Biology subjects

Franko, N.

Publications and source records attributed to Franko, N..

7 recordsLinked to original sources

bioRxiv2022

Anamnestic Humoral Correlates of Immunity Across SARS-CoV-2 Variants of Concern

While immune correlates against SARS-CoV-2 are typically defined at peak immunogenicity following vaccination, immunologic responses that expand selectively during the anamnestic response following infection can provide mechanistic and detailed insights into the immune mechanisms of protection. Moreover, whether anamnestic correlates are conserved across VoCs, including the Delta and more distant Omicron variant of concern (VoC), remains unclear. To define the anamnestic correlates of immunity, across VOCs, we deeply profiled the humoral immune response in individuals recently infected with either the Delta or Omicron VoC. While limited acute N-terminal domain and RBD-specific immune expansion was observed following breakthrough, a significant immunodominant expansion of opsinophagocytic Spike-specific antibody responses focused largely on the conserved S2-domain of SARS-CoV-2 was observed 1 week after breakthrough infection. This S2-specific functional humoral response continued to evolve over 2-3 weeks following both Delta and Omicron breakthrough infection, targeting multiple VoCs and common coronaviruses. These responses were focused largely on the fusion peptide 2 and heptad repeat 1, both associated with enhanced rates of viral clearance. Taken together, our results point to a critical role of highly conserved, functional S2-specific responses in the control of SARS-CoV-2 infection, across VOCs, and thus humoral response linked to virus attenuation can guide next-generation generation vaccine boosting approaches to confer broad protection against future SARS-CoV-2 VoCs.

immunology↗

bioRxiv2022

Imprinted antibody responses against SARS-CoV-2 Omicron sublineages

SARS-CoV-2 Omicron sublineages carry distinct spike mutations and represent an antigenic shift resulting in escape from antibodies induced by previous infection or vaccination. We show that hybrid immunity or vaccine boosters result in potent plasma neutralizing activity against Omicron BA.1 and BA.2 and that breakthrough infections, but not vaccination-only, induce neutralizing activity in the nasal mucosa. Consistent with immunological imprinting, most antibodies derived from memory B cells or plasma cells of Omicron breakthrough cases cross-react with the Wuhan-Hu-1, BA.1 and BA.2 receptor-binding domains whereas Omicron primary infections elicit B cells of narrow specificity. While most clinical antibodies have reduced neutralization of Omicron, we identified an ultrapotent pan-variant antibody, that is unaffected by any Omicron lineage spike mutations and is a strong candidate for clinical development.

immunology↗

bioRxiv2022

The SARS-CoV-2 Delta variant induces an antibody response largely focused on class 1 and 2 antibody epitopes

Exposure histories to SARS-CoV-2 variants and vaccinations will shape the specificity of antibody responses. To understand the specificity of Delta-elicited antibody immunity, we characterize the polyclonal antibody response elicited by primary or mRNA vaccine-breakthrough Delta infections. Both types of infection elicit a neutralizing antibody response focused heavily on the receptor-binding domain (RBD). We use deep mutational scanning to show that mutations to the RBDs class 1 and class 2 epitopes, including sites 417, 478, and 484-486 often reduce binding of these Delta-elicited antibodies. The anti-Delta antibody response is more similar to that elicited by early 2020 viruses than the Beta variant, with mutations to the class 1 and 2, but not class 3 epitopes, having the largest effects on polyclonal antibody binding. In addition, mutations to the class 1 epitope (e.g., K417N) tend to have larger effects on antibody binding and neutralization in the Delta spike than in the D614G spike, both for vaccine- and Delta-infection-elicited antibodies. These results help elucidate how the antigenic impacts of SARS-CoV-2 mutations depend on exposure history.

microbiology↗

bioRxiv2021

Delta breakthrough infections elicit potent, broad and durable neutralizing antibody responses

The SARS-CoV-2 Delta variant is currently responsible for most infections worldwide, including among fully vaccinated individuals. Although these latter infections are associated with milder COVID-19 disease relative to unvaccinated subjects, the specificity and durability of antibody responses elicited by Delta breakthrough cases remain unknown. Here, we demonstrate that breakthrough infections induce serum binding and neutralizing antibody responses that are markedly more potent, durable and resilient to spike mutations observed in variants of concern than those observed in subjects who were infected only or received only two doses of COVID-19 vaccine. However, wee show that Delta breakthrough cases, subjects who were vaccinated after SARS-CoV-2 infection and individuals vaccinated three times (without infection) have serum neutralizing activity of comparable magnitude and breadth indicate that multiple types of exposure or increased number of exposures to SARS-CoV-2 antigen(s) enhance spike-specific antibody responses. Neutralization of the genetically divergent SARS-CoV, however, was moderate with all four cohorts examined, except after four exposures to the SARS-CoV-2 spike, underscoring the importance of developing vaccines eliciting broad sarbecovirus immunity for pandemic preparedness.

immunology↗

bioRxiv2021

Regulation of protein secretion through chemical regulation of endoplasmic reticulum retention signal cleavage

