Euthanasia Assessment in Ebola Virus Infected Nonhuman Primates

Abstract

Multiple products are being developed for use against filoviral infections. Efficacy for these products will likely be demonstrated in nonhuman primate models of filoviral disease to satisfy licensure requirements under the Animal Rule, or to supplement human data. Typically, the endpoint for efficacy assessment will be survival following challenge; however, there exists no standardized approach for assessing the health or euthanasia criteria for filovirus-exposed nonhuman primates. Consideration of objective criteria is important to (a) ensure test subjects are euthanized without unnecessary distress; (b) enhance the likelihood that animals exhibiting mild or moderate signs of disease are not prematurely euthanized; (c) minimize the occurrence of spontaneous deaths and loss of end-stage samples; (d) enhance the reproducibility of experiments between different researchers; and (e) provide a defensible rationale for euthanasia decisions that withstands regulatory scrutiny. Historic records were compiled for 58 surviving and non-surviving monkeys exposed to Ebola virus at the US Army Medical Research Institute of Infectious Diseases. Clinical pathology parameters were statistically analyzed and those exhibiting predicative value for survival are reported. These findings may be useful for standardization of objective euthanasia assessments in rhesus monkeys exposed to Ebola virus and may serve as a useful approach for other standardization efforts.

Therapeutic efficacy of the small molecule GS-5734 against Ebola virus in rhesus monkeys

“…Study personnel alleviated unnecessary suffering of infected animals by euthanizing clinically moribund animals. The criteria used as the basis for euthanasia of moribund animals were defined before study initiation and included magnitude of responsiveness, reduced body temperature, and/or specified alterations to serum chemistry parameters 35 . Serum chemistry was analysed using a Vitros 350 Chemistry System (Ortho Clinical Diagnostics), and coagulation parameters were evaluated using a Sysmex CA-1500 coagulation analyser (Siemens Healthcare Diagnostics).…”

A conserved transcriptional response to intranasal Ebola virus exposure in nonhuman primates prior to onset of fever

“…Physical examinations and blood collection were performed under anesthesia on days 0 (before challenge), 3,6,10,14,21,28,35, and 41 (end of study) and at terminal. Euthanasia was performed via intracardiac administration of a pentobarbitalbased euthanasia solution under deep anesthesia when an animal was deemed moribund (37).…”

Clinical Laboratory Values as Early Indicators of Ebola Virus Infection in Nonhuman Primates

“…We conducted all studies in Biosafety Level 4 containment. Beginning on day 0 and continuing for the duration of the in-life phase, we recorded clinical observations and closely monitored animals at least 3 times daily for disease progression ( 22 ). According to protocol, we provided the NHPs with basic support with regard to pain, oral hydration, and antimicrobial drugs.…”

“…We administered antimicrobial drugs only if the facility veterinarian diagnosed a secondary bacterial infection. Moribund animals were euthanized on the basis of prespecified criteria ( 22 ).…”