Yu Cong

Inhalation of aerosolized particles containing pathogens is a potential route of exposure for many diseases. The concentration of airborne etiologic agent, host factors, and aerodynamic particle si...

Experimental vaccines for the deadly zoonotic Nipah (NiV), Hendra (HeV), and Ebola (EBOV) viruses have focused on targeting individual viruses, although their geographical and bat reservoir host overlaps warrant creation of multivalent vaccines. Here we explored whether replication-incompetent pseudotyped vesicular stomatitis virus (VSV) virions or NiV-based virus-like particles (VLPs) were suitable multivalent vaccine platforms by co-incorporating multiple surface glycoproteins from NiV, HeV, and EBOV onto these virions. We then enhanced the vaccines’ thermotolerance using carbohydrates to enhance applicability in global regions that lack cold-chain infrastructure. Excitingly, in a Syrian hamster model of disease, the VSV multivalent vaccine elicited safe, strong, and protective neutralizing antibody responses against challenge with NiV, HeV, or EBOV. Our study provides proof-of-principle evidence that replication-incompetent multivalent viral particle vaccines are sufficient to provide protection against multiple zoonotic deadly viruses with high pandemic potential.

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.

Following the largest Ebola virus disease outbreak from 2013 to 2016, viral RNA has been detected in survivors from semen and breast milk long after disease recovery. However, as there have been few cases of sexual transmission, it is unclear whether every RNA positive fluid sample contains infectious virus. Virus isolation, typically using cell culture or animal models, can serve as a tool to determine the infectivity of patient samples. However, the sensitivity of these methods has not been assessed for the Ebola virus isolate, Makona. Described here is an efficiency comparison of Ebola virus Makona isolation using Vero E6, Huh-7, monocyte-derived macrophage cells, and suckling laboratory mice. Isolation sensitivity was similar in all methods tested. Laboratory mice and Huh-7 cells were less affected by toxicity from breast milk than Vero E6 and MDM cells. However, the advantages associated with isolation in Huh-7 cells over laboratory mice, including cost effectiveness, sample volume preservation, and a reduction in animal use, make Huh-7 cells the preferred substrate tested for Ebola virus Makona isolation.

Identifying effective antivirals for treating Ebola virus disease (EVD) and minimizing transmission of such disease is critical. A variety of cell-based assays have been developed for evaluating compounds for activity against Ebola virus. However, very few reports discuss the variable assay conditions that can affect the results obtained from these drug screens. Here, we describe variable conditions tested during the development of our cell-based drug screen assays designed to identify compounds with anti-Ebola virus activity using established cell lines and human primary cells. The effect of multiple assay readouts and variable assay conditions, including virus input, time of infection, and the cell passage number, were compared, and the impact on the effective concentration for 50% and/ or 90% inhibition (EC₅₀, EC₉₀) was evaluated using the FDA-approved compound, toremifene citrate. In these studies, we show that altering cell-based assay conditions can have an impact on apparent drug potency as measured by the EC₅₀. These results further support the importance of developing standard operating procedures for generating reliable and reproducible in vitro data sets for potential antivirals.