• Vaccine Name: live attenuated Brucella abortus mutant A19mut2 vaccine
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0009538
• Type: Live attenuated vaccine
• Status: Research
• Host Species for Licensed Use: Cattle
• Host Species as Laboratory Animal Model: Mus musculus
• Antigen: wbkC gene replaced by wbdR gene (modified O-polysaccharide)
• Preparation: Live attenuated mutant strain with modified lipopolysaccharide due to gene replacement. (Abdelgawad et al, 2023)
• Description: The vaccine candidate A19mut2 was developed by replacing the formyltransferase gene wbkC in Brucella abortus A19 with the acetyltransferase gene wbdR from E. coli O157, resulting in a modified O-polysaccharide that does not induce antibodies against wild-type Brucella LPS, enabling DIVA (Differentiating Infected from Vaccinated Animals) capability. Efficacy: A19mut2 showed decreased residual virulence compared to A19 but induced significant humoral and cellular immune responses similar to A19; protection efficacy against B. abortus S2308 NalR infection was comparable to A19 immunization. Immune response: Induced significant humoral immunity (IgG and subtypes) and cellular immunity (IFN-γ and IL10 cytokine release) in vaccinated mice; antibodies induced by A19mut2 did not cross-react with wild-type LPS, allowing serological differentiation. (Abdelgawad et al, 2023)

Mouse Response

• Immune Response: Induced significant humoral immunity (IgG and subtypes) and cellular immunity (IFN-γ and IL10 cytokine release) in vaccinated mice; antibodies induced by A19mut2 did not cross-react with wild-type LPS, allowing serological differentiation. (Abdelgawad et al, 2023)
• Efficacy: A19mut2 showed decreased residual virulence compared to A19 but induced significant humoral and cellular immune responses similar to A19; protection efficacy against B. abortus S2308 NalR infection was comparable to A19 immunization. (Abdelgawad et al, 2023)
• Description: Growth curve analysis, agglutination tests, Western blotting, stress resistance assays, histopathological examination, bacterial colonization in spleens of vaccinated mice, measurement of IgG and IgG subtypes, cytokine release (IFN-γ and IL10) in splenocytes, and ELISA using wild-type LPS to distinguish antibody responses. (Abdelgawad et al, 2023)