Immunogenic properties of the protein component of Treponema pallidum.

Ina previous paper(Metzger andPodwiinska, 1967) evidence waspresented thatthedevelopment ofagglutinability whichoccursinageing suspensions ofT.pallidum (Hardy andNell, 1955, 1957; Metzger andPodwinska, 1965) proceeds atdifferent rates todifferent agglutinating antibodies present insyphilitic orimmunesera. Mostremarkable was thebehaviour ofthetreponemes ina serumthat contained antibody totheheat-labile treponeme componentonly;theagglutinability ofthetreponemes, suspended inphosphate buffered saline ofpH7-4andmaintained at4°C., increased sharply inthefirst daysafter their extraction fromsyphilitic testes, reached maximal values betweenthesixth andthetenthdayofstorage, andthereafter decreased rapidly so that, as a rule,14-day-old organisms werepractically notagglutinated bythis antibody. Moreover, itwasfound(Metzger and Podwiniska, 1968)thattreponemes stored longer than14dayswerealsoincapable ofstimulating the production ofantibody totheheat-labile antigen in rabbits. Thesefindings wereinterpreted asproof thatthe heat-labile component of T.pallidum becomes destroyed duringprolonged maintenance, most probably through theaction ofautolytic enzymes, andisabsent fromthebodies ofstored treponemes. Further experiments (Metzger andPodwinska, 1968) haveshownthatthisantigen doesnotresist heating at56°C. for1hr,andiseasily destroyed by proteolytic enzymes: trypsin, papain, andpronase, anda numberofchemicals, suchasformalin, phenol, merthiolate, sodiumdesoxycholate; only lysozyme andpenicillin werefoundnottoaffect thiscomponent. Thedestroying effect exerted by proteolytic enzymes upontheheat-labile treponeme antigen hasindicated itsprotein nature. Thepresent study wasdesigned toinvestigate theroleofthis treponeme component ininducing immunity against syphilitic infection. Theresults showthattheprotein antigen ofT.pallidum isa carrier ofimmunogenicity.