraminidase #immunity in the presence of #hemagglutinin with the next generation of #influenza #vaccines

Source: npj Vaccines, https://www.nature.com/articles/s41541-024-01011-x

Abstract
Neuraminidase (NA), the second most abundant surface glycoprotein on the influenza virus, plays a key role in viral replication and propagation. Despite growing evidence showing that NA-specific antibodies correlate with resistance to disease in humans, current licensed vaccines focus almost entirely on the hemagglutinin (HA) antigen. Here, we demonstrate that recombinant NA (rNA) protein is highly immunogenic in both naïve mice and ferrets, as well as in pre-immune ferrets, irrespective of the level of match with preexisting immunity. Ferrets vaccinated with rNA developed mild influenza disease symptoms upon challenge with human H3N2 influenza virus, and anti-NA antibody responses appeared correlated with reduction in disease severity. The addition of rNA to a quadrivalent HA-based vaccine induced robust NA-specific humoral immunity in ferrets, while retaining the ability to induce HA-specific immunity. These results demonstrate that the addition of rNA is a viable option to increase immunogenicity and potentially efficacy versus currently licensed influenza vaccines by means of boosting NA immunity.

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#aH1n1 #aH3n2 #abstract #animalModels #health #influenzaA #mrna #news #research #vaccine #vaccines

Source: MedRxIV, https://www.medrxiv.org/content/10.1101/2024.10.31.24316514v1

Abstract
Avian H5N1 influenza viruses are circulating widely in cattle and other mammals and pose a risk for a human pandemic. Previous studies suggest that older humans are more resistant to H5N1 infections due to childhood imprinting with other group 1 viruses (H1N1 and H2N2); however, the immunological basis for this is incompletely understood. Here we show that antibody titers to historical and recent H5N1 strains are highest in older individuals and correlate more strongly with year of birth than with age, consistent with immune imprinting. After vaccination with an A/Vietnam/1203/2004 H5N1 vaccine, both younger and older humans produced H5-reactive antibodies to the vaccine strain and to a clade 2.3.4.4b isolate currently circulating in cattle, with higher seroconversion rates in young children who had lower levels of antibodies before vaccination. These studies suggest that younger individuals might benefit more from vaccination than older individuals in the event of an H5N1 pandemic.

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https://etidioh.wordpress.com/2024/11/03/immune-history-shapes-human-antibody-responses-to-h5n1-influenza-viruses-repost/

#aH1n1 #aH2n2 #aH5n1 #abstract #avianInfluenza #AVIANINFLUENZA #birdFlu #h5n1 #health #immunology #news #pandemicInfluenza #research #vaccination

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.10.23.619695v1

Abstract
The most recent outbreak of highly pathogenic avian H5 influenza (HPAI) virus in cattle is now widespread across the U.S. with spillover events happening to other mammals, including humans. Several human cases have been reported with clinical signs ranging from conjunctivitis to respiratory illness. However, most of those infected report mild to moderate symptoms, while previously reported HPAI H5Nx infections in humans have had mortality rates upwards of 50%. We recently reported that mice with pre-existing immunity to A/Puerto Rico/08/1934 H1N1 virus were protected from lethal challenge from highly pathogenic clade 2.3.4.4b H5N1 influenza virus. Here, we demonstrate that mice infected with the 2009 pandemic H1N1 virus strain A/California/04/2009 (Cal09) or vaccinated with a live-attenuated influenza vaccine (LAIV) were moderately-to-highly protected against a lethal A/bovine/Ohio/2024 H5N1 virus challenge. We also observed that ferrets with mixed pre-existing immunity, either from LAIV vaccination and/or from Cal09 infection, showed protection against a HPAI H5N1 clade 2.3.4.4b virus isolated from a cat. Notably, this protection occurred independently of any detectable hemagglutination inhibition titers (HAIs) against the H5N1 virus. To explore factors that may contribute to protection, we conducted detailed T cell epitope mapping using previously published sequences from H1N1 strains. This analysis revealed a high conservation of amino acid sequences within the internal proteins of our bovine HPAI H5N1 virus strain. These data highlight the necessity to explore additional factors that contribute to protection against HPAI H5N1 viruses, such as memory T cell responses, in addition to HA-inhibition or neutralizing antibodies.

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https://etidioh.wordpress.com/2024/10/24/immune-history-modifies-disease-severity-to-hpai-h5n1-clade-2-3-4-4b-viral-challenge/

#aH1n1 #aH5n1 #abstract #animalModels #avianInfluenza #ferrets #h1n1pdm09 #immuneSystem #research

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.10.13.618054v2

Abstract
Influenza represents one of the biggest health threats facing humanity. Seasonal epidemics can transition to global pandemics, with cross-species infection presenting a continuous challenge. Although vaccines and several anti-viral options are available, constant genetic drifts and shifts vitiate any of the aforementioned prevention and treatment options. Therefore, we describe an approach targeted at the virus’s channel to derive new anti-viral options. Specifically, Influenza A’s M2 protein is a well-characterized channel targeted for a long time by aminoadamantane blockers. However, widespread mutations in the protein render the drugs ineffective. Consequently, we started by screening a repurposed drug library against aminoadamantane-sensitive and resistant M2 channels using bacteria-based genetic assays. Subsequent in cellulo testing and structure-activity relationship studies yielded a combination of Theobromine and Arainosine, which exhibits stark anti-viral activity by inhibiting the virus’s channel. The drug duo was potent against H1N1 pandemic swine flu, H5N1 pandemic avian flu, aminoadamantane-resistant and sensitive strains alike, exhibiting activity that surpassed Oseltamivir, the leading anti-flu drug on the market. When this drug duo was tested in an animal model, it once more outperformed Oseltamivir, considerably reducing disease symptoms and viral RNA progeny. In conclusion, the outcome of this study represents a new potential treatment option for influenza alongside an approach that is sufficiently general and readily applicable to other viral targets.

