PubMed Health⌕ Search

Biomedical subjects

Felix A Rey

Publications and source records attributed to Felix A Rey.

8 recordsLinked to original sources
PubMed2026

Affinity-matured B cell responses neutralizing type-I interferons underlie severe viral infections.

Autoantibodies neutralizing type-I interferons (AAN-I-IFNs) emerge as global, common, and strong determinants of a growing number of severe viral diseases. We report that AAN-I-IFNs+ patients with life-threatening COVID-19 pneumonia harbor circulating type-I IFN-specific B cells indistinguishable from patients bearing T cell tolerance defects of genetic origin. This autoimmune response mobilizes a highly diverse and stable circulating B cell response that is detected prior to severe viral infection and acquires high affinity and neutralization potential to type-I IFNs through extended somatic hypermutation. X-ray crystallography and AlphaFold3 structural analysis of hundreds of patient-derived monoclonal antibodies reveals the extended breadth of this response, targeting three major B cell epitopes covering all facets of type-I IFNs. These findings support a model in which a germinal-center-derived memory B cell response directed against type-I IFNs is established before severe viral infection, providing a core mechanism linking T cell tolerance defect to pathogenic AAN-I-IFNs underlying severe viral diseases.

Humans↗
PubMed2007

The nine C-terminal amino acids of the respiratory syncytial virus protein P are necessary and sufficient for binding to ribonucleoprotein complexes in which six ribonucleotides are contacted per N protein protomer.

The respiratory syncytial virus (RSV) phosphoprotein (P) is a major polymerase co-factor that interacts with both the large polymerase fragment (L) and the nucleoprotein (N). The N-binding domain of RSV P has been investigated by co-expression of RSV P and N proteins in Escherichia coli. Pull-down assays performed with a series of truncated forms of P fused to glutathione S-transferase (GST) revealed that the region comprising the last nine C-terminal amino acid residues of P (233-DNDLSLEDF-241) is sufficient for efficient binding to N. Site-directed mutagenesis shows that the last four residues of this peptide are crucial for binding and must be present at the end of a flexible C-terminal tail. The presence of the P oligomerization domain (residues 100-160) was an important stabilizing factor for the interaction. The tetrameric full-length P fused to GST was able to pull down both helical and ring structures, whereas a monomeric C-terminal fragment of P (residues 161-241) fused to GST pulled down exclusively RNA-N rings. Electron-microscopy analysis of the purified rings showed the presence of two types of complex: undecamers (11N) and decamers (10N). Mass-spectrometry analysis of the RNA extracted from rings after RNase A treatment showed two peaks of 22,900 and 24,820 Da, corresponding to a mean RNA length of 67 and 73 bases, respectively. These results suggest strongly that each N subunit contacts 6 nt, with an extra three or four bases further protected from nuclease digestion by the ring structure at both the 5' and 3' ends.

Amino Acid Substitution↗
PubMed2005

Dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN)-mediated enhancement of dengue virus infection is independent of DC-SIGN internalization signals.

Dengue virus (DV) is a mosquito-borne flavivirus that causes hemorrhagic fever in humans. In the natural infection, DV is introduced into human skin by an infected mosquito vector where it is believed to target immature dendritic cells (DCs) and Langerhans cells (LCs). We found that DV productively infects DCs but not LCs. We show here that the interactions between DV E protein, the sole mannosylated glycoprotein present on DV particles, and the C-type lectin dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) are essential for DV infection of DCs. Binding of mannosylated N-glycans on DV E protein to DC-SIGN triggers a rapid and efficient internalization of the viral glycoprotein. However, we observed that endocytosis-defective DC-SIGN molecules allow efficient DV replication, indicating that DC-SIGN endocytosis is dispensable for the internalization step in DV entry. Together, these results argue in favor of a mechanism by which DC-SIGN enhances DV entry and infection in cis. We propose that DC-SIGN concentrates mosquito-derived DV particles at the cell surface to allow efficient interaction with an as yet unidentified entry factor that is ultimately responsible for DV internalization and pH-dependent fusion into DCs.

Base Sequence↗
PubMed2004

Structural biology of hepatitis C virus.

