RECOMBINANT BIVALENT LIVK VACCINES AGAINST NEONATAL COLIBACILLOSIS IN PIGLETS

摘要

The genes of colonization factor K88 and avirulent heat-labile enterotoxin LT A-B+ of enterotoxigenic E. coli (ETEC) have been ligated, and a vaccine strain containing recombinant plasmid that efficiently expresses two antigens has been obtained. Using the activity of β-galactosidase as a selection marker instead of drug resistance, another bivalent vaceire strain with the same expression level has also been constructed. The vaccinestrains have no toxicity and do not cause any adverse reactions. In chellenge study and field trials, a high degree of protection from colibacillosis was afforded to piglets when their dams were immunized orally or parenterally. Practice of bivalent live vaccines including colonization factor and enterotoxin antigens and without antibiotic resistance gene shows effective.