Liposome containing potassium thiocyanate extract of Pasteurella multocida 8A and 2T35 were studied on their physicochemical properties, immunogenicity to induce immune response, and the invitro bactericidal effect of immune sera. The particle size of liposomes were in the range of 23.34 and 30.12 mu m and the percent protein entrapment of liposomes were in the range of 59.69 to 63.69. The antibody titer of immune sera were determined by ELISA with homologous strain and the result indicated that liposome induced the highest antibody titer compared to that of alum and KSCN extract. The correlation of the immune response and bactericidal activity of immune sera induced by liposome, alum, and potassium thiocyanate extract of P. multocida 8A and 2T35 was investigated. The antibody titer was determined by ELISA against potassium thiocyanate extract and heat killed Pasteurella multocida. The highest immune response was produced from liposome, while the lower response were produced by alum, and potassium thiocyanate extract. The similar result was obtained from the bactericidal activity. There was good correlation between antibody titer against whole cell and bactericidal activity of antiserum against P. multocida 8A and 2T35.
