A novel live DNA tagging system for African swine fever virus shows that bisbenzimide Hoechst 33342 can effectively block its replication.

African swine fever virus (ASFV) infection causes a frequently fatal disease in domestic swine that has affected more than 50 countries worldwide since 2021, with a major impact on animal welfare and economy. The development of effective vaccines or antivirals against this disease are urgently required for its effective control. Live detection of viral replication has been used as a tool for the screening and characterization of antiviral compounds in other dsDNA genome containing viruses.

Engineering recombinant replication-competent bluetongue viruses expressing reporter genes for and non-invasive studies.

Bluetongue virus (BTV) is the causative agent of the important livestock disease bluetongue (BT), which is transmitted via Culicoides bites. BT causes severe economic losses associated with its considerable impact on health and trade of animals. By reverse genetics, we have designed and rescued reporter-expressing recombinant (r)BTV expressing NanoLuc luciferase (NLuc) or Venus fluorescent protein.

African swine fever virus transmembrane protein pEP84R guides core assembly.

African swine fever virus (ASFV) causes a devastating hemorrhagic disease with worldwide circulation and no widely available therapeutic prevention. The infectious particle has a multilayered architecture that is articulated upon an endoplasmic reticulum (ER)-derived inner envelope. This membrane acts as docking platform for the assembly of the outer icosahedral capsid and the underlying core shell, a bridging layer required for the formation of the central genome-containing nucleoid.

Endoplasmic reticulum expansion throughout the differentiation of teleost B cells to plasmablasts.

The differentiation of B cells into antibody-secreting cells is fundamental for the generation of humoral immunity. In mammals, this process involves a series of metabolic and intracellular changes, not studied to date in teleost fish, where a clear distinction between naive B cells and plasmablasts/plasma cells (PCs) is still missing. Thus, in the current study, we have established that upon activation, teleost B cells undergo an expansion of the endoplasmic reticulum (ER) but experience no significant changes in mitochondria content.

Plasmolipin regulates basolateral-to-apical transcytosis of ICAM-1 and leukocyte adhesion in polarized hepatic epithelial cells.

Apical localization of Intercellular Adhesion Receptor (ICAM)-1 regulates the adhesion and guidance of leukocytes across polarized epithelial barriers. Here, we investigate the molecular mechanisms that determine ICAM-1 localization into apical membrane domains of polarized hepatic epithelial cells, and their effect on lymphocyte-hepatic epithelial cell interaction. We had previously shown that segregation of ICAM-1 into apical membrane domains, which form bile canaliculi and bile ducts in hepatic epithelial cells, requires basolateral-to-apical transcytosis.

High ulcerative colitis and Crohn's disease ratio in a population-based registry from Córdoba, Argentina.

Background: Few studies have described the epidemiology and clinical behavior of inflammatory bowel disease (IBD) in South America. The aim of this study was to report on the prevalence, phenotype, and treatment of patients with IBD diagnosis in Capital Department of the Province of Córdoba, Argentina.

Methods: Data from adult patients (≥ 18 years-old) with IBD diagnosis that attended 12 public or private centers between 05/2014 and 05/2019 were included in a common registry.

African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration.

African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) causing a lethal hemorrhagic disease that currently threatens the global pig industry. Despite its relevance in the infectious cycle, very little is known about the internalization of ASFV in the host cell. Here, we report the characterization of ASFV protein pE199L, a cysteine-rich structural polypeptide with similarity to proteins A16, G9, and J5 of the entry fusion complex (EFC) of poxviruses.

The cryo-EM structure of African swine fever virus unravels a unique architecture comprising two icosahedral protein capsids and two lipoprotein membranes.

African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) that causes a devastating swine disease currently present in many countries of Africa, Europe, and Asia. Despite intense research efforts, relevant gaps in the architecture of the infectious virus particle remain. Here, we used single-particle cryo-EM to analyze the three-dimensional structure of the mature ASFV particle.

