Immunogenicity and Efficacy of Two Rabies Vaccines in Wild-Caught, Captive Raccoons

Brown, L.; Rosatte, Rick; Fehlner-Gardiner, Christine; Knowles, M. Kimberly; Bachmann, Peter; Davies, J. Chris; Wandeler, Alexander I.; Sobey, Kirk; Donovan, Dennis M.

doi:10.7589/0090-3558-47.1.182

Cited by 20 publications

(15 citation statements)

References 31 publications

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“… (11.8% survived); Szanto (40% survived); Brown et al . , (15.4% and 11.1% survived, respectively)]. In addition, a large amount of variation has been found in MHC genes in raccoons (Castillo et al .…”

Section: Introductionmentioning

confidence: 99%

Spatial patterns of neutral and functional genetic variations reveal patterns of local adaptation in raccoon (Procyon lotor) populations exposed to raccoon rabies

et al. 2014

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Local adaptation is necessary for population survival and depends on the interplay between responses to selective forces and demographic processes that introduce or retain adaptive and maladaptive attributes. Host-parasite systems are dynamic, varying in space and time, where both host and parasites must adapt to their ever-changing environment in order to survive. We investigated patterns of local adaptation in raccoon populations with varying temporal exposure to the raccoon rabies virus (RRV). RRV infects approximately 85% of the population when epizootic and has been presumed to be completely lethal once contracted; however, disease challenge experiments and varying spatial patterns of RRV spread suggest some level of immunity may exist. We first assessed patterns of local adaptation in raccoon populations along the eastern seaboard of North America by contrasting spatial patterns of neutral (microsatellite loci) and functional, major histocompatibility complex (MHC) genetic diversity and structure. We explored variation of MHC allele frequencies in the light of temporal population exposure to RRV (0-60 years) and specific RRV strains in infected raccoons. Our results revealed high levels of MHC variation (66 DRB exon 2 alleles) and pronounced genetic structure relative to neutral microsatellite loci, indicative of local adaptation. We found a positive association linking MHC genetic diversity and temporal RRV exposure, but no association with susceptibility and resistance to RRV strains. These results have implications for landscape epidemiology studies seeking to predict the spread of RRV and present an example of how population demographics influence the degree to which populations adapt to local selective pressures.

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Section: Introductionmentioning

confidence: 99%

Spatial patterns of neutral and functional genetic variations reveal patterns of local adaptation in raccoon (Procyon lotor) populations exposed to raccoon rabies

et al. 2014

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“…While foxes and coyotes tend to pick up the entire bait with their mouth, releasing a full dose of vaccine into the buccal cavity as they chew, raccoons hold the vaccine sachet on the ground and bite only small portions at a time, allowing the open sachet to leak. Pen trials have repeatedly shown raccoons spilling much of the liquid contents of the sachet (Brown et al, 2011).…”

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confidence: 99%

Mucosal Adjuvants to Improve Wildlife Rabies Vaccination

Fry

Dalen

Hurley

et al. 2012

Journal of Wildlife Diseases

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ABSTRACT:RABORAL V-RGH a is a recombinant vaccine used in oral rabies vaccination (ORV) programs for wildlife in the United States. Vaccination rates for raccoons are substantially lower than vaccination rates for gray foxes and coyotes. Research suggests that the low viscosity of the oral vaccine may preclude animals from receiving an effective dose when biting into the vaccine bait delivery system. We evaluated the possibility of using two benign compounds, chitosan and N,N,Ntrimethylated chitosan (TMC), to increase the viscosity of the vaccine and potentially act as adjuvants to improve the immune response in raccoons (Procyon lotor). Forty mildly sedated raccoons were orally vaccinated via needleless syringe with either RABORAL V-RG (n512), chitosan+RABORAL V-RG (n512), TMC+ RABORAL V-RG (n512), or no vaccine (n54), on day 0 and again on day 90. We collected sera every 2-4 wk for 4 mo and evaluated rabies virus-neutralizing antibodies (rVNA). Raccoons were considered responders if rVNA titers were $0.1 IU/mL. Eleven of 12 raccoons vaccinated with TMC+RABORAL V-RG responded after one dose of vaccine, as did eight of 12 vaccinated with RABORAL V-RG, and three of 12 vaccinated with chitosan+ RABORAL V-RG. Our results suggest that the inclusion of an adjuvant, such as TMC, could increase vaccine efficacy to aid in controlling rabies virus spread in wildlife reservoirs.

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“…For the Central Park outbreak, oral rabies vaccine was ruled out because of the small but potential risk for vaccinia infections of humans ( 7 , 8 ), given the large volume of park visitors and poor raccoon seroconversion rates (9%–61%) ( 9 – 14 ). Depopulation was also eliminated because it would have overwhelmed the animal shelter system with demand for humane euthanasia and decapitations and because a national animal welfare organization and the public voiced opposition.…”

Section: The Programmentioning

confidence: 99%