Verification of immunosuppression in chicks caused by Cryptosporidium baileyi infection using Brucella abortus strain 1119-3

Humoral immune response of young chicks to Brucella abortus strain 1119-3 inoculation was monitored to verify the degree of immunosuppression caused by infection with Cryptosporidium baileyi. Young chicks (2-day-old) were orally inoculated each with 2 × 10⁶ oocysts of C. baileyi, and then injected intramuscularly with 0.3 ml B. abortus strain 1119-3 containing 1 × 10⁹ living organisms on day 14 postinoculation (PI). Serum samples were tested by plate agglutination test on day 17 PI onwards at an interval of 3-6 days over a period of 36 days. Infected chicks with the coccidium showed significantly lower antibody titers than those of uninfected controls (P < 0.05). These findings document that C. baileyi infection in early life stage may predispose chicks easily to other potential poultry diseases.     

Improvements in the fermenter growth of Brucella abortus strain 19

Summary The fermenter-growth conditions for a high yield of non-dissociated strain 19 Brucella abortus are described allowing a yield of close to 200×10⁹ viable bacteria ml^-1 of culture medium in less than 48 h. Details are also given of an improved growth-medium which may be sterilized by filtration or more advantageously by autoclaving in situ.     

Safety of Brucella abortus strain RB51 in deer mice

Brucella abortus strain RB51 is an approved brucellosis vaccine for use in cattle that may have potential as an oral vaccine for use in elk (Cervus elaphus) and/or bison (Bison bison). This study was designed to determine effects of strain RB51 on deer mice (Peromyscus maniculatus), a nontarget species that could have access to treated baits in a field situation. In February 1994, 90 mice were orally dosed or intraperitoneally injected with 1 x 10(8) colony forming units strain RB51 and 77 controls were similarly dosed with sterile saline. At weekly intervals through early April 1994, 4 to 6 mice from each group were euthanized, gross necropsies performed, spleens and uteruses cultured, and tissues examined histologically. All orally inoculated mice cleared the infection by 6 wk post-inoculation (PI). While most of the injected mice cleared the infection by 7 wk PI, a few required 9 wk. There were minimal adverse effects attributable to strain RB51. Apparently, strain RB51 would not negatively impact P. maniculatus populations if it were used in a field situation. Also, deer mice appear to be able to clear the vaccine in 6 to 9 wk, thus the probability of these mice transmitting the vaccine to other animals is low.     

Experimental Brucella abortus infection in wolves

Four juvenile male wolves (Canis lupus) each received an oral dose of 1.6-1.7 x 10(12) colony-forming units of Brucella abortus biovar 1 isolated from a bison (Bison bison) in Wood Buffalo National Park (Canada), and two others served as negative controls. Infected wolves did not show clinical signs of disease but did develop high Brucella antibody titers. Small numbers of B. abortus were excreted sporadically in feces until day 50 postinoculation (PI). Very small numbers of the bacterium were isolated from urine of only one wolf late on the same day that it was infected, and very small numbers of colonies of B. abortus were obtained from buccal swabs of three wolves for up to 48 hr PI. Two infected wolves euthanized 6 mo after the start of the experiment had no lesions, and colonies of B. abortus were isolated from thymus and most major lymph nodes. The other two infected wolves euthanized 12 mo after the start of the experiment had no lesions, and smaller numbers of brucellae were recovered from fewer lymph nodes compared with the wolves killed 6 mo earlier. The sporadic excretion of very small numbers of brucellae by the wolves was insignificant when compared with the infective dose for cattle. Brucella abortus, brucellosis, Canis lupus, pathogenesis, serology, wolf.     

Production and control of freeze-dried Brucella abortus strain 19 vaccine by using cells produced by fermentation units

Summary A method of producing freeze-dried Brucella abortus Strain 19 vaccine by using batch cultures on fermentation units is described. Details of the equipment and technique employed, results on microbiological and biological controls are given.     

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.     

Brucella abortus in Bison. II. Evaluation of strain 19 vaccination of pregnant cows

Protection against Brucella abortus induced abortion and infection provided by strain 19 (S19) vaccination was evaluated in American bison (Bison bison). Forty-eight pregnant bison were manually inoculated (MI) with S19 vaccine, 44 were ballistically inoculated (BI) with an absorbable hollow pellet containing lyophilized S19, and 46 were manually injected with buffered saline as non-vaccinated controls (NVC). All bison were Brucella spp. seronegative prior to the experiment, in the second trimester of pregnancy, and were randomly assigned to experimental groups. Approximately 60 days post-vaccination, abortions were observed in the vaccinated bison. Brucella abortus strain 19 was recovered from a bison that had recently aborted, her fetus, and from 11 of 12 other aborted fetuses. Fifty-eight percent (53 of 92) of vaccinated bison aborted, and no abortions were observed in the NVC bison. One cow aborted during her second post-vaccinal pregnancy and S19 was identified from the dam and fetus indicating that chronic S19 infections can occur in bison. Positive antibody titers were present 10 mo post-vaccination in 73% (66 of 91) of the bison. Thirteen mo post-vaccination, 30 MI vaccinates, 27 BI vaccinates, and 30 NVC bison were challenged during the second trimester of pregnancy with 1 x 10(7) CFU of B. abortus strain 2308 via bilateral conjunctival inoculation. Protection against abortion was 67% (P less than or equal to 0.0001) for vaccinated bison compared to 4% in NVC. Protection against B. abortus infection was determined to be 39% (P greater than or equal to 0.001) for vaccinates and 0% (zero of 30) for NCV. Persistent antibody titers, vaccine induced abortions, and chronic S19 infections indicate that the S19 vaccine doses used in this study are not suitable for pregnant bison.     

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.     

The Brucella abortus vaccine strain B19 carries a deletion in the erythritol catabolic genes

Abstract Brucella abortus B19, an avirulent strain obtained by spontaneous mutation, is used worldwide as a vaccine for the control of bovine brucellosis. B19 differs from other B. abortus strains in its sensitivity to erythritol. We took advantage of a previously obtained erythritol sensitive Tn 5 insertion mutant of B. abortus 2308 to clone the chromosomal region containing erythritol catabolic genes from this representative pathogenic strain and from the vaccine strain B19. Physical mapping with restriction endonucleases and nucleotide sequence determination revealed the existence of a 702 bp long deletion, occurring between two short direct repeats, in the chromosome of B19. This deletion rendered the B19 strain sensitive to erythritol. Two oligonucleotides whose sequences flank this deletion provided an easy method to differentiate B19 from all other B. abortus isolates.     

Use of Mitomycin C to Distinguish Brucella abortus Field Strains from the Vaccinal Brucella abortus Strain 19

Field strains of Brucella abortus were resistant to mitomycin C, whereas strain 19 was sensitive; therefore, the antibiotic was used to distinguish B. abortus strain 19 from other strains.