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Differential expression of Pmp10 in cell culture infected with Chlamydia pneumoniae CWL029
A S Pedersen1, G Christiansen, S Birkelund
1Loke Diagnostics ApS, Science Park Aarhus, Gustav Wieds Vej 10 C, DK-8000 Aarhus C, Denmark. annas@biobase.dk
Abstract:
The complete genome of Chlamydia pneumoniae contains a total of 21 genes encoding polymorphic membrane proteins (Pmp). From this large Pmp family three genes, pmp8, pmp10 and pmp11, were cloned and antibodies against recombinant full-length Pmp proteins were produced. Indirect immunofluorescence microscopy of HEp-2 cells infected with C. pneumoniae CWL029 was performed with the Pmp antibodies in combination with a Chlamydia-specific anti-lipopolysaccharide (LPS) antibody. This double staining technique clearly showed that expression of Pmp10 was differential. Additional double staining with monoclonal antibodies to the surface of C. pneumoniae elementary bodies and the anti-LPS antibody resulted in identification of seven monoclonal antibodies that reacted identically to the Pmp10 antibody indicating that Pmp10 is an immunodominant protein. Finally, the molecular mechanism responsible for differential expression is suggested to be variation in the guanine residues in the polyG tract of pmp10.
Insights
Chlamydia pneumoniae expresses polymorphic membrane protein 10 (Pmp10) differentially, identified as an immunodominant protein. Variations in guanine residues within the pmp10 gene
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- The Chlamydia pneumoniae genome encodes 21 polymorphic membrane proteins (Pmp).
- Understanding Pmp expression is crucial for Chlamydia pathogenesis and vaccine development.
Purpose of the Study:
- To investigate the expression patterns of specific Pmp family members in Chlamydia pneumoniae.
- To identify immunodominant Pmp proteins and elucidate the mechanism of differential expression.
Main Methods:
- Cloning of pmp8, pmp10, and pmp11 genes from Chlamydia pneumoniae.
- Production of antibodies against recombinant full-length Pmp proteins.
- Indirect immunofluorescence microscopy using HEp-2 cells infected with C. pneumoniae, employing double staining with Chlamydia-specific anti-lipopolysaccharide (LPS) and monoclonal antibodies.
Main Results:
- Differential expression of Pmp10 was observed in infected HEp-2 cells.
- Seven monoclonal antibodies reacted identically to the Pmp10 antibody, identifying Pmp10 as an immunodominant protein.
- Variations in guanine residues within the polyG tract of the pmp10 gene are suggested as the mechanism for differential expression.
Conclusions:
- Pmp10 is an immunodominant protein in Chlamydia pneumoniae with differential expression.
- The polyG tract in the pmp10 gene likely plays a role in regulating its expression.