Some improved versions of methods for the indirect detection of staphylococcal protein A gene expressed in Escherichia coli. |
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Authors: | J Sakurada Y Sumi |
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Affiliation: | Department of Bacteriology, Jikei University School of Medicine, Tokyo, Japan. |
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Abstract: | Several versions of methods for the indirect detection of expression of staphylococcal protein A gene (spa) in Escherichia coli (E. coli) were devised by making use of biological properties of staphylococcal protein A (SpA). i) Hemagglutination of sheep red blood cells (SRBC) sensitized with anti-SRBC-antibodies using heat-treated spa-transformed E. coli organisms; Native spa-transformed E. coli organisms did not agglutinate the sensitized SRBC. The heat-treatment (60 C, 4 hr) of the transformants, however, caused positive hemagglutination like SpA-positive Staphylococcus aureus (S. aureus) organisms. ii) Halo formation around colonies on agar plates containing normal dog serum, which is originally used for the detection of SpA of S. aureus. A mutant strain NMJ was isolated, which showed formation of the halo of precipitate due to interaction between immunoglobulin and SpA. iii) A new version of immunodetection; After lysis of the transformants grown on a nitrocellulose membrane by alkali, SpA could be directly detected by immuno-detection procedures after inactivation of endogenous peroxidase in bacteria by phenylhydrazine and hydrogen peroxide. |
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