Secreted proteins, such as hormones or cytokines, are key mediators in multicellular organisms. Protein secretion based on transcriptional control is rather slow, as proteins requires transcription, translation, followed by the transport from the endoplasmic reticulum (ER) through the conventional protein secretion (CPS) pathway towards the plasma membrane. An alternative faster bypass would be valuable. Here we present two genetically encoded orthogonal secretion systems, which rely on the retention of pre-synthesized proteins on the ER membrane (membER, released by cytosolic protease) or inside the ER lumen (lumER, released by ER luminal protease), respectively, and their release by the chemical signal-regulated proteolytic removal of an ER-retention signal, without triggering ER stress due to protein aggregates. Design of orthogonal chemically-regulated split proteases enables precise combination of signals into logic functions and was demonstrated on a chemically regulated insulin secretion. Regulation of ER escape represents a platform for the design of fast responsive and tightly-controlled modular and scalable protein secretion system. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/464966v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@12beb61org.highwire.dtl.DTLVardef@6a664corg.highwire.dtl.DTLVardef@1621e5borg.highwire.dtl.DTLVardef@b728ac_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOAbstract figure:C_FLOATNO membER and lumER system. By equipping a protein of interest (POI) with an N-terminal signaling sequence, which initiates the transport of proteins into the endoplasmic reticulum (ER), and a C-terminal KDEL ER retention sequence for luminal proteins or a KKXX sequence for transmembrane proteins, we can retain those proteins inside the ER and cis-Golgi apparatus (GA) through retrograde transport. Insertion of a protease cleavage site adjacent to the retention signal allows for the regulated fast secretion through proteolytic cleavage. The membrane bound, ER membrane (membER) and ER-luminal (lumER) systems allow for the controlled secretion of pre-synthesized protein, stored inside the ER. This platform enables release of target proteins several hours faster than systems relying transcription and translation. C_FIG

synthetic biology↗

bioRxiv2021

Comprehensive characterization of the antibody responses to SARS-CoV-2 Spike protein after infection and/or vaccination

BackgroundControl of the COVID-19 pandemic will rely on SARS-CoV-2 vaccine-elicited antibodies to protect against emerging and future variants; an understanding of the unique features of the humoral responses to infection and vaccination, including different vaccine platforms, is needed to achieve this goal. MethodsThe epitopes and pathways of escape for Spike-specific antibodies in individuals with diverse infection and vaccination history were profiled using Phage-DMS. Principal component analysis was performed to identify regions of antibody binding along the Spike protein that differentiate the samples from one another. Within these epitope regions we determined potential escape mutations by comparing antibody binding of peptides containing wildtype residues versus peptides containing a mutant residue. ResultsIndividuals with mild infection had antibodies that bound to epitopes in the S2 subunit within the fusion peptide and heptad-repeat regions, whereas vaccinated individuals had antibodies that additionally bound to epitopes in the N- and C-terminal domains of the S1 subunit, a pattern that was also observed in individuals with severe disease due to infection. Epitope binding appeared to change over time after vaccination, but other covariates such as mRNA vaccine dose, mRNA vaccine type, and age did not affect antibody binding to these epitopes. Vaccination induced a relatively uniform escape profile across individuals for some epitopes, whereas there was much more variation in escape pathways in in mildly infected individuals. In the case of antibodies targeting the fusion peptide region, which was a common response to both infection and vaccination, the escape profile after infection was not altered by subsequent vaccination. ConclusionsThe finding that SARS-CoV-2 mRNA vaccination resulted in binding to additional epitopes beyond what was seen after infection suggests protection could vary depending on the route of exposure to Spike antigen. The relatively conserved escape pathways to vaccine-induced antibodies relative to infection-induced antibodies suggests that if escape variants emerge, they may be readily selected for across vaccinated individuals. Given that the majority of people will be first exposed to Spike via vaccination and not infection, this work has implications for predicting the selection of immune escape variants at a population level. FundingThis work was supported by NIH grants AI138709 (PI Overbaugh) and AI146028 (PI Matsen). Julie Overbaugh received support as the Endowed Chair for Graduate Education (FHCRC). The research of Frederick Matsen was supported in part by a Faculty Scholar grant from the Howard Hughes Medical Institute and the Simons Foundation. Scientific Computing Infrastructure at Fred Hutch was funded by ORIP grant S10OD028685.

immunology↗

bioRxiv2021

Molecular basis of immune evasion by the delta and kappa SARS-CoV-2 variants

Worldwide SARS-CoV-2 transmission leads to the recurrent emergence of variants, such as the recently described B.1.617.1 (kappa), B.1.617.2 (delta) and B.1.617.2+ (delta+). The B.1.617.2 (delta) variant of concern is causing a new wave of infections in many countries, mostly affecting unvaccinated individuals, and has become globally dominant. We show that these variants dampen the in vitro potency of vaccine-elicited serum neutralizing antibodies and provide a structural framework for describing the impact of individual mutations on immune evasion. Mutations in the B.1.617.1 (kappa) and B.1.617.2 (delta) spike glycoproteins abrogate recognition by several monoclonal antibodies via alteration of key antigenic sites, including an unexpected remodeling of the B.1.617.2 (delta) N-terminal domain. The binding affinity of the B.1.617.1 (kappa) and B.1.617.2 (delta) receptor-binding domain for ACE2 is comparable to the ancestral virus whereas B.1.617.2+ (delta+) exhibits markedly reduced affinity. We describe a previously uncharacterized class of N-terminal domain-directed human neutralizing monoclonal antibodies cross-reacting with several variants of concern, revealing a possible target for vaccine development.

immunology↗