Research article

Potential effect of prior raccoonpox virus infection in raccoons on vaccinia-based rabies immunization

J Jeffrey Root¹ , Robert G McLean¹ , Dennis Slate² , Kathleen A MacCarthy¹ and Jorge E Osorio³

¹  United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, Fort Collins, CO 80521, USA

²  United States Department of Agriculture, Wildlife Services, National Rabies Management Program, Concord, NH 03301, USA

³  University of Wisconsin – Madison, School of Veterinary Medicine, Madison, WI 53706, USA

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BMC Immunology 2008, 9:57doi:10.1186/1471-2172-9-57

Published:	3 October 2008

Abstract

Background

The USDA, Wildlife Services cooperative oral rabies vaccination (ORV) program uses a live vaccinia virus-vectored (genus Orthopoxvirus) vaccine, Raboral V-RG^® (V-RG), to vaccinate specific wildlife species against rabies virus in several regions of the U.S. Several naturally occurring orthopoxviruses have been found in North America, including one isolated from asymptomatic raccoons (Procyon lotor). The effect of naturally occurring antibodies to orthopoxviruses on successful V-RG vaccination in raccoons is the focus of this study.

Results

Overall, raccoons pre-immunized (n = 10) with a recombinant raccoonpox virus vaccine (RCN-F1) responded to vaccination with V-RG with lower rabies virus neutralizing antibody (VNA) titers than those which were not pre-immunized (n = 10) and some failed to seroconvert for rabies VNA to detectable levels.

Conclusion

These results suggest that the success of some ORV campaigns may be hindered where raccoonpox virus or possibly other orthopoxvirus antibodies are common in wildlife species targeted for ORV. If these areas are identified, different vaccination strategies may be warranted.