Biology subjects

Moro, S. G.

Publications and source records attributed to Moro, S. G..

5 recordsLinked to original sources

bioRxiv2026

Structural basis of diverse antibody recognition of conserved coronavirus spike S2 epitopes that contribute to protective immunity

Conserved epitopes within the coronavirus spike S2 domain elicit broadly reactive antibodies, yet many characterized responses show limited neutralizing and variable protective activity, leaving their contribution to antiviral immunity unclear. Building on our previous mapping of evolutionarily conserved spike coldspots, we isolated human monoclonal antibodies targeting four conserved epitopes in the spike S2 domain: the internal fusion peptide (iFP), the central helix (CH), the connector domain (CD), and a membrane-proximal epitope in the heptad repeat 2 that we term the lower stalk (LS). A crystal structure of an LS-directed antibody defined a previously unresolved mode of antibody recognition of this membrane-proximal epitope, while cryogenic electron microscopy (cryo-EM) structures revealed that genetically diverse CH-specific antibodies use distinct binding modes to converge on conserved features of the prefusion S2 apex. Despite minimal neutralizing activity, CH- and LS-directed antibodies exhibited distinct antiviral functions. LS-directed antibodies mediated Fc{gamma} receptor-dependent effector activity in vitro, whereas the broadly reactive CH-directed antibody ch.007 lacked detectable antibody-dependent cellular cytotoxicity (ADCC) or cellular phagocytosis (ADCP) activity yet protected mice from lethal SARS-CoV-2 MA10 challenge, with protection abrogated by Fc{gamma} receptor-silencing mutations. Together, these findings expand the genetic, structural and functional landscape of human antibody responses to conserved coronavirus S2 epitopes and demonstrate that CH-directed antibodies can contribute to protective immunity through Fc-dependent mechanisms not predicted by in vitro neutralization or conventional in vitro Fc effector assays.

biophysics↗

bioRxiv2026

Human antibodies against West Nile and related orthoflaviviruses

West Nile virus (WNV) is a mosquito-borne pathogen of global concern that can cause fatal neuroinvasive disease. No specific prophylaxis or treatment exists for WNV or related orthoflavivirus infections, and the determinants of human disease severity remain poorly understood. Here, we report that neutralizing autoantibodies against type I interferons do not impair antiviral antibody development. Among the fully human monoclonal antibodies with potent neutralizing activity against WNV that were discovered, W010 targets a unique epitope within the envelope protein domain III (EDIII) and confers both pre- and post-exposure protection in a murine WNV model, even when interferon signaling is impaired. A second protective antibody, W014, exhibits broad cross-neutralization of other pathogenic orthoflavivirus members, including Japanese encephalitis virus, Murray Valley encephalitis virus, Saint Louis encephalitis virus, and Usutu virus. These findings identify key neutralizing epitopes on WNV EDIII and provide candidates for the development of antibody-based interventions against encephalitic orthoflavivirus infections.

immunology↗

bioRxiv2025

Dual Role of Plasmacytoid Dendritic Cells in Humoral and CD8⁺ T Cell Memory Post COVID-19 mRNA Vaccination

The Pfizer-BioNTech coronavirus vaccine (BNT162b2), one of the first nanoparticle-based vaccines approved by the World Health Organisation (WHO), demonstrated 95% efficacy in preventing against Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the precise mechanism of action underlying its effectiveness remains poorly understood. This study investigated the early immune responses in the draining lymph node (dLN) and its role in mediating antiviral protection following vaccination. Here, we focused on the involvement of antigen-presenting cells (APCs) in adaptive immunity. In this study, we demonstrated that the Pfizer-BioNTech coronavirus vaccine is rapidly transported to the dLN and is primarily captured by leukocytes that initiate the expression of the viral antigenic spike protein. Notably, we demonstrated that plasmacytoid dendritic cells (pDCs) are key orchestrators of the inflammatory and humoral response, as their specific depletion led to impaired antibody production and diminished neutralization capacity. Furthermore, single-cell transcriptomic analysis revealed an interaction between pDCs and CD8+ T cells that facilitates T cell activation. In vivo experiments confirmed that pDCs expressing the viral spike protein directly engage with CD8+ T cells, promoting their differentiation and expansion. Moreover, the absence of pDCs affected the formation of antigen-specific memory T cells. Overall, these findings highlight that pDCs are essential players in mediating both adaptive and humoral responses to the Pfizer-BioNTech coronavirus vaccine, providing insights into the mechanistic functioning of mRNA vaccines and establishing a novel role for pDCs as professional APCs.

immunology↗

bioRxiv2024

Crosstalk between the RNA-binding proteins Regnase-1 and -3 shapes mast cell survival and cytokine expression

Post-transcriptional regulation of immune-related transcripts by RNA-binding proteins (RBPs) impacts immune cell responses, including mast cell functionality. Despite their importance in immune regulation, the functional role of most RBPs remains to be understood. By manipulating the expression of specific RBPs in mast cells, coupled with mass spectrometry and transcriptomic analyses, we found that the Regnase family of proteins acts as a potent regulator of mast cell physiology. Specifically, Regnase-1 is required to maintain basic cell proliferation and survival, while both Regnase-1 and -3 cooperatively regulate the expression of inflammatory transcripts upon mast cell activation, with Tnf being a primary target of both proteins. In mast cells, Regnase-3 directly interacts with Regnase-1 and is necessary to restrain Regnase-1 expression through the destabilization of its transcript. Overall, our study identifies protein interactors of endogenously expressed Regnase factors, characterizes the regulatory interplay between Regnase family members in mast cells, and establishes their role in the control of mast cell homeostasis and inflammatory responses.

immunology↗

bioRxiv2018

Using ribosome profiling to quantify differences in protein expression: a case study in Saccharomyces cerevisiae oxidative stress conditions

Cells respond to changes in the environment by modifying the concentration of specific proteins. Paradoxically, the cellular response is usually examined by measuring variations in transcript abundance by high throughput RNA sequencing (RNA-Seq), instead of directly measuring protein concentrations. This happens because RNA-Seq-based methods provide better quantitative estimates, and more extensive gene coverage, than proteomics-based ones. However, variations in transcript abundance do not necessarily reflect changes in the corresponding protein abundance. How can we close this gap? Here we explore the use of ribosome profiling (Ribo-Seq) to perform differentially gene expression analysis in a relatively well-characterized system, oxidative stress in bakers yeast. Ribo-Seq is an RNA sequencing method that specifically targets ribosome-protected RNA fragments, and thus is expected to provide a more accurate view of changes at the protein level than classical RNA-Seq. We show that gene quantification by Ribo-Seq is indeed more highly correlated with protein abundance, as measured from mass spectrometry data, than quantification by RNA-Seq. The analysis indicates that, whereas a subset of genes involved in oxidation-reduction processes is detected by both types of data, the majority of the genes that happen to be significant in the RNA-Seq-based analysis are not significant in the Ribo-Seq analysis, suggesting that they do not result in protein level changes. The results illustrate the advantages of Ribo-Seq to make inferences about changes in protein abundance in comparison with RNA-Seq.

genomics↗