Preparation and application of lipopolysaccharide on Actinobacillus pleuropneumoniae

The lipopolysaccharide of serotype 3,4,5,7 and 8 on Actinobacillus pleuropneumoniae were collected and roughly purified by hydroxybenzene-water,then the extracted lipopolysaccharide were used as antigens to challenge the mouse with the same serotype bacteria,the results showed that the mouse were well protected immunized with 20 μg lipopolysaccharide.The mouse challenged with the same serotype bacteria were not dead at this dose,while the mouse of controled group were all dead.Two days after immunization,IgG was examined in the mouse.At the 6th day,the mouse exhibited significantly high IgG against lipopolysaccharide.Then the IgG slowly began to decline.In this research we found that the LPS of serotype 3 had no cross-reactions with APP of serotype 5 and 7,LPS of serotype 4 had no cross-reactions with APP of serotype 5 and 7,and most of the mice challenged with the different serotype bacteria were dead.While LPS of serotype 3 had cross-reactions with APP of serotype 4 and 8,LPS of serotype 4 had cross-reactions with APP of serotype 3 and 8,LPS of serotype 5,7 and 8 had cross-reactions with APP of all 5 serotypes,no mouse were dead after challenging with the different serotype bacteria.These results revealed that lipopolysaccharide would be one of the main protective antigens of Actinobacillus pleuropneumoniae.This research provided the foundation for preparation and application of the subunit vaccine on Actinobacillus pleuropneumoniae.