Author
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Pekas, Jerome |
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Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/11/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Previous findings in this research project showed that active immunization against CCK stimulated feed intake and growth in young swine and the response was proportional to the antisera titers elicited. This indicated that definitive studies and further progress employing this technology would require more immunogenic antigens. The objective of this study was to design and evaluate various CCK:protein conjugates in search of a superior CCK antigen. The results showed that CCK:KLH (Keyhole limpet hemocyanin) and CCK:PPD (Tuberculin purified protein derivative) conjugates were significantly superior to CCK:BSA (bovine serum albumin) and superior to the original antigen (CCK:HSG; human serum globulin). CCK:PPD was unusual because titers rose abruptly between 43 and 50 days after initiation of the immunization protocol to significantly higher titer values than the other three antigens. PPD and KLH are proposed as superior conjugates as antigens for CCK, and likely for other small peptides in swine. Technical Abstract: The objective was to develop a more efficacious antigen to raise antisera against cholecystokinin(CCK) to support more definitive studies of the effect of immunoneutralization of cholecystokinin on feed intake in pigs. Four immunogenic carrier proteins were compared. Unsulfated cholecystokinin octapeptide (CCK8ns) was conjugated to each of HSG, BSA, Keyhole limpet hemocyanin (KLH), and Tuberculin purified protein derivative (PPD). Forty crossbred pigs were randomly assigned to the four antigens by litter. The antigens, suspended in Freund's complete or incomplete adjuvants, were administered by subdermal subcutaneous injection between day 1 and 43. Numerous blood samples were drawn and analyzed to follow the time course of antisera titer expression. Antisera titers were highly variable. The mean titer over the 92-d study was 256; the mean titer by day (n = 40) reached a peak value of 645 on day 57. Titers, compared by ANOVA of log titer values, were different (P<.01) between antigens and between litters. Mean titer was 28, 86, 242, and 666 for BSA, KLH, PPD, and HSG conjugated antigens, respectively. The mean titer by litter group fell in the range 13.5 to 1,653 with a CV of 118%. Some litters did not respond well to any of the four antigens; other litters responded to each antigen. It is concluded that the carrier protein component of the conjugated CCK antigens has an important effect on immunogenicity in pigs. The BSA conjugate was inferior, KLH and PPD conjugates were superior to the original HSG conjugated antigen. |
