A survey of IgA protease production among clinical isolates of Proteeae
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B W Senior1, M Albrechtsen, M A Kerr
1Department of Medical Microbiology, Dundee University Medical School, Ninewells Hospital.
Abstract:
A collection of 100 strains of Proteeae, in which all species within the tribe were represented, was examined for IgA protease production. The strains were isolated from various clinical specimens from sick and healthy persons in several countries. IgA protease-producing strains were not found amongst species of Providencia and Morganella but were common in Proteus spp. All the strains of P. mirabilis and P. penneri and many of the strains of P. vulgaris examined produced an EDTA-sensitive protease that cleaved the IgA heavy chain outside the hinge region. The proteus enzyme was different in this respect from the EDTA-sensitive, hinge-cutting proteases of other bacteria. The ability to produce IgA protease was unrelated to the O antigenicity, biotype or bacteriocin type of the strain. IgA protease production may be an important virulence mechanism for Proteus strains.
Insights
Proteus bacteria commonly produce Immunoglobulin A (IgA) protease, an enzyme that cleaves IgA outside the hinge region. This IgA protease production may be a key virulence factor for Proteus strains.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Enzymology
Background:
- Immunoglobulin A (IgA) protease is an enzyme produced by various bacteria that cleaves IgA antibodies, a crucial component of mucosal immunity.
- The role of IgA protease in bacterial virulence is an area of ongoing research.
- The tribe Proteeae, including genera like Proteus, Providencia, and Morganella, are clinically relevant bacteria.
Purpose of the Study:
- To investigate the prevalence of Immunoglobulin A (IgA) protease production among different species within the tribe Proteeae.
- To characterize the enzymatic properties of IgA proteases produced by Proteus species.
- To determine if IgA protease production is associated with specific strain characteristics or represents a virulence mechanism.
Main Methods:
- Screening of 100 strains from the tribe Proteeae (including all species) for IgA protease activity.
- Isolation of strains from diverse clinical specimens across multiple countries.
- Biochemical characterization of the protease, including its sensitivity to EDTA and cleavage site on the IgA heavy chain.
Main Results:
- IgA protease production was common in Proteus species (P. mirabilis, P. penneri, P. vulgaris) but absent in Providencia and Morganella species.
- Proteus-derived IgA protease was EDTA-sensitive and cleaved the IgA heavy chain outside the hinge region, distinguishing it from other bacterial IgA proteases.
- The ability to produce IgA protease was independent of O antigenicity, biotype, or bacteriocin type.
Conclusions:
- Proteus species are significant producers of a unique IgA protease.
- This enzyme's ability to cleave IgA may contribute to the virulence of Proteus infections.
- Further research into IgA protease as a virulence factor in Proteus is warranted.