Biology subjects

Funk, M.

Publications and source records attributed to Funk, M..

6 recordsLinked to original sources

bioRxiv2025

The receptor binding properties of H5Nx influenza A viruses have evolved to promiscuously bind to avian-type mucin-like O-glycans

Highly pathogenic H5Nx influenza A viruses are causing unprecedented, season-independent outbreaks across avian and mammalian species, including dairy cattle, a novel reservoir. The sialoside-binding properties of influenza A hemagglutinin (HA) are strongly related to its ability to infect and transmit between hosts. Mucin-like O-glycans, omnipresent in respiratory tracts, have been understudied as viral receptors due to their complexity. To address this, we synthesized 25 O-linked glycans with diverse sialosides, including modifications by fucosides and sulfates. Our findings reveal that H5Nx 2.3.4.4b viruses uniquely bind core 3 sialyl-Lewisx and Sia-Gal-{beta}3GalNAc, glycans not recognized by classical H5 or other avian viruses. By determining its crystal structure, we resolved the structural features of both structures in an H5 hemagglutinin (HA) from a 2016 2.3.4.4b virus. While these viruses do not bind human-type receptors, their promiscuous receptor specificity enhances binding to human tracheal tissues, suggesting that O-glycan recognition contributes to their zoonotic potential.

microbiology↗

bioRxiv2024

A 2022 avian H5N1 influenza A virus from clade 2.3.4.4b attaches to and replicates better in human respiratory epithelium than a 2005 H5N1 virus from clade 2.3.2.1

BackgroundHighly pathogenic avian influenza (HPAI) H5 viruses of the A/Goose/Guangdong/1/1996 (GsGd) lineage pose significant global risks to wildlife, domestic animals, and humans. Recent cross-species transmission events to mammals, including humans, highlight this risk. Critical determinants for cross-species and intra-species transmission include the ability to attach to and replicate in respiratory epithelial cells. Although these factors have been studied for HPAI H5N1 viruses in the past, limited studies are available for currently circulating strains. MethodsWe compared level of adaptation to human respiratory tract of a HPAI H5N1 clade 2.3.4.4b (H5N12022) virus with those of well characterized HPAI H5N1 clade 2.1.3.2 (H5N12005) and seasonal H3N22003 viruses by three methods. First, we compared pattern of virus attachment by virus histochemistry. Second, we compared efficiency of infection and replication, as well as innate immune responses in human respiratory epithelium in vitro. Lastly, we compared polymerase complex activity in a minigenome assay. FindingsThe H5N12022 virus attached more abundantly to and replicated more efficiently in cells of the human respiratory tract compared to H5N12005 and H3N2 viruses. This increased replication was not associated with an increased polymerase activity of H5N12022 virus compared to H3N22003 virus. The efficient replication of H5N12022 virus infection induced a robust innate immune response almost comparable to H3N22003. InterpretationThe pattern of virus attachment and replication efficiency of a HPAI H5N12022 virus resembled that of H3N22003 virus more closely than a HPAI H5N12005. This could contribute to an increased risk for both human infection and virus adaptations to humans. FundingThe Netherlands Organization for Health Research and Development Research in contextO_ST_ABSEvidence before this studyC_ST_ABSHighly pathogenic avian influenza (HPAI) H5 viruses of the A/Goose/Guangdong/1/1996 (GsGd) lineage (clade 2.3.4.4b) have the ability to spread to a wide range of domesticated and wild mammalian species, including humans. Cross species transmission and transmission among humans requires-- among other factors--efficient infection of epithelial cells in the respiratory epithelium of the upper respiratory tract. Added value of this studyIn our study we show that a recent clade 2.3.4.4b HPAI H5N1 virus attached to and replicated more efficiently in respiratory epithelium than a clade 2.1.3.2 H5N1 virus that circulated in 2005. Implications of all the available dataThese data suggest that there might be an increased risk of human infections with the currently circulating 2.3.4.4b HPAI H5N1 viruses, which might facilitate opportunities for human adaptation.

microbiology↗

bioRxiv2024

A vaccine antigen central in influenza A(H5) virus antigenic space confers subtype-wide immunity

