A surface protein identified from Streptococcus suis serotype 2 exhibits neutrophil-resistant ability via its polysaccharide capsule

Fang Ma; Guangyu Wang; Zhe Ma; Huixing Lin; Hongjie Fan

doi:10.1016/j.micpath.2024.107270

A surface protein identified from Streptococcus suis serotype 2 exhibits neutrophil-resistant ability via its polysaccharide capsule

Microb Pathog. 2024 Dec 30:199:107270. doi: 10.1016/j.micpath.2024.107270. Online ahead of print.

Authors

Fang Ma¹, Guangyu Wang², Zhe Ma³, Huixing Lin⁴, Hongjie Fan⁵

Affiliations

¹ MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR China; Institute of Veterinary Immunology & Engineering, National Research Center of Engineering and Technology for Veterinary Biologicals, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, PR China. Electronic address: [email protected].
² College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, 210023, PR China. Electronic address: [email protected].
³ MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR China. Electronic address: [email protected].
⁴ MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR China. Electronic address: [email protected].
⁵ MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR China; College of Animal Science, Anhui Science and Technology University, Fengyang, 233100, PR China. Electronic address: [email protected].

PMID: 39742898
DOI: 10.1016/j.micpath.2024.107270

Abstract

Streptococcus suis serotype 2 (SS2) is an emerging zoonotic agent responsible for a variety of diseases. The septicemia caused by SS2 suggests that it can evade the bactericidal effects of innate immune cells. However, the mechanisms by which SS2 evades innate immunity remain largely unknown. Neutrophils are critical components of innate immunity for antimicrobial defense. In this study, we identified a cell surface protein (CSP) insertion mutant in an SS2 transposon mutant library that significantly induces neutrophil extracellular traps (NETs) and shows poor survival compared to the parent SS2 in the bloodstream. CSP deletion mutant (ΔCSP) was constructed and it exhibits a defective polysaccharide capsule and enhanced biofilm formation. Although ΔCSP induces increased NET release and ROS formation, its survival and proliferation within neutrophils and NETs are significantly reduced. Additionally, ΔCSP stimulates extracellular signal-regulated kinase 1/2 (ERK1/2) signaling in neutrophils, which may enhance neutrophil bactericidal activity. Importantly, purified polysaccharide capsule from SS2 can inhibit neutrophil bactericidal effects. This study identifies bacterial virulence factors that prevent SS2 clearance by neutrophils, offering potential antigens or drug targets for the prevention and control of swine streptococcosis.

Keywords: Host-pathogen interactions; Neutrophil-resistant; Polysaccharide capsule; Streptococcus suis serotype 2; Virulence factor.