Abstract
The genomic DNA of Haemophilus paragallinarum (Hpg) serotype A strain 221 was cloned into vector plasmid pBR322. The recombinant plasmids were introduced into Escherichia coli (E. coli) strain C600. Subsequently, a total of 277 transformants were obtained. One, designated strain no.6, expressed hemagglutination activity against chicken erythrocytes. Strain no.6 contained the recombinant plasmid pNV102, and DNA of about 2.57 kb was inserted into pNV102. When strain no.6 was cured of pNV102, the strain lost hemagglutination activity. When the cured strain was retransformed with pNV102, hemagglutination activity was restored. E. coli strain no.6 reacted with monoclonal antibody specific to the hemagglutinin of Hpg serotype A in a dot-blotting analysis. Chickens immunized with the inactivated strain no.6 produced the hemagglutination inhibition (HI) antibody, and chickens possessing the HI antibody showed protection against challenge exposure by Hpg strain 221.
