[Expression, purification and hIgG-binding activity identification of truncated Streptococcus suis factor H-binding...

Area of Science:

• Molecular Biology
• Bacteriology
• Immunology

Background:

• Streptococcus suis serotype 2 is a significant zoonotic pathogen.
• The factor H-binding protein (Fhb) of S. suis plays a role in immune evasion.
• Understanding Fhb's interaction with host immune components like human IgG (hIgG) is vital for elucidating pathogenesis.

Purpose of the Study:

• To construct prokaryotic expression vectors for His-tagged Fhb fragments (Fhb-N and Fhb-C) from S. suis serotype 2.
• To express and purify these recombinant Fhb fragments in E. coli.
• To investigate the binding activity of Fhb fragments with human IgG (hIgG).

Main Methods:

• Genes for Fhb-N (amino acids 45-344) and Fhb-C (amino acids 345-644) were amplified and cloned into the pET28a⁺ vector.
• Recombinant plasmids were transformed into E. coli BL21 (DE3) and induced for protein expression.
• Proteins were purified using nickel affinity chromatography and identified by Western blotting; hIgG was purified, and binding was assessed by Western blotting and biolayer interferometry (BLI).

Main Results:

• Prokaryotic expression vectors for His-Fhb-N and His-Fhb-C were successfully constructed.
• The target recombinant proteins were expressed, purified, and identified.
• Specific binding activity between His-Fhb-N and hIgG was confirmed, with the binding region localized to Fhb-N(45-344aa).

Conclusions:

• The N-terminal fragment of Fhb (His-Fhb-N) specifically binds to human IgG.
• This interaction provides a basis for further research into the role of Fhb-hIgG binding in Streptococcus suis pathogenesis.
• The findings contribute to understanding host-pathogen interactions in S. suis infections.