Active immunization with angiotensin I peptide analogue vaccines selectively reduces the presser effects of exogenous angiotensin I in conscious rats

1 Male, Sprague-Dawley rats were actively immunized with novel angiotensin vaccines, and their presser responses to exogenous angiotensin I (AI) and a ngiotensin II (AII) were assessed in vivo. Serum antibody titres were also measured. 2 The most effective vaccine consisted of an AI analogue conjugated with a tetanus toroid carrier protein and adjuvanted with aluminium hydroxide. Whe n this vaccine was injected on days 0, 21 and 42, pressor responses to AI o n day 63 were significantly inhibited (maximum, 8.9 fold shift), but respon ses to AII were unaffected. The anti-angiotensin antibody titre was increas ed 32,100 fold, and, uniquely, these antibodies also cross-reacted with ang iotensinogen. 3 These findings indicate that active immunization against AI may be a usef ul approach for treating cardiovascular disorders involving the renin-angio tensin system.