Sustained protection against tuberculosis conferred to a wildlife host by single dose oral vaccination
Landcare Research - Manaaki Whenua, PO Box 40, Lincoln 7640, New Zealand. Electronic address: . Vaccine
(Impact Factor: 3.62).
12/2012; 31(6). DOI: 10.1016/j.vaccine.2012.12.003
Vaccination of wildlife against bovine tuberculosis (TB) is being considered by several countries to reduce the transmission of Mycobacterium bovis infection to livestock. In New Zealand, where introduced brushtail possums (Trichosurus vulpecula) are the major wildlife hosts, we have previously shown that repeat applications of a lipid-encapsulated oral bacille Calmette-Guerin (BCG) vaccine reduce the incidence of naturally acquired TB in wild possums. Here we extend this conceptual demonstration to an operational level, assessing long-term protection against TB conferred to free-living possums by a single oral immunisation.
Possums in a non-TB area were randomly allocated to receive lipid-formulated BCG vaccine or remained unvaccinated. After initial trials to assess vaccine immunogenicity and establishment of protection within the first year post-vaccination, 13 individuals of each treatment group were relocated to a biosecurity facility and challenged (at 28 months post-vaccination) by subcutaneous injection of virulent M. bovis.
Vaccine immunogenicity and short-term protection were confirmed at 2 months and 12 months post-vaccination, respectively. In the long-term assessment, vaccinated possums had significantly reduced bacterial counts in peripheral lymph nodes compared to controls, with 0.6-2.3 log(10)-fold reductions in M. bovis burdens.
The magnitude of protective response by possums to experimental challenge at 28 months post-vaccination is known to equate to a high degree of protection against natural infection in this species. With techniques for oral bait delivery well advanced, the longevity of protection demonstrated here shows that an operable wildlife vaccine against TB is feasible.
Available from: Catherine Elizabeth Cowie
- "Gut-piles to vultures Dupont et al., 2011; Jennelle et al., 2009; Moreno-Opo et al., 2012; Pozio et al., 2001; Vicente et al., 2011; Zanella et al., 2012; Gortázar et al. 2010 5 Use wildlife proof fencing to prevent wildlife access to the farm Wildlife proof fencing Barasona et al., 2013; Brook, 2010; Judge et al., 2011; Ward et al., 2010, 2006 6 Cull wild boar on farms to reduce densities by 50% Cull wild boar Boadella et al., 2012; Carstensen and Doncarlos, 2011; Donnelly et al., 2007; García-Jiménez et al., 2013; Gortázar et al., 2008 7 Always use interferon test in addition to skin test to improve accuracy of cattle TB testing Use interferon test De la Rua-Domenech et al., 2006; Gormley et al., 2006 8 Introduce geographical limitation – accept that an area has a high disease prevalence and prevent spread beyond this area Geographical limitation Renwick et al., 2007 9 Maintain cattle separately from goats Separate goats Gutierrez and Marin, 1999; Napp et al., 2013 10 Maintain cattle separately from pigs Separate pigs Bailey et al., 2013; Di Marco et al., 2012 11 Feed cattle in high feeders that wildlife cannot access Use high feeders Humblet et al., 2009; Kaneene et al., 2002; Palmer et al., 2004; Roper et al., 2003 12 Vaccinate 70% of wild boar population using an oral bait Vaccinate wild boar Ballesteros et al., 2011; Beltrán-Beck et al., 2012; Cross et al., 2007m; Tompkins et al., 2013 13 Manage water to prevent build-up of areas of mud (where the latest research suggests M. bovis may survive in the soil) "
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ABSTRACT: Livestock disease control strategies are usually determined at national and international levels, yet their successful implementation is determined by stakeholders operating at local scales. Such stakeholders may also have detailed knowledge that would contribute to the development of disease control options suited to the socio-cultural and environmental conditions where management is undertaken. The aim of this study was to evaluate stakeholders' opinions of a list of potential bovine tuberculosis (TB) management interventions for South Central Spain. This area has high TB prevalence in wildlife and livestock, so veterinarians, livestock farmers and hunters are all key stakeholders in TB management. A literature review identified possible management activities. The effectiveness of each intervention was ranked by local experts, and practicality was ranked by hunters, cattle farmers and veterinarians, using a best-worst scaling exercise as part of a questionnaire. The most effective intervention, the banning of supplemental feeding of game species, was not considered practical by stakeholders. The most effective and practical interventions were the separation of wildlife and livestock access to waterholes, testing cattle every 3 months on farms with a recent positive TB case and removing gut-piles from the land after hunting events. Although all three of these options were well supported, each stakeholder group supported different approaches more strongly, suggesting that it might be effective to promote different disease management contributions in different stakeholder communities. This integrated approach contributes to the identification of the optimum combination of management tools that can be delivered effectively.
