Longitudinal in vivo imaging of acute neuropathology in a monkey model of Ebola virus infection

Identification of potential inhibitors targeting Ebola virus VP35 protein: a computational strategy

Ebola virus (EBOV) poses a severe threat as a highly infectious pathogen, causing devastating hemorrhagic fever in both humans and animals. The EBOV virus VP35 protein plays a crucial role in viral replication and exhibits the ability to suppress the host interferon cascade, leading to immune system depletion. As a potential drug target, VP35 protein inhibition holds promise for combating EBOV. To discover new drug candidates, we employed a computer-aided drug design approach, focusing on compounds capable of inhibiting VP35 protein replication. In this connection, a pharmacophore model was generated using molecular interactions between the VP35 protein and its inhibitor. ZINC and Cambridge database were screened using validated pharmacophore model. Further the compounds were filtered based on Lipinski's rule of five and subjected to MD simulation and relative binding free energy calculation. Six compounds manifest a significant docking score and strong binding interaction towards VP35 protein. MD simulations further confirmed the remarkable stability of these six complexes. Relative binding free energy calculations also showed significant ΔG value in the range of -132.3 and -49.3 kcal/mol. This study paves the way for further optimization of these compounds as potential inhibitors of VP35, facilitating subsequent experimental in vitro studies.Communicated by Ramaswamy H. Sarma.

Molecular Imaging of Infections: Advancing the Search for the Hidden Enemy

Even before the coronavirus disease 2019 pandemic, infections were a major threat to human health, as the third leading cause of death and the leading cause of morbidity among all human diseases. Although conventional imaging studies are routinely used for patients with infections, they provide structural or anatomic information only. Molecular imaging technologies enable noninvasive visualization of molecular processes at the cellular level within intact living subjects, including patients, and hold great potential for infections. We hope that this supplement will spur interest in the field and establish new collaborations to develop and translate novel molecular imaging approaches to the clinic.

Advances and Challenges in Molecular Imaging of Viral Infections

Molecular imaging of viral infection, using a variety of advanced imaging techniques such as optical and nuclear imaging, can and has been used for direct visualization of the virus as well as assessment of virus-host interactions. Unlike imaging of other pathogens such as bacteria and fungi, challenging aspects of imaging viral infections include the small size of viruses, the complexity of viral infection animal models (eg, species dependence), and the high-level containment needs for many high-consequence pathogens, among others. In this review, using representative viral infections, we discuss how molecular imaging can reveal real-time infection dynamics, improve our understanding of disease pathogenesis, and guide optimization of treatment and prevention strategies. Key findings from human and animal studies are highlighted.

The Promise of Molecular Imaging: Focus on Central Nervous System Infections

Central nervous system (CNS) infections can lead to high mortality and severe morbidity. Diagnosis, monitoring, and assessing response to therapy of CNS infections is particularly challenging with traditional tools, such as microbiology, due to the dangers associated with invasive CNS procedures (ie, biopsy or surgical resection) to obtain tissues. Molecular imaging techniques like positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging have long been used to complement anatomic imaging such as computed tomography (CT) and magnetic resonance imaging (MRI), for in vivo evaluation of disease pathophysiology, progression, and treatment response. In this review, we detail the use of molecular imaging to delineate host-pathogen interactions, elucidate antimicrobial pharmacokinetics, and monitor treatment response. We also discuss the utility of pathogen-specific radiotracers to accurately diagnose CNS infections and strategies to develop radiotracers that would cross the blood-brain barrier.

