PHYSICOCHEMICAL AND IMMUNOLOGICAL STUDIES ON THE STABILITY OF FREE AND MICROSPHERE-ENCAPSULATED TETANUS TOXOID IN-VITRO

The stability of tetanus toroid released from experimental, slow-relea se microsphere vaccines was compared with that of free toroid under di fferent conditions over a 3 month period The amount of antigenicity re maining as measured by ELISA, correlated well with loss of toroid stru cture, as determined by circular dichroism and fluorescence spectrosco py, At 37 degrees C and low pH, pH 2.5 for free toxoid, or under the a cidic conditions generated by the hydrolysis of fast-release microsphe res, a gradual unfolding of the polypeptide chain was observed within the first few weeks with more rapid denaturation beyond 30 days. Copyr ight (C) 1996 Elsevier Science Ltd.