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Available from: Eric Vander Wal
- "Vaccines selecting for increased virulence have important evolutionary implications for malaria (Mackinnon et al. 2008) and human papilloma virus vaccination programs (Stearns 2012). While vaccines are often among the tools available to wildlife managers (Wobeser 2002); e.g., raccoon rabies variant (Rosatte et al. 2008), tuberculosis (Tompkins et al. 2013), brucellosis (Cross et al. 2013), their impermanence, and their role as selective agents are rarely considered. "
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ABSTRACT: Wildlife disease has the potential to cause significant ecological, socioeconomic, and health impacts. As a result, all tools available need to be employed when host–pathogen dynamics merit conservation or management interventions. Evolutionary principles, such as evolutionary history, phenotypic and genetic variation, and selection, have the potential to unravel many of the complex ecological realities of infectious disease in the wild. Despite this, their application to wildlife disease ecology and management remains in its infancy. In this article, we outline the impetus behind applying evolutionary principles to disease ecology and management issues in the wild. We then introduce articles from this special issue on Evolutionary Perspectives on Wildlife Disease: Concepts and Applications, outlining how each is exemplar of a practical wildlife disease challenge that can be enlightened by applied evolution. Ultimately, we aim to bring new insights to wildlife disease ecology and its management using tools and techniques commonly employed in evolutionary ecology.
Available from: Mitchell Palmer
- "The colony-forming units (CFUs) of BCG were determined retrospectively by plating on 7H11 agar plates (Becton Dickinson, Cockeysville, MD) as described previously (Buddle et al., 1994). BCG Danish is known to provide protection against bTB in experimentally infected deer, is commercially available, and is frequently used in vaccine efficacy trials with other host species (Palmer et al. 2009; Carter et al. 2012; Tompkins et al. 2013; Ballesteros et al. 2009b). Aseptically prepared baits were cooled in a biological safety cabinet following baking. "
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ABSTRACT: White-tailed deer (Odocoileus virginianus) in Michigan, USA, are wildlife reservoirs of bovine tuberculosis (bTB) with documented spread to cattle. In vaccine efficacy trials, Mycobacterium bovis bacillus Calmette–Guerin (BCG) administered orally reduces colonization and bTB-associated lesions in white-tailed deer after experimental challenge with virulent M. bovis. The objective of this study was to develop and evaluate the palatability of a molasses-based bait for oral delivery of BCG to white-tailed deer. Relevant practical properties of the bait such as physical stability under various environmental conditions were evaluated, as well as palatability. Captive deer consumed baits within 3 h of introduction during 48 of 50 trials. Digital game cameras revealed consumption of all placed baits by one deer over 62 % of the time. Addition of BCG vaccine did not negatively impact palatability. Physical stability analysis demonstrated that ice and water significantly reduced bait stability as measured with a compression assay. Storage of BCG-containing baits at 4 °C showed a slight decrease in colony-forming units (CFUs) by day 31. In contrast, storage at −20 or −80 °C over the same 31-day period showed no significant decrease in BCG viability. The results of this study suggest that molasses-based baits, as prepared here, represent a plausible means of oral delivery of BCG to white-tailed deer under most environmental conditions.
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