Hepatitis C virus (HCV) causes acute and chronic liver disease in humans, including chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Studies of this virus have been hampered by the lack of a productive cell culture system; most information thus has been obtained from analysis of the HCV genome, heterologous expression systems, in vitro and in vivo models, and structural analyses. Structural analyses of HCV components provide an essential framework for understanding of the molecular mechanisms of HCV polyprotein processing, RNA replication, and virion assembly and may contribute to a better understanding of the pathogenesis of hepatitis C. Moreover, these analyses should allow the identification of novel targets for antiviral intervention and development of new strategies to prevent and combat viral hepatitis. This article reviews the current knowledge of HCV structural biology.

Hepacivirus↗
PubMed2004

Characterization of a membrane-associated trimeric low-pH-induced Form of the class II viral fusion protein E from tick-borne encephalitis virus and its crystallization.

The interaction of a dimeric membrane anchor-free form of the envelope protein E (sE dimer) from tick-borne encephalitis virus with liposomes at acidic pH levels leads to its conversion into membrane-inserted sE trimers. Electron microscopy shows that these trimers have their long dimensions along the threefold molecular axis, which is oriented perpendicularly to the plane of the membrane, where the protein inserts via the internal fusion peptide. Liposomes containing sE at their surface display paracrystalline arrays of protein in a closely packing arrangement in which each trimer is surrounded by six others, suggesting cooperativity in the insertion process. sE trimers, solubilized with nonionic detergents, yielded three-dimensional crystals suitable for X-ray diffraction analysis.

Cell Line↗
PubMed2004

Purification and crystallization reveal two types of interactions of the fusion protein homotrimer of Semliki Forest virus.

The fusion proteins of the alphaviruses and flaviviruses have a similar native structure and convert to a highly stable homotrimer conformation during the fusion of the viral and target membranes. The properties of the alpha- and flavivirus fusion proteins distinguish them from the class I viral fusion proteins, such as influenza virus hemagglutinin, and establish them as the first members of the class II fusion proteins. Understanding how this new class carries out membrane fusion will require analysis of the structural basis for both the interaction of the protein subunits within the homotrimer and their interaction with the viral and target membranes. To this end we report a purification method for the E1 ectodomain homotrimer from the alphavirus Semliki Forest virus. The purified protein is trimeric, detergent soluble, retains the characteristic stability of the starting homotrimer, and is free of lipid and other contaminants. In contrast to the postfusion structures that have been determined for the class I proteins, the E1 homotrimer contains the fusion peptide region responsible for interaction with target membranes. This E1 trimer preparation is an excellent candidate for structural studies of the class II viral fusion proteins, and we report conditions that generate three-dimensional crystals suitable for analysis by X-ray diffraction. Determination of the structure will provide our first high-resolution views of both the low-pH-induced trimeric conformation and the target membrane-interacting region of the alphavirus fusion protein.

Animals↗
PubMed2002

Scaffolds for protein crystallisation.

In the absence of a method to ensure that crystals can be obtained for any given protein, the possibility of developing scaffolds for protein crystallisation becomes attractive. Among several approaches that could yield scaffolds, two are particularly promising: the first is based on immunoglobulin Fab fragments and immunoglobulin binding proteins while the second is based on fusion proteins. In the Fab based scaffold, the protein of interest is the antigen recognised by the antibody. In the second case, it is a protein fused to one of the scaffold components. The operational difference between the two methods is the existence of a flexible covalent tether compared to a highly specific interaction. The relative merits and disadvantages of each approach are discussed here. We also describe a lattice obtained through a combinatorial approach which appears to have the required properties to be considered a scaffold. The system makes use of an Fab derived from a rheumatoid factor and an Fc-fusion protein. The Fc-fusion system is ideal for enhanced expression of glycoproteins in mammalian cells and provides a useful tag for their purification. The molecular replacement shows a mode of binding for this rheumatoid factor that is not competitive with bacterial Fc-binding proteins. Hence it may be possible to generalize the method to include bacterial expression of fusion proteins with either protein A or protein G as the fusion partner.

Amino Acid Sequence↗