• Vaccine Name: B. melitensis vaccine strain Rev. 1
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• 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).

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).

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).

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).