The Integrated Research Facility at Fort Detrick (IRF-Frederick) team has extensive experience in testing potential medical countermeasures for high-consequence viral pathogens. Leveraging this experience, scientists at the IRF-Frederick have developed and are using cell‑based in vitro assays and animal models to test potential therapeutics for and vaccines against COVID‑19. The unique medical imaging capabilities of the IRF-Frederick are also being used to understand pathological consequences of SARS‑CoV‑2 in relevant animal models of disease. Following are examples of the IRF-Frederick’s contribution to solving the challenge of COVID-19 for the world and for the nation.
High-Throughput Assay Platform
The IRF-Frederick has developed drug-screening and virus-neutralization assays using the PerkinElmer Operetta high-content imaging system. Fluorescence and chemiluminescence cell-based assays provide automated data capture and analysis.
Drug Screening Assay
The IRF-Frederick is currently working with both government and industry partners to screen individual compounds and combinations of compounds in cell-based high-content imaging assays.
Cell-culture screening assays of effective therapeutics that have been developed for Ebola, Marburg, Lassa, and Nipah viruses and MERS-CoV are being applied to SARS-CoV-2.
Plasma-based therapies demonstrate potential as treatment of SARS-CoV-2 infection. NIAID’s Division of Clinical Research (DCR) is working to produce intravenous immunoglobulin (IVIG) and other plasma‑based therapies for use in clinical trials (e.g., NCT04546581). In support of this effort, the IRF‑Frederick scientists have developed a microneutralization assay for SARS-CoV-2 that uses either wild-type virus or a neon green reporter virus. This assay was quickly designed based on similar assays developed at the IRF-Frederick for Ebola virus, Nipah virus, and MERS-CoV. This assay is also being used to screen monoclonal antibodies as potential therapeutics.
Immunoglobulin M (IgM) and Immunoglobulin G (IgG) Enzyme-Linked Immunosorbent Assays (ELISAs)
As part of in-house experimental animal-model work, the IRF-Frederick scientists developed IgM and IgG ELISAs for SARS-CoV-2, targeting both the viral spike protein and the receptor-binding domain (RBD) within the spike protein. The SARS-CoV-2 assays are being developed for both animal and human studies to evaluate the efficacy of medical countermeasures, particularly vaccines.
Small Animal Model Development
The IRF-Frederick scientists are using golden hamsters as the disease model of choice for COVID‑19 studies. Exposure by intranasal inoculation of SARS-CoV-2 results in mild to moderate disease in the hamsters, including dramatic weight loss and lung pathology similar to that observed in human COVID‑19 patients. Other disease parameters measured in studies are the presence of viral RNA in the upper and lower respiratory tracts, extrapulmonary organs, and blood harvested from virus‑infected hamsters. Histopathological analysis of lung samples identified interstitial pneumonia on Day 2 and Day 5, with resolution at Day 8 post-exposure. From these findings, the IRF-Frederick was able to support a rapid 5- to 7-day model for initial efficacy evaluation of therapeutic monoclonal antibodies.
- Aerosol exposure of small animal models
- Use of positron emission tomography (PET), computed tomography (CT) imaging, and fluorodeoxyglucose (FDG) PET/CT to monitor disease progression
- Testing of medical countermeasures, including vaccine candidates, antiviral drugs, and antibody therapeutics against SARS-CoV-2
The IRF-Frederick has developed imaging to assess 18fluorodeoxyglucose (FDG) kinetic changes in the lungs of aged hamsters versus young in the context of evaluating disease progression. Aged hamsters develop more severe lung disease than young hamsters. Interstitial pneumonia was demonstrated and quantified through imaging, which helps overcome limitations of these models by providing the following results:
- Qualitative CT assessments that mimic human disease
- Quantitative CT assessments that correspond to histopathology
- PET signal corresponds to CT lung lesions
- Gross and histopathology support radiological findings
Nonhuman Primate Model Development
IRF-Frederick scientists have developed a nonhuman primate model through a natural history study of SARS-CoV-2 in crab-eating (cynomolgus) macaques. Nonhuman primate studies at the IRF‑Frederick include a variety of SARS-CoV-2-specific assays, as well as CT imaging and percent change in lung hyperdensity (PCLH), to quantifiably and objectively evaluate disease progression and the efficacy of medical countermeasures. The unique medical imaging capabilities of the IRF‑Frederick enable the exploration of correspondence between structural (CT scan) and physiologic (18fluorodeoxyglucose [FDG] PET).
Three-dimensional rendering of crab-eating macaque (Macaca fascicularis) lungs from qualitative computed tomography (CT) before and after intrabronchial instillation of SARS-CoV-2 (from baseline [BL] to Day 6 [D6]); airways (blue); normal lung (gray); vessels (red); imaging abnormalities (yellow). See more SARS-CoV-2 imaging examples.
- Real-time reverse transcription polymerase chain reaction (RT-qPCR)
- Fluorescence reduction neutralization assay (FRNA)
- Plaque assay
- In situ hybridization (ISH), immunohistochemistry (IHC), and IgG ELISAs for total spike protein (total S), N‑terminal globular subunit 1 (S1), and subunit 2 (S2)
- Percent change in lung hyperdensity (PCLH)
- FDG PET
Human Clinical Trials
The response team at IRF-Frederick is actively engaged in the design of and support for multiple clinical studies. In partnership with Partnership for Research on Ebola Vaccines in Liberia (PREVAIL) and Pamoja Tulinde Maisha (PALM) in the Democratic Republic of the Congo, the team is developing and implementing natural history studies to examine and analyze the progression to severe COVID-19 disease in these populations. These studies will also provide insight into the spread of disease in this region and aid in the ability of partners in this region to respond to this pandemic. The team is also supporting the international Adaptive COVID-19 Treatment Trial (ACTT) with preparation of critical laboratory reagents.