Immunologic responses of bison to vaccination with Brucella abortus strain RB51: Comparison of parenteral to ballistic delivery via compressed pellets or photopolymerized hydrogels

This study compared responses of bison calves to 1010 CFU of Brucella abortus strain RB51 (SRB51) delivered by parenteral or ballistic methods. Two types of biobullet payloads were evaluated; compacted SRB51 pellets or SRB51 encapsulated in photopolymerized poly(ethylene glycol) hydrogels. Bison were vaccinated with saline, parenteral SRB51 alone, or in combination with Spirovac™, or ballistically with compressed SRB51 or hydrogel biobullets. Bison parenterally vaccinated with SRB51 had greater (P < 0.05) immunologic responses when compared to control bison. Co-administration of Spirovac™ as an adjuvant did not influence immunologic responses. As compared to compressed SRB51 biobullets, ballistic vaccination with hydrogel biobullets increased cellular immune responses at some sampling times. Our data suggest that hydrogel formulations of SRB51 may be a superior alternative to compressed SRB51 tablets for ballistic vaccination of bison. Although preliminary, data suggests that immunologic responses of bison to SRB51 hydrogel bullets are similar to responses after parenteral vaccination with SRB51.