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A Streptococcus suis Strain Δcps/ssna-msly (P353L)-SC19 Provides Cross-Protection against Serotypes 2 and 9 Strain
Xi Lu1,2, Lei Xu1,2, Lan Lin1,2,3,4
1State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
Abstract:
Streptococcus suis is an important zoonotic pathogen that mainly causes meningitis, septicemia, and arthritis. Due to the limited cross-protection between numerous serotypes, the existing inactive vaccines in clinical use fail to offer sufficient protection. In this study, a gene deletion-attenuated strain Δcps/ssna-msly (P353L)-SC-19 was constructed by deleting cps and ssna genes from the epidemic strain SC-19 with a mutation of SLY (P353L). The safety of Δcps/ssna-msly (P353L)-SC-19 was confirmed in both in vitro and in vivo experiments. We further demonstrated that immunization with Δcps/ssna-msly (P353L)-SC-19 induced significant cellular immunity and humoral immunity in mice and protected against infections caused by type 2 strain SC-19 (100% protection) and type 9 strain S29 (50% protection), while also preventing meningitis induced by S29. This study highlights the potential of using CPS-deficient strains to achieve cross-protection against different Streptococcus suis serotypes and develop a promising universal live vaccine.
Insights
A novel live vaccine strain, Δcps/ssna-msly (P353L)-SC-19, was developed for Streptococcus suis. This attenuated strain shows safety and induces protective immunity against multiple serotypes, offering potential for a universal vaccine.
Area of Science:
- Veterinary Microbiology
- Infectious Diseases
- Vaccine Development
Background:
- Streptococcus suis is a significant zoonotic pathogen causing severe diseases like meningitis and septicemia.
- Current inactivated vaccines offer limited cross-protection due to the diverse serotypes of Streptococcus suis.
Purpose of the Study:
- To construct and evaluate a novel live attenuated vaccine candidate for Streptococcus suis.
- To assess the safety and immunogenicity of the developed strain.
- To determine the protective efficacy against homologous and heterologous Streptococcus suis serotypes.
Main Methods:
- Construction of a gene deletion-attenuated strain (Δcps/ssna-msly (P353L)-SC-19) from an epidemic strain.
- In vitro and in vivo safety assessments of the attenuated strain.
- Immunization of mice with the candidate vaccine, followed by challenge with virulent Streptococcus suis strains.
- Evaluation of cellular and humoral immune responses.
Main Results:
- The constructed strain Δcps/ssna-msly (P353L)-SC-19 was confirmed safe in vitro and in vivo.
- Immunization induced significant cellular and humoral immunity in mice.
- The vaccine provided 100% protection against homologous type 2 strain SC-19 and 50% protection against heterologous type 9 strain S29.
- Protection against meningitis induced by S29 was also observed.
Conclusions:
- CPS-deficient Streptococcus suis strains hold promise for achieving cross-protection.
- The developed attenuated strain demonstrates potential as a universal live vaccine against Streptococcus suis infections.
- Further research into CPS-deficient strains could lead to broader vaccine efficacy.
