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Abstract Vaccines for Haemophilosis diseases, including Hismophilus somni are necessary especially under desert conditions due to economic impacts of these diseases. Haemophilus local field isolates were recovered from diseased sheep. They were identified biochemically,bacteriologically and by specific16 s rRNA PCR. Comparative study of the pathogenecity structure of different local isolates of H. somni isolated from diseased animals beside reference strain by SDS-PAGE revealed immunogenic bands (virulent factors) in isolates from diseased animals which considered a good candidate for vaccine preparation. Four sets of vaccines were prepared using H. somni washed cultures inactivated with (1) formalin, (2) phenol, (3) saponin, and (4) subunit 27 kDa aluminium hydroxide adjuvant vaccines. All sets, except for saponin-vaccine, were adjuvated with aluminium hydroxide. Laboratory evaluation of the prepared vaccine was determined by protection test in G.pig through challenging with field strains of H. somni after immunization with different prepared vaccines subunit 27 kDa aluminium hydroxide adjuvant vaccines gave a highest protection degree. Saponin and phenol inactivated vaccines gave a lower protection degree and formalin gave the lowest protection degree. For G-pig evaluation of prepared vaccines, five groups of ten G-pig were injected twice with prepared vaccines, 4 weeks in between. Sera were assayed by ELISA. G-pig vaccinated with subunit 27 kDa aluminium hydroxide adjuvant vaccines showed a high antibody response. These results suggest that this vaccine is effective and that their use could limit the spreading of H. somni infection. |