• Vaccine Name: live attenuated Brucella ovis delta abcBA vaccine
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0009337
• Type: Live attenuated vaccine
• Status: Research
• Host Species for Licensed Use: Sheep
• Host Species as Laboratory Animal Model: Mus musculus
• Antigen: abcBA deletion mutant | abcBA deletion
• Adjuvant: | alginate; alginate plus vitelline protein B (VpB) | alginate and chitosan
• Preparation: B. ovis ΔabcBA strain encapsulated with sterile alginate or non encapsulated vaccine strain. (Silva et al, 2015a)
  Two formulations were tested: BoΔabcBA encapsulated with alginate alone and BoΔabcBA encapsulated with alginate plus vitelline protein B (VpB). (Costa et al, 2020)
  B. ovis ΔabcBA strain encapsulated by alginate with chitosan or with copolymer Poloxamer 407 as polymeric adjuvants. (Brunno et al, 2024)
• Description: This study aimed to evaluate protection induced by the vaccine candidate B. ovis ΔabcBA against experimental challenge with wild type B. ovis in rams. Efficacy: Immunization, particularly with encapsulated B. ovis ΔabcBA, prevented infection, secretion of wild type B. ovis in semen and urine, shedding of neutrophils in semen, and development of clinical changes, gross and microscopic lesions induced by wild type B. ovis. (Silva et al, 2015a)
  Brucella ovis ΔabcBA is a live attenuated candidate vaccine strain tested for protection against Brucella melitensis infection. Efficacy: Both vaccine formulations reduced Brucella melitensis 16M counts in liver and spleen compared to nonimmunized controls, with approximately 1-log10 reduction in spleen bacterial load. Immune response: Splenocytes from mice immunized with BoΔabcBA encapsulated with alginate plus VpB secreted IFN-γ upon stimulation with B. melitensis antigens, whereas those immunized with alginate alone did not. Spleen size was larger in mice immunized with alginate formulation compared to alginate plus VpB or controls. (Costa et al, 2020)
  The Brucella ovis ΔabcBA strain encapsulated in alginate provides an experimental vaccine formulation that protects against Brucella spp. infection. Efficacy: The formulation with alginate and chitosan resulted in the lowest bacterial recovery in spleen and liver compared to non-vaccinated mice; Poloxamer 407 formulation did not reduce bacterial recovery significantly. Immune response: Alginate and chitosan formulation induced higher levels of Immunoglobulin G, with an increase in the IgG2b subclass, indicating a Th1 type immune response important for controlling intracellular infections; Poloxamer 407 did not induce significant humoral response. (Brunno et al, 2024)

Mouse Response

• Immune Response: Splenocytes from mice immunized with Bo∆abcBA encapsulated with alginate plus VpB secreted IFN-γ upon stimulation with B. melitensis antigens, whereas those immunized with alginate alone did not. Spleen size was larger in mice immunized with alginate formulation compared to alginate plus VpB or controls. (Costa et al, 2020)
• Challenge Protocol: Mice were immunized with the two vaccine formulations and then challenged experimentally with Brucella melitensis strain 16M. (Costa et al, 2020)
• Efficacy: Both vaccine formulations reduced Brucella melitensis 16M counts in liver and spleen compared to nonimmunized controls, with approximately 1-log10 reduction in spleen bacterial load. (Costa et al, 2020)
• Description: Mice were immunized with the two vaccine formulations and then challenged experimentally with Brucella melitensis strain 16M. Bacterial counts in liver and spleen were measured one week post-infection. Splenocyte cytokine secretion (IFN-γ) was assessed in vitro after stimulation with B. melitensis antigens. (Costa et al, 2020)

Mouse Response

• Immune Response: Alginate and chitosan formulation induced higher levels of Immunoglobulin G, with an increase in the IgG2b subclass, indicating a Th1 type immune response important for controlling intracellular infections; Poloxamer 407 did not induce significant humoral response. (Brunno et al, 2024)
• Challenge Protocol: Mice were vaccinated with B. ovis ∆abcBA associated with different polymeric adjuvants and challenged with B. ovis; bacterial recovery in spleen and liver was measured; humoral immune response was assessed by IgG and IgG subclass levels. (Brunno et al, 2024)
• Efficacy: The formulation with alginate and chitosan resulted in the lowest bacterial recovery in spleen and liver compared to non-vaccinated mice; Poloxamer 407 formulation did not reduce bacterial recovery significantly. (Brunno et al, 2024)
• Description: Mice were vaccinated with B. ovis ∆abcBA associated with different polymeric adjuvants and challenged with B. ovis; bacterial recovery in spleen and liver was measured; humoral immune response was assessed by IgG and IgG subclass levels. (Brunno et al, 2024)