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Rough brucella strain RM57 is attenuated and confers protection against Brucella melitensis
Yu Feng1, Xiaowei Peng2, Hui Jiang2
1Department of Inspection Technology Research, China Institute of Veterinary Drug Control, Beijing 100081, China; College of Animal Science and Veterinary Medicine, Shandong Agriculture University, Taian, Shandong 270018, China.
Abstract:
Brucella melitensis (B. melitensis) is a facultative intracellular pathogen, which is the main epidemic strain in China. To overcome disadvantages of traditional live attenuated vaccines, in this study a rough mutant RM57 was induced from a B. melitensis isolate M1981. In order to uncover the reason of changes in the LPS of RM57, the nucleotide sequences and transcription levels of all known genes related to LPS synthesis were detected. As LPS plays an important role in outer membrane integrity, the sensitivities of RM57 to SDS and polymyxin B were examined. The results showed that the expression level of LPS genes of RM57 was not significantly changed, and RM57 was sensitive to polymyxin B, compared to its parent strain. In further study, the virulence and protective efficacy of RM57 in mice and guinea pigs were determined, and our data indicated that RM57 was attenuated and had good protection effects, especially in guinea pigs model. Overall, these results demonstrated that the artificially induced rough mutant strain RM57 was an efficacious vaccine candidate against the challenge of virulent B. melitensis. Our data presented here provided additional insight into the mechanism of LPS synthesis of Brucella spp.
Insights
A new rough mutant strain, RM57, was developed from Brucella melitensis (B. melitensis) to create a safer vaccine. This attenuated strain showed good protective effects in animal models, indicating its potential as an effective B. melitensis vaccine candidate.
Area of Science:
- Microbiology
- Vaccinology
- Immunology
Background:
- Brucella melitensis (B. melitensis) is a significant cause of brucellosis, particularly in China.
- Traditional live attenuated vaccines face limitations, necessitating the development of safer alternatives.
- Lipopolysaccharide (LPS) is crucial for bacterial outer membrane integrity and virulence in Brucella spp.
Purpose of the Study:
- To induce and characterize a rough mutant of B. melitensis for vaccine development.
- To investigate the molecular basis for changes in LPS synthesis in the mutant strain.
- To evaluate the virulence and protective efficacy of the induced rough mutant (RM57) in animal models.
Main Methods:
- Induction of a rough mutant (RM57) from B. melitensis M1981.
- Analysis of nucleotide sequences and transcription levels of LPS synthesis genes.
- Assessment of bacterial sensitivity to SDS and polymyxin B.
- Determination of virulence and protective efficacy in mouse and guinea pig models.
Main Results:
- The rough mutant RM57 exhibited no significant changes in LPS gene expression compared to the parent strain.
- RM57 demonstrated increased sensitivity to polymyxin B, suggesting alterations in outer membrane structure.
- The RM57 strain was significantly attenuated in virulence.
- RM57 provided good protection against virulent B. melitensis challenge, particularly in the guinea pig model.
Conclusions:
- The artificially induced rough mutant strain RM57 is a promising vaccine candidate against B. melitensis.
- RM57 offers an attenuated profile with significant protective efficacy, addressing limitations of traditional vaccines.
- This study provides insights into LPS synthesis mechanisms in Brucella spp. and supports the development of novel Brucella vaccines.