Biology subjects

Frueh, S. P.

Publications and source records attributed to Frueh, S. P..

4 recordsLinked to original sources

bioRxiv2025

Unraveling new characteristics of γδT cells using scRNA-seq in TCR KO chicken

The characterization of T cells in chickens has proven to be challenging, primarily due to the lack of specific markers to differentiate classical Th1, Th2, and Th17 subsets. Furthermore, chickens possess a notably high proportion of {gamma}{delta} T cells, making them a unique model for investigating the poorly understood role of these cells not only in chickens but also in mammals. To gain deeper insights into the functions and characteristics of the {beta} and {gamma}{delta} T cell subsets in chickens, whole transcriptome analysis (WTA) on CD3+ single cells isolated from wild type (WT), TCR C{beta} knockout (KO) and TCR C{gamma} KO chickens at embryonic day (ED) 18, day (d) 3, and d14 post-hatch was conducted. The results indicate that {gamma}{delta} T cells exhibit cytolytic activity in both TCR C{beta} KO and WT chickens. A distinct cluster of {gamma}{delta} T cells expressing genes associated with the interferon pathway was revealed in TCR C{beta} KO chickens, which may contribute to the severe phenotype in these chickens, which is characterized by severe inflammation of spleen, gut and stomach. Additionally, novel gene markers were identified that precisely define the {beta} and {gamma}{delta} T cell subsets. These findings provide new insights into chicken T cell biology and contribute to a better understanding of the mechanisms underlying the severe phenotype observed in TCR C{beta} KO chickens.

immunology↗

bioRxiv2025

Type I and type III interferon receptor knockout chickens: Novel models for unraveling interferon dynamics in influenza infection

The rapid cross-species transmission of highly pathogenic avian influenza presents a significant zoonotic threat. Elucidating the avian interferon (IFN) system, the primary antiviral defense in chickens, is critical for controlling the virus at its source and preventing its spillover into humans and other species. We engineered type I (IFN-/{beta}) and type III (IFN-{lambda}) IFN receptor knockout chickens to dissect the role of IFNs in viral infections. Results revealed that type I IFN predominantly modulates innate immune cell populations, T cell subsets, and their contribution to antibody production following immunization under physiological conditions. In ovo and in vivo challenge experiments utilizing diverse influenza A virus strains demonstrated strain-specific roles of both IFN-/{beta} and IFN-{lambda} in orchestrating viral pathogenesis, immunological responses, and tissue-tropism effects. Notably, type I IFN was particularly crucial in the initial defense mechanisms against H3N1 avian influenza A virus infection. These novel models offer unprecedented insights into avian IFN biology within the context of avian influenza, which is essential for developing more effective strategies to prevent and control this public health challenge.

immunology↗

bioRxiv2024

Cell binding, uptake and infection of influenza A virus using recombinant antibody-based receptors.

Human and avian influenza A viruses bind to sialic acid (Sia) receptors on cells as their primary receptors, and this results in endocytic uptake of the virus. While the role of Sia on glycoproteins and/or glycolipids for virus entry is crucial, the roles of the carrier proteins are still not well understood. Furthermore, it is still unclear how receptor binding leads to infection, including whether the receptor plays a structural or other roles beyond being a simple tether. To enable the investigation of the receptor binding and cell entry processes in a more controlled manner, we have designed a protein receptor for pandemic H1 influenza A viruses. The engineered receptor possesses the binding domains of an anti-HA antibody prepared as a single chain variable fragment (scFv) fused with the stalk, transmembrane and cytoplasmic sequences of the feline transferrin receptor type-1 (fTfR). When expressed in cells that lack efficient display of Sia due to a knockout of the Slc35A1gene which encodes for the Solute Carrier Family 35 transporter (SLC35A1), the anti-H1 receptor was displayed on the cell surface, bound virus or hemagglutinin proteins, and the virus was efficiently endocytosed into the cells. Infection occurred at similar levels to those seen after Sia reconstitution, and treatment with clathrin-mediated endocytosis (CME) inhibitors significantly reduced viral entry. IMPORTANCE.Influenza A viruses mostly circulate among avian reservoirs, and also can jump hosts to cause epidemics in mammals, including among humans. A key interaction of the viruses is with host cell Sia, which vary in chemical form, in their linkages within the oligosaccharide, and in the attachment to surface glycoproteins or glycolipids with different properties. Here we report a new method for examining the processes of receptor binding and uptake into cells during influenza A virus infection, by use of an engineered HA-binding membrane glycoprotein, where an antibody is used as the binding domain and the transferrin receptor uptake structures mediate efficient entry, which should allow us to test and manipulate the processes of cell binding, entry, and infection.

microbiology↗

bioRxiv2023

Viral capsid, antibody, and receptor interactions: experimental analysis of the antibody escape evolution of canine parvovirus

Canine parvovirus (CPV) is a small non-enveloped single-stranded DNA virus that causes serious diseases in dogs worldwide. The original strain of the virus (CPV-2) emerged in dogs during the late-1970s due to a host range switch of a virus similar to the feline panleukopenia virus (FPV) that infected another host. The virus that emerged in dogs had altered capsid receptor- and antibody-binding sites, with some changes affecting both functions. Further receptor and antibody binding changes arose when the virus became better adapted to dogs or to other hosts. Here, we use in vitro selection and deep sequencing to reveal how two antibodies with known interactions select for escape mutations in CPV. The antibodies bind two distinct epitopes, and one largely overlaps the host receptor binding site. We also engineered antibody variants with altered binding structures. Viruses were passaged with the wild type or mutated antibodies, and their genomes deep sequenced during the selective process. A small number of mutations were detected only within the capsid protein gene during the first few passages of selection, and most sites remained polymorphic or were slow to go to fixation. Mutations arose both within and outside the antibody binding footprints on the capsids, and all avoided the TfR-binding footprint. Many selected mutations matched those that have arisen in the natural evolution of the virus. The patterns observed reveal the mechanisms by which these variants have been selected in nature and provide a better understanding of the interactions between antibody and receptor selections. IMPORTANCEAntibodies protect animals against infection by many different viruses and other pathogens, and we are gaining new information about the epitopes that induce antibody responses against viruses and the structures of the bound antibodies. However, less is known about the processes of antibody selection and antigenic escape and the constraints that apply in this system. Here, we use an in vitro model system and deep genome sequencing to reveal the mutations that arise in the virus genome during selection by each of two monoclonal antibodies or their engineered variants. High-resolution structures of each of the Fab: capsid complexes revealed their binding interactions. The engineered forms of the wild-type antibodies or mutant forms allowed us to examine how changes in antibody structure influence the mutational selection patterns seen in the virus. The results shed light on the processes of antibody binding, neutralization escape, and receptor binding, and likely have parallels for many other viruses.

evolutionary biology↗