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[IgA protease activity of microbes in the genus Bordetella]
Abstract:
Monoclonal IgA paraproteins of subclasses 1 and 2, isolated from the sera of myeloma patients, were incubated for 4, 24, 48 and 72 hours with B. pertussis, B. parapertussis, B. bronchiseptica cultures, as well as Haemophilus influenzae strain. The fragmentation of IgA was studied by immunielectrophoresis with antisera to alpha-chain, to Fab alpha + Fc alpha, to Fab alpha and with antisera to light chains corresponding to the type of paraprotein. B. pertussis and B. parapertussis were found to have subclass-unspecific IgA protease which splitted off a cathode fragment, similar to Fab-fragment and, probably, corresponding to the variable domain of alpha-chain (Fv), after 48-hour incubation. Similar IgA protease was detected in H. influenzae, found to have classical IgA1 protease as well. All Bordetella species under study splitted off anode components from IgA paraproteins of both subclasses. These components, containing the determinants of heavy and light IgA chains, were either IgA - alpha I-antitrypsin complexes or some IgA fragments with high electrophoretic motility. None of the strains under study splitted monoclonal IgG.
Insights
Certain bacteria, including Bordetella species and Haemophilus influenzae, possess IgA proteases that degrade IgA paraproteins. These proteases cleave IgA, affecting its structure and function, with implications for understanding bacterial-host interactions.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Immunoglobulin A (IgA) is a crucial antibody in mucosal immunity.
- Myeloma patients produce monoclonal IgA paraproteins, useful for studying IgA structure and function.
- Bacterial IgA proteases are virulence factors that cleave IgA, impacting host defense.
Purpose of the Study:
- To investigate the IgA protease activity of Bordetella species and Haemophilus influenzae against monoclonal IgA paraproteins.
- To characterize the subclass specificity and fragmentation patterns of IgA cleaved by these bacterial proteases.
Main Methods:
- Monoclonal IgA paraproteins (subclasses 1 and 2) from myeloma patients were incubated with bacterial cultures.
- Immunelectrophoresis was used to analyze IgA fragmentation patterns.
- Specific antisera against IgA chains and fragments were employed for detailed analysis.
Main Results:
- B. pertussis and B. parapertussis exhibited subclass-unspecific IgA protease activity, cleaving off a Fab-like fragment (likely Fv domain) after 48 hours.
- H. influenzae displayed both a subclass-unspecific IgA protease and a classical IgA1 protease.
- All Bordetella species produced anode components from IgA, possibly IgA-alpha I-antitrypsin complexes or highly electrophoretic fragments.
Conclusions:
- Bordetella species and H. influenzae possess IgA proteases capable of degrading both IgA subclasses.
- The identified IgA proteases generate distinct fragments, suggesting varied mechanisms of IgA cleavage.
- These findings contribute to understanding bacterial evasion strategies and the role of IgA in host defense.