A type of agalactiae streptococcus Mu-20, its construction method and application

By constructing the agalactiae Streptococcus Mu-20, the problems of drug residues and pathogen resistance in the prevention and control of streptococcal disease in fish have been solved, achieving low-cost, high-immunogenic prevention and control of streptococcal disease in fish, and making it a suitable attenuated live vaccine for streptococcal disease in fish.

CN120249151BActive Publication Date: 2026-01-06PEARL RIVER FISHERY RES INST CHINESE ACAD OF FISHERY SCI
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Patent Information

Application Number
CN202510270840.8
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-03-07
Publication Date
2026-01-06
Estimated Expiration
2045-03-07

AI Technical Summary

Technical Problem

In the current technology, the prevention and control of streptococcal disease in fish relies on chemical and biological agents such as antibiotics and inactivated vaccines, which leads to drug residues, increased drug resistance in pathogens, decreased efficacy of chemical drug treatment, and limited use of vaccines. Subunit vaccines have high production costs and weak immune responses, while attenuated vaccine strains have low production costs but have not been commercialized.

Method used

A strain of Streptococcus agalactiae, Mu-20, was constructed by deleting capsule synthesis-related gene clusters, hyaluronidase genes, hemolysin synthesis-related genes, and trehalose utilization-related genes through genetic engineering. This resulted in a capsule-deficient fish-derived attenuated Streptococcus agalactiae strain, which reduced pathogenicity and increased immunogenicity.

Benefits of technology

Streptococcus agalactiae Mu-20 significantly reduces pathogenicity to fish, can survive in fish for a long time, stimulates immune response, provides good protection, and has low production cost, good immunization effect, and high biosafety, making it suitable for the prevention and control of streptococcal disease in fish.

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Abstract

The present application belongs to the technical field of genetic engineering, and particularly relates to a Streptococcus agalactiae Mu-20 and a construction method and application thereof. The present application constructs a fish-derived Streptococcus agalactiae strain with a capsule polysaccharide deficiency, no hyaluronidase activity, no hemolysis and no trehalose fermentation, and the strain number is Mu-20. The strain was preserved in the Guangdong Microbial Culture Collection Center on June 13, 2022, and the preservation number is GDMCC No: 62540. The strain does not carry a chloramphenicol resistance marker gene, has high biological safety, has no risk of virulence returning to strength, has high immunogenicity, can protect immunized fish against the invasion of Streptococcus agalactiae, and is easy to cultivate, simple to use and low in production cost. The strain involved in the present application can be used to prepare a live attenuated vaccine for fish streptococcosis, and has extremely high commercial application value.
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