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Phase variation among major surface antigens of Mycoplasma penetrans
K Röske1, A Blanchard, I Chambaud
1Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, D-01307 Dresden, Germany.
Abstract:
The pathogenicity and prevalence of Mycoplasma penetrans, a Mycoplasma species recently isolated from humans, are still debated. A major P35 antigen, which is used as target epitope in serological assays, was shown to be a phase-variable lipid-associated membrane protein (LAMP). In this study, we performed a comparative analysis of the LAMP patterns from five M. penetrans clinical isolates and from the type strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles and immunoblots with sera serially collected from an M. penetrans-infected patient indicated that these strains expressed different LAMP repertoires. Furthermore, the intraclonal variation in the expression of LAMPs (P34A, P34B, P35, and P38) was monitored by immunoblot analysis with three specific monoclonal antibodies (MAbs) developed in this study and MAb 7 to P35. The phase variation of these LAMPs occurs in an independent manner, with frequencies of variation ranging from 10(-2) to 10(-4) per cell per generation. Consistent with their amphipathic nature, the P34B and P38 antigens were found exposed at the cell surface. The DNA sequence encoding the P38 antigen was defined and found to be related to those of the P35 gene and other putative LAMP-encoding genes, suggesting that these variable antigens are encoded by a family of related genes. Finally, the serum samples from an M. penetrans-infected patient contained antibodies that reacted with a P36 antigen expressed in different M. penetrans strains but not in the isolate recovered from this patient. This result suggested that in vivo phase variation of P36 occurred, which would support a role for these LAMP variations in avoiding the host's immune vigilance.
Insights
Mycoplasma penetrans exhibits phase-variable lipid-associated membrane proteins (LAMPs) that change independently, potentially helping the bacteria evade host immunity. This variation was observed in clinical isolates and the type strain.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- The role of Mycoplasma penetrans in human health is not fully understood.
- Lipid-associated membrane proteins (LAMPs), including the P35 antigen, are key targets for serological detection but are known to be phase-variable.
Purpose of the Study:
- To comparatively analyze LAMP expression patterns in different Mycoplasma penetrans strains.
- To investigate the intraclonal variation and frequencies of LAMP expression.
- To explore the potential role of LAMP variation in immune evasion.
Main Methods:
- Comparative analysis of LAMP profiles using SDS-PAGE and immunoblotting.
- Monitoring phase variation of specific LAMPs (P34A, P34B, P35, P38) using monoclonal antibodies.
- DNA sequencing of the P38 antigen gene.
- Analysis of patient serum antibodies against LAMPs.
Main Results:
- Clinical isolates and the type strain of Mycoplasma penetrans displayed distinct LAMP repertoires.
- Phase variation of LAMPs occurred independently at frequencies of 10^-2 to 10^-4 per cell per generation.
- The P34B and P38 antigens were cell-surface exposed, and P38 shared sequence homology with P35.
- Patient antibodies recognized a P36 antigen not present in the patient's isolate, suggesting in vivo phase variation.
Conclusions:
- Mycoplasma penetrans exhibits significant, independent phase variation in its LAMPs.
- These variable LAMPs are likely involved in evading the host immune system.
- The findings contribute to understanding Mycoplasma penetrans pathogenicity and immune evasion strategies.