• Vaccine Ontology ID: VO_0000723
• Type: attenuated live vaccine
• Antigen: Whole Brucella organism
• Preparation: The 45/20 strain was isolated from guinea pigs in 1938 (Moriyon et al., 2004).
• Virulence: The original strain of 45/20 was known to revert to smooth pathogenic forms when injected into cattle. Due to this instability, the vaccine is not currently marketed (Moriyon et al., 2004).
  
• Description: B. abortus strain 45/20 is a rough form of the bacterium that can confer immunity (Moriyon et al., 2004).

• Vaccine Ontology ID: VO_0000710
• Type: Attenuated live vaccine
• Status: Licensed
• Antigen: Rev.1 is a live attenuated Brucella melitensis strain derived from a virulent B. melitensis isolate.
• RpsL gene engineering:
  • Type: Recombinant protein preparation
  • Description: The gene rpsL of B. melitensis reference strain 16 M encodes for ribosomal protein S12. This gene was mutated in the vaccine strain Rev. 1 during its natural selection process. Nucleotide sequencing has revealed that a mutation in the rpsL gene of vaccine strain Rev . 1 compared to that of reference strain 16M leading to an amino acid Pro- to -Leu change at codon position 91 ( Pro91Leu ) (Cloeckaert et al., 2002).
  • Detailed Gene Information: Click Here.
• Preparation: Rev . 1 vaccine, obtained in the 1950s by a two-step selection involving firstly, a streptomycin resistance and/or dependence, and secondly, a reversion of dependence but maintaining streptomycin resistance (ELBERG and FAUNCE, 1957). Acquired chromosomal streptomycin resistance is frequently due to mutations in the gene encoding for ribosomal protein S12, rpsL (Cloeckaert et al., 2002).
• Virulence: Whether Rev. 1 is virulent is unclear. A Rev. 1-like strain was isolated from the membranes of an aborted fetus at an intensively managed farm that had complied with the vaccination regimen, i.e. ewelambs were vaccinated between two and six months. When the whole flock (410 ewes) was serologically tested, 34 animals showed a positive complement fixation test. The ewes were slaughtered and attempts to culture additional isolates from milk, major lymph nodes, and mammary glands were unsuccessful. A few months later , the flock owner contracted brucellosis and Brucella was cultured from his blood (Banai, 2002).
• Storage: The vaccine was kept on plates at 5 degrees celsius (ELBERG and FAUNCE, 1957).
• Description: The live attenuated strain of B melitensis Rev . 1 is considered the best vaccine available for the prophylaxis of brucellosis in sheep and goats (Cloeckaert et al., 2002).

• Vaccine Ontology ID: VO_0000338
• Type: Live, attenuated vaccine
• Antigen: The antigen for this vaccine is Brucella melitensis containing a deletion of the bp26 gene, a strain called CGV26 (Guilloteau et al., 2006).
• RL3382 gene engineering:
  • Type: Recombinant protein preparation
  • Description: The CGV26 and CGV2631 strains were engineered with Brucella melitensis Rev.1 mutant strains containing deletions in the bp26 gene or both bp26 and omp31 genes (Guilloteau et al., 2006).
  • Detailed Gene Information: Click Here.
• Preparation: Mutants were kept freeze-dried. Bacteria were rehydrated in sterile buffered saline solution, seeded on Trypticase Soy Agar, supplemented with yeast extract and incubated at 37 °C. Fresh bacterial suspensions were harvested in BSS from 24 h cultures and spectrophotometrically adjusted. Each suspension used was always checked for purity and dissociation and the exact doses were assembled (Guilloteau et al., 2006).
• Virulence: The virulence of the CGV26 mutant was similar to that of the parental Rev.1 strain (Guilloteau et al., 2006).

• Product Name: B. melitensis Rev. 1 with bp26 and omp31 deletions
• Vaccine Ontology ID: VO_0001171
• Type: Live, attenuated vaccine
• Status: Research
• Antigen: B. melitensis Rev. 1 with bp26 and omp31 deletions (Jacques et al., 2007).
• Immunization Route: Intramuscular injection (i.m.)

Mouse Response

• Vaccination Protocol: Several groups of 10 (or eight mice in the assay after storage or passage) were vaccinated subcutaneously with Rev. 1 strains. Control unvaccinated mice received BSS alone (Bosseray, 1991).
• Challenge Protocol: Vaccinated and control mice were challenged intraperitoneally 30 or 45 days after vaccination with The virulent B. abortus 544 CO2-dependent reference challenge strain (Bosseray, 1991).

Goat Response

• Host Strain: Angora
• Vaccination Protocol: Four to five-year-old goats were used. Each goat received 1.5 x 10^9 cells of the bacteria subcutaneously in the left prescapular region. At 2,4,5,7,10,11, and 14 weeks the goats were sacrificed and tested for the presence of brucellae (ELBERG and FAUNCE, 1957).
• Persistence: At the third week organisms from the spleen, bone marrow, left and right prescapular regions, left and right supramammary nodes, right precrural and the mediastinal nodes were detected. By the fourteenth week, the infection in the single goat sacrificed was isolated to the left prescapular node. It was assumed that at this point the animals were free from infection (ELBERG and FAUNCE, 1957).
• Immune Response: The mutant strain stimulated an antibody-producing mechanism within the first ten days of vaccination. The antibody titers were highest at about 20 days postinfection (ELBERG and FAUNCE, 1957).
• Challenge Protocol: The challenge consisted of 33 ID doses of B. melitensis. It was administered 90 days after vaccination (ELBERG and FAUNCE, 1957).
• Efficacy: The vaccine was proven to be an effective immunizing agent for the host species tested (ELBERG and FAUNCE, 1957).

