Submitted to: Biologicals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2000
Publication Date: N/A
Interpretive Summary: Brucella abortus is a disease of cattle that causes abortion and associated economic losses in infected herds. A recently approved vaccine to protect cattle against brucellosis, strain RB51, is being used widely in the United States. In this study, we evaluated the effect of different stabilizing media and storage temperatures in an effort to identify the most efficient combination for maintaining viability of the RB51 vaccine over time. A ne combination media developed during this research, World Health Organization-Lactose salt media, was found to be best for maintaining viability of strain RB51 during lyophilization and during storage. Lyophilized RB51 vaccine maintained best viability when stored at -25C. Liquid RB51 vaccine was found to maintain a high viability percentage when stored for 12 weeks at 4C. Understanding of the shelf life characteristics of strain RB51 will be of benefit to regulatory personnel in the Animal and dPlant Health Inspection Service and other state and federal regulatory agencies by ensuring that appropriate RB51 vaccine dosages are administered to protect livestock against brucellosis. This data also will benefit veterinarians administering the RB51 vaccine by enhancing their ability to maintain viability of RB51 vaccine under field conditions.
Technical Abstract: Brucella abortus strain RB51 (SRB51) is a new cattle vaccine that is approved for use in the U.S. for prevention of brucellosis. In the current study, the effect of 3 stabilizing media, 2 fill volumes (1 and 3 ml), and 3 storage temperatures (-25, 4, and 25C) on the viability of lyophilized SRB51 over a 52-week period was determined. The effects of 3 concen- trations of bacteria (5 x 10**8, 1 x 10**9, or 5 x 10**9 CFU/ml) and 2 storage temperatures (4 or 25C) on viability of liquid SRB51 vaccine also were determined. For lyophilized strain RB51 vaccine, fill volume did not influence viability (P>0.05) during lyophilization. Although fill volume did not influence viability during storage in World Health Organization (WHO) media or media containing both WHO and Lactose Salt (LS) media, 1 ml fill volumes of SRB51 in LS media had greater (P<0.05) viability when compared to 3 ml fill volumes. Lyophilized SRB51 vaccine stored at 25C had da more rapid decline in viability (P<0.05) when compared to vaccine stored at -25 or 4C. With the exception of the 3 ml fill volumes of LS media, all three stabilizing media were similar in maintaining viability of SRB51 at -25C storage temperatures. However, when compared to WHO or WHO/LS media, stabilization in LS media was associated with a more rapid decline in viability during storage at 4 or 25C (P<0.05). Initial SRB51 concentration in liquid vaccine did not influence (P>0.05) viability during storage at 4 or 25C. When compared to liquid SRB51 vaccine stored at 25C, storage at 4C was associated with a slower decline in viability (P<0.05) during 12 weeks of storage. Biochemical and morphological characteristics of SRB51 were stable. This study suggests that viability of SRB51 can be readily maintained during storage as a lyophilized or liquid brucellosis vaccine.