Streptococcus suis sbp_bac_5 gene deletion strain and its construction method and application

Abstract

The invention discloses a Streptococcus suis SBP_bac_5 gene deletion strain as well as a construction method and application thereof. The deletion strain is SSΔSBP_bac_5 without resistance marker, and the preservation number is: CGMCC No.10076. The invention adopts the RecA homologous recombination system and uses the temperature-sensitive suicide plasmid pSET4s as a carrier to knock out the gene encoded by the Streptococcus suis type 7 strain SBP_bac_5, and destroys the expression of the SBP_bac_5 protein. The S. suis 7 type SS△SBP_bac_5 strain obtained by the invention is weaker in toxicity than the parent strain and safe for animals. Vaccines were made with recombinant bacteria and CD1 mice were immunized. The experimental results showed that the recombinant Streptococcus suis vaccine could effectively induce the body to produce a specific humoral immune response, so that the immunized mice could obtain protection against S. suis challenge, and could Effectively prevent the proliferation of bacteria in the body. The engineering bacterium obtained by the invention provides an important basis for the development of the Streptococcus suis vaccine.

Description

technical field [0001] The invention belongs to the technical field of bacterial genetic engineering, and relates to a Streptococcus suis serotype 7 SBP_bac_5 gene deletion strain without a resistance marker, a construction method and application thereof. Background technique [0002] Streptococcus suis (S.suis) is a Gram-positive coccus and an important zoonotic pathogen. In 1998 and 2005, two large-scale outbreaks of S. suis disease in pigs and humans occurred in China. A total of 204 cases of S. suis infection in humans were reported, including 38 deaths, which seriously affected public health safety. So far, there is still no effective vaccine for the prevention of this disease. Current research shows that there are more than 35 serotypes of S. suis capsular antigen, among which serotype 2 is the main pathogenic bacteria type in the world. However, in recent years, S. suis type 7 has been frequently reported in the detection of diseased pigs all over the world, and its...

AI Technical Summary

Problems solved by technology

[0004] The current commercialized whole-bacteria inactivated vaccines and subunit vaccines can alleviate the clinical symptoms and mortality caused by homologous serotypes, but they cannot prevent tissue lesions and chronic infections, and cannot provide complete protection against heterologous serotypes. cross protection

Therefore, the use of inactivated vaccines and subunit vaccines is not the best choice, and there is an urgent need for safer and more efficient new vaccines to prevent and control the occurrence and prevalence of this infectious disease

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