Sheep Response

• Vaccination Protocol: 15 lambs were vaccinated with 45/20 bacterin, and a control group remained unvaccinated. Revaccinations were performed 18 weeks later. At regular intervals after vaccination and revaccination, blood samples were taken and animals were examined for genital lesions (Blasco et al., 1993).
  
• Side Effects: One ram died from enterotoxemia during the course of the experiment (Blasco et al., 1993).
  
• Challenge Protocol: Challenge inoculations were performed 31 weeks after the second vaccination with a virulent strain of B. ovis obtained from a naturally infected ram. Each ram received a total volume of 60 uL ( 1 x 10^9 CFU), as shown by viable cell counts made on the day of inoculation), both conjunctivally (30 uL) and preputially (30 uL) (Blasco et al., 1993).
• Efficacy: Two weeks after challenge, ten of the 15 control rams excreted B. ovis. All animals were slaughtered 15 weeks after the challenge inoculation and subjected to bacteriological and histological examinations. A ram was classified as protected if no B. ovis was isolated from any of the 13 organs sampled at necropsy. Significant levels of protection in comparison with the control group were obtained by vaccination with 45/20 bacterin (PC 0.05) (Blasco et al., 1993).
  

Sheep Response

• Vaccination Protocol: Seven groups, 22 sheep/group were either vaccinated subcutaneously (SC) or conjunctivally (CJ) (right eye) at the age of four months with the following actual doses, Rev.1, 1.1 × 10^9 CFU (SC) and 1.33 × 10^9 CFU (CJ); CGV26, 1.25 × 10^9 CFU (SC) and 1.22 × 10^9 cfu (CJ); CGV2631, 1.11 × 10^9 cfu (SC) and 1.30 × 10^9 cfu (CJ). The vaccine doses (<1 mL) were utilized where administered SC and 30 uL where administered CJ (Jacques et al., 2007).
• Challenge Protocol: One week before challenge, of 154 ewes, 99 of whiche were pregnant assesd by progesterone levels were were kept in a high security pen. Each ewe was challenged CJ (left eye) with 5.1 × 10^7 CFU of B. melitensis strain H38 after 76 days of pregnancy. Each animal was submitted to periodic immunological, clinical, and bacteriological tests and sacrificed 4–6 weeks after delivery. To follow cellular response, six ewes from each group were selected for further investigation (Jacques et al., 2007).
• Efficacy: Regardless of the route of administration of Rev.1 vaccine (SC or CJ), the results obtained agreed with those of previous studies [35], Rev.1 effectively protected ewes challenged at middle of pregnancy with 5 × 10^7 CFU of strain H38. In the control group (unvaccinated ewes), 100% aborted (Jacques et al., 2007).

Sheep Response

• Host Strain: Préalpes
• Vaccination Protocol: 42 Brucella-free Préalpes females of 3–4 months of age were randomly allotted into seven groups of six animals. Six groups were inoculated either by CJ or SC route with 1 × 10^9 cfu of CGV26 mutant or the Rev.1 vaccine as a vaccinated control group. The vaccine suspension was administered conjunctivally with a calibrated dropper by depositing 33 μl on the surface of the right eye or subcutaneously with a needle by injecting 1 ml just behind the left elbow joint. One group remained as a separate uninfected control group. Swabs were taken from the conjunctiva and nostrils in groups inoculated by CJ route for bacteriological analyses. At regular intervals after inoculation, blood samples were collected for analysis of the immune response induced (Guilloteau et al., 2006).
• Persistence: The local persistence of the CGV26 mutant was not statistically different from the Rev.1 strain (Guilloteau et al., 2006).
• Immune Response: The results together showed that the CGV26 mutant was able to induce both specific antibody response and systemic lymphoproliferation in sheep. Specific systemic antibody response to S-LPS of Brucella was induced after inoculation of the mutant and the Rev.1 strain. The intensity of this response was much higher and earlier after SC vaccination (1 week) than that after CJ vaccination (second week) (Guilloteau et al., 2006).
• Efficacy: This mutant induced significant specific antibody and cell-mediated immunity in sheep (Guilloteau et al., 2006).

Sheep Response

• Vaccination Protocol: Sheep were conjunctivally or subcutaneously vaccinated at 4 months old (Jacques et al., 2007).
• Challenge Protocol: Sheep were challenged with B. melitensis H38 at the middle of the first pregnancy following vaccination (Jacques et al., 2007).
• Efficacy: eletion of bp26 and omp31 genes did not significantly affect the well recognised capacity of Rev.1 to protect sheep against B. melitensis challenge. However, the protection conferred by the CGV2631 mutant was significantly lower than that conferred by the CGV26 mutant or the Rev.1 strain (Jacques et al., 2007).