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https://etidioh.wordpress.com/2024/10/15/potent-anti-influenza-synergistic-activity-of-theobromine-and-arainosine/

#aH1n1 #aH5n1 #abstract #adamantanes #antivirals #drugsRepurposing #drugsResistance #influenzaA #oseltamivir #research

Source: Lancet Microbe, https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(24)00175-7/fulltext

Summary
Background
Influenza A viruses (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.

Methods
Using a pan-IAV RT-quantitative PCR assay, six wastewater treatment works (WWTWs) across Northern Ireland were screened from Aug 1 to Dec 5, 2022. A nanopore 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. For comparative purposes, clinical data (PCR test results) were supplied by The Regional Virus Laboratory, Belfast Health and Social Care Trust (Belfast, Northern Ireland, UK).

Findings
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 IAV strains. The relative proportion of IAV reads of human versus avian origin differed across time and sample site. A diversity in subtypes and lineages was detected (eg, H1N1, H3N2, and several avian). Avian segment 8 related to those found in recent H5N1 clade 2.3.4.4b was identified.

Interpretation
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.

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https://etidioh.wordpress.com/2024/10/13/wastewater-monitoring-of-human-and-avian-influenza-a-viruses-in-northern-ireland-a-genomic-surveillance-study/

#aH1n1 #aH3n2 #aH5n1 #abstract #avianInfluenza #research #seasonalInfluenza #UK

Source: Vopr Virusol., https://virusjour.crie.ru/jour/article/view/16674

Abstract
Relevance. Influenza A virus is characterized by a segmented single-stranded RNA genome. Such organization of the virus genome determines the possibility of reassortment, which can lead to the emergence of new virus variants. The main natural reservoir of most influenza A virus subtypes are wild waterfowl. Seasonal migrations gather waterfowl from all major migration routes to nesting areas near the northern and southern polar circles. This makes intercontinental spread of influenza A viruses possible.

Objective ‒ to conduct molecular genetic monitoring and study the phylogenetic relationships of influenza A virus variants circulating in Antarctica in 2023.

Materials and methods. We studied 84 samples of biological material obtained from birds and marine mammals in April‒May 2023 in coastal areas of Antarctica. For 3 samples, sequencing was performed on the Miseq, Illumina platform and phylogenetic analysis of the obtained nucleotide sequences of the influenza A virus genomes was performed.

Results. The circulation of avian influenza virus in the Antarctic region was confirmed. Heterogeneity of the pool of circulating variants of the influenza A virus (H3N8, H1N1) was revealed. Full-length genomes of the avian influenza virus were sequenced and posted in the GISAID database (EPI_ISL_19032103, 19174530, 19174467).

Conclusion. The study of the genetic diversity of influenza A viruses circulating in the polar regions of the Earth and the identification of the conditions for the emergence of new genetic variants is a relevant task for the development of measures to prevent biological threats.

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https://etidioh.wordpress.com/2024/10/04/first-detection-of-influenza-a-virus-subtypes-h1n1-and-h3n8-in-the-antarctic-region-king-george-island-2023/

#aH1n1 #aH3n8 #abstract #antarctica #avianInfluenza #research #wildBirds

Source: Journal of Virology, https://journals.asm.org/doi/full/10.1128/jvi.00689-24?af=R

Abstract

The high genetic diversity of influenza viruses means that traditional serological assays have too low throughput to measure serum antibody neutralization titers against all relevant strains. To overcome this challenge, we developed a sequencing-based neutralization assay that simultaneously measures titers against many viral strains using small serum volumes using a workflow similar to traditional neutralization assays. The key innovation is to incorporate unique nucleotide barcodes into the hemagglutinin (HA) genomic segment, and then pool viruses with numerous different barcoded HA variants and quantify the infectivity of all of them simultaneously using next-generation sequencing. With this approach, a single researcher performed the equivalent of 2,880 traditional neutralization assays (80 serum samples against 36 viral strains) in approximately 1 month. We applied the sequencing-based assay to quantify the impact of influenza vaccination on neutralization titers against recent human H1N1 strains for individuals who had or had not also received a vaccine in the previous year. We found that the viral strain specificities of the neutralizing antibodies elicited by vaccination vary among individuals and that vaccination induced a smaller increase in titers for individuals who had also received a vaccine the previous year—although the titers 6 months after vaccination were similar in individuals with and without the previous-year vaccination. We also identified a subset of individuals with low titers to a subclade of recent H1N1 even after vaccination. We provide an experimental protocol (https://doi.org/10.17504/protocols.io.kqdg3xdmpg25/v1) and computational pipeline (https://github.com/jbloomlab/seqneut-pipeline) for the sequencing-based neutralization assays to facilitate the use of this method by others.

https://etidioh.wordpress.com/2024/09/24/high-throughput-sequencing-based-neutralization-assay-reveals-how-repeated-vaccinations-impact-titers-to-recent-human-h1n1-influenza-strains/

#aH1n1 #abstract #h1n1pdm09 #research #seasonalInfluenza #serology #vaccine