Molecular characterization of the cfb gene encoding group B streptococcal CAMP-factor

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Group B Streptococcus (GBS) is a major cause of neonatal infections.
• The CAMP-factor (cfb) is a key virulence factor produced by GBS.
• Understanding the cfb gene and its expression is crucial for GBS pathogenesis research.

Purpose of the Study:

• To fully characterize the cfb gene sequence in GBS strain R268.
• To investigate the presence and expression of the cfb gene in clinical GBS isolates.
• To determine the functional activity of the recombinant CAMP-factor.

Main Methods:

• Polymerase chain reaction (PCR) for gene amplification and sequencing.
• Inverted PCR for flanking sequences.
• Northern blot and primer extension assays for transcript analysis.
• Cloning and expression of the cfb gene in E. coli.
• Sheep-blood agar assay for hemolytic activity.

Main Results:

• A complete cfb gene (cfbR268) was identified, with minor deviations from the published sequence.
• The cfb gene was detected in 19 clinical GBS isolates, including CAMP-negative strains.
• The cfb transcript was approximately 1100 bp, with its promoter located.
• Recombinant CAMP-factor demonstrated co-hemolytic activity, inhibitable by antiserum.

Conclusions:

• The characterized cfb gene is present in diverse GBS strains, suggesting its conserved role.
• The recombinant CAMP-factor's co-hemolytic activity confirms its functional significance.
• This research provides a foundation for further studies on GBS virulence and CAMP-factor function.