Magnetic Resonance Imaging for Monitoring of Hepatic Disease Induced by Ebola Virus: a Nonhuman Primate Proof-of-Concept Study

Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD). However, the role of hepatic involvement in EVD progression is understudied. Medical imaging in established animal models of EVD (e.g., nonhuman primates [NHPs]) can be a strong complement to traditional assays to better investigate this pathophysiological process in vivo and noninvasively. In this proof-of-concept study, we used longitudinal multiparametric magnetic resonance imaging (MRI) to characterize liver morphology and function in nine rhesus monkeys after exposure to Ebola virus (EBOV). Starting 5 days postexposure, MRI assessments of liver appearance, morphology, and size were consistently compatible with the presence of hepatic edema, inflammation, and congestion, leading to significant hepatomegaly at necropsy. MRI performed after injection of a hepatobiliary contrast agent demonstrated decreased liver signal on the day of euthanasia, suggesting progressive hepatocellular dysfunction and hepatic secretory impairment associated with EBOV infection. Importantly, MRI-assessed deterioration of biliary function was acute and progressed faster than changes in serum bilirubin concentrations. These findings suggest that longitudinal quantitative in vivo imaging may be a useful addition to standard biological assays to gain additional knowledge about organ pathophysiology in animal models of EVD. IMPORTANCE Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD), but the contribution of hepatic pathophysiology to EVD progression is not fully understood. Noninvasive medical imaging of liver structure and function in well-established animal models of disease may shed light on this important aspect of EVD. In this proof-of-concept study, we used longitudinal magnetic resonance imaging (MRI) to characterize liver abnormalities and dysfunction in rhesus monkeys exposed to Ebola virus. The results indicate that in vivo MRI may be used as a noninvasive readout of organ pathophysiology in EVD and may be used in future animal studies to further characterize organ-specific damage of this condition, in addition to standard biological assays.

Intramuscular [18F]F-FDG Administration for Successful PET Imaging of Golden Hamsters in a Maximum Containment Laboratory Setting

Positron emission tomography (PET) is becoming an important tool for the investigation of emerging infectious diseases in animal models. Usually, PET imaging is performed after intravenous (IV) radiotracer administration. However, IV injections are difficult to perform in some small animals, such as golden hamsters. This challenge is particularly evident in longitudinal imaging studies, and even more so in maximum containment settings used to study high-consequence pathogens. We propose the use of intramuscular (IM) administration of 2-deoxy-2[¹⁸F]fluoro-D-glucose ([¹⁸F]F-FDG) for PET imaging of hamsters in a biosafety level 4 (BSL-4) laboratory setting. After [¹⁸F]F-FDG administration via IM or IV (through surgically implanted vascular access ports), eight hamsters underwent static or dynamic PET scans. Time-activity curves (TACs) and standardized uptake values (SUVs) in major regions of interest (ROIs) were used to compare the two injection routes. Immediately after injection, TACs differed between the two routes. At 60 min post-injection, [¹⁸F]F-FDG activity for both routes reached a plateau in most ROIs except the brain, with higher accumulation in the liver, lungs, brain, and nasal cavities observed in the IM group. IM delivery of [¹⁸F]F-FDG is an easy, safe, and reliable alternative for longitudinal PET imaging of hamsters in a BSL-4 laboratory setting.

Toward the determination of sensitive and reliable whole-lung computed tomography features for robust standard radiomics and delta-radiomics analysis in a nonhuman primate model of coronavirus disease 2019

Purpose

We propose a method to identify sensitive and reliable whole-lung radiomic features from computed tomography (CT) images in a nonhuman primate model of coronavirus disease 2019 (COVID-19). Criteria used for feature selection in this method may improve the performance and robustness of predictive models.

Approach

Fourteen crab-eating macaques were assigned to two experimental groups and exposed to either severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or a mock inoculum. High-resolution CT scans were acquired before exposure and on several post-exposure days. Lung volumes were segmented using a deep-learning methodology, and radiomic features were extracted from the original image. The reliability of each feature was assessed by the intraclass correlation coefficient (ICC) using the mock-exposed group data. The sensitivity of each feature was assessed using the virus-exposed group data by defining a factor R that estimates the excess of variation above the maximum normal variation computed in the mock-exposed group. R and ICC were used to rank features and identify non-sensitive and unstable features.

