Preparation of fluorescein-labelled immune globulin for the identification of Treponema pallidum

Immunofluorescent staining for the detection of Treponema pallidum in early syphilitic lesions

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Membrane filtration of the Reiter treponeme

A membrane filtration technique with commercially available membrane filters (Millipore Corp.) was effective for the removal of Reiter treponemes from liquids such as fluorescent-antibody conjugates, to which the organisms are added for adsorption. Reiter treponemes from an 8-day culture were not microscopically detectable in filtrates through membranes with a pore diameter of 0.45 mum, but treponemes were demonstrated in the filtrate by cultural methods. No organisms of the 8-day culture passed through a membrane filter having a pore size of 0.22 mum, as determined by microscopy and culture. Culture data indicated that a filter with a pore size of 0.1 mum was necessary to prevent passage of treponemes from 4-day cultures. It is recommended that a membrane filter with a pore size of 0.22 mum or smaller be used for the removal of Reiter treponemes from suspensions and that the age of the culture be considered in choosing filter pore size.

Effect of the fluorescein to protein ratio on anti-Treponema pallidum conjugates

The effect of using different labeling techniques and various amounts of fluorescein-isothiocyanate was tested with several pools of antisera to Treponema pallidum. Optimal labeling occurred in all serum pools at a fluorescien to protein ratio of 15. The use of pure dye and the dialysis method of labeling is recommended as the method of choice because of its effectiveness in the reduction of nonspecific staining.