The safety of ONRAB® in select non-target wildlife

Abstract

ONRAB® is a recombinant human adenovirus type 5 (HAd5) with the rabies glycoprotein gene incorporated into its genome. ONRAB® has been used in Canada as an oral rabies vaccine in target wildlife species such as: red fox (Vulpes vulpes), raccoon (Procyon lotor), and striped skunk (Mepthis mephitis). We evaluated the safety of ONRAB® in non-target wildlife species likely to contact the vaccine baits during oral rabies vaccine campaigns in the United States. We investigated the effects of oral inoculation of high titer ONRAB®, approximately ten times the dose given to target species, in wood rats (Neotoma spp.), eastern cottontail rabbits (Sylvilagus floridanus), Virginia opossums (Didelphis virginiana), eastern wild turkeys (Meleagris gallopavo silvestri), and fox squirrels (Sciurus niger). We performed real-time polymerase chain reaction (PCR) on fecal swabs, oral swabs, and tissues, including lung, liver, kidney, small intestine, large intestine, and when appropriate nasal turbinates, to detect ONRAB® DNA from inoculated animals. By seven days post-inoculation, turkeys, opossums, and cottontails had all stopped shedding ONRAB® DNA. One wood rat and one fox squirrel still had detectable levels of ONRAB® DNA in fecal swabs 14 days post-inoculation. Real-time PCR analysis of the tissues revealed some ONRAB® DNA persisting in certain tissues; however, there were no significant gross or histologic lesions associated with ONRAB® in any of the species studied. Our results suggest that many non-target species are not likely to be impacted by the distribution of ONRAB® as part of oral rabies vaccination programs in the United States.