Experimental infection of captive axis deer with Brucella abortus

Four captive-raised axis deer, Axis axis (Erxleben), which were negative serologically to Brucella were inoculated with 1 X 10(8) virulent Brucella abortus biotype 1 organisms (Texas #221 isolate) administered bilaterally into the conjunctival sac. Sera collected from each deer prior to inoculation and 30 days post-inoculation (PI) were examined for Brucella antibodies by the buffered Brucella antigen (card), the rivanol precipitation, the standard tube agglutination, and the cold complement fixation tube serologic tests. All four axis deer converted serologically as determined by all tests at 30 days PI. Brucella abortus biotype 1 was isolated from 26 of 32 tissue samples collected at necropsy and also from milk from the lactating female.     

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 bnucellosis in wild bison (Bison bison) and elk (Cervus elaphus) populations in the Greater Yellowstone Area (USA). Evaluation of the vaccines 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 time 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 morbidity or mortality in ravens, ground squirrels, deer mice, or prairie voles.     

Glucose Transport in Brucella abortus

Brucella abortus British strain 19 transported glucose with an apparent K(m) of 0.16 mM and an apparent V(max) of 250 nmol per min per mg of N. The only common glucose analogue transported was 2-deoxyglucose (2-DOG), with an apparent K(i) of 0.73 mM. Alpha- or beta-methyl glucosides and 3-O-methylglucose were not transported. Transport was linear for 70 to 90 s, depending on the concentration of substrate used. 2-Deoxyglucose was transported as the free sugar and was not further metabolized once inside the cell. There was no glucose phosphoenolpyruvate phosphotransferase system (PEP-PTS) present, and there were no inhibitors present in Brucella cell-free extract that inhibited the Escherichia coli glucose PEP-PTS. N-Ethylmaleimide (NEM) and p-chloromercuribenzoate (pCMB) completely inhibited transport of glucose and 2-DOG. Glutathione, dithiothreitol, and beta-mercaptoethanol reversed the effects of pCMB but not of NEM. A pH optimum of 7.2 and a temperature optimum of 37 to 45 C were observed for both K(m) and V(max). The glucose transport system appeared to be constitutive for glucose transport in cells grown on fructose, galactose, erythritol, or glucose. The electron transfer inhibitors carbonyl cyanide, m-chlorophenylhydrazone, NaN(3), 2,4-dinitrophenol, and KCN inhibited 2-DOG transport to a greater extent than did the metabolic energy inhibitors NaAsO(4), iodoacetate, KF, and 2-heptyl-4-hydroxyquinoline-N-oxide. Dicyclohexylcarbodiimide, an inhibitor of membrane-bound adenosine triphosphatases, inhibited transport by 100%.     

The effects of superovulation on Brucella abortus infection in the bovine uterus

Uterine flushings were collected three times at predetermined intervals from 11 mixed-breed beef cows and cultured for Brucella abortus . Prior to sampling, all cows had aborted fetuses from which brucellae had been isolated. Initial collections were made between 21 and 34 days following abortion. The second flushing was conducted at the onset of injections used for inducing superovulation and the third flushing was conducted 6 to 8 days after the ensuing estrus. The latter two flushes were conducted between 60 and 120 days following abortion. Brucellae were isolated from uterine flushings collected from 6 of the 11 cows on the initial round of sampling. Cultures of all subsequent uterine flushings collected before and after injections for superovulation were negative. It was concluded that the superovulatory treatment is not likely to reactivate the release of brucellae into the uterine lumen during the period when embryos are normally collected.     

Enhancement activity of anti-brucella sera in experimental Brucella abortus infection in mice.

The passive transfer of rabbit anti-brucella sera promotes the multiplication of Brucella abortus in the spleen of mice infected intravenously with a low dose of this bacteria. The enhancement activity of the anti-brucella sera is related to their modes of preparation in rabbits. The agglutinin titers of all these antisera were relatively high, while there was some discrepancies in their content in haemagglutinating, immune adherence and complement fixing antibodies.     

Endogenous gamma interferon and interleukin-10 in Brucella abortus 2308 infection in mice

Abstract CD-1 mice intravenously infected with the virulent Brucella abortus 2308 strain simultaneously produce significant levels of gamma interferon (IFN-γ) and interleukin-10 (IL-10) in their spleens between the second and eighth day post-infection with no production of interleukin-4 (IL-4). Endogenous synthesis of IL-10 does not affect the production of IFN-γ in this organ, while the production of both cytokines during this period of time is accompanied by a statistically significant increase ( P < 0.001) in the number of colony forming units (cfu) of B. abortus 2308 present in the organ. These findings suggest that although the endogenous synthesis of IL-10 apparently does not affect IFN-γ production, it may affect the effector functions of macrophages to control intracellular brucellae. Production of the Th1 cytokine IFN-γ during B. abortus 2308 infection is also associated with a specific IgG3 and IgG2a response against the B. abortus 2308 lipopolysaccharide (S-LPS) antigen.