ABSTRACT
A total 120 chickens of L.B.S.L. of one day old were divided into 6 groups "20 chickens for each". The first three groups were vaccinated with oil emulsified inactivated NewCastle "ND", egg drop syndrome "EDS" vaccine and Pasteurella multosida [P .multosida] Lipopolysaccaride extract "LPS" in single doses which are 0.5 ml, 1/M respectively. The fourth group was vaccinated with bivalent oil adjuvant of ND and EDS. The fifth group was vaccinated with bivalent oil adjuvant vaccine of ND, EDS and LPS. The third and fifth groups received 2 doses of LPS to study its mitogenic effect on the vaccinated chickens. Blood sera were collected till 7 weeks post-vaccination for estimation of cell mediated immunity by lymphocyte transformation, phagocytic activity, phagocytic index and heterophils lymphocytes ratio. Humeral immunity was determined by IHA, HI, ELISA and challenge test. The obtaining data revealed that LPS protein complex of P. multocida had a mitogenic effect on chicken B lymphocytes vaccinated with combined NDV and EDS, enhancing the humeral antibodies and the protection against challenge of P. multocida and NDV were 80% and 90% respectively