Highly pathogenic avian influenza A(H5) viruses globally impact wild and domestic birds, and mammals, including humans, underscoring their pandemic potential. The antigenic evolution of the A(H5) hemagglutinin (HA) poses challenges for pandemic preparedness and vaccine design. Here, the global antigenic evolution of the A(H5) HA was captured in a high-resolution antigenic map. The map was used to engineer immunogenic and antigenically central vaccine HA antigens, eliciting antibody responses that broadly cover the A(H5) antigenic space. In ferrets, a central antigen protected as well as homologous vaccines against heterologous infection with two antigenically distinct viruses. This work showcases the rational design of subtype-wide influenza A(H5) pre-pandemic vaccines and demonstrates the value of antigenic maps for the evaluation of vaccine-induced immune responses through antibody profiles.

microbiology↗

bioRxiv2024

Transient RNA structures underlie highly pathogenic avian influenza virus genesis

Highly pathogenic avian influenza viruses (HPAIVs) cause severe disease and high fatality in poultry1. They emerge exclusively from H5 and H7 low pathogenic avian influenza viruses (LPAIVs)2. Although insertion of a furin-cleavable multibasic cleavage site (MBCS) in the hemagglutinin gene was identified decades ago as the genetic basis for LPAIV-to-HPAIV transition3,4, the exact mechanisms underlying said insertion have remained unknown. Here we used an innovative combination of bioinformatic models to predict RNA structures forming around the influenza virus RNA polymerase during replication, and circular sequencing5 to reliably detect nucleotide insertions. We show that transient H5 hemagglutinin RNA structures predicted to trap the polymerase on purine-rich sequences drive nucleotide insertions characteristic of MBCSs, providing the first strong empirical evidence of RNA structure involvement in MBCS acquisition. Insertion frequencies at the H5 cleavage site were strongly affected by substitutions in flanking genomic regions altering predicted transient RNA structures. Introduction of H5-like cleavage site sequences and structures into an H6 hemagglutinin resulted in MBCS-yielding insertions never observed before in H6 viruses. Our results demonstrate that nucleotide insertions that underlie H5 HPAIV emergence result from a previously unknown RNA-structure-driven diversity-generating mechanism, which could be shared with other RNA viruses.

microbiology↗

bioRxiv2020

Insertions of codons encoding basic amino acids in H7 hemagglutinins of influenza A viruses occur by recombination with RNA at hotspots near snoRNA binding sites

The presence of multiple basic amino acids in the protease cleavage site of the hemagglutinin (HA) protein is the main molecular determinant of virulence of highly pathogenic avian influenza (HPAI) viruses. Recombination of HA RNA with other RNA molecules of host or virus origin is a dominant mechanism of multi basic cleavage site (MBCS) acquisition for H7 subtype HA. Using alignments of HA RNA sequences from documented cases of MBCS insertion due to recombination, we show that such recombination with host RNAs is most likely to occur at particular hotspots in ribosomal RNAs (rRNAs), transfer RNAs (tRNAs) and viral RNAs. The locations of these hotspots in highly abundant RNAs indicate that RNA recombination is facilitated by the binding of small nucleolar RNA (snoRNA) near the recombination points.

microbiology↗

bioRxiv2020

Activation of group II metabotropic receptors attenuates cortical E-I imbalance in a 15q13.3 microdeletion mouse model

Animal models reflecting human risk for schizophrenia are essential research tools for gaining further insight into the convergence of CNS pathology and clinical biomarkers. Amongst the variety of animal models that display schizophrenia-related neuronal network deficits, transgenic mice for rare and highly penetrant copy number variants (CNVs) provide a unique opportunity to study pathological correlates in models with strong construct validity. The Df(h15q13)/+ mouse model of the human 15q13.3 microdeletion CNV has been shown to mimic deficits in parvalbumin positive (PV+) interneuron and cortical network function. However, the corresponding changes in synapse density and activity within the medial prefrontal cortex (mPFC) have not been described. Using high-content immunofluorescence imaging, we have shown a reduced density of PV+ neurons and inhibitory synapses in the mPFC of Df(h15q13)/+ mice. We found that the reduced detection of PV+ synapses were accompanied by changes in spontaneous inhibitory and excitatory synaptic activity onto layer 2/3 pyramidal neurons. The aberrant cortical function was also evident in awake animals by a reduced high frequency auditory steady-state responses (ASSR), reliably monitored by EEG. Importantly, the imbalance of excitatory to inhibitory function could be attenuated on a cellular and cortical network level by activation of mGlu2/3 receptors, indicating the relevance of excessive excitatory transmission to the cortical network deficit in the Df(15q13)/+ mouse model. Our findings highlight the preclinical value of genetic risk and in particular CNV models such as the Df(15q13)/+ mice to investigate pathological network correlates of schizophrenia risk and to probe therapeutic opportunities based on clinically relevant biomarkers.

neuroscience↗