The preparation and some properties of purified diphtheria toxoid / by Arthur Frederick Watson and Elsie Langstaff.

  • Watson, A. F.
Date:
[1926?]
Catalogue details

Licence: In copyright

Credit: The preparation and some properties of purified diphtheria toxoid / by Arthur Frederick Watson and Elsie Langstaff. Source: Wellcome Collection.

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    Terminology. A survey of the terminology at present in use in the field of immunological research has recently been made by Glenny, Pope and Waddington [1925]. The term purified toxin is used in the present paper to denote the active fraction obtained from culture filtrates of the diphtheria bacillus by precipitation at low temperature with glacial acetic acid and rapid separation of the precipitate, which is then dissolved in cooled dilute caustic soda to 8-0 [Watson and Wallace, 1924, 2]. Purified toxoid is employed to denote the active fraction obtained from diphtheria toxoid by precipitation at 35° or less with glacial acetic acid and separation of the precipitate which is then dissolved in dilute caustic soda to pH 8-0. Many of the purified toxoid solutions used during the course of the work were not completely atoxic, the original toxins having been only partially converted into toxoids before concentration. The terms ultra-purified toxin and toxoid are employed to denote purified toxin or toxoid which has been subjected to further purification by means of acetic acid precipitation, or alcohol precipitation [Moloney and Weld, 1925] or by dialysis against water for periods of 48-72 hours. Methods. The media used for culture filtrates were prepared by different variations of enzyme digests of horse muscle [Watson and Langstaff, 1926] or by the solution of commercial peptones in muscle extracts. The media, sterilised by filtration through a Seitz filter press followed by a short steaming, were inoculated with Park William No. 8 strain of C. diphtheriae and incubated for 10 days in the case of digest medium and 7 days in the case of peptone medium. To obtain diphtheria toxin, the filtrates from each culture were then tested and graded accordingly. Each group of cultures was filtered through a Berkefeld candle either without preservative or else with 0-5 % added phenol or toluene. To prepare diphtheria toxoid a similar technique was adopted but the cultures were treated directly with 0*5 % neutralised formalin. The filtrates were either concentrated at this stage or else were incubated for varying periods (sometimes with the addition of extra formaldehyde) to complete the toxin-toxoid change. A preliminary assay of a group of bulked and filtered toxoids was carried out. Total, Van Slyke, and precipitable nitrogen [Watson and Wallace, 1924, 1] and total solids content were estimated. The Lf value1 was also determined in each case. A similar series of data was accumulated for the purified solutions and from these observations some idea could be obtained as to the degree of purity that had been reached relative to the original unpurified toxoid. 1 The Lf dose is that amount of “toxin” which is equivalent to one unit of antitoxin by the flocculation test [Glenny and Okell, 1924]. 50—2