Results

Out of 111 radiomic features, 43% had excellent reliability ( ICC > 0.90 ), and 55% had either good ( ICC > 0.75 ) or moderate ( ICC > 0.50 ) reliability. Nineteen features were not sensitive to the radiological manifestations of SARS-CoV-2 exposure. The sensitivity of features showed patterns that suggested a correlation with the radiological manifestations.

Conclusions

Features were quantified and ranked based on their sensitivity and reliability. Features to be excluded to create more robust models were identified. Applicability to similar viral pneumonia studies is also possible.

Infectious disease and cognition in wild populations

Infectious disease is linked to impaired cognition across a breadth of host taxa and cognitive abilities, potentially contributing to variation in cognitive performance within and among populations. Impaired cognitive performance can stem from direct damage by the parasite, the host immune response, or lost opportunities for learning. Moreover, cognitive impairment could be compounded by factors that simultaneously increase infection risk and impair cognition directly, such as stress and malnutrition. As highlighted in this review, however, answers to fundamental questions remain unresolved, including the frequency, duration, and fitness consequences of infection-linked cognitive impairment in wild animal populations, the cognitive abilities most likely to be affected, and the potential for adaptive evolution of cognition in response to accelerating emergence of infectious disease.

Designing a novel multi‑epitope vaccine against Ebola virus using reverse vaccinology approach

Ebola virus (EBOV) is a dangerous zoonotic infectious disease. To date, more than 25 EBOV outbreaks have been documented, the majority of which have occurred in Central Africa. The rVSVG-ZEBOV-GP vaccine (ERVEBO), a live attenuated vaccine, has been approved by the US Food and Drug Administration (FDA) to combat EBOV. Because of the several drawbacks of live attenuated vaccines, multi-epitope vaccines probably appear to be safer than live attenuated vaccines. In this work, we employed immunoinformatics tools to design a multi-epitope vaccine against EBOV. We collected sequences of VP35, VP24, VP30, VP40, GP, and NP proteins from the NCBI database. T-cell and linear B-cell epitopes from target proteins were identified and tested for antigenicity, toxicity, allergenicity, and conservancy. The selected epitopes were then linked together in the vaccine's primary structure using appropriate linkers, and the 50S ribosomal L7/L12 (Locus RL7 MYCTU) sequence was added as an adjuvant to the vaccine construct's N-terminal. The physicochemical, antigenicity, and allergenicity parameters of the vaccine were all found to be satisfactory. The 3D model of the vaccine was predicted, refined, and validated. The vaccine construct had a stable and strong interaction with toll-like receptor 4 (TLR4) based on molecular docking and molecular dynamic simulation (MD) analysis. The results of codon optimization and in silico cloning revealed that the proposed vaccine was highly expressed in Escherichia coli (E. coli). The findings of this study are promising; however, experimental validations should be carried out to confirm these findings.

Nonhuman Primates in Translational Research

Nonhuman primates are critically important animal models in which to study complex human diseases, understand biological functions, and address the safety of new diagnostics and therapies proposed for human use. They have genetic, physiologic, immunologic, and developmental similarities when compared to humans and therefore provide important preclinical models of human health and disease. This review highlights select research areas that demonstrate the importance of nonhuman primates in translational research. These include pregnancy and developmental disorders, infectious diseases, gene therapy, somatic cell genome editing, and applications of in vivo imaging. The power of the immune system and our increasing understanding of the role it plays in acute and chronic illnesses are being leveraged to produce new treatments for a range of medical conditions. Given the importance of the human immune system in health and disease, detailed study of the immune system of nonhuman primates is essential to advance preclinical translational research. The need for nonhuman primates continues to remain a high priority, which has been acutely evident during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) global pandemic. Nonhuman primates will continue to address key questions and provide predictive models to identify the safety and efficiency of new diagnostics and therapies for human use across the lifespan.