Immune Responses of Elk to Initial and Booster Vaccinations withBrucella abortusStrain RB51 or 19

Abstract

Previous studies have suggested that currently available brucellosis vaccines induce poor or no protection in elk (Cervus elaphus nelsoni). In this study, we characterized the immunologic responses of elk after initial or booster vaccination with Brucella abortus strains RB51 (SRB51) and 19 (S19). Elk were vaccinated with saline or 10 10 CFU of SRB51 or S19 (n ‫؍‬ seven animals/treatment) and booster vaccinated with a similar dosage of the autologous vaccine at 65 weeks. Compared to nonvaccinates, elk vaccinated with SRB51 or S19 had greater (P < 0.05) antibody responses to SRB51 or S19 after initial vaccination and after booster vaccination. Compared to nonvaccinated elk, greater (P < 0.05) proliferative responses to autologous antigen after initial vaccination occurred at only a few sample times in SRB51 (6, 14, and 22 weeks) and S19 (22 weeks The regulatory programs for the elimination of brucellosis within the United States began in 1934 as a state-federal cooperative program to reduce the cattle population during severe drought conditions. As the Brucellosis Eradication Program for cattle nears completion in the United States after 70 years of regulatory efforts, the persistence of Brucella abortus in wildlife reservoirs remains a concern. The identification of Brucella-infected cattle herds in Wyoming in 2003 led to the loss of that state's brucellosis-free status. Epidemiologic and molecular data suggest that the likely reservoir for the Brucella abortus infections in Wyoming cattle were free-ranging elk (Cervus elaphus nelsoni).

Immune Responses and Protection against Experimental Challenge after Vaccination of Bison withBrucella abortusStrain RB51 or RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes

“…Data suggest that domestic livestock and wildlife reservoirs have diverse immunologic responses to RB51 and S19 vaccines, with differing levels of protection (3,4,6,8,10). In an effort to develop new and more efficacious vaccines, Brucella strains have been generated via recombinant DNA techniques and screened through laboratory animal models.…”

INFECTION OF C57BL/6 MICE BYTRYPANOSOMA MUSCULIMODULATES HOST IMMUNE RESPONSES DURINGBRUCELLA ABORTUSCOCOLONIZATION

“…This finding suggests that antigens associated with S19 or RB51 are unable to stimulate proinflammatory elements of the adaptive immune system and appear to be related to failure of immune memory formation (Olsen et al 2006). The elk vaccination studies also showed that elk do, in fact, develop a robust humoral response to vaccination, though some consider the humoral response insufficient to mediate clearance (Olsen et al 2006). The failure of the elk vaccination program in Wyoming has likely allowed Brucella to continue to persist in the Greater Yellowstone area.…”

“…Failure of both RB51 and S19 to induce protective memory responses in elk is not well understood and is further confounded by the observation that elk appear to respond initially to vaccination. Despite this observation, analysis of peripheral blood mononuclear cells recovered from vaccinated animals and exposed to c-irradiated S19 or RB51 showed no change in IFN-c production compared to controls (Olsen et al 2006). This finding suggests that antigens associated with S19 or RB51 are unable to stimulate proinflammatory elements of the adaptive immune system and appear to be related to failure of immune memory formation (Olsen et al 2006).…”

“…Despite this observation, analysis of peripheral blood mononuclear cells recovered from vaccinated animals and exposed to c-irradiated S19 or RB51 showed no change in IFN-c production compared to controls (Olsen et al 2006). This finding suggests that antigens associated with S19 or RB51 are unable to stimulate proinflammatory elements of the adaptive immune system and appear to be related to failure of immune memory formation (Olsen et al 2006). The elk vaccination studies also showed that elk do, in fact, develop a robust humoral response to vaccination, though some consider the humoral response insufficient to mediate clearance (Olsen et al 2006).…”

“…This finding adds credence to the hypothesis that T. cervi (or other indigenous microorganisms), by altering the appropriate memory response to B. abortus, is contributing to the failure of the RB51 vaccination campaign. Vaccination of elk with either of the two approved live attenuated vaccines (B. abortus strains RB51 and S19) for cattle has been unsuccessful in cervids (Cook et al 2002;Olsen et al 2002Olsen et al , 2006Olsen 2010). Failure of both RB51 and S19 to induce protective memory responses in elk is not well understood and is further confounded by the observation that elk appear to respond initially to vaccination.…”