Biology subjects

Doering, J.

Publications and source records attributed to Doering, J..

3 recordsLinked to original sources

bioRxiv2020

Endpoint and Epitope-specific Antibody Responses as Correlates of Vaccine-mediated Protection of Mice against Ricin Toxin

The successful licensure of vaccines for biodefense is contingent upon the availability of well-established correlates of protection (CoP) in at least two animal species that can then be applied to humans, without the need to assess efficacy in the clinic. In this report we describe a multivariate model that combines pre-challenge serum antibody endpoint titers (EPT) and values derived from an epitope profiling immune-competition capture (EPICC) assay as a predictor in mice of vaccine-mediated immunity against ricin toxin (RT), a Category B biothreat. EPICC is a modified competition ELISA in which serum samples from vaccinated mice were assessed for their ability to inhibit the capture of soluble, biotinylated (b)-RT by a panel of immobilized monoclonal antibodies (mAbs) directed against four immunodominant toxin-neutralizing regions on the enzymatic A chain (RTA) of RT. In a test cohort of mice (n=40) vaccinated with suboptimal doses of the RTA subunit vaccine, RiVax(R), we identified two mAbs, PB10 and SyH7, which had EPICC inhibition values in pre-challenge serum samples that correlated with survival following a challenge with 10 x LD50 of RT administered by intraperitoneal (IP) injection. Analysis of a larger cohort of mice (n=645) revealed that a multivariate model combining endpoint titers and an epitope-profiling immune-competition capture (EPICC) assay values for PB10 and SyH7 as predictive variables had significantly higher statistical power than any one of the independent variables alone. Establishing the correlates of vaccine-mediated protection in mice represents an important steppingstone in the development of RiVax(R) as a medical countermeasure under the United States Food and Drug Administrations "Two Animal Rule."

immunology↗

bioRxiv2020

Navigating the translational roadblock: Towards highly specific and effective all-optical interrogations of neural circuits

Two-photon (2-P) all-optical approaches combine in vivo 2-P calcium imaging and 2-P optogenetic modulations and have the potential to build a framework for network-based therapies, e.g. for rebalancing maladaptive activity patterns in preclinical models of neurological disorders. Here, our goal was to tailor these approaches for this purpose: Firstly, we combined in vivo juxtacellular recordings and GCaMP6f-based 2-P calcium imaging in layer II/III of mouse visual cortex to tune our detection algorithm towards a 100 % specific identification of AP-related calcium transients. False-positive-free detection was achieved at a sensitivity of approximately 73 %. To further increase specificity, secondly, we minimized photostimulation artifacts as a potential source for false-positives by using extended-wavelength-spectrum laser sources for optogenetic stimulation of the excitatory opsin C1V1. We achieved artifact-free all-optical experiments performing photostimulations at 1100 nm or higher and simultaneous calcium imaging at 920 nm in mouse visual cortex in vivo. Thirdly, we determined the spectral range for maximizing efficacy of optogenetic control by performing 2-P photostimulations of individual neurons with wavelengths up to 1300 nm. The rate of evoked transients in GCaMP6f/C1V1-co-expressing cortical neurons peaked already at 1100 nm. By refining spike detection and defining 1100 nm as the optimal wavelength for artifact-free and effective stimulations of C1V1 in GCaMP-based all-optical interrogations, we increased the translational value of these approaches, e.g. for the use in preclinical applications of network-based therapies. One Sentence SummaryWe maximize translational relevance of 2-P all-optical physiology by increasing specificity, minimizing artifacts and optimizing stimulation efficacy.

neuroscience↗

bioRxiv2019

Inhibition of Invasive Salmonella by Orally Administered IgA and IgG Monoclonal Antibodies

BackgroundNon-typhoidal Salmonella enterica strains, including serovar Typhimurium (STm), are an emerging cause of invasive disease among children and the immunocompromised, especially in regions of sub-Saharan Africa. STm invades the intestinal mucosa through Peyers patch tissues before disseminating systemically. While vaccine development efforts are ongoing, the emergence of multidrug resistant strains of STm affirms the need to seek alternative strategies to protect high-risk individuals from infection.\n\nMethodology/Principal FindingsIn this report we investigated the potential of an orally administered O5 serotype-specific IgA monoclonal antibody (mAb), called Sal4, to protect mice against invasive Salmonella enterica serovar Typhimurium (STm) infection. Sal4 IgA was delivered to mice prior to or concurrently with STm challenge. Infectivity was measured as bacterial burden in Peyers patch tissues one day after challenge. Using this model, we defined the minimal amount of Sal4 IgA required to significantly reduce STm uptake into Peyers patches. The relative efficacy of Sal4 in dimeric and secretory IgA (SIgA) forms was compared, as was a second lower avidity O5-specific IgA mAb that we produced from STm immunized mice. To assess the role of isotype in oral passive immunization, we engineered a recombinant IgG1 mAb carrying the Sal4 variable regions and evaluated its ability to block invasion of STm into epithelial cells in vitro and Peyers patch tissues.\n\nConclusions/SignificanceOur results demonstrate the potential of orally administered monoclonal IgA and SIgA, but not IgG, to passively immunize against invasive Salmonella. Nonethless, the prophylactic window of IgA/SIgA in the mouse was on the order of minutes, underscoring the need to develop formulations to protect mAbs in the gastric environment and to permit sustained release in the small intestine.\n\nAuthor SummaryThe bacterium Salmonella enterica is responsible for significant morbidity and mortality in the developed and developing worlds. While the pathogen is most renowed as the causative agent of typhoid fever, the emergence of invasive non-typhoid strains like S. enterica serovar Typhimurium (STm) are of great concern because of their propensity to cause severe disease in children under the age of five. In this report, we demonstrate in a mouse model that oral administration of a monoclonal antibody targeting the surface of STm is able to prevent the bacterium from infecting gastrointestinal tissues, the first step in the dissemination process. We show that IgA antibodies (which are normally found in the gut) were far superior than an equivalent IgG antibody (normally found in blood) at protecting the intestine from STm infection. These results lay the foundation for future studies aimed at the development of an orally administered antibody cocktail capable of providing temporary immunity to pathogens like S. enterica.

immunology↗