شناسایی پروتیین (های) ایمنی زای مشترک بین پاستورلا مولتوسیدا سروتیپ جدا شده از موارد پاستورلوز طیور در ایران 4‭: A:1, A:3, A‬های

pasteurellosis of birds ,also called Fowl Cholera, is a bacterial disease of poultry and wild birds which causes noticeable morbidity and economical lost in traditional and industrial poultry farms. The disease is caused by different serotypes of Gram-negative bacterium named Pasteurella multocida. In Iran, serotypes A:1, A:3, and A:4 have been reported as the causative agents of the disease in infected farms and populations. Vaccination considered as the best method of prevention by all the infected countries and Iran. Razi vaccine and serum research institute (RVSRI) produces an inactivated formalin killed whole cell vaccine adjuvanted with Alum gel in order to supply the nation demand for coverage of country infected areas. Vaccination can only cause a homologue protection between different serotypes. This is the reason some vaccine producers have to include even up to three serotypes in vaccine (trivalent) in order to increase vaccine efficacy against other causative serotypes. Several studies have been focused on identification of immunogenic molecules shared between different serotypes in the hope of production of a wide-range vaccine effective against all causative serotypes. In the present study, crude sonicated cell extracts of P. multocida serotypes A:1, A:3, and A:4 were immunoblo@ed against chicken hyper-immune sera in order to identify cross-reac6ve immunogenic proteins of them. To do this, 35 chickens aged two months randomly divided into 7 groups of five and were injected by inocula consisted of cell suspensions of P. multocida of each serotype (monovalent) or three serotypes (trivalent). Birds received four intra-muscular (IM) injections with the time intervals of 14 days between first and second injec6ons, and 10 days between second and third, and also third and forth injections. The first inoculom was aduvanted with complete Freund adjuvant (CFA), the second and third inocula were adjuvanted with incomplete Freund adjuvant (IFA), and the forth one was without any adjuvant. In the Control group, the same time table of injection was followed but with normal saline as inoculom. Blood samples were taken 7 days aWer the last injec6on, sera were collected and kept in -20 C up to experiments. 30 Results showed that there are at least 5 cross-reactive immunogenic proteins in serotypes A:1, A:3, and A:4, in a way that an6bodies produced by chicken in an immune response to immunization with whole cell Pasteurella suspensions are able to react with each of the 3 serotypes. These cross-reactive agents are proteins (or at least in some parts) with the molecular weight of 39, 40, 37, 53, and 30 K.Da. The 39 K.Da band was the most prominent immunoblott and introduced as candidate for molecular identification and future studies. Future research is suggested to also be the study of the possibility of the improvement of the present Razi Fowl Cholera vaccine by supplementing with 39 K.Da agent in order to improve the range of the immunogenicity of the vaccine against different serotypes. Key words: Pasteurella multocida; fowl cholera; cross-reactive immunogen; vaccine.