Biology subjects

Nguyen, Y. T. K.

Publications and source records attributed to Nguyen, Y. T. K..

3 recordsLinked to original sources

bioRxiv2025

The conserved bridging domain on HCV E1E2 glycoprotein complex is targeted by neutralizing antibodies from diverse lineages

The induction of potent and cross-reactive neutralizing antibody (nAb) responses remains a challenge in vaccine development against antigenically diverse viruses such as hepatitis C virus (HCV). The HCV E1E2 glycoprotein complex contains two major neutralizing sites: the neutralizing face (NF) and the less explored bridging domain (BD). Here, we characterized 25 BD-targeting nAbs isolated from infection or immunization. These antibodies arise from diverse B cell lineages but share convergent CDRH3 features. Epitope mapping by alanine scanning and negative-stain electron microscopy revealed overlapping epitopes on BD spanning antigenic regions AR4 and AR5, with variable back layer engagement. The crystal structure of a non-human primate BD nAb RM3-26 in complex with E2 uncovered a back layer-directed recognition mode analogous to that of the human nAb hcab40. Together, BD- and NF-directed nAbs exhibited additivity in their neutralization, highlighting BD as a conserved site of vulnerability on HCV and a valuable target for rational vaccine design.

immunology↗

bioRxiv2025

Structural and genetic signatures of two classes of HCV E2 neutralizing face antibodies from non-human primates immunized with a recombinant E1E2

Hepatitis C continues to be a significant public health problem despite advancements in antiviral therapeutics. To eliminate this disease, an effective vaccine against new infections and re-infections is needed. However, to date only one Hepatitis C virus (HCV) envelope protein (E1E2) immunogen, developed by Chiron Inc., has been tested in a Phase I clinical trial (ClinicalTrials.gov identifier NCT00500747). To establish a benchmark for elicitation of broadly neutralizing antibodies (bnAbs) by E1E2, we previously immunized non-human primates (NHPs) with this immunogen and isolated monoclonal nAbs that exhibit neutralization potency comparable to human nAbs. Here we show that NHP nAbs, encoded by germline genes IGHV1-138*01 and IGHV4-NL_5*01 (homologs of human IGHV1-69*10 and IGHV4-59*12, respectively), recognize a relatively E2 conserved region (neutralizing face) proximal to antigenic region 3 (AR3). These NHP AR3-targeting nAbs share highly similar binding modes to human AR3-targeting nAbs, suggesting a similarity in human and NHP immune responses to the same HCV immunogen.

immunology↗

bioRxiv2021

Mfsd2b and Spns2 are essential for maintenance of blood vessels during development and protection of anaphylaxis

Sphingosine-1-phosphate (S1P) is a potent lipid mediator that is secreted by several cell types to induce signaling. We recently showed that Mfsd2b is an S1P transporter from hematopoietic cells, which contributes approximately 50% plasma S1P. To further determine the sources of plasma S1P, here, we report the characterizations of compound deletions of Mfsd2b and Spns2, another S1P transporter from endothelial cells. Global deletion of Mfsd2b and Spns2 (gDKO) resulted in embryonic lethality between E13.5 and E14.5 with severe hemorrhage that largely recapitulated the phenotypes from global S1P1 knockout mice, indicating that together with Mfsd2b, Spns2 also provides embryonic source of S1P for S1P1 stimulation. The hemorrhagic phenotypes in gDKO embryos were accompanied by increased angiogenesis and defects of tight junction proteins, indicating that S1P from Mfsd2b and Spns2 is essential for blood vessel integrity and maturation. The various sources of S1P in postnatal stages are yet to be fully understood. Postnatal ablation of S1P synthesis enzymes using Mx1Cre shows that Mx1Cre-sensitive cells provide most of plasma S1P. Interestingly, we showed that compound postnatal deletion of Mfsd2b and Spns2 using Mx1Cre (ctDKO-Mx1Cre) resulted in maximal reduction of 80% plasma S1P. Thus, a small amount of plasma S1P is supplied from other sources independent of Mfsd2b and Spns2. Nevertheless, the vasculature in the lung of ctDKO-Mx1Cre mice was compromised. Furthermore, ctDKO-Mx1Cre mice also exhibited severe susceptibility to anaphylaxis, indicating that S1P from Mfsd2b and Spns2 is indispensable during vascular stress. Together, our results show that Mfsd2b and Spns2 provide a critical source of S1P for embryonic development and they also provide a majority of plasma S1P for vascular homeostasis.

molecular biology↗