Studien zur Diagnose von spontan auftretender infektiöser Bursitis (IBD) bei Hühnern unter Verwendung histopathologischer Methoden und der Immunoperoxidase-Methode

Domestic poultry production has been highly improved in Turkey in the last two decades and it has become a large industrial sector, contributing to both national economy and public nutrition by means of eggs, meat and by-products (feather, internal organs, feces, etc). Parallel to the improvement in the poultry sector, various diseases have emerged and substantial economic losses have occurred due to uncontrolled import of breeder flocks, commercial eggs and other factors such as vaccines and feed additives and by insufficient and uncontrolled management (Ademoğullari et al., 1993; Babi̇la et al., 1988). One of the above mentioned diseases is the Gumboro disease (Infectious Bursal Disease, IBD). IBD was first recognized in our country as a specific disease entity in 1978 (Kandi̇l, 1988; zkul, 1980). This contagious viral disease is frequently encountered both in broiler breeder and broiler flocks, and also in layers and leads to significant economic losses (Arda et al., 1990; Türe, 1994). The causative agent of Gumboro disease is an RNA virus, yet considered being a member of the family Birnaviridae (Van Den Berg et al., 1991). Although the disease has rarely been observed in chickens between 2 and 15 weeks of age, the most critical age group with reported clinical signs is the period between 3–6 weeks. The primary target organ of the virus is the bursa of Fabricius. This is particularly important with regard to economics (Arda et al., 1990; Türe, 1994; Jordan, 1990; Lukert and Saif, 1991). The earliest clinical sign in birds is picking the cloacal area and a whitish coloured diarrhea. Bursal lesions are the only gross morphological findings in post-mortem examinations. On the 2nd and 3rd day of infection, the bursae become swollen and take a gelatinous appearance. On the 3rd and 4th day of infection, they gradually shrink in size and become atrophied ( zkul, 1980; Jordan, 1990; Gürel and Yeşi̇ldere, 1992; Naqi and Miller, 1979). In microscopical examinations of bursae Fabricii, the disease is characterized by necrosis in follicular cells, inflammatory cell infiltrations in interfollicular regions and in some severe conditions atrophy of lymphoid follicles and cyst formations may also be encountered ( zkul, 1980; Jordan, 1992; Lukert and Saif, 1991; Tsukamota et al., 1995). The mortality rate related to the disease varies between 2 and 15%. However, in recent years, the mortality rate caused by the infections of highly virulent strains especially has peaked up to 50% (Arda et al., 1990; Lukert and Saif, 1991; Chettle et al., 1989). Immunohistochemistry is the method to use to localizing a molecule (mostly a protein or a virus) of a cell or a tissue in situ, on a light or electron-microscopic level with the antibodies prepared by special methods against this molecule. By means of this method, it may be possible to observe the exact location of an antigen in a cell or a tissue. If the antibody recognizes its specific antigen, it binds to the antigen in an appropriate incubation period (Can, 1996; Giorno, 1984). Recently, developed immuno-enzyme techniques have enabled observation of viral antigen particles in paraffin embedded tissue sections (Cruz-Coy et al., 1993; Bourgon and Charlton, 1987). It is also reported in related studies regarding the disease that the antigen is determined in various tissues by using a specific monoclonal antibody (Tsukamota et al., 1995; Cruz-Coy et al. 1993; Jönsson et al. 1986; Kumar and Rao, 1992). As it is mentioned in the previous sections, the clinical and microscopical findings in the bursa of Fabricius are important for the disease. The disease may probably be diagnosed by recognizing these lesions. However, it is a disadvantage that similar lesions are formed in more diseases such as Marek’s disease (MD), Chicken Infectious Anemia (CIA), Coli septicemia, Inclusion Body Hepatitis (IBH) and Avian Influenza (AI) (Jordan, 1990; Hofstad et al., 1992; Hoffmann and Dorn, 1978; McNeill et al., 1991; Nakamura et al., 1986; Aksoy, 1992). Thus, in some cases, histopahological examinations are not adequate for a definitive diagnosis, and misdiagnosis may sometimes increase the amount of economical losses due to administration of improper drugs and enhancing the severity of the disease due to retarded diagnosis. Although virus isolation is another important method used in diagnosis (Van Den Berg et al., 1991; Lukert and Saif, 1991), it is geneally considered to be time consuming. However, in studies performed by immuno-peroxidase method, the disease may be exactly diagnosed via labeling the causative agent in the relevant organ in an approximate period of two days (Cruz-Coy et al, 1993; Bourgon and Charlton, 1987; Cho et al., 1987). Thus, early diagnosis