EXPERIMENTAL INFECTION OF NONTARGET SPECIES OF RODENTS AND BIRDS WITH BRUCELLA ABORTUS STRAIN RB51 VACCINE

The Brucella abortus vaccine strain RB51 (SRB51) is being considered for use in the management of brucellosis in wild bison (Bison bison) and elk (Cervus elaphus) populations in the Greater Yellowstone Area (USA). Evaluation of the vaccine's safety in non-target species was considered necessary prior to field use. Between June 1998 and December 1999, ground squirrels (Spermophilus richardsonii, n = 21), deer mice (Peromyscus maniculatus, n = 14), prairie voles (Microtus ochrogaster, n = 21), and ravens (Corvus corax, n = 13) were orally inoculated with SRB51 or physiologic saline. Oral and rectal swabs and blood samples were collected for bacteriologic evaluation. Rodents were necropsied at 8 to 10 wk and 12 to 21 wk post inoculation (PI), and ravens at 7 and 11 wk PI. Spleen, liver and reproductive tissues were collected for bacteriologic and histopathologic evaluation. No differences in clinical signs, appetite, weight loss or gain, or activity were observed between saline- and SRB51-inoculated animals in all four species. Oral and rectal swabs from all species were negative throughout the study. In tissues obtained from SRB51-inoculated animals, the organism was isolated from six of seven (86%) ground squirrels, one of six (17%) deer mice, none of seven voles, and one of five (20%) ravens necropsied at 8, 8, 10, and 7 wk PI, respectively. Tissues from four of seven (57%) SRB51-inoculated ground squirrels were culture positive for the organism 12 wk PI; SRB51 was not recovered from deer mice, voles, or ravens necropsied 12, 21, or 11 wk, respectively, PI. SRB51 was not recovered from saline-inoculated ground squirrels, deer mice, or voles at any time but was recovered from one saline-inoculated raven at necropsy, 7 wk PI, likely attributable to contact with SRB51-inoculated ravens in an adjacent aviary room. Spleen was the primary tissue site of colonization in ground squirrels, followed by the liver and reproductive organs. The results indicate oral exposure to SRB51 does not produce morbibity or mortality in ravens, ground squirrels, deer mice, or prairie voles.

[1]  M. Palmer,et al.  Immune and pathologic responses in mice infected with Brucella abortus 19, RB51, or 2308 , 1994, Infection and immunity.

[2]  P. Elzer,et al.  Comparative histopathology in BALB/c mice infected with virulent and attenuated strains of Brucella abortus. , 1990, Veterinary immunology and immunopathology.

[3]  M. Palmer,et al.  Morphometric and Histopathologic Analysis of Lymphoid Depletion in Murine Spleens Following Infection with Brucella abortus strains 2308 or RB51 or an htrA Deletion Mutant , 1996, Veterinary pathology.

[4]  L. Miller,et al.  EXPERIMENTAL INFECTIONS BY Brucella suis type 4 IN ALASKAN RODENTS , 1980, Journal of wildlife diseases.

[5]  G. Schurig,et al.  Biological properties of RB51; a stable rough strain of Brucella abortus. , 1991, Veterinary microbiology.

[6]  J. Mohler Report of the Chief of the Bureau of Animal Industry, 19[41-]42. , 1922 .

[7]  J. Verger,et al.  Techniques for the Brucellosis Laboratory , 1988 .

[8]  S. Olsen,et al.  SAFETY AND EFFICACY OF BRUCELLA ABORTUS STRAIN RB51 VACCINE IN CAPTIVE PREGNANT ELK , 2000, Journal of wildlife diseases.

[9]  M. Palmer,et al.  Immune responses and resistance to brucellosis in mice vaccinated orally with Brucella abortus RB51 , 1996, Infection and immunity.

[10]  S. Olsen,et al.  Selective media for isolation of Brucella abortus strain RB51. , 2000, Veterinary microbiology.

[11]  O. Julander,et al.  The Elk of North America , 1953 .

[12]  S. Halling,et al.  Immune responses and protection against infection and abortion in cattle experimentally vaccinated with mutant strains of Brucella abortus. , 1993, American journal of veterinary research.

[13]  E. Williams,et al.  Safety of Brucella abortus Strain RB51 in Deer Mice , 2001, Journal of wildlife diseases.

[14]  B. Bricker,et al.  Enhancement of the Brucella AMOS PCR assay for differentiation of Brucella abortus vaccine strains S19 and RB51 , 1995, Journal of clinical microbiology.

[15]  E. Williams,et al.  SAFETY OF BRUCELLA ABORTUS STRAIN RB51 IN BULL ELK , 2000, Journal of wildlife diseases.

[16]  T. Ficht,et al.  DNA sequence and expression of the 36-kilodalton outer membrane protein gene of Brucella abortus , 1989, Infection and immunity.

[17]  S. Hagius,et al.  Safety of Brucella abortus Strain RB51 in Bison , 1998, Journal of wildlife diseases.