ABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between the immune response of anti-tetrodotoxin vaccine, including its dose-response, and to select optimal immunization dose so as to enhance antitoxic effect of the anti-tetrodotoxin vaccine.</p><p><b>METHODS</b>Tetrodotoxin (TTX) was coupled to Tachypleus tridentatus hemocyanin (TTH) chemically to form artificial antigen (TTX-TTH), and with which Balb/c mice were immunized. Influence of different immunization doses [100 microg as the higher (H) and 25 microg as the lower (L) dose group] on the protective effects of TTX vaccine was compared. The quality of antisera and effects of vaccine in anti-TTX poisoning were observed.</p><p><b>RESULTS</b>The sera antibody quality increased more quickly in group L than that in group H after immunization. The dose at which the half of immunized mice survived when challenged once with TTX were 16 x LD (1 LD = 13.5 microg/kg, i.p.) in group L and 11 x LD in group H. When TTX was used time and again, the half of immunized mice could tolerate as high as 40 x LD and 22 x LD of accumulated dose, and the maximum tolerable cumulated dose was 104 x LD and 90 x LD for group L and H respectively. The scheme L was better both in antibody quality and effect of protecting against TTX toxicity than that in scheme H.</p><p><b>CONCLUSIONS</b>The experimental vaccine of TTX could effectively protect animal from TTX intoxication. The lower immunization dose in this study is selected as the optimal immunization scheme.</p>