Biology subjects

Darling, T.

Publications and source records attributed to Darling, T..

3 recordsLinked to original sources

bioRxiv2024

Defining a highly conserved B cell epitope in the receptor binding motif of SARS-CoV-2 spike glycoprotein

SARS-CoV-2 mRNA vaccines induce robust and persistent germinal centre (GC) B cell responses in humans. It remains unclear how the continuous evolution of the virus impacts the breadth of the induced GC B cell response. Using ultrasound-guided fine needle aspiration, we examined draining lymph nodes of nine healthy adults following bivalent booster immunization. We show that 77.8% of the B cell clones in the GC expressed as representative monoclonal antibodies recognized the spike protein, with a third (37.8%) of these targeting the receptor binding domain (RBD). Strikingly, only one RBD-targeting mAb, mAb-52, neutralized all tested SARS- CoV-2 strains, including the recent KP.2 variant. mAb-52 utilizes the IGHV3-66 public clonotype, protects hamsters challenged against the EG.5.1 variant and targets the class I/II RBD epitope, closely mimicking the binding footprint of ACE2. Finally, we show that the remarkable breadth of mAb-52 is due to the somatic hypermutations accumulated within vaccine-induced GC reaction. One Sentence SummaryBooster SARS-CoV-2 mRNA vaccine recruits and broadens GC B cell responses targeting a highly conserved site on receptor binding domain of spike glycoprotein.

immunology↗

bioRxiv2023

The highly conserved stem-loop II motif is dispensable for SARS-CoV-2

The stem-loop II motif (s2m) is a RNA structural element that is found in the 3 untranslated region (UTR) of many RNA viruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Though the motif was discovered over twenty-five years ago, its functional significance is unknown. In order to understand the importance of s2m, we created viruses with deletions or mutations of the s2m by reverse genetics and also evaluated a clinical isolate harboring a unique s2m deletion. Deletion or mutation of the s2m had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also compared the secondary structure of the 3 UTR of wild type and s2m deletion viruses using SHAPE-MaP and DMS-MaPseq. These experiments demonstrate that the s2m forms an independent structure and that its deletion does not alter the overall remaining 3UTR RNA structure. Together, these findings suggest that s2m is dispensable for SARS-CoV-2. IMPORTANCERNA viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contain functional structures to support virus replication, translation and evasion of the host antiviral immune response. The 3 untranslated region of early isolates of SARS-CoV-2 contained a stem-loop II motif (s2m), which is a RNA structural element that is found in many RNA viruses. This motif was discovered over twenty-five years ago, but its functional significance is unknown. We created SARS-CoV-2 with deletions or mutations of the s2m and determined the effect of these changes on viral growth in tissue culture and in rodent models of infection. Deletion or mutation of the s2m element had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also observed no impact of the deletion on other known RNA structures in the same region of the genome. These experiments demonstrate that the s2m is dispensable for SARS-CoV-2.

microbiology↗

bioRxiv2020

A single intranasal or intramuscular immunization with chimpanzee adenovirus vectored SARS-CoV-2 vaccine protects against pneumonia in hamsters.

The development of an effective vaccine against SARS-CoV-2, the etiologic agent of COVID-19, is a global priority. Here, we compared the protective capacity of intranasal and intramuscular delivery of a chimpanzee adenovirus-vectored vaccine encoding a pre-fusion stabilized spike protein (ChAd-SARS-CoV-2-S) in Golden Syrian hamsters. While immunization with ChAd-SARS-CoV-2-S induced robust spike protein specific antibodies capable or neutralizing the virus, antibody levels in serum were higher in hamsters immunized by an intranasal compared to intramuscular route. Accordingly, ChAd-SARS-CoV-2-S immunized hamsters were protected against a challenge with a high dose of SARS-CoV-2. After challenge, ChAd-SARS-CoV-2-S-immunized hamsters had less weight loss and showed reductions in viral RNA and infectious virus titer in both nasal swabs and lungs, and reduced pathology and inflammatory gene expression in the lungs, compared to ChAd-Control immunized hamsters. Intranasal immunization with ChAd-SARS-CoV-2-S provided superior protection against SARS-CoV-2 infection and inflammation in the upper respiratory tract. These findings support intranasal administration of the ChAd-SARS-CoV-2-S candidate vaccine to prevent SARS-CoV-2 infection, disease, and possibly transmission.

microbiology↗