Generation of BTAA reactive antibodies in mice and rats. Groups of Swiss (n = 10), Balb/c (n = 6) mice and Sprague Dawley rats (n = 4) were immunized intravenously with PBS, BTAA alone (25 µg), or BTAA (25 µg) in combination with NLP (1 unit) weekly for 4 weeks. The presence of BTAA reactive antibodies in the sera of the immunized animals was assayed by ELISA. Immunization with NLP produces similar response as PBS. Each data point represents the mean ± 1 SD of observations from individual mice. *Significantly greater than the other values (P < 0.01).