Biology subjects

Johnston, S. C.

Publications and source records attributed to Johnston, S. C..

4 recordsLinked to original sources

bioRxiv2025

Dose response comparison of Nipah virus strains Malaysia and Bangladesh in hamsters exposed by the intranasal or intraperitoneal route

Nipah virus, a zoonotic pathogen, can cause debilitating disease and death in humans. Currently, countermeasures are limited, with several in various stages of testing but none yet FDA-approved for human use. Evaluation of countermeasure candidates requires safety testing in humans, as well as efficacy testing against lethal challenge in animal models. Herein, we describe the characterization and comparison of the intraperitoneal and intranasal Syrian golden hamster models for Nipah virus strains Malaysia and Bangladesh. Overall, the intraperitoneal route of exposure resulted in a more consistent lethal outcome, regardless of virus strain. Therefore, the IP model was subsequently used to evaluate the use of Favipiravir as a potential positive control for future studies investigating NiV countermeasures. In contrast to prior reported results regarding Favipiravir in Nipah virus-infected hamsters, Favipiravir was only fifty percent effective at preventing death following lethal challenge, regardless of Nipah virus strain. The data suggest that Favipiravir is only partially protective against Nipah virus in hamsters, and, thus, would likely not be an ideal candidate as a positive control in future efficacy studies.

microbiology↗

bioRxiv2022

A SARS-CoV-2 Spike Ferritin Nanoparticle Vaccine is Protective and Promotes a Strong Immunological Response in the Cynomolgus Macaque Coronavirus Disease 2019 (COVID-19) Model

The COVID-19 pandemic has had a staggering impact on social, economic, and public health systems worldwide. Vaccine development and mobilization against SARS-CoV-2 (the etiologic agent of COVID-19) has been rapid. However, novel strategies are still necessary to slow the pandemic, and this includes new approaches to vaccine development and/or delivery, which improve vaccination compliance and demonstrate efficacy against emerging variants. Here we report on the immunogenicity and efficacy of a SARS-CoV-2 vaccine comprised of stabilized, pre-fusion Spike protein trimers displayed on a ferritin nanoparticle (SpFN) adjuvanted with either conventional aluminum hydroxide or the Army Liposomal Formulation QS-21 (ALFQ) in a cynomolgus macaque COVID-19 model. Vaccination resulted in robust cell-mediated and humoral responses and a significant reduction of lung lesions following SARS-CoV-2 infection. The strength of the immune response suggests that dose sparing through reduced or single dosing in primates may be possible with this vaccine. Overall, the data support further evaluation of SpFN as a SARS-CoV-2 protein-based vaccine candidate with attention to fractional dosing and schedule optimization.

microbiology↗

bioRxiv2020

Animal Model Prescreening: Pre-exposure to SARS-CoV-2 impacts responses in the NHP model

COVID-19 presents herculean challenges to research and scientific communities for producing diagnostic and treatment solutions. Any return to normalcy requires rapid development of countermeasures, with animal models serving as a critical tool in testing vaccines and therapeutics. Animal disease status and potential COVID-19 exposure prior to study execution may severely bias efficacy testing. We developed a toolbox of immunological and molecular tests to monitor countermeasure impact on disease outcome and evaluate pre-challenge COVID-19 status. Assay application showed critical necessity for animal pre-screening. Specifically, real-time PCR results documented pre-exposure of an African Green Monkey prior to SARS-CoV-2 challenge with sequence confirmation as a community-acquired exposure. Longitudinal monitoring of nasopharyngeal swabs and serum showed pre-exposure impacted both viral disease course and resulting immunological response. This study demonstrates utility in a comprehensive pre-screening strategy for animal models, which captured the first documented case of community-acquired, non-human primate infection. One Sentence SummaryPre-exposure to SARS-CoV-2 affects biomarker responses in animal models, highlighting a need for robust pre-screening protocols prior to medical countermeasure studies.

immunology↗

bioRxiv2020

Development of a Coronavirus Disease 2019 Nonhuman Primate Model Using Airborne Exposure

Airborne transmission is predicted to be a prevalent route of human exposure with SARS-CoV-2. Aside from African green monkeys, nonhuman primate models that replicate airborne transmission of SARS-CoV-2 have not been investigated. A comprehensive and comparative evaluation of COVID-19 in African green monkeys, rhesus macaques, and cynomolgus macaques following airborne exposure to SARS-CoV-2 was performed to define parameters critical to disease progression and the extent to which they correlate with human COVID-19. Respiratory abnormalities and viral shedding were noted for all animals, indicating successful infection. Cynomolgus macaques developed fever, and thrombocytopenia was measured for African green monkeys and rhesus macaques. Type II pneumocyte hyperplasia and alveolar fibrosis were more frequently observed in lung tissue from cynomolgus macaques and African green monkeys. The data indicate that, in addition to African green monkeys, macaques can be successfully infected by airborne SARS-CoV-2, providing viable macaque natural transmission models for medical countermeasure evaluation. One Sentence SummaryNonhuman primates develop COVID-19 following airborne virus exposure.

microbiology↗