EFFECT OF PASSIVE-IMMUNIZATION WITH SEROTYPE-SPECIFIC MONOCLONAL-ANTIBODIES ON ACTINOBACILLUS-PLEUROPNEUMONIAE INFECTION OF MICE

Specific monoclonal antibodies (MoAbs) to Actinobacillus pleuropneumon iae (APP) serotypes 1 and 2 which recognized serotype-specific antigen s were produced. It was revealed that the two serotype-specific MoAbs H1-18 and H22-7 recognized O polysaccharides of the lipolysaccharide ( LPS) from APP serotypes 1 and 2, respectively, in the results of antig en analysis by means of SDS-PAGE and Western blotting. Furthermore, dd Y mice immunized passively with the above type-specific MoAbs were pro tected against challenge infection by the homologous serotype of APP a t 24 or 48 hr later. However, H1-9 and H3-2 MoAbs recognizing serotype -common protein antigens of APP did not show sips of any protective ef fect. These results showed that LPS from APP bacterial cells was one o f the structural substances in the serotype-specific antigens, and an important component as one of the antigens protecting against the homo logous serotype strain.