Biology subjects

Sol, A.

Publications and source records attributed to Sol, A..

4 recordsLinked to original sources

bioRxiv2026

Bovine coronavirus evolution preserves spike architecture while remodeling key functional regions

Bovine coronavirus (BCoV) is a major pathogen of cattle and the closest known ancestor of the human coronavirus OC43, yet how viral evolution reshapes spike protein structure and function remains poorly understood. Here, we combined comparative genomics, glycoproteomics, cryo-EM, and antigenic characterization to define the structural mechanisms underlying spike evolution across representative BCoV lineages. We identify a previously unrecognized lineage-specific N-glycosylation site in contemporary European viruses and validate its occupancy by glycoproteomics. High-resolution cryo- EM structures reveal that BCoV evolution preserves the overall prefusion architecture of the spike glycoprotein while selectively remodeling key functional regions involved in receptor recognition, conformational dynamics, and antigenicity. Comparative analysis with OC43 demonstrates increased conformational heterogeneity of the receptor-binding loop, whereas the Mebus vaccine strain exhibits enhanced membrane-proximal stalk flexibility despite maintaining thermal stability. Finally, structural modeling together with antibody-binding experiments reveals substantial antigenic remodeling despite >90% spike sequence identity between BCoV and OC43. Together, these findings establish a mechanistic framework for Embecovirus spike evolution and provide structural insights that may inform the development of vaccines based on contemporary circulating strains.

microbiology↗

bioRxiv2024

Primary bovine white blood cells support dissemination of Lumpy Skin Disease Virus while suppressing viral replication

Lumpy skin disease (LSD) is a severe infectious, emerging transboundary disease of cattle, caused by a Pox family DNA virus. Lumpy skin disease virus (LSDV) infection is associated with a febrile response followed by emergence of widespread dermal nodules. In addition to the skin, LSDV resides in multiple internal organs and can be isolated from the blood of infected cattle. LSDV is suggested to be mechanically transmitted by biting arthropods. Live attenuated vaccines are commonly used to control disease and its spread. We have characterized the tropism, replication, and dissemination of a LSDV field isolate and of an attenuated vaccine strain using in vitro systems. To follow virus infection and dissemination in living cells, we have generated recombinant viruses expressing green fluorescent protein (GFP) under a synthetic viral promoter. Recombinant, GFP-expressing, LSDVs demonstrated similar replication kinetics to their corresponding parental LSDV strains in a bovine kidney cell line (MDBK). We further demonstrated that LSDV-GFP productively replicated in a bovine macrophage cell line and in primary bovine foreskin cells with no apparent differences between the field isolate and the vaccine strain. When bovine peripheral blood mononuclear cells (PBMCs) were infected with either LSDV recombinant strain, we observed specific viral driven GFP fluorescence as well as significant viral gene expression. However, infected PBMCs failed to support substantial viral DNA replication and release of infectious progeny. Subsequent analysis of the anti-viral response revealed that heat treated (HT) LSDV induced the expression of interferon- stimulated genes (ISGs) in PBMCs, but this response was suppressed by infectious viruses. Finally, we show that despite failed replication, LSDV infected PBMCs transmitted the virus to recipient co-cultured MDBK cells and produced infectious foci, suggesting a potential role of PBMCs in LSDV dissemination. HighlightsO_LIVirulent and attenuated LSDV productively replicated in bovine kidney and bovine macrophage cell lines as well as in primary fibroblasts. C_LIO_LIAdherent white blood cells were susceptible to LSDV field and attenuated vaccine infection. C_LIO_LILSDV showed active viral transcription in PBMCs yet no significant viral genome replication or production of infectious progeny. C_LIO_LIPBMCs infected with heat-treated LSDV but not with fully infectious viruses upregulated ISGs RNA. C_LIO_LIPBMCs transmitted and disseminated LSDV to contacting permissive cells. C_LI

microbiology↗

bioRxiv2022

5' Untranslated mRNA Regions Allow Bypass of Host Cell Translation Inhibition by Legionella pneumophila

Legionella pneumophila grows within membrane-bound vacuoles in alveolar macrophages during human disease. Pathogen manipulation of the host cell is driven by bacterial proteins translocated through a type IV secretion system (T4SS). Although host protein synthesis during infection is arrested by the action of several of these translocated effectors, translation of a subset of host proteins predicted to restrict the pathogen is maintained. To identify the spectrum of host proteins selectively synthesized after L. pneumophila challenge, macrophages infected with the pathogen were allowed to incorporate the amino acid analog azidohomoalanine (AHA) during a two-hour time window, and newly synthesized macrophage proteins were isolated by orthogonal chemistry followed by mass spectrometry. Among the proteins isolated were interferon-stimulated genes (ISGs) as well as proteins translated from highly abundant transcripts. Surprisingly, a large number of the identified proteins were from low abundance transcripts. These proteins were predicted to be among the most efficiently translated per unit transcript in the cell based on ribosome profiling datasets. To determine if high ribosome loading was a consequence of efficient translation initiation, the 5 untranslated regions (5UTR) of transcripts having the highest and lowest predicted loading levels were inserted upstream of a reporter, and translation efficiency was determined in response to L. pneumophila challenge. The efficiency of reporter expression largely correlated with predicted ribosome loading and lack of secondary structure. Therefore, determinants in the 5UTR allow selected host cell transcripts to overcome a pathogen-driven translation blockade.

microbiology↗

bioRxiv2018

Legionella pneumophila translocated translation inhibitors are required for bacterial-induced host cell cycle arrest

The cell cycle machinery controls diverse cellular pathways and is tightly regulated. Misregulation of cell division plays a central role in the pathogenesis of many disease processes. Various microbial pathogens interfere with the cell cycle machinery to promote host cell colonization. Although cell cycle modulation is a common theme among pathogens, the role that this interference plays in promoting diseases is unclear. Previously we demonstrated that the G1 and G2/M phases of the host cell cycle are permissive for Legionella pneumophila replication, while S phase provides a toxic environment for bacterial replication. In this study we show that L. pneumophila avoids host S phase by blocking host DNA synthesis and preventing cell cycle progression into S phase. Cell cycle arrest upon Legionella contact is dependent on the Icm/Dot secretion system. In particular, we found that cell cycle arrest is dependent on the intact enzymatic activity of translocated substrates that inhibits host translation. Moreover, we show that early in infection, the presence of these translation inhibitors is crucial to induce the degradation of the master regulator cyclin D1. Our results demonstrate that the bacterial effectors that inhibit translation are associated with preventing entry of host cells into a phase associated with restriction of L. pneumophila. Furthermore, control of cyclin D1 may be a common strategy used by intracellular pathogens to manipulate the host cell cycle and promote bacterial replication.\n\nSignificanceRecently, we showed that host cell cycle regulatory proteins control L. pneumophila growth. In particular, bacterial replication was found to be depressed in S-phase. This indicates that bacterial control of the host cell cycle can limit exposure of the pathogen to antimicrobial events that are cycle-specific. Here we uncovered bacterial factors that induce host cell cycle arrest by inhibiting host protein synthesis and preventing S phase transition. These data are consistent with S-phase toxicity serving as an important antimicrobial response that limits growth of some intracellular pathogens. Moreover, identification of microbial factors that block cell cycle progression and uncovering host cell cycle partners are candidates for future drug development. Our data point to a unifying role of the cell cycle in multiple disease processes.

microbiology↗