Detection of Ebola Virus RNA through Aerosol Sampling of Animal Biosafety Level 4 Rooms Housing Challenged Nonhuman Primates

Abstract : Ebola Virus Disease is a serious illness of humans and nonhuman primates (NHPs) caused by the Ebola Virus (EBOV). Historically, transmission of EBOV has occurred primarily among close contacts and family members providing medical care for affected individuals. While direct contact has been shown to be the primary source of EBOV transmission, there is limited evidence of aerosol transmission among humans. Due to the inconsistent evidence of EBOV aerosol transmission, we utilized a high volume air sampler to determine if EBOV viral RNA could be detected over the course of a study with NHPs challenged with EBOV. Air sampling was conducted during three separate NHP studies across three distinct ABSL-4 suites with independent husbandry staffs for each study. Initial proof of concept studies demonstrated EBOV viral RNA recovery from filters placed within a Class III BSC during a sham spray. Viral RNA was recovered during day 9 and 10 of Study I and day 7 and 8 of Study III. Viral RNA levels were below limits of detection during all other sample collection time points. CT values for positive samples were between 34.43 and 39.79 indicating a small amount of viral RNA was recovered from the filters despite continuous sampling. The combination of the low levels of viral RNA observed during the studies combined with the protection factor of the BSL-4 positive pressure encapsulating suit (in excess of 105 even in the event of a breach) demonstrate that BSL-4 workers are protected from potentially infectious aerosols in a BSL-4 environment provided that proper engineering and administrative controls are implemented.