Safety Precautions and Operating Procedures in an (A)BSL-4 Laboratory: 4. Medical Imaging Procedures

Computed Tomography Imaging for Monitoring of Marburg Virus Disease: a Nonhuman Primate Proof-Of-Concept Study

Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. The pathogenesis of MVD remains poorly understood, partially due to the low number of cases that can be studied, the absence of state-of-the-art medical equipment in areas where cases are reported, and limitations on the number of animals that can be safely used in experimental studies under maximum containment animal biosafety level 4 conditions. Medical imaging modalities, such as whole-body computed tomography (CT), may help to describe disease progression in vivo, potentially replacing ethically contentious and logistically challenging serial euthanasia studies. Towards this vision, we performed a pilot study, during which we acquired whole-body CT images of 6 rhesus monkeys before and 7 to 9 days after intramuscular MARV exposure. We identified imaging abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to clinical, virological, and gross pathological hallmarks of MVD in this animal model. Quantitative image analysis indicated hepatomegaly with a significant reduction in organ density (indicating fatty infiltration of the liver), splenomegaly, and edema that corresponded with gross pathological and histopathological findings. Our results indicated that CT imaging could be used to verify and quantify typical MVD pathogenesis versus altered, diminished, or absent disease severity or progression in the presence of candidate medical countermeasures, thus possibly reducing the number of animals needed and eliminating serial euthanasia. IMPORTANCE Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. Much is unknown about disease progression and, thus, prevention and treatment options are limited. Medical imaging modalities, such as whole-body computed tomography (CT), have the potential to improve understanding of MVD pathogenesis. Our study used CT to identify abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to known clinical signs of MVD in this animal model. Our results indicated that CT imaging and analyses could be used to elucidate pathogenesis and possibly assess the efficacy of candidate treatments.

Deep Learning for Automated Liver Segmentation to Aid in the Study of Infectious Diseases in Nonhuman Primates

With the advent of deep learning, convolutional neural networks (CNNs) have evolved as an effective method for the automated segmentation of different tissues in medical image analysis. In certain infectious diseases, the liver is one of the more highly affected organs, where an accurate liver segmentation method may play a significant role to improve the diagnosis, quantification, and follow-up. Although several segmentation algorithms have been proposed for liver or liver-tumor segmentation in computed tomography (CT) of human subjects, none of them have been investigated for nonhuman primates (NHPs), where the livers have a wide range in size and morphology. In addition, the unique characteristics of different infections or the heterogeneous immune responses of different NHPs to the infections appear with a diverse radiodensity distribution in the CT imaging. In this study, we investigated three state-of-the-art algorithms; VNet, UNet, and feature pyramid network (FPN) for automated liver segmentation in whole-body CT images of NHPs. The efficacy of the CNNs were evaluated on 82 scans of 37 animals, including pre and post-exposure to different viruses such as Ebola, Marburg, and Lassa. Using a 10-fold cross-validation, the best performance for the segmented liver was provided by the FPN; an average 94.77% Dice score, and 3.6% relative absolute volume difference. Our study demonstrated the efficacy of multiple CNNs, wherein the FPN outperforms VNet and UNet for liver segmentation in infectious disease imaging research.

Current status and future prospect of management of biosafety laboratories for emerging infectious diseases

In recent years, there have been several outbreaks of infectious diseases around the world, including severe acute respiratory syndrome, Ebola virus disease, Middle East respiratory syndrome, and corona virus disease 2019. Experience suggests that the detection and research of emergent infectious diseases play a crucial role in the process of responding to the epidemic, which also brings great challenges to biosafety laboratories. In the face of unknown biological risk factors, the non-standard biosafety protection measures have a serious impact on the life safety of laboratory staff and the research of infectious diseases, which stresses the necessity of safety protection in biosafety laboratories. This article will briefly review the current status and future prospect of management of biosafety laboratories both in China and other countries in terms of safety protection measures during new sudden infectious disease incidents.

Cranial Vena Cava Syndrome in Guinea Pigs with Chronic Jugular Vein Catheters

Guinea pigs are a premier small animal model for infectious disease research, and chronic indwelling venous access ports may be used to facilitate various procedures. Here we report catheter-related lesions in 5 uninfected Dunkin-Hartley guinea pigs with chronic jugular vein catheters used for imaging studies. Three guinea pigs were found dead with no premonitory signs. At necropsy, there was severe bilateral pulmonary atelectasis due to 20 to 29 mL of pleural effusion resulting from catheter-related thrombosis and cranial vena cava syndrome. In addition, one of these 3 guinea pigs had a polymicrobial catheter infection with abscessation. A 4th clinically normal guinea pig was euthanized at the end of the study, having spontaneously lost its catheter 7 mo prior, and had 17 mL of pleural effusion. The 5th guinea pig was euthanized following pooling of contrast material around the distal catheter in the cranial vena cava on CT. By histology, affected animals had recent and remote thrombosis or fibrosis (or both) of the cranial vena cava and right atrial wall, with osseous and cartilaginous metaplasia. Cranial vena cava syndrome should be considered as a differential for dyspnea or death in chronically catheterized laboratory animals.