Antiangiogenic Vascular Endothelial Growth Factor-Blocking Peptides Displayed on the Capsid of an Infectious Oncolytic Parvovirus: Assembly and Immune Interactions.

As many tumor cells synthetize vascular endothelial growth factors (VEGF) that promote neo-vascularization and metastasis, frontline cancer therapies often administer anti-VEGF (α-VEGF) antibodies. To target the oncolytic parvovirus minute virus of mice (MVM) to the tumor vasculature, we studied the functional tolerance, evasion of neutralization, and induction of α-VEGF antibodies of chimeric viruses in which the footprint of a neutralizing monoclonal antibody within the 3-fold capsid spike was replaced by VEGF-blocking peptides: P6L (PQPRPL) and A7R (ATWLPPR). Both peptides allowed viral genome replication and nuclear translocation of chimeric capsid subunits.

A Proteomic Atlas of the African Swine Fever Virus Particle.

African swine fever virus (ASFV) is a large and complex DNA virus that causes a highly lethal swine disease for which there is no vaccine available. The ASFV particle, with an icosahedral multilayered structure, contains multiple polypeptides whose identity is largely unknown. Here, we analyzed by mass spectroscopy the protein composition of highly purified extracellular ASFV particles and performed immunoelectron microscopy to localize several of the detected proteins.

African Swine Fever Virus Gets Undressed: New Insights on the Entry Pathway.

African swine fever virus (ASFV) is a large, multienveloped DNA virus composed of a genome-containing core successively wrapped by an inner lipid envelope, an icosahedral protein capsid, and an outer lipid envelope. In keeping with this structural complexity, recent studies have revealed an intricate entry program. This Gem highlights how ASFV uses two alternative pathways, macropinocytosis and clathrin-mediated endocytosis, to enter into the host macrophage and how the endocytosed particles undergo a stepwise, low pH-driven disassembly leading to inner envelope fusion and core delivery in the cytoplasm.

Novel role for the midbody in primary ciliogenesis by polarized epithelial cells.

The primary cilium is a membrane protrusion that is crucial for vertebrate tissue homeostasis and development. Here, we investigated the uncharacterized process of primary ciliogenesis in polarized epithelial cells. We show that after cytokinesis, the midbody is inherited by one of the daughter cells as a remnant that initially locates peripherally at the apical surface of one of the daughter cells.

African Swine Fever Virus Undergoes Outer Envelope Disruption, Capsid Disassembly and Inner Envelope Fusion before Core Release from Multivesicular Endosomes.

African swine fever virus (ASFV) is a nucleocytoplasmic large DNA virus (NCLDV) that causes a highly lethal disease in domestic pigs. As other NCLDVs, the extracellular form of ASFV possesses a multilayered structure consisting of a genome-containing nucleoid successively wrapped by a thick protein core shell, an inner lipid membrane, an icosahedral protein capsid and an outer lipid envelope. This structural complexity suggests an intricate mechanism of internalization in order to deliver the virus genome into the cytoplasm.

Podoplanin is a component of extracellular vesicles that reprograms cell-derived exosomal proteins and modulates lymphatic vessel formation.

Podoplanin (PDPN) is a transmembrane glycoprotein that plays crucial roles in embryonic development, the immune response, and malignant progression. Here, we report that cells ectopically or endogenously expressing PDPN release extracellular vesicles (EVs) that contain PDPN mRNA and protein. PDPN incorporates into membrane shed microvesicles (MVs) and endosomal-derived exosomes (EXOs), where it was found to colocalize with the canonical EV marker CD63 by immunoelectron microscopy.

Establishment of a Zebrafish Infection Model for the Study of Wild-Type and Recombinant European Sheatfish Virus.

Amphibian-like ranaviruses include pathogens of fish, amphibians, and reptiles that have recently evolved from a fish-infecting ancestor. The molecular determinants of host range and virulence in this group are largely unknown, and currently fish infection models are lacking. We show that European sheatfish virus (ESV) can productively infect zebrafish, causing a lethal pathology, and describe a method for the generation of recombinant ESV, establishing a useful model for the study of fish ranavirus infections.

Cutting Edge: Regulation of Exosome Secretion by the Integral MAL Protein in T Cells.

Exosomes secreted by T cells play an important role in coordinating the immune response. HIV-1 Nef hijacks the route of exosome secretion of T cells to modulate the functioning of uninfected cells. Despite the importance of the process, the protein machinery involved in exosome biogenesis is yet to be identified.

African swine fever virus assembles a single membrane derived from rupture of the endoplasmic reticulum.

Collective evidence argues that two members of the nucleocytoplasmic large DNA viruses (NCLDVs) acquire their membrane from open membrane intermediates, postulated to be derived from membrane rupture. We now study membrane acquisition of the NCLDV African swine fever virus. By electron tomography (ET), the virion assembles a single bilayer, derived from open membrane precursors that collect as ribbons in the cytoplasm.

The MAL protein is crucial for proper membrane condensation at the ciliary base, which is required for primary cilium elongation.

The base of the primary cilium contains a zone of condensed membranes whose importance is not known. Here, we have studied the involvement of MAL, a tetraspanning protein that exclusively partitions into condensed membrane fractions, in the condensation of membranes at the ciliary base and investigated the importance of these membranes in primary cilium formation. We show that MAL accumulates at the ciliary base of epithelial MDCK cells.

Developmental regulation of apical endocytosis controls epithelial patterning in vertebrate tubular organs.

Epithelial organs develop through tightly coordinated events of cell proliferation and differentiation in which endocytosis plays a major role. Despite recent advances, how endocytosis regulates the development of vertebrate organs is still unknown. Here we describe a mechanism that facilitates the apical availability of endosomal SNARE receptors for epithelial morphogenesis through the developmental upregulation of plasmolipin (pllp) in a highly endocytic segment of the zebrafish posterior midgut.

Exosomes as Hedgehog carriers in cytoneme-mediated transport and secretion.

The Hedgehog signalling pathway is crucial for development, adult stem cell maintenance, cell migration and axon guidance in a wide range of organisms. During development, the Hh morphogen directs tissue patterning according to a concentration gradient. Lipid modifications on Hh are needed to achieve graded distribution, leading to debate about how Hh is transported to target cells despite being membrane-tethered.

Cyclic adenosine monophosphate-response element-binding protein mediates the proangiogenic or proinflammatory activity of gremlin.

Objective: Angiogenesis and inflammation are closely related processes. Gremlin is a novel noncanonical vascular endothelial growth factor receptor-2 (VEGFR2) ligand that induces a proangiogenic response in endothelial cells (ECs). Here, we investigated the role of the cyclic adenosine monophosphate-response element (CRE)-binding protein (CREB) in mediating the proinflammatory and proangiogenic responses of ECs to gremlin.

Cytonemes are required for the establishment of a normal Hedgehog morphogen gradient in Drosophila epithelia.

Hedgehog (Hh) signalling is important in development, stem cell biology and disease. In a variety of tissues, Hh acts as a morphogen to regulate growth and cell fate specification. Several hypotheses have been proposed to explain morphogen movement, one of which is transport along filopodia-like protrusions called cytonemes.

Engineering a replication-competent, propagation-defective Middle East respiratory syndrome coronavirus as a vaccine candidate.

Unlabelled: Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging coronavirus infecting humans that is associated with acute pneumonia, occasional renal failure, and a high mortality rate and is considered a threat to public health. The construction of a full-length infectious cDNA clone of the MERS-CoV genome in a bacterial artificial chromosome is reported here, providing a reverse genetics system to study the molecular biology of the virus and to develop attenuated viruses as vaccine candidates. Following transfection with the cDNA clone, infectious virus was rescued in both Vero A66 and